17-103635Irerracon
March 9, 2017
William Warren Group
4301 DTC Blvd. RECEIVEi'_'
Greenwood Village, CO 80111 I�
I I I I 9 R 7n17
Attn: Mr. Jon Suddarth
P: (303) 842-5690 COMMUNITY DF
E: iuddarth , williamwarren.com
Re: Geotechnical Engineering Report Addendum — Stormwater Infiltration and Landslide
Hazard Assessment
StorQuest Self Storage
298th Block Pacific Highway South (SR 99)
Federal Way, Washington
Terracon Project Number: 81165135
Dear Mr. Suddarth:
This letter is an addendum to, and should be used in conjunction with, our Geotechnical
Engineering Report for the project that was submitted to you on January 11, 2017. This report
addendum has been completed in accordance with our Supplemental Scope and Fee Proposal
dated February 2, 2017. The purpose of this addendum is to provide recommendations for
design of stormwater infiltration facilities and discussion of landslide hazard areas for the above
referenced site. The recommendations provided -in this letter supersede the preliminary
infiltration recommendations contained in our previously completed addendum letter, dated
February 3, 2017.
Project Information
Based on discussions with the architect and the project civil engineer, we understand the
current development plan includes a 4-story self -storage building to be located in approximately
the western three quarters of the site. Due to existing grades, the lower two floors of the
proposed building will be below grade on the west side of the building and will daylight on the
east. A below -grade infiltration gallery will be utilized below the eastern parking lot for infiltration
of stormwater runoff. The proposed parking lot grades in the area generally range from about
elevation 429 to 431 feet and the base of the infiltration gallery would be located at an
approximate elevation of421'/zfeet. PERMIT #: 17-103635-00-CO
ADDRESS: 29600 Pacific Hwy S
PROJECT: New Storage Building
STORQUEST
DATE: 7128117
Terracon Consultants, Inc. 21905 64th Avenue, Suite 100 Mountlake Terrace, Washington 98043
P [425] 771 3304 F [425] 771 3549 terracon.com
Geotechnical Engineering Report — Stormwater Infiltration Addendum Irerracon
Proposed StorQuest Self Storage Facility Federal Way, Washington
March 14, 2017 Terracon Project No. 81165135
Subsurface Conditions
As a part of our original scope, we advanced four borings and four test pits on the site. One of
the borings and three of the test pits were located in the lower, east side of the site
approximately within the extents of the proposed infiltration gallery. Two additional test pits were
advanced within the proposed infiltration gallery to perform infiltration testing. Based on the
conditions encountered in these explorations, soil at the proposed infiltration depths in this area
appears to generally consist of dense to very dense sand with silt and gravel Advance Outwash
deposits. Above the Advance Outwash deposits, we encountered existing fill soil above
elevations ranging from about 422Y2 feet to 430'/2 feet.
Groundwater was observed at a depth of about 19Y2 feet in Boring B-3, southwest of the
proposed infiltration gallery. Groundwater was not observed within the full depth Boring B-4,
however, which is located near the east -central portion of the proposed infiltration gallery and
extended to a depth of approximately 5Y2 feet below the elevation of proposed infiltration.
Groundwater was also not observed within our test pits or infiltration test excavations.
Stormwater Infiltration Rate
Two infiltration tests (IT-1 and IT-2) were completed within the area of the proposed infiltration
facility at the locations shown on Exhibit A-1. Logs of the soil conditions encountered in IT-1 and
IT-2 are attached to the end of this letter. The infiltration test pits were excavated by a
subcontractor to Terracon to the approximate elevation of the base of the proposed infiltration
facility. A metal ring with a diameter of 6 feet was placed at the base of the excavations to
prevent sidewall cave-ins during testing. Infiltration tests were completed within the excavations
in general accordance with the requirements of Section 5.2.1 of the 2016 King County Surface
Water Design Manual (KCSWDM).
We observed measured short-term infiltration rates of 20 and 12 inches per hour in IT-1 and IT-
2, respectively. In accordance with the KCSWDM, correction Factors of 0.3, 0.8, and 0.9 were
applied to the measured rate to account for test type, facility geometry, and soil type,
respectively. After applying these factors to the measured rates, we recommend an allowable
infiltration rate of 3 inches per hour be used in design of the proposed infiltration gallery.
Landslide Hazard Areas
As described in our geotechnical report, relatively steep slopes are present along the west side
of the site sloping down from the west property line along 161h Avenue South to the general
grade of the site. A rockery is present at the toe of the slope along all of the slope except within
about 30 feet of the south property line. Ground surface elevations along the west property line
range from about 464 to 474 feet. The ground surface elevation near the toe of the rockery (or
toe of slope where a rockery is not present) is about 440 feet.
Responsive Resourceful Reliable 2
Geotechnical Engineering Report — Stormwater Infiltration Addendum Irerracon
Proposed StorQuest Self Storage Facility Federal Way, Washington
March 14, 2017 Terracon Project No. 81165135
Based on the topography of this site and the surrounding area, it is evident that the relatively
steep slope along the west side of the site was created by cutting into the existing topography at
some time in the past to create a relatively level portion of the site and construction of a rockery
at the toe of the slope. Presumably this cut slope and rockery was constructed under some
previous grading permit. The existing cut slope above the rockery appears to have a slope of
approximately 1.5H:1 V to 1.7H:1 V (horizontal:vertical) for most of the slope above the rockery
based on site topography provided to us. The rockery is not present within about 30 feet of the
south property line and the slope in this area extends more into the site to the east with an
average slope of about 1.8H:1 V to 2H:1 V based on topography provided to us.
The existing cut slope is highly vegetated with brush and trees. Significant blackberry bushes
obscure much of the ground, surface on the steep slope. To the extent that the slope is visible,
we were not able to identify indications of past slope failures or existing slope instability features
on the existing cut slope.
With a slope greater than 40 percent and a vertical relief of over 10 feet, this slope is classified
as a Landslide Hazard Area according to Section 19.05.070 of the City of Federal Way Revised
Code. Section 19.145.220 of the code regulates development activities on or within 50 feet of
Landslide Hazard Areas. However, Section 19.145.230(4) notes that buffers and setbacks may
be reduced or improvements may be located within a Landslide Hazard Area when a qualified
professional determines the improvements will not create an increased slide hazard or be at risk
of damage by the landslide hazard.
As a part of our original scope, we advanced one boring (B-1) atop the slope near 16th Avenue
South to a depth of approximately 50 feet. We encountered very dense Advance Outwash sand
and gravel within the full depth of boring B-1 and did not encounter groundwater seepage at the
time of our exploration. The boring advanced at the top of the slope and the geologic mapping
of the site indicate the presence of dense to very dense, glacially -consolidated soil composed
primarily of gravelly sand with variable silt content and some cobbles. Existing cut slopes as
steep as 1.5H:1 V are expected to be stable with an appropriate factor of safety in these soil
conditions.
The proposed site layout indicates the new building will extend approximately 20 feet into the
base of the slope. Current building plans include the use of temporary soldier pile with tieback
anchors or soil nail shoring along the west building wall and the western ends of the south and
north walls to facilitate construction. Once complete, the below -grade portions of the building
walls are designed to support the retained soil. The current plans show that the slope above the
building will be flattened to a 2H:1 V slope. The slope along the south and north sides of the
planned building will be graded to a 2H:1V or flatter slope and a two-tier retaining wall will be
constructed near the northwest corner of the building. In our opinion, cut slopes in the natural
soil at the site or fill slopes composed of properly placed and compacted structural fill sloped at
2H:1 V or flatter will be stable with an appropriate factor of safety against slope instability.
Responsive : Resourceful Reliable 3
Geotechnical Engineering Report — Stormwater Infiltration Addendum
Proposed StorQuest Self Storage Facility Federal Way, Washington Il "�i:
March 14, 2017 Terracon Project No. 81165135
Construction of the building as currently planned will reduce the exposed height of the western
slope from approximately 30 feet to approximately 15 feet. Provided the temporary shoring and
permanent building walls are designed and constructed in accordance with the
recommendations provided in our original geotechnical report, the building will act as a buttress
to the slope and will work to significantly improve the stability of the slope as compared to
existing conditions. Regrading the existing slope to a 21-1:1 V or flatter slope as compared to the
existing slope will also improve slope stability. As currently proposed, the development will
reduce the existing landslide hazard and improve the overall stability of the slope. The
development would not be at risk of damage by the remaining slope, in our opinion.
General Comments
The recommendations presented in this addendum are based upon the data obtained from the
borings and test pits at the locations indicated in the original Geotechnical Engineering Report
and the attached Exhibit A-1, and from other information discussed in the report and the above
paragraphs. This letter does not reflect variations that may occur between explorations, across
the site, or due to the modifying effects of construction or weather. The nature and extent of
such variations may not become evident until during or after construction. If variations appear,
we should be immediately notified so that further evaluation and supplemental
recommendations can be provided.
We appreciate the opportunity to perform these services for you. Please contact us if you have
questions regarding this information or if we can provide any additional services.
Sincerely,
Terracon Consultants, I
�GHAE L SC'
= of wAs,&
-n
Ryan M. Scheffle P GNA LS�G Dennis R. Stettler, PE
Project Engineer Senior Engineering Consultant
Cc: John Kay, Magellan Architects
Attachments: Exhibit A-1
Exhibits A-2 to A-3
Site and Exploration Plan
Test Pit Logs IT-1 to IT-2
Responsive Resourceful Reliable 4
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PROJECT: StorQuest Federal Way CLIENT: William Warren Group
SITE: 298th Block Pacific Highway South
Federal Way, Washington
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WATER LEVEE. OBSERVATIONS
Test Pit Started: 2/16/2017
'Test Pit Completed: 2/16/2017
Groundwater not encountered
Irerracon
21905 64th Ave W Ste 100
Excavator.
Operator. NW Excavating
Mountlake Terrace, WA
Project No.: 81165135
Exhibit: A-2
TEST PIT LOG NO. IT-2
Page
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PROJECT:
StorQuest Federal Way CLIENT: William
298th Block Pacific Highway South
Warren Group
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21905 64th Ave W Ste 100
Mountlake Terrace, WA
Project No.:81165135
ExhlbK: A-3
FILED FOR RECORD AT REQUEST OF:
20180305000097
MISCELLANEOUS Rec: $77.00
3/5/2018 9:33 AM
MAIL TO: KING COUNTY, WA
CITY OF FEDERAL WAY
33325 8th Ave. S.
FEDERAL WAY, WA 98003-6325
ATTN: Kevin Peterson, Public Works Department
EXHIBIT D
LICENSE
Grantor (s): 29600 PACIFIC SP, LLC, a foreign limited liability company
Grantee (s): CITY OF FEDERAL WAY, a Washington municipal corporation
Property Legal Description (abbreviated): Lot l of City of Federal Way BLA #93-0014, Additional Legal
Description indicated below.
Assessor's Tax Parcel ID#(s): 042104-9035
The undersigned owner of certain real property located in Federal Way, Washington and legally
described as follows:
Full Legal description attached hereto as Exhibit 111" and incorporated herein by this
reference hereinafter "Property"
hereby grants an irrevocable license to the City of Federal Way ("City") and the City's agents, employees,
contractors or representatives to enter upon the Property to inspect the construction of improvements, the
performance of work or to allow the City to perform any necessarygiamtenance or work, all pursuant to
that certain Agreement and PerformancefMaintenance Bond dated �lZA�q.f�, 20f entered into
between the City and SEA CON, LLC, and incorporated herein by this reference.
DATED this day ofph, 20
Signature page follows
2W
Clark Porter, Manager
STATE OF WASHINGTON )
ss.
COUNTY OF
On this day personally appeared"bcfore me Clark Porter, to me known to be the M, ana of 29600
PACIFIC P. LLC that executed the foregoing instrument, and acknowledged the said instrument to be
the free and voluntary act and deed of said ligited liability company, for the uses and purposes therein
mentioned, and on oath stated that he was authono execute said instrument.
GIVEN my hand and official seal this day
(typed/printed name of not
Notary Public in and for the State
My commission expires
See Attached WOry
acknowledgment 0"Itlfleate
Rev 412017
20
CALIFORNIA ALL-PURPOSE ACKNOWLEDGMENT CIVIL CODE § 1189
A notary public or other officer completing this certificate verifies only the identity of the individual who signed the
document to which this certificate is attached, and not the truthfulness, accuracy, or validity of that document. —
State of California )
County of
On loll before me.
ate H j#oV Insert NM e and Title of he Officer
personally appeared � � � - . - .-- -
Nam of Signero
who proved to me on the basis of satisfactory evidence to bet erson(0 whose name ri aye
cribed to the within Instrument and acknow dged to me that h executed the sa a in
is authorized capacity(ics), and that by�I7erfti�eir signatureM on the instrument the personM,
or the entity upon behalf of which the person(s) acted, executed the instrument.
I certify under PENALTY OF PERJURY under the laws
of the State of California that the foregoing paragraph
is true and correct.
MARGARET A. FUJII WITNESS my han d #f'scial. al.
Commission * 2125082
NPtiotsry Public - caiitofnis
WX Los AnpeM County Signature
Comm, ivnims Am 29.2019 t at o ►y Public
Place Notary Seat Above
OPTIONAL
Though this section is optional, completing this information can deter alteration of the document or
fraudulent reattachment of this form to an unintended document.
Description of Attached Document WIC
Title or Type of Document:
Document Date: w„
Signer(s) Other Than Named Above:
Capacity(ies) Claimed by Signer(s)
Signer's Name:
Corporate Officer ,- Title(s):
Partner ;:' Limited General
Individual =:_. Attorney in Fact
Trustee Guardian or Conservator
Other:
Signer Is Representing:
Number of
Signer's Name:
I Corporate Officer — Title(s):
Partner — <.. Limited i..:i General
:". Individual i ,� Attorney in Fact
Trustee mm: Guardian or Conservator
nthor
Signer Is Representing:
02016 National Notary Association • www.Nationa!Notary.org - 1-800-US NOTARY (1-800-876-6827) Item #5907
EXHIBIT 1
LOT 1, CITY OF FEDERAL WAY BOUNDARY LINE ADJUSTMENT NO. BLA93-0014,
RECORDED UNDER RECORDING NUMBER 9512139004, IN KING COUNTY,
WASHINGTON;
EXCEPT THE EAST 6.50 FEET THEREOF, CONDEMNED PURSUANT TO JUDGEMENT
AND DECREE OF APPROPRIATION ENTERED IN KING COUNTY SUPERIOR COURT
CAUSE NO.06-2-01388-3 KNT, RECORDED UNDER RECORDING NUMBER
20061003000440.
Return Address:
FederalCity of Attn: Kev nPete son, Public Works Department
e8th Avenue South
F20200122001254
Federal Way, WA 98003-6325
WARRANTY DEED Ree: $107.50
1122/2020 2:37 PM
KING COUNTY, WA
STATUTORY WARRANTY DEED
Grantor (s): 29600 PACIFIC SP, LLC, a Delaware limited liability company
Grantee (s): CITY OF FEDERAL WAY, a Washington municipal corporation
Property Legal Description (abbreviated): Lot 1, City of Federal Way BLA # 93-0014,
Recorded under Recording No. 9512139004, in King Co., WA
Additional Legal(s) on Exhibit A
Assessor's Tax Parcel ID#: 042104-9035
THE GRANTOR(S) 29600 PACIFIC SP, LLC, a Delaware limited liability company,
for and in consideration of the City of Federal Way's approval of a building permit, No. 17-
103635-00-CO, for construction of a Self -Storage Facility, and other good and valuable
consideration, convey(s) and warrant(s) to the CITY OF FEDERAL WAY, a Washington
municipal corporation, all of its right, title and interest, and any after -acquired interest therein,
in and to the real property described in Exhibit A and depicted in Exhibit A-1 herewith
attached and made a part hereof, situated in King County in the State of Washington.
DATED THIS V day of 04a 202D.
[signature page follows]
E3030761
EXCISE TAX AFFIDAVITS
112212020 2:37 PM KING COUNTY, WA
Tax Amount:$10.00
STANT OF
) ss.
COUNTY
Signature
V ,��W(kin (Y)
Printed Name
V ylkw"
Title �
29600 PACIFIC SP, LLC
P.O. BOX 2034
SANTA MAONICA, CA 90406
On this day person appeared before me , to me known to be
the of 29600 PACIFIC SP LLC that executed the foregoing
instrument, and acknowledg he said instrument to be the free and voluntary act and deed of
said limited liability company, the uses and purposes therein mentioned, and on oath
stated that he/she was authorized to a ute said instrument.
GIVEN my hand and official seal h day of
$Be attached N°tarY
Acknowledgment Ceriticate
Rev. 10/17
(typed/printed name of not&
Notary Public in and for the
My commission expires
roll
CALIFORNIA ACKNOWLEDGMENT CIVIL CODE § 1189
A notary public or other officer completing this certificate verifies only the identity of the individual who signed the document
to which this certificate is attached, and not the truthfulness, accuracy, or validity of that document.
State of California ��
County of . ° e _
On N b) l�o before me, �� 1�� 4 }� ►" v
Date �` 11 Her n rt ame and Ti le of the Officer
personally appeared '"i " *A
Name{$) of Signerf4
who proved to me on the basis of satisfactory evidence to be the person(s) whose name(s) is/are subscribed
to the within instrument and acknowledged to me that he/she/they executed the same in his/her/their
authorized capacity(ies), and that by his/her/their signature(s) on the instrument the person(s), or the entity
upon behalf of which the person(s) acted, executed the instrument.
MARGARET FUN
Notary Public - California s
Los Angeles County
Commission # 2299610
My Comm. Expires Aug 28, 2023
Place Notary Seal and/or Stamp Above
I certify under PENALTY OF PERJURY under the
laws of the State of California that the foregoing
paragraph is true and correct.
WITNESS my hand and official seal.
Signature ��e—
i n t of Notary Public
OPTIONAL —
Completing this information can deter alteration of the document or
fraudulent reattachment of this form to an unintended document.
Description of Attached Document
Title or Type of Document: MP
Document Date:
Signer(s) Other Than Named Above:
Capacity(ies) Claimed by Signer(s)
Signer's Name:
❑ Corporate Officer — Title(s):
❑ Partner — ❑ Limited ❑ General
❑ Individual ❑ Attorney in Fact
❑ Trustee ❑ Guardian or Conservator
❑ Other:
Signer is Representing:
02018 National Notary Association
Number of PAges:
Signer's Name:
❑ Corporate Officer — Title(s):
❑ Partner — ❑ Limited ❑ General
❑ Individual ❑ Attorney in Fact
❑ Trustee ❑ Guardian or Conservator
❑ Other:
Signer is Representing:
EXHIBIT A
THE WESTERLY 3.00 FEET OF LOT 1, CITY OF FEDERAL WAY BOUNDARY L NE
ADJUSTMENT NO. BLA 93-0014, RECORDED UNDER RECORDING NUMBER 9512139004, IN
KING COUNTY, 'NASHINGTON.
CONTAINING AN AREA OF ±585 S.F.
r
-tRAVI
of 11A
48372
ass °�a LS L
NW 1/4, SW 1/4, SEC, 4, TWP. 21N,, RGE. 4E., W.M.
CITY OF FEDERAL WAY, KING COUNTY, WASHINGTON
www.axismap.com
JOB NO. DATE
�1 16-179 12/16/19
IS15241 NE 90'H S?
REC'.�OND, WA 98052 DRAWN BY CHECKED BY
TEL. 425.823-5700 JM WTB
Survey & Mapping FAX 425.823-6700 SCALE SHEET
N/A
EXHIBIT A-1
i
f GRAPHIC SCALE
I
TPN:0421049259
0 30 60
+33 1„= 60'
l�
-
3' RIGHT OF WAY DEDICATION
s r
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:> CITY OF FEDERAL WAY BOUNDARY LINE
AD)US T MENT NO BLA 93-0014
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LOT 2
T_PN:0421_049038
- EXHIBIT NOTE THIS EXHIBIT HAS BEEN PREPARED
TO ASSIST IN THE INTERPRETATION
OF THE ACCOMPAN
YING LEGAL
DESCRIPTION. IF THERE IS A
CONFLICT BETWEEN THE WRITTEN
LEGAL DESCRIP-ION AND THIS
SKETCH, THE LEGAL DESCRIPTION
SHALL PREVAIL,
NW 1/4, SW 1/4, SEC. 4, TWP. 21N., RGE. 4E., W.M.
CITY OF FEDERAL WAY, KING COUNTY, WASHINGTON
www,axismap.cam
" JOB NO, DATE
16-179 12/16/19
AA4K1 5241 NE 907H 5T
REDb1CND, WA 98052 DRAWN BY CHECKED 6Y
TEL, 425.823-5700 ]M WTB
Survey & Mapping FAX 425.823-6700 SCALE SHEET
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Geotechnical Engineering Report
StorQuest Self Storage
Federal Way, Washington
January 11, 2017
Terracon Project No. 81165135
Prepared for:
William Warren Group
Denver, Colorado
Prepared by:
Terracon Consultants, Inc.
Mountlake Terrace, Washington
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RECEIVED
AUG 01 2017
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Irerracon
January 11, 2017
William Warren Group
4301 DTC Blvd.
Greenwood Village, CO 80111
Attn: Mr. Jon Suddarth
P: [303] 842-5690
E: juddarth@williamwarren.com
Re: Geotechnical Engineering Report
StorQuest Self Storage
Federal Way, Washington
Terracon Project Number: 81165135
Dear Mr. Suddarth:
Terracon Consultants, Inc. (Terracon) has completed the geotechnical engineering services
for the above referenced project. This study was performed in general accordance with our
proposal number P81165135 dated September 22, 2016 and the supplemental agreement
dated December 2, 2016. This report presents the findings of the subsurface exploration and
provides geotechnical recommendations concerning earthwork and the design and
construction of foundations, floor slabs, pavement, retaining walls, and temporary shoring for
the proposed project.
We appreciate the opportunity to be of service to you on this project. If you have any
questions concerning this report, or if we may be of further service, please contact us.
Sincerely,
Terracon Consultants, Inc.
r Ryan M. SeKefFler, P.E.
Project Engineer
-�� � Q
'VYz-'-
'fN/1
Dennis R. Stettler, P.E.
Senior Engineering Consultant
Terracon Consultants, Inc. 21905 6411, Avenue, Suite 100 Mountlake Terrace, Washington 98043
TABLE OF CONTENTS
Page
EXECUTIVESUMMARY.............................................................................................................i
1.0
INTRODUCTION.............................................................................................................1
2.0
PROJECT
INFORMATION.............................................................................................1
2.1
Project Description...............................................................................................1
2.2
Site Location and Description..............................................................................2
3.0
SUBSURFACE CONDITIONS........................................................................................2
3.1
Geology...............................................................................................................2
3.2
Typical Profile......................................................................................................2
3.3
Groundwater........................................................................................................3
4.0
RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION......................................3
4.1
Geotechnical Considerations...............................................................................3
4.2
Earthwork............................................................................................................4
4.2.1 Site Preparation........................................................................................4
4.2.2 Temporary Cut Slopes..............................................................................5
4.2.3 Existing Steep Slopes...............................................................................5
4.2.4 Permanent Cut and Fill Slopes..................................................................6
4.2.5 Material Requirements.............................................................................6
4.2.6 Compaction Requirements.......................................................................7
4.2.7 Grading and Drainage..............................................................................7
4.2.8 Earthwork Construction Considerations....................................................7
4.3
Foundations.........................................................................................................9
4.3.1 Foundation Design Recommendations....................................................-9
4.3.2 Foundation Construction Considerations................................................10
4.4
Floor Slabs.........................................................................................................11
4.4.1 Floor Slab Design Recommendations....................................................11
4.4.2 Floor Slab Construction Considerations.................................................12
4.5
Seismic Considerations......................................................................................12
4.5.1 Fault Zones............................................................................................13
4.5.2 Liquefaction............................................................................................13
4.5.3 Seismic Surcharge.................................................................................13
4.6
Lateral Earth Pressures.................................................................13
4.7
Pavements.........................................................................................................16
4.7.1 Subgrade Preparation............................................................................17
4.7.2 Design Considerations...........................................................................17
4.7.3 Estimates of Minimum Pavement Thickness............................................18
4.7.4 Pavement Drainage................................................................................19
4.7.5 Pavement Maintenance..........................................................................20
4.8
Temporary Shoring ............... .................................................
................... .......20
4.8.1 Soil Nail Wall Design Recommendations................................................20
4.8.2 Soil Nail Shoring Installation...................................................................21
4.8.3 Soldier Piles...........................................................................................22
4.8.4 Soldier Pile Shoring Installation..............................................................23
4.8.5 Monitoring of Temporary Shoring...........................................................24
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TABLE OF CONTENTS (continued)
5.0 GENERAL COMMENTS.........................................................
APPENDIX A — FIELD EXPLORATION
Exhibit A-1 Site Location Map
Exhibit A-2 Site and Exploration Plan
Exhibit A-3 Section A -A'
Exhibit A-4 Field Exploration Description
Exhibits A-5 through A-8 Boring Logs B-1 through B-4
Exhibits A-9 through A-12 Test Pit Logs TP-1 through TP-4
APPENDIX B — LABORATORY TESTING
Exhibit B-1 Laboratory Testing Description
Exhibit B-2 and B-3 Grain Size Distributions
APPENDIX C — SUPPORTING DOCUMENTS
Exhibit C-1 General Notes
Exhibit C-2 Unified Soil Classification System
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Geotechnical Engineering Report Irerracon
StorQuest Self Storage Federal Way, Washington
January 11, 2017 . Terracon Project No. 81165135
EXECUTIVE SUMMARY
A geotechnical exploration program has been performed for the proposed project located in the
298t' block of Pacific Highway South (SR 99) in Federal Way, Washington. Terracon's
geotechnical scope of services included the advancement of four test pits and four soil test
borings to approximate depths of 9'h to 50 feet below the existing ground surface (bgs). The
site appears suitable for the proposed construction based upon geotechnical conditions
encountered in the explorations and our current understanding of the proposed development.
The following geotechnical considerations were identified:
In our explorations we encountered undocumented fill or reworked soil, sometimes including
organic soil or a buried topsoil horizon, to depths of/Z to 11'/Z feet, primarily in the eastern
portion of the site. We recommend complete removal of the undocumented fill and
reworked soil below and immediately adjacent to the building footprint. An allowable
bearing pressure of 3,500 pounds per square foot (psf) can be used for shallow footings
bearing on medium dense native material or structural fill extending to medium dense to
very dense native soil.
Explorations in the central and western portion of the site disclosed dense to very dense
gravelly sand or sandy gravel with variable silt content at shallow depths and at deeper depths
below fill in the eastern portion of the site. This soil is interpreted to be Advance Outwash,
which is a glacially -overridden soil that is typically found in a dense to very dense condition.
Foundations bearing on dense to very dense, glacially -overridden native soil can be designed
for an allowable soil bearing pressure of 8,000 psf.
Assuming the owner is willing to accept the risk of unpredictable settlement response in the
pavement areas by leaving some of the undocumented fill below the pavement section, we
recommend removal of at least the upper 12 inches of pavement subgrade, scarification and
compaction of the exposed subgrade, and replacement of the removed material with
structural fill.
The western portion of the site slopes up steeply to 16"' Avenue South. Given the planned
location and floor elevation of the building, sufficient room is not available to construct the
building with a temporary excavation and shoring will be required. Shoring will likely require
temporary ground anchors to extend into the 16"' Avenue South right -of --way and a construction
easement to allow these anchors would be required from the City of Federal Way.
a The on -site soil typically appears suitable for reuse as structural fill if placed at a moisture
content near the optimum value. However, this soil contains a significant fraction of fines
(silt and clay passing the No. 200 mesh sieve) and will quickly become unstable, soft and
unsuitable for reuse as structural fill when exposed to excessive moisture. If work is
planned for the winter months, the site soil will likely not be suitable for reuse on the site.
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StorQuest Self Storage . Federal Way, Washington
January 11, 2017 Terracon Project No. 81165135
Groundwater seepage was observed at a depth of 19Y2 feet bgs in boring B-3 while drilling.
Groundwater level fluctuations occur due to seasonal variations in the amount of rainfall,
runoff, and other factors not evident at the time the explorations were performed. Based on
our understanding of the proposed development, we do not expect groundwater to affect
construction. If encountered, typical construction dewatering methods such as trench and
sump pumping should be used.
The seismic site classification for this site is C, based on the conditions encountered in our
explorations.
Close monitoring of the construction operations discussed herein will be critical in achieving the
design subgrade support. We therefore recommend that Terracon be retained to monitor this
portion of the work. This summary should be used in conjunction with the entire report for
design purposes. It should be recognized that details were not included or fully developed in this
section, and the report must be read in its entirety for a comprehensive understanding of the items
contained herein. The section titled GENERAL COMMENTS should be read for an understanding
of the report limitations.
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GEOTECHNICAL ENGINEERING REPORT
StorQuest Self Storage
Federal Way, Washington
Terracon Project No. 81165135
January 11, 2017
1.0 INTRODUCTION
Terracon Consultants, Inc. (Terracon) is pleased to present the results of our geotechnical
engineering services for the proposed storage facility. The site is located in the 298t' block of
Pacific Highway South in Federal Way, Washington at the general location shown on the Site
Location Map, Exhibit A-1. Terracon's geotechnical scope of services included the
advancement of four test pits and four soil test borings to approximate depths of 9'/2 to 50 feet
below the existing ground surface (bgs).
The purpose of these services is to provide information and geotechnical engineering
recommendations relative to:
subsurface soil conditions ■ foundation design and construction
groundwater conditions a slab design and construction
earthwork ■ seismic considerations
pavement design recommendations ■ lateral earth pressures
temporary shoring recommendations
2.0 PROJECT INFORMATION
2.1 Project Description
Item Description
Site layout See Appendix A, Exhibit A-2: Site and Exploration Plan
The proposed project would consist of a single, 3-story+daylight
basement, fully enclosed self -storage facility with roughly 101,950
Proposed improvements gross square feet of total building area and a building footprint
taking up most of the site with the exception of a 15 foot setback on
three sides and a 40 foot setback that will contain a parking area
between the building and Pacific Highway South_
Finished floor elevation Approximate elevation of 432 feet based on Site Section developed
by Magellan Architects.
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2.2 Site Location and Description
Item Description
This project is located in the 298t' block of Pacific Highway South
Location (SR 99) in Federal Way, Washington. The site encompasses tax
parcel 0421049035.
The site consists of a primarily undeveloped lot with bushes and
Existing improvements trees. A short rockery lies at the base of the relatively steep slope
on the west side of the site, and along the north side of the site
separating the site from the Federal Way Motel to the north.
Site grades up slightly east to west and north to south. The
Existing topography property rises very steeply near the west edge of the property. The
east side of the property slopes down to Pacific Highway South.
3.0 SUBSURFACE CONDITIONS
3.1 Geology
The geologic map of the area, Geologic Map of the Poverty Bay 7.5' Quadrangle, King and
Pierce Counties, Washington (USGS, Booth et al, 2004), shows the surficial geology for the site
is mapped as Qva — Advance outwash deposit. Advance outwash consists of well -bedded sand
and less common gravel deposited subaqueously or by streams and rivers in front of the
advancing ice sheet. Advance outwash is typically overridden by a glacial till soil deposited
beneath advancing glaciers. Glacial till is mapped near the site. Our interpretation of the soil
disclosed in the explorations is that the soil is advance outwash, although glacial till is mapped
nearby and could be present near the ground surface over higher elevation portions of the site.
3.2 Typical Profile
Soil conditions on the site were explored by advancing four test pits and four soil test borings to
approximate depths of 9% to 50 feet bgs. Logs of the explorations and a description of the field
exploration procedures are presented in Appendix A. The locations of the explorations on the site
are shown on Exhibit A-2 in Appendix A.
Conditions encountered at each exploration location are indicated on the individual exploration
logs. Stratification boundaries on the exploration logs represent the approximate location of
changes in soil types; in situ, the transition between materials may be gradual. .
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January 11, 2017 Terracon Project No. 81165135
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Based on the results of the explorations, a generalized subsurface profile is presented along
section A -A' in Exhibit A-3. The subsurface conditions on the project site can be generalized as
follows:
Approximate Depth to Consistency/
Stratum Bottom of Stratum Material Description Density
(feet)
Uncontrolled fill' or reworked soil consisting Very loose to
1 '/z to 11'/2 of silty sand with gravel with organics. medium dense
22 14 Silty sand with gravel Medium dense
Gravelly sand with variable silt and gravel 1 Dense to very
3 Undetermined3 content (Advance Outwash) dense
1. Uncontrolled fill is material that was placed without moisture and density control. This material is
typically variable in composition, consistency, density, moisture, and depth and in some locations
could include organic materials and clearing debris.
2. Stratum 2 was only encountered on the east side of the site.
3. Borings and test pits were terminated at their planned depths within this stratum.
3.3 Groundwater
The eight on -site explorations were observed while drilling/excavating for the presence and level
of groundwater. Groundwater seepage was encountered in boring B-3 at a depth of
approximately 19'/z feet bgs. The seven other explorations did not encounter groundwater at
the time of exploration.
Groundwater level fluctuations occur due to seasonal variations in the amount of rainfall, runoff,
and other factors not evident at the time the explorations were performed. In addition, perched
water can develop over low -permeability soil. Therefore, groundwater levels during construction
or at other times in the life of the structure may be higher or lower than the levels indicated on
the exploration logs.
4.0 RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION
4.1 Geotechnical Considerations
Based on the results of the subsurface exploration, laboratory testing, and our geotechnical
engineering analyses, it is our opinion that the proposed building can be supported on shallow
foundations bearing on medium dense to very dense native soil or compacted structural fill
extending to medium dense to very dense native soil. Geotechnical engineering
recommendations for foundation systems and other earth -connected phases of the project are
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outlined below. The recommendations contained in this report are based upon the results of
data presented herein, engineering analyses, and on our current understanding of the proposed
project.
ASTM and Washington State Department of Transportation (WSDOT) specification codes cited
herein respectively refer to the current manual published by the American Society for Testing &
Materials and the 2016 edition of the WSDOT Standard Specifications for Road, Bridge, and
Municipal Construction (Publication M41-10).
We encountered undocumented fill or reworked soil to depths of Y2 to 11 Y2 feet in our
explorations. Fill depths encountered in the explorations were deepest in the northeast corner
of the site and were observed to be shallower in the explorations to the south and west. Fill,
especially undocumented fill, by nature can be highly variable and could vary greatly between
sample locations. There is an inherent risk for the owner that compressible fill or unsuitable
material within or buried by the fill will not be discovered. This risk of unforeseen conditions
cannot be eliminated without completely removing the undocumented fill. For the purposes of
this report, we assume complete removal of the fill and replacement with structural fill will be
limited to the area under and adjacent to the building pad. In addition to the fill soil, any loose or
organic -rich soil should be removed and replaced in a similar manner. The lateral extent of
undocumented fill removal and replacement beyond the building pad footprint is defined later in
this report.
4.2 Earthwork
Based on the subsurface conditions encountered in our exploration, we expect that all of the on -
site soil within the limits of construction can be removed with conventional excavation
equipment. Cobbles and boulders may have been encountered in our explorations based on
our interpretation of drilling action and are commonly found in glacial soil. The contractor should
be prepared to deal with cobbles and boulders. Recommendations for site preparation,
structural fill, and permanent slopes are presented below
4.2.1 Site Preparation
Prior to equipment arriving onsite, clearing and grading limits should be established and
marked. Silt fences should be constructed along the downslope side of all areas planned for
clearing and grading. Preparation for site grading and construction should begin with
procedures intended to control surface water runoff. The sandy soil on site is moderately
susceptible to erosion by flowing water. We anticipate that the use of shallow ditches, with
sumps and pumps as needed, will be adequate for surface water control during wet weather
and wet site conditions.
Stripping efforts should include removal of vegetation, organic materials, and any deleterious
debris from the proposed structure's footprint. It appears that up to about 6 inches of stripping
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January 11, 2017 : Terracon Project No. 81165135
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will be necessary in areas with light vegetation. Greater depths of stripping and grubbing may
be necessary in areas with thick vegetation and tree roots. These materials are not suitable for
reuse as structural fill. Site disturbance beyond the work area should be limited to reduce the
potential for erosion and off -site sediment transport. Disturbance of existing vegetation and soil
structure on the slope up to 16th Avenue South should be avoided if at all practical until
temporary shoring is installed.
Areas that are stripped or excavated to the design subgrade elevation, or that are to receive
structural fill, should be proofrolled with heavy rubber -tired construction equipment (e.g. loaded
dump truck). Any soft, loose, or otherwise unsuitable areas identified during proofrolling should
be recompacted if practical or removed and replaced with structural fill. We recommend that
proofrolling of the subgrade be observed by a representative of our firm to assess the adequacy
of the subgrade conditions and identify areas needing remedial work. We recommend that this
procedure not be performed during wet weather. During wet conditions, systematic probing
should be used to evaluate the subgrade.
4.2.2 Temporary Cut Slopes
We anticipate that temporary open cuts and/or trenches will be utilized during construction of
the project. Temporary slope stability is a function of many factors, including the following:
The presence and abundance of groundwater
The type and density of the various soil strata
The depth of cut
Surcharge loading adjacent to the excavation
The length of time the excavation remains open
It is exceedingly difficult under the variable circumstances to pre -establish a safe and
"maintenance -free" temporary cut slope angle. Therefore, it should be the responsibility of the
contractor to maintain safe slope configurations since the contractor is continuously at the job
site, able to observe the nature and condition of the cut slopes, and able to monitor the
subsurface materials and groundwater conditions encountered. It may be necessary to drape
temporary slopes with plastic or to otherwise protect the slopes from the elements and minimize
sloughing and erosion. We do not recommend vertical slopes or cuts deeper than 4 feet if
J worker access is necessary. The cuts should be adequately sloped or supported to prevent
injury to personnel from local sloughing and spalling. The excavations should conform to
applicable Federal, State, and local regulations.
4.2.3 Existing Steep Slopes
Relatively steep slopes are present along the west side of the site sloping down from the west
property line along 16th Avenue South to the general grade of the site. A rockery is present at
the toe of the slope along all of the slope except within about 30 feet of the south property line.
Ground surface elevations along the west property line range from about 464 to 474 feet. The
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StorQuest Self Storage Federal Way, Washington
January 11, 2017 Terracon Project No. 81165135
ground surface elevation near the toe of the rockery (or toe of slope where a rockery is not
present) is about 440 feet.
Based on the topography of this site and the surrounding area, it is evident that the relatively
steep slope along the west side of the site was created by cutting into the existing topography at
some time in the past to create a relatively level portion of the site and construction of a rockery
at the toe of the slope. Presumably this cut slope and rockery was constructed under some
previous grading permit. The existing cut slope above the rockery appears to have a slope of
approximately 1.5H:1 V to 1.7H:1 V (horizontal:vertical) for most of the slope above the rockery
based on site topography provided to us. The rockery is not present within about 30 feet of the
south property line and the slope extends more into the site to the east with an average slope of
about 1.8H:1 V to 2H:1 V based on topography provided to us.
The existing cut slope is highly vegetated with brush and trees. Significant blackberry bushes
obscure much of the ground surface on the steep slope. To the extent that the slope is visible,
we were not able to identify indications of past slope failures or existing slope instability features
on the existing cut slope. The boring advanced at the top of the slope and the geologic
mapping of the site indicate the presence of dense to very dense, glacially -consolidated soil
composed primarily of gravelly sand with variable silt content and some cobbles. Existing cut
slopes as steep as 1.5H:1 V are expected to be stable with an appropriate factor of safety in
these soil conditions.
Steep slopes can be subject to erosion if not protected. We recommend that the vegetation be
kept in place on the existing cut slope. To the extent that vegetation is removed on this slope,
we recommend specific attention to erosion protection including placement of erosion protection
matting and other features to limit the potential for erosion followed by prompt planting on the
slope to reestablish a suitable vegetative protective slope cover.
4.2.4 Permanent Cut and Fill Slopes
We recommend newly constructed permanent cut and fill slopes be constructed at 2H:1 V or
flatter. Any exposed slopes should be protected from erosion during construction and by
establishment of appropriate permanent vegetative cover to limit the potential for erosion.
4.2.5 Material Requirements
Compacted structural fill should meet the following material property requirements:
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Fill Type WSDOT Standard Acceptable Location for Placement
yp Specification
9-03.12(1)A Gravel Backfill for
Foundations Class A
9-03.9(1) Ballast Beneath and adjacent to the structure's slab
Structural Fill and foundation; beneath pavement sections
9-03.9(3) Crushed Surfacing
Base Course
Native gravelly sand with silt'
Trench Backfill Native gravelly sand with silt' Utility Trenches
1. Fines content of near -surface native gravelly sand with silt make this material moisture
sensitive and therefore likely unsuitable for use during periods of wet weather.
4.2.6 Compaction Requirements
Item
Fill Lift Thickness
Description
8 inches or less in loose thickness when heavy, self-
propelled compaction equipment is used
4 inches in loose thickness when hand -guided equipment
(i.e. jumping jack or plate compactor) is used
Minimum 95% of the material's modified Proctor maximum
Minimum Compaction Requirements dry density (ASTM D 1557)
Moisture Content — Granular Material Workable moisture levels'
1. Typically within 2% of optimum
4.2.7 Grading and Drainage
Adequate positive drainage of exposed subgrades should be provided during construction and
maintained throughout the life of the development to prevent an increase in moisture content of
J the foundation and pavement subgrades and excavation backfill materials. Surface water
drainage should be controlled to prevent undermining of structures during and after
construction. Additionally, surface water should be directed away from steep slopes on the site
to the extent feasible to reduce the risk of erosion and instability.
Roof gutters and downspouts should be routed into tightline pipes that discharge into a
Jmunicipal storm drain or other suitable location. Splash -blocks should also be considered below
hose bibs and water spigots if the area is not paved.
J4.2.8 Earthwork Construction Considerations
It is anticipated that excavations for the proposed construction can be accomplished with
J conventional earthmoving equipment. Advance outwash can contain cobbles and occasionally
boulders. The contractor should be prepared to remove cobbles and boulders from excavations
if encountered.
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Upon completion of filling and grading, care should be taken to maintain the subgrade moisture
content prior to construction of floor slabs and pavements. Construction traffic over the
completed subgrade should be avoided to the extent practical. The site should also be graded
to prevent ponding of surface water on the prepared subgrades or in excavations. If the
subgrade should become frozen, desiccated, saturated, or disturbed, the affected material
should be removed or these materials should be scarified, moisture conditioned, and
recompacted prior to floor slab and pavement construction and observed by Terracon.
Surface water should not be allowed to pond on the site and soak into the soil during
construction. Construction staging should provide drainage of surface water and precipitation
away from the building and pavement areas. Any water that collects over or adjacent to
construction areas should be promptly removed, along with any softened or disturbed soil.
Surface water control in the form of sloping surfaces, drainage ditches and trenches, and sump
pits and pumps will be important to avoid ponding and associated delays due to precipitation
and seepage.
Groundwater seepage was encountered at a depth of 19'/2 feet bgs in boring B-3. Based on our
understanding of the proposed development, we do not expect groundwater to affect
construction. If groundwater is encountered during construction, some form of temporary
dewatering may be required. Conventional dewatering methods, such as pumping from sump
pits, should likely be adequate for temporary removal of groundwater encountered during
excavation at the site.
Temporary excavations will probably be required during grading operations. The grading
contractor, by his contract, is usually responsible for designing and constructing stable,
temporary excavations and should shore, slope or bench the sides of the excavations as
required to maintain stability of both the excavation sides and bottom. All excavations should
comply with applicable local, state and federal safety regulations, including the current
Occupational Health and Safety Administration (OSHA) Excavation and Trench Safety
Standards. All excavations should be sloped or braced as required by OSHA regulations to
provide stability and safe working conditions.
Construction site safety is the sole responsibility of the contractor who controls the means,
methods and sequencing of construction operations. Under no circumstances shall the
information provided herein be interpreted to mean that Terracon is assuming any responsibility
for construction site safety or the contractor's activities; such- responsibility shall neither be
implied nor inferred.
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4.3 Foundations
Irerracon
We encountered undocumented fill or reworked soil to depths of '/2 to 11'/z feet in our
F explorations. Due to the unpredictability of undocumented fill, we recommend complete
removal of undocumented fill below the proposed building pad. Any loose or organic soil
observed below the fill should also be removed. The lateral extent of removal and replacement
for the building pads should be at least two-thirds of the depth of excavation beyond the building
pad footprint at the perimeter footing location.
In our opinion, after these overexcavations are completed, the proposed building can be
supported by a shallow, spread footing foundation system bearing on compacted structural fill
extending to medium dense to dense native soil. Since the finished floor elevation of 432 feet
requires excavation below existing site grades, we expect foundations for the central and
western thirds of the proposed building will likely bear on dense to very dense, glacially -
consolidated, advance outwash soil. For foundations bearing on the dense to very dense
outwash, a higher allow soil bearing pressure could be used, if desired. Design
recommendations for shallow foundations for the proposed structures are presented in the
following paragraphs.
4.3.1 Foundation Design Recommendations
i
Description
Net allowable bearing pressure'
Compacted structural fill or medium
dense to dense native soil
Dense to very dense Advance Outwash
Column Wall
I
3,500 psf
8,000 psf
3,500 psf
8,000 psf
Minimum dimensions
24 inches
18 inches
Minimum embedment below finished floor
18 inches
18 inches
1
grade for perimeter footings2
Minimum embedment below finished floor
12 inches
12 inches
J
grade for interior footings
_
Approximate total settlement from foundation
<1 inch
<1 inch
loads3
Estimated differential settlement from
<Y2 inch between
<Y2 inch over 40 feet
foundation loads3
columns
Ultimate coefficient of sliding friction
0.5
Ultimate passive earth pressure
400 pcf
1. The recommended net allowable bearing pressure is the pressure in excess of the minimum
Jsurrounding overburden pressure at the footing base elevation. Assumes any unsuitable
undocumented fill or soft soil, if encountered, will be undercut and replaced with compacted
structural fill. Based upon a minimum Factor of Safety of 3.
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Description Column Wall
2. For frost protection and to reduce the effects of seasonal moisture variations in the subgrade soil.
For perimeter footing and footings beneath unheated areas.
3. The foundation settlement will depend upon the variations within the subsurface soil profile, the
structural loading conditions, the embedment depth of the footings, the thickness of compacted fill
and the quality of the earthwork operations.
The allowable foundation bearing pressures apply to dead loads plus design live load
conditions. The design bearing pressure may be increased by one-third when considering total
loads that include wind or seismic conditions. The weight of the foundation concrete below
grade may be neglected in dead load computations.
Footings, foundations, and masonry walls should be reinforced as necessary to reduce the
potential for distress caused by differential foundation movement. The use of joints at openings
or other discontinuities in masonry walls is recommended.
Foundation excavations should be observed by a Terracon representative. If the soil conditions
encountered differ from those presented in this report, supplemental recommendations may be
required. Confirmation of the soil conditions in the foundation excavations is required at the
time of construction for the allowable soil bearing pressures provided in this report to be valid.
We recommend that the building be encircled with a perimeter foundation drain to collect
exterior seepage water. This drain should consist of a 4-inch-diameter perforated pipe within an
envelope of pea gravel or washed rock, extending at least 6 inches on all sides of the pipe. The
gravel envelope should be wrapped with filter fabric (such as Mirafi 140N) to reduce the
migration of fines from the surrounding soil. Ideally, the drain invert would be installed no more
than 8 inches above or below the base of the perimeter footings. The perimeter foundation
drain with cleanouts should not be connected to roof downspout drains and should be
constructed to discharge into the site storm water system or other appropriate outlet.
4.3.2 Foundation Construction Considerations
We recommend that the existing fill or reworked and organic soil disclosed in the eastern portion
of the site be totally excavated and removed from beneath and immediately adjacent to the
building footprint as recommended previously in this report. Following removal of the existing fill
or reworked and organic soil, we recommend the excavation be backfilled with compacted
structural fill as recommended in the Earthwork section of this report. The actual horizontal and
vertical extent of the recommended removal of unsuitable soil will require visual observation by
Terracon at the time of construction.
In the event that unsuitable soil is disclosed at the planned foundation level at localized areas in
other portions of the site at the time of construction, overexcavation and removal of the
unsuitable soil will be required in those areas as well. Overexcavation below footings should
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extend laterally beyond all edges of the footings at least 8 inches per foot of overexcavation
depth below footing base elevation. The overexcavation should then be backfilled up to the
footing base elevation with well -graded granular material placed in lifts of 8 inches or less in
loose thickness and compacted to at least 95 percent of the material's modified Proctor
maximum dry density (ASTM D 1557). In areas where overexcavation is required for use of the
higher bearing pressure associated with the dense to very dense advance outwash, we
recommend that the foundation either be deepened or the foundation overexcavation be
backfilled with lean concrete. The overexcavation and backfill procedure is described in the
figure below.
Design tM
Footing Level 1.
Design 213D 1Y `'-1 213D
Footing Level r +
COMPACTED
LEAN STRUCTURAL P '
Recommended CONCRETE Recommended FILL
Excavation Level 2, Excavation Level
i-
Lean Concrete Backfill Overexcavation / Backfill
NOTE: Excavations in sketches shown vertical for convenience. Excavations should be sloped as necessary for safety.
4.4 Floor Slabs
We recommend complete removal of undocumented fill encountered below the proposed
building floor slab, as described above for the foundation subgrade. Removed soil should be
replaced with structural fill placed and compacted in accordance with the Earthwork section of
this report. A subgrade prepared and tested as recommended in this report should provide
adequate support for a moderately loaded floor slab.
4.4.1 Floor Slab Design Recommendations
Item Description
Interior floor system Slab -on -grade concrete)
Floor slab support
Structural fill placed and compacted in accordance with
the Earthwork section of this report.
Aggregate base course/capillary break Minimum 4-inch thickness compacted layer of free
draining, uniform gravel
1. Floor slabs should be structurally independent of any building footings or walls to reduce floor
slab cracking caused by differential movements between the slab and foundation. The slabs
should be appropriately reinforced to support the proposed loads.
2. The base course serves as a capillary break layer, a drainage layer, a leveling layer, and a
bearing layer.
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We recommend subgrades be maintained at the proper moisture condition until floor slabs are
constructed. If the subgrade should become desiccated prior to construction of floor slabs, the
affected material should be removed or the materials scarified, moistened, and recompacted.
Upon completion of grading operations in the building areas, care should be taken to maintain
the recommended subgrade moisture content and density prior to construction of the building
floor slabs.
Where appropriate, saw -cut control joints should be placed in the slab to help control the
location and extent of cracking. For additional recommendations refer to the ACI Design
Manual.
The use of a vapor retarder or barrier should be considered beneath concrete slab -on -grade
floors that will be covered with wood, tile, carpet or other moisture -sensitive or impervious
coverings, or when the slab will support equipment sensitive to moisture. When conditions
warrant the use of a vapor retarder, the slab designer and slab contractor should refer to ACI
302 and ACI 360 for procedures and cautions regarding the use and placement of a vapor
retarder/barrier.
4.4.2 Floor Slab Construction Considerations
On most project sites, the site grading is generally accomplished early in the construction phase.
However as construction proceeds, the subgrade may be disturbed due to utility excavations,
construction traffic, desiccation, rainfall, etc. As a result, the floor slab subgrade may not be
suitable for placement of the base course and concrete slab, and corrective action may be
required.
All floor slab subgrade areas should be moisture conditioned and properly compacted to the
recommendations in this report and then thoroughly proofrolled prior to final grading and
placement of the base course. Particular attention should be paid to high traffic areas that were
rutted and disturbed earlier and to areas where backfilled trenches are located. Areas where
unsuitable conditions are located should be repaired by removing and replacing the affected
material with properly compacted structural fill.
4.5 Seismic Considerations
Description
Value
International Building Code (IBC) and 2010 C 2
ASCE 7'
Site Latitude
Site Longitude
47.3344°N
122.3124°W
Ss — Short Period Spectral Acceleration for Site 1.306 g
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Class C
S1 —1-Second Period Spectral Acceleration for 0.499 g
Site Class C _
Fa — Short Period Site Coefficient _ 1.000
Fv —1-Second Period Site Coefficient 1.301
1. The 2010 ASCE 7 document indicates that the seismic site classification is based on the average
soil and bedrock properties in the top 100 feet. The current scope does not include a 100-foot
soil profile determination. This seismic site class definition considers that soil encountered at
depth in our explorations continue below the termination depths. Additional exploration to deeper
depths would be required to confirm the conditions below the current depth of exploration.
2. Site Class C applies to an average soil profile within the top 100 feet consisting predominantly of
very dense soil and soft rock. This soil is characterized by Standard Penetration Test blow counts
in exceedance of 50, a shear wave velocity of between 1,200 and 2,500 feet per second, and. an
undrained shear strength in exceedance of 2,000 pounds per square foot.
4.6.1 Fault Zones
Risk of damage from onsite fault rupture appears to be low based on review of the Washington
State Department of Natural Resources Geologic Hazards interactive map accessed on
December 20, 2016. The site is located within the Tacoma fault zone. The closest estimation
of the trace of this fault lies approximately 1,000 feet to the north.
4.5.2 Liquefaction
The term liquefaction refers to a phenomenon by which saturated soil develops high pore water
pressures during seismic shaking and, as a result, loses its strength characteristics. This
phenomenon generally occurs in areas of high seismicity, where groundwater is relatively
shallow and where loose granular soil (mainly sands) or non -plastic fine-grained soil (mainly
silts) is present. Considering the likely depth to groundwater and the dense to very dense
glacially -consolidated soil encountered at depth in our explorations, our opinion is that risk from
liquefaction is very low.
4.5.3 Seismic Surcharge
For backfilled walls or walls cast directly against shoring, we recommend a uniform seismic
lateral surcharge pressure equal to 12H, where H is equal to the wall height in feet, and
pressure is in pounds per square foot (psf). Basement walls between floors can be designed for
80% of the factored seismic load combination to account for the concentration of load at the
relatively stiff floor slabs.
4.6 Lateral Earth Pressures
Reinforced concrete walls with unbalanced backfill levels on opposite sides should be designed
for earth pressures at least equal to those indicated in the following table. Earth pressures will
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be influenced by structural design of the walls, conditions of wall restraint, methods of
construction and/or compaction and the strength of the materials being restrained. Two wall
restraint conditions are shown. Active earth pressure is commonly used for design of
free-standing cantilever retaining walls and assumes wall movement. The "at -rest" condition
assumes no wall movement. The recommended design lateral earth pressures do not include a
factor of safety and do not provide for possible hydrostatic pressure on the walls.
S = Surcharge
For active pressure movement
(0.002 H to 0.004 H)
TS
For at -rest pressure
--
- No Movement Assumed
Horizontal
Finished
//17
r
Grade
i
H
Horizontal
Finished Grade
�p2-11p,—/1
Retaining Wall
Earth
Pressure Coefficients
Earth Pressure
Conditions and
Coefficient for
Equivalent Fluid
Surcharge Earth Pressure,
backslope
Backfill Type
Density (pcf)
Pressure, p, (psf) pZ (psf)
Active (Ka)
Horizontal
0.31
40
(0.31)S (40)H
2:1 Slope
0.45
60
(45)S (60)H
At -Rest (Ko)
Horizontal
0.47
60
(0.47)S (47)H
r 2:1 Slope
0.68
90
(0.68)S (90)H
Passive (Kp)
3.25
400
--- ---
ApoliGable conditions to the above include:
For active earth pressure, wall must rotate about base, with top lateral movements of about
0.002 H to 0.004 H, where H is wall height
For passive earth pressure to develop, wall must move horizontally to mobilize resistance
Uniform surcharge, where S is surcharge pressure
e In -situ soil backfill weight a maximum of 135 pcf
a Backfill compacted between 92 and 95 percent of modified Proctor maximum dry density
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Loading from heavy compaction equipment not included
No hydrostatic pressures acting on wall
No dynamic loading
No safety factor included
Ignore passive pressure in frost zone
Backfill placed against structures should consist of granular soil as described in Section 4.2.3.
For these values to be valid, the granular backfill must extend out and up from the base of the
wall at an angle of at least 45 and 60 degrees from vertical for the active and passive cases,
respectively. To calculate the resistance to sliding, a value of 0.50 should be used as the
ultimate coefficient of friction between the footing and the underlying soil.
A perforated rigid plastic or metal drain line installed behind the base of walls that extend below
adjacent grade is recommended to prevent hydrostatic loading on the walls. The invert of a
drain line around a below -grade building area or exterior retaining wall should be placed near
foundation bearing level. The drain line should be sloped to provide positive gravity drainage or
to a sump pit and pump. The drain line should be surrounded by clean, free -draining granular
material having less than 5 percent passing the No. 200 sieve. The free -draining aggregate
should be encapsulated in a filter fabric and should extend to within 2 feet of final grade, where
- it should be capped with compacted low permeability fill to reduce infiltration of surface water
into the drain system.
Slope to drain
away from building
Layer of
cohesive fill
Foundation wall.
u\\�\\\ Badcfill (see report
` requirements)
Free draining graded���
J granular filter material or
non -graded free -draining
material encapsulated in
an appropriate filterZ\\ — Native, undisturbed
fabric (see report): — sal or engineered fill
II 111 P
W
Perforated drain pipe (Rigid PVC
unless stated otherwise in report)
As an alternative to free -draining granular fill, a pre -fabricated drainage structure may be used.
A pre -fabricated drainage structure is a plastic drainage core or mesh which is covered with
filter fabric to prevent soil intrusion, and is fastened to the wall prior to placing backfill.
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If controlling hydrostatic pressure behind the wall as described above is not possible, then
combined hydrostatic and lateral earth pressures should be calculated using an equivalent fluid
weighing 85 and 90 pcf for active and at -rest, respectively. These pressures do not include the
influence of surcharge, equipment, or pavement loading, which should be added as applicable.
Heavy equipment should not operate within a distance closer than the exposed height of
retaining walls to prevent lateral pressures more than those provided.
We recommend that permanent basement walls constructed flush against shoring be designed
to withstand uniform rectangular lateral pressure equal to 22 H, in psf, where H equals the wall
height in feet. Permanent walls should be provided with drainage as described subsequently in
this report.
A surcharge load should be added to the lateral pressure if traffic or other loading is anticipated
within a zone extending back from the wall a distance equal to the wall height. A traffic
surcharge equal to 2 feet of retained soil is recommended for traffic loading. A seismic
surcharge, as discussed in Section 4.5.3 should also be considered in the design. For other
loads adjacent to the basement wall, such as adjacent building foundations, please, contact
Terracon to estimate appropriate surcharge pressures.
These equivalent fluid pressures are based on the assumption of a uniform backfill and no
buildup of hydrostatic pressures behind the wall. To prevent the buildup of lateral earth
pressures in excess of the above designed pressures, over compaction of fill behind the walls
should be avoided. This can be accomplished by placing the backfill within 24 inches of the wall
in lifts not exceeding 4 inches in loose depth and compacting with hand -operated or self-
propelled equipment.
Care should be taken where utilities penetrate through basement walls. Minor settlement of the
backfill can put significant soil loading on utilities, and some form of flexible connection may be
appropriate at backfilled wall penetrations.
4.7 Pavements
We encountered undocumented fill soil to depths of/2 to 11% in our explorations. Provided the
owner is willing to accept the risk of unpredictable settlement response of the undocumented fill
under pavement sections, we recommend limited risk mitigation measures including removal of
at least the upper 12 inches of pavement subgrade, scarification and compaction of the exposed
subgrade, and replacement of the removed material with structural fill in accordance with the
earthwork section of this report. Based on the results of our explorations, the undocumented fill
soil is generally in a very loose to medium dense condition and represents a moderate risk of
excessive settlements due to traffic loading after completion of the recommended
improvements, though areas of unsuitable or compressible fill may be present within the fill
areas that were not observed in our explorations.
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4.7.1 Subgrade Preparation
On most project sites, the site grading is accomplished relatively early in the construction phase.
However, as construction proceeds, excavations are made into these areas, rainfall and surface
water saturates some areas, heavy traffic from concrete trucks and other construction vehicles
disturbs the subgrade, and many surface irregularities are filled in with loose soil to temporarily
improve driving conditions. As a result, the pavement subgrades, initially prepared early in the
project, should be carefully evaluated as the time for pavement construction approaches.
We recommend that the moisture content and density of the top 12 inches of the subgrade be
evaluated and that the pavement subgrades be proofrolled within two days prior to
commencement of actual paving operations. Areas not in compliance with the required ranges of
moisture or density should be moisture conditioned and recompacted. Particular attention should
be paid to high traffic areas that were rutted and disturbed earlier and to areas where backfilled
trenches are located. Areas where unsuitable conditions are located should be repaired by
removing and replacing the materials with properly compacted structural fills. If a significant
precipitation event occurs after the evaluation or if the surface becomes disturbed, the subgrade
should be reviewed by qualified personnel immediately prior to paving. The subgrade should be
in its finished form at the time of the final review.
4.7.2 Design Considerations
We anticipate that traffic loads will be produced primarily by automobile and light traffic and by
occasional larger moving trucks and trash -removal trucks. The thickness of pavements
subjected to heavy truck traffic should be determined using expected traffic volumes, vehicle
types, and vehicle loads and should be in accordance with local, city or county ordinances.
Pavement thickness were determined using AASHTO methods based on assumed values of
maximum ESAL loading of 100,000 (ESAL = equivalent 18-kip single axle load) for standard
duty car and light truck parking areas over a 20-year design life. For heavy duty truck traffic
areas, we used an assumed traffic loading of 250,000 ESALs in our analysis. If traffic loading
developed by the civil engineer differs significantly from these assumed values, the pavement
thickness design should be revisited.
The minimum pavement sections outlined below were determined based on the estimated
�j subgrade support and post -construction traffic loading conditions. These pavement sections do
not account for heavy construction traffic during development. A partially constructed structural
f section may be subjected to heavy construction traffic that can result in pavement deterioration
J and premature failure. Our experience indicates that this pavement construction practice can
result in pavements that will not perform as intended. Considering this information, several
J alternatives are available to mitigate the impact of heavy construction traffic on the pavement
construction. These include using thicker sections to account for the construction traffic; using
l some method of soil stabilization to improve the support characteristics of the pavement
J
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subgrade; routing heavy construction traffic around paved areas; or delaying paving operations
until as near the end of construction as is feasible.
Pavement performance is affected by its surroundings. In addition to providing preventive
maintenance, the civil engineer should consider the following recommendations in the design
and layout of pavements:
Final grade adjacent to parking lots and drives should slope down from pavement edges at
a minimum 2 percent;
The subgrade and the pavement surface should have a minimum '/ inch per foot slope to
promote proper surface drainage;
Install pavement drainage surrounding areas anticipated for frequent wetting (e.g.,
landscaping areas, etc.);
Install joint sealant and seal cracks immediately;
Seal all landscaped areas in, or adjacent to pavements to reduce moisture migration to
subgrade soil, and;
Place compacted, low permeability backfill against the exterior side of curb and gutter
Our pavement design was conducted using an assumed CBR value of 20 percent. To obtain
this CBR value in the field, the pavement subgrade must be thoroughly compacted to at least 95
percent of the modified Proctor density within 2 percent of its optimum moisture. Any imported
structural fill placed below proposed pavement areas should have a CBR value of at least 20
percent.
4.7.3 Estimates of Minimum Pavement Thickness
MINIMUM STANDARD -DUTY PAVEMENT SECTION FOR
CAR AND LIGHT TRUCK -ONLY AREAS
Layer
Thickness
Compaction/Material
(inches)
Specification
Asphalt Surface
3.0
WSDOT: 9-03.8(2) 3/4-inch HMA
4.0
WSDOT: 9-03.8(6) 3/-inch Aggregate
WSDOT: 9-03.9(3) Base Course
Crushed Aggregate Base
Compacted Structural Fill
12
95% of Modified Proctor MDD, -2 to
Subgrade
+2% OMC
Total Pavement Section
7.0
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MINIMUM HEAVY DUTY -PAVEMENT SECTION FOR TRUCK AREAS
Thickness
Layer (inches)
Asphalt Surface Course 4.0
Crushed Aggregate Base 6.0
Compacted Structural Fill
Subgrade
Total Pavement Section
12
10.0
Compaction/Material
Specification
WSDOT: 9-03.8(2) %-inch HMA
WSDOT: 9-03.8(6) 3/4-inch Aggregate
WSDOT: 9-03.9(3) Base Course
95% of Modified Proctor MDD, -2 to
+2% OMC
The abbreviations MDD, OMC, and HMA in the tables above refer to Maximum Dry Density,
Optimum Moisture Content, and Hot Mix Asphalt, respectively. The graded crushed aggregate
base should be compacted to a minimum of 95 percent of the material's modified Proctor
(ASTM D 1557, Method C) maximum dry density. We recommend that asphalt be compacted
to a minimum of 92 percent of the Rice (theoretical maximum) density or 96 percent of Marshall
(maximum laboratory) density.
We recommend that a Portland cement concrete pavement (CCP) be utilized in entrance and
exit sections, dumpster pads, loading dock areas, or other areas where extensive wheel
maneuvering or repeated loading are expected. The dumpster pad should be large enough to
support the wheels of the truck which will bear the load of the dumpster: We recommend a
minimum of 6 inches of CCP underlain by 4 inches of crushed aggregate base. Although not
required for structural support, the base course layer is recommended to help reduce potentials
for slab curl, shrinkage cracking, and subgrade "pumping" through joints. Proper joint spacing
will also be required to prevent excessive slab curling and shrinkage cracking. All joints should
be sealed to prevent entry of foreign material and dowelled where necessary for load transfer.
Portland cement concrete should be designed with proper air -entrainment and have a minimum
compressive strength of 4,000 psi after 28 days of laboratory curing. Adequate reinforcement
and number of longitudinal and transverse control joints should be placed in the rigid pavement
in accordance with ACI requirements. The joints should be sealed as soon as possible (in
accordance with sealant manufacturer's instructions) to minimize water infiltration into the soil.
4.7.4 Pavement Drainage
Pavements should be sloped to provide rapid drainage of surface water. Water allowed to pond
on or adjacent to the pavements could saturate the subgrade and contribute to premature
pavement deterioration. In addition, the pavement subgrade should be graded to provide positive
drainage within the crushed aggregate base section.
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We recommend drainage be included at the bottom of the crushed aggregate base layer at the
storm structures to aid in removing water that may enter this layer. Drainage could consist of
small diameter weep holes excavated around the perimeter of the storm structures. The weep
holes should be excavated at the elevation of the crushed aggregate base and soil interface.
The excavation should be covered with crushed aggregate which is encompassed in Mirafi
140NL or approved equivalent which will aid in reducing fines from entering the storm system.
4.7.5 Pavement Maintenance
The pavement sections provided in this report represent minimum recommended thicknesses.
Therefore preventive maintenance should be planned and provided for through an on -going
pavement management program. Preventive maintenance activities are intended to slow the rate
of pavement deterioration, and to preserve the pavement investment. Preventive maintenance
consists of both localized maintenance (e.g., crack and joint sealing and patching) and global
maintenance (e.g., surface sealing). Preventive maintenance is usually the first priority when
implementing a planned pavement maintenance program. Prior to implementing any
maintenance, additional engineering observation is recommended to determine the type and
extent of a cost-effective program. Even with periodic maintenance, some movements and
related cracking may still occur and repairs may be required.
4.8 Temporary Shoring
Based on the soil conditions observed at the exploration locations and the proposed floor slab
elevation, we recommend that either soldier pile or soil nail shoring be considered to temporarily
support the excavation during construction. Provided adequate distance is available, temporary
slope cuts can be combined with the shoring system to reduce the height retained by the
shoring. The shoring required to support the excavation is typically used as back forms for the
permanent basement walls.
Terracon is in discussions with the design team regarding design of temporary shoring systems
for this project at the time of this report. The following design and construction parameters are
provided for preliminary planning purposes.
4.8.1 Soil Nail Wall Design Recommendations
The basic concept of soil nailing is to reinforce and strengthen the existing ground by installing
closely spaced steel bars commonly referred to as "nails" into a slope or excavation as
construction proceeds from the top, downward. This produces a reinforced zone that is itself
stable and helps to support the un-reinforced ground behind it. The nails are considered
passive as tension is applied as they resist the deformation of the adjacent soil. The nail
reinforcement improves stability in two ways. First, soil nailing reduces the driving force along
the potential failure surfaces. Second, in frictional soil, nailing increases the normal force and
hence the soil shear resistance along potential failure surfaces. If required, vertical elements
typically consisting of closely spaced steel beams or pipes placed in augered holes and
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backfilled with lean concrete can be installed to improve face stability and temporary conditions
during nail installation.
Based on the subsurface conditions encountered during our site investigation, the portion of the
site where shoring will likely be required consists of glacially -consolidated deposits of advance
sand composed of dense to very dense gravelly sand with variable silt and cobble content. At
the time of this report, shoring is not anticipated within the uncontrolled fill soil in the eastern
portion of the site. If future plans require shoring within the fill, Terracon should be consulted to
provide additional design recommendations.
The following parameters are recommended for design of soil nail walls:
Advance Outwash
Friction Angle: 38 degrees
Cohesion: 100 psf
Moist Unit Weight: 135 pcf
Ultimate Pullout Strength (minimum 6-inch diameter soil nail): 6 kip/ft.
Allowable Pullout Strength (minimum 6-inch diameter soil nail): 3 kip/ft.
The actual adhesion value will depend on the materials and installation methods and should be
confirmed by testing. Larger diameter drill holes and/or secondary grouting may be required to
achieve the recommended pull out capacity. Installation methods should be the responsibility of
the contractor. The location and presence of existing features should be checked during the
design as these may affect the location and lengths of the soil nails.
Vertical elements may be used to provide cantilever support where utilities or adjacent
�. structures prevent installation of soil nails in the upper portion of the shoring wall. The vertical
elements should be designed using the recommendations presented in the soldier pile sections
of this report. The allowable passive resistance can be represented as an equivalent fluid
weight of 350 pcf above the groundwater table and 200 pcf below and can be assumed to act
over three times the concrete pile diameter or pile spacing, whichever is less.
We recommend that soil nail shoring be designed in general accordance with local standard of
practice and soil surcharge pressures from slopes, construction loads, and traffic be included in
the analysis and design, where appropriate.
4.8.2 Soil Nail Shoring Installation
Cased holes may be required to prevent caving and loss of ground within any surficial fill and
sandy zones within the glacially overridden deposits. The soil nail grout should be pumped into
the soil nail holes by tremie methods in order to force grout up from the bottom of the hole and
to provide a continuously grouted soil nail.
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A minimum of two sacrificial, 200 percent verification tests should be performed in each soil type
to be nailed in order to evaluate the ultimate soil friction capacity and the load deformation
performance of the soil nail. Verification testing should be accomplished as soon as each soil
type is encountered and prior to installation of production nails. The location of the verification
tests should be selected by the contractor and approved by the engineer of record. The drilling
method, hole diameter, and depth of soil nail should be identical to the production soil nails.
Additionally, 5 percent of production soil nails should be proof tested to 150 percent of design
load to confirm the design capacity and appropriate construction methods.
4.8.3 Soldier Piles
Soldier piles for shoring are typically set in drilled holes and backfilled with lean or structural
concrete. Soldier pile installation may involve casing the holes and/or drilling with a mud slurry
to cut-off groundwater seepage. Passive earth pressures acting on the embedded portion of the
soldier piles resist horizontal loads on the shoring system. We recommend using an allowable
equivalent fluid unit weight of 350 pcf. The passive earth pressure will act over three diameters
of the concreted soldier pile section or the pile spacing, whichever is less. The active earth
pressures act over the concreted pile diameter below the base of the excavation.
For a cantilevered shoring system or shoring with one row of tieback anchors or internal
bracing, we recommend the following:
Use an equivalent fluid unit weight of 30 pounds per cubic foot (pcf) for active earth
pressures and 50 pcf for at -rest earth pressures;
For the case of street loads adjacent to the shoring, add a uniform surcharge load
equivalent to 2 additional feet of soil;
For the case of a slope above the shoring, add a uniform surcharge that is the product of the
appropriate equivalent fluid unit weight (e.g., 30 pcf) and one-half the height of the cut slope;
and
For other loads adjacent to the shoring (e.g., heavy construction loads and building
foundations), contact Terracon to estimate appropriate surcharge pressures.
For tieback anchors, the anchor portion of the tieback should be located sufficiently far behind
the excavation shoring to stabilize the excavation face. The no "load" zone limits is the area
behind the soldier pile equal to a lateral distance from the base of the excavation equal to the
exposed wall height (H in feet) divided by four, or five feet, whichever is greater, and a line
sloping up and back at 60 degrees from horizontal.
The selection of the tieback materials and installation methods should be the responsibility of
the contractor. The actual adhesion values will depend on the materials and installation method
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and should be confirmed by testing. For non -pressure grouted anchors, the allowable design
concrete/soil adhesion value of 2,000 psf can be used for preliminary design and cost
estimating purposes. For pressure grouted anchors, this value can typically be increased by
two to three times. We recommend all tieback anchors be proof tested to at least 130% of the
design capacity prior to locking off at the specified post tensioned design load. Prior to
installation of production anchors, two verification tests to 200% of the design pull out capacity
are recommend for each soil type in order to confirm the design capacity.
A minimum anchor spacing of four feet center to center is recommended for tieback anchors.
The anchor holes should be drilled at an angle of 15 to 30 degrees down from horizontal. A
minimum anchor bond of 10 feet is recommended. The location and presence of existing
features such as utilities and foundation should be checked during the design as these may
affect the location and length of tieback anchors.
Vertical capacity of the soldier piles may be provided by a combination of end bearing and side
friction below the base of the excavation. The piles can be designed for an allowable end
bearing resistance of 20 ksf with an allowable side friction of 2 ksf for that portion of the pile
embedded into the dense to very dense glacially consolidated soil. A factor of safety of 3 and 2
apply to the allowable end bearing and side friction, respectively.
We recommend timber lagging, or some other form of protection, be installed in all areas. Due
to soil arching effects, lagging may be designed for 40 percent of the lateral earth pressure used
for shoring design. Prompt and careful installation of lagging would reduce potential loss of
ground. The requirements for lagging should be made the responsibility of the shoring
subcontractor to prevent soil failure, sloughing, and loss of ground. Proper installation of
lagging is critical to provide safe working conditions. We recommend that any voids between
the lagging and soil be backfilled promptly. However, the backfill should not allow potential
hydrostatic pressure to build-up behind the wall. Drainage behind the wall must be maintained.
4.8.4 Soldier Pile Shoring Installation
The contractor should be required to prevent caving and loss of ground in all soldier pile drill
holes. The shoring contractor will need to use methods to minimize caving and sloughing of the
drill holes, such as the use of augercast methods or installation of casing. If more than one foot
of water is present in the bottom of the hole, placement of concrete from the bottom of the hole
will be required.
When drilling tieback anchor holes, casing may be required to prevent caving and loss of
ground. The anchor grout should be pumped into the anchor zone by tremie methods in order
to remove water from the hole and to provide a continuous grouted anchor.
Responsive Resourceful : Reliable 23
Geotechnical Engineering Report Irerracon
StorQuest Self Storage � Federal Way, Washington
January 11, 2017 ■ Terracon Project No. 81165135
Voids behind the lagging should be backfilled immediately with a permeable granular soil
material or lean concrete. The excavation height prior to lagging installation should not exceed
5 feet to maintain stability of the cut face.
4.8.5 Monitoring of Temporary Shoring
Any time an excavation is made below the level of existing buildings, utilities, or other
structures, there is risk of damage even if a well -designed shoring system has been planned.
We recommend, therefore, that a systematic program of observations be conducted on adjacent
facilities and structures. The monitoring program should include measurements of the
horizontal and vertical movements of the adjacent structures and the shoring system itself. At
least two reference lines should be established adjacent to the excavation at horizontal
distances back from the excavation space of about 1/3H and H, where H is the final excavation
height. Monitoring of the shoring system should include measurements of horizontal
movements at the top of every other soldier pile. If local wet areas are noted within the
excavation, additional monitoring points may be recommended by Terracon.
The measuring system used for shoring monitoring should have an accuracy of at least 0.01-
feet. All reference points on the existing structures should be installed and readings taken prior
to commencing the excavation. All reference points should be read prior to and during critical
stages of construction. The frequency of readings will depend on the results of previous
readings and the rate of construction. As a minimum, readings should be taken about once a
week throughout construction until the basement walls are completed. All readings should be
reviewed by Terracon.
In order to establish the condition of existing facilities prior to construction, we recommend that
William Warren Group makes a complete inspection and evaluation of pavements, structures,
utilities, and other facilities near the project site. This inspection should be directed towards
detecting any existing signs of damage, particularly those caused by settlement or lateral
movement. The observations should be documented by pictures, notes, survey drawings, or
other means of verification. The contractor should also establish for their own records the
existing conditions prior to construction.
5.0 GENERAL COMMENTS
Terracon should be retained to review the final design plans and specifications so comments
can be made regarding interpretation and implementation of our geotechnical recommendations
in the design and specifications. Terracon also should be retained to provide observation and
testing services during grading, excavation, foundation construction and other earth -related
construction phases of the project.
Responsive Resourceful Reliable 24
Geotechnical Engineering Report
StorQuest Self Storage : Federal Way, Washington
January 11, 2017 Terracon Project No. 81165135
1rerracon
The analysis and recommendations presented in this report are based upon the data obtained
from the explorations performed at the indicated locations and from other information discussed
in this report. This report does not reflect variations that may occur between explorations,
across the site, or due to the modifying effects of construction or weather. The nature and
extent of such variations may not become evident until during or after construction. If variations
appear, we should be immediately notified so that further evaluation and supplemental
recommendations can be provided.
The scope of services for this project does not include either specifically or by implication any
environmental or biological (e.g., mold, fungi, bacteria) assessment of the site or identification or
prevention of pollutants, hazardous materials or conditions. If the owner is concerned about the
potential for such contamination or pollution, other studies should be undertaken.
This report has been prepared for the exclusive use of William Warren Group and their design
consultants for specific application to the project discussed and has been prepared in
accordance with generally accepted geotechnical engineering practices. No warranties, either
express or implied, are intended or made. Site safety, excavation support, and dewatering
requirements are the responsibility of others. In the event that changes in the nature, design, or
location of the project as outlined in this report are planned, the conclusions and
recommendations contained in this report shall not be considered valid unless Terracon reviews
the changes and either verifies or modifies the conclusions of this report in writing.
JResponsive . Resourceful Reliable 25
APPENDIX A
FIELD EXPLORATION
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Geotechnical Engineering Report Irerracon
StorQuest Self Storage Federal Way, Washington
January 11, 2017 Terracon Project No. 81165135
Field Exploration Description
The subsurface exploration consisted of drilling and sampling four borings and excavating four
test pits at the site to depths ranging from about 9Y2 to 50 feet below existing grade. The boring
and test pit locations were laid out by Terracon personnel. Distances from these locations to
the reference features indicated on the attached diagram are approximate and were estimated.
The locations of the borings should be considered accurate only to the degree implied by the
means and methods used to define them. Horizontal boring locations were determined using a
handheld GPS instrument. The boring elevations were interpolated from the topographic survey
provided by Magellan Architects.
Field logs of each boring and test pit were prepared by the engineer or geologist on site. These
logs included visual classifications of the materials encountered during drilling/excavating as
well as the engineer or geologist's interpretation of the subsurface conditions between samples.
Final boring and test pit logs included with this report represent an interpretation of the field logs
and include modifications based on laboratory observation and tests of the samples obtained in
the field. The enclosed boring and test pit logs indicate the vertical sequence of soil and
materials encountered in each exploration. Where a soil contact was observed to be
gradational, our logs indicate the average contact depth.
The samples were classified in the laboratory based on visual observation, texture and
plasticity. The descriptions of the soil indicated on the boring logs are in general accordance
with the enclosed General Notes and the Unified Soil Classification System. Estimated group
symbols according to the Unified Soil Classification System are given on the boring logs. A brief
description of this classification system is attached to this report.
Soil Boring Procedures
The borings were drilled with a track -mounted rotary drill rig using hollow stem augers to
advance the boreholes. Representative soil samples were obtained by the split -barrel sampling
procedure. In the split -barrel sampling procedure, the number of blows required to advance a
standard 2-inch O.D. split -barrel sampler the last 12 inches of the typical total 18-inch
penetration by means of a 140-pound hammer with a free fall of 30 inches, is the standard
penetration resistance value (N). These values are indicted on the borings logs at the depths of
occurrence. This value is used to estimate the in -situ relative density of cohesionless soil and
the consistency of cohesive soil. The sampling depths and penetration distance, plus the
standard penetration resistance values, are shown on the boring logs. The samples were
sealed and taken to the laboratory for testing and classification.
An automatic SPT hammer was used to advance the split -barrel sampler in the borings
performed on this site. A greater efficiency is typically achieved with the automatic hammer
compared to the conventional safety hammer operated with a cathead and rope. Published
correlations between the SPT values and soil properties are based on the lower efficiency
Responsive Resourceful Reliable Exhibit A-4
Geotechnical Engineering Report Irerracon
StorQuest Self Storage . Federal Way, Washington
January 11, 2017 Terracon Project No. 81165135
cathead and rope method. This higher efficiency affects the standard penetration resistance
blow count (N) value by increasing the penetration per hammer blow over what would obtained
using the cathead and rope method. The effect of the automatic hammer's efficiency has been
considered in the interpretation and analysis of the subsurface information for this report.
Test Pit Procedures
Test pits were excavated with a tracked excavator operated by an excavation company
(Northwest Excavating) working under subcontract to Terracon. A geologist from our firm
continuously observed the test pits, logged the subsurface conditions that were encountered,
and obtained disturbed representative soil samples. The samples were stored in moisture -tight
containers and transported to our laboratory for visual classification and testing.
After completion of the test pits, the resulting excavations were backfilled with the excavated
material. The backfill was compacted in lifts by means of bucket tamping with the excavator.
Some settlement of the backfill should be expected
Responsive Resourceful Reliable Exhibit A-4
I
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BORING LOG NO. B-1 Page 1 of 3
PROJECT: StorQuest Federal Way CLIENT: William Warren Group
I
SITE: 298th Block Pacific Highway South
Federal Way, Washington
0
LOCATION See Exhibit A-2
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Latitude: 47.3343' Longitude:-122.3133'
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—6 inches Topsoil-GRAVLLLY
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16
N=88
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6
(blowcount on gravel may be overstated)
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17
19-36-50/5"
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10
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2
Stratification lines are approximate. In -situ, the transition may be gradual.
Hammer
Type:
Automatic SPT Hammer
Advancement Method:
See Exhibit A-4 for description of field
Notes:
Hollow Stem Auger
procedures
See Appendix B for description of laboratory
procedures and additional data (if any).
Abandonment Method:
See Appendix C for explanation of symbols and
Borings backfilled with bentonite chips upon completion
abbreviations.
Elevations were interpolated from a topographic
_WATER LEVEL 013SERVATIONS
Boring Started: 10/25/2016
Boring Completed: 10/25/2016
Groundwater not encountered
Irerracon
Drill Rig: Track
Driller: Holocene
21905 64th Ave W Ste 100
Mountlake Terrace, WA
Project No.: 81165135
Exhibit: A-5
BORING LOG NO. B-1
Page 2 of 3
PROJECT: StorQuest Federal Way CLIENT: William Warren Group
SITE: 298th Block Pacific Highway South
Federal Way, Washington
0
OJ
LOCATION See Exhibit A-2
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(continued)
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4
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5
Stratification lines are approximate. In -situ, the transition may be gradual. Hammer Type: Automatic SPT Hammer
Advancement Method:
See Exhibit A4 for description of field
Notes:
Hollow Stem Auger
procedures
See Appendix B for description of laboratory
procedures and additional data (if any).
Abandonment Method:
See Appendix C for explanation of symbols and
Borings backfilled with bentonite chips upon completion
abbreviations.
Elevations were interpolated from a topographic
WATER LEVEL OBSERVATIONS
Boring
Irerraccin Drill
Started: 10/25/2016
Boring Completed: 10/25/2016
Groundwater not encountered
Rig: Track
Driller: Holocene
21905 64th Ave W Ste 100
Mountlake Terrace. WA Project
No.: 81165135
Exhibit: A-5
I
BORING LOG NO. B-2
PROJECT: StorQuest Federal Way
CLIENT: William Warren Group
SITE: 298th Block Pacific Highway South
Federal Way, Washington
C7 LOCATION See Exhibit A-2
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Latitude:47.3343° Longitude:-122.3129°
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Surface Elev.: 438 (Ft.)
0
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DEPTH ELEVATION Ft.
W
m
U
W
a
§ILTY SAND WITH SRAVEL (SMI. brawn, medium dense, moist
(FILL)
14
9-10-25
S-1
1.5 436.5
SANDY WELL GRADFI2 GRAVEL tGW with cobbles, trace silt,
brown, very dense, moist (ADVANCE OUTWASH)
16
45-38-45
S-2
15
N=83
10
25-38-50/6"
S-3
6
(blowcount on gravel may be overstated)
5
-
S-4
1
50/2"
N=50/2"
(blowcount on gravel may be overstated)
1
S-5
4
35-50/2"
I
N=50/2"
—
1
—
-
9
25-28-30
S-6
16
5
N=58
2
—
13
15-31-36
N=67
S-7
2d-0 414
` , brown, very dense,
4°. moist to wet (ADVANCE OUTWASH)
Ivancement Method:
Hollow Stem Auger
Abandonment Method:
Borings backfilled with bentonite chips upon completion
WATER LEVEL OBSERVA
Groundwater not encountered
�„ W
See Exhibit A-4 for description of field
procedures
See Appendix B for description of laboratory
procedures and additional data (if any).
See Appendix C for explanation of symbols and
abbreviations.
Elevations were interpolated from a topographic
Irerracon
21905 64th Ave W Ste 100
Mountlake Terrace, WA
nen"ne1 1 yya. „mvnrauc ar r nammer
Notes:
odng Started: 10/26/2016
rill Rig: Track
rolect No.: 81165135
Completed: 10/26/2016
Holocene
Exhibit: A-6
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BORING LOG NO. B-2 Page 2 of 2
PROJECT: StorQuest Federal Way CLIENT: William Warren Group
SITE: 298th Block Pacific Highway South
Federal Way, Washington
t9
LOCATION See Exhibit A-2
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DEPTH ELEVATION Ft.
SI LA= SAND WITH GRAVEL ISM) brown, very dense,
19-23-35
S-8
°�
moist to wet (ADVANCE OUTWASH) (continued)
X8
N=58
`1
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27.0 411
-
SILTY SANd WITH GRAVEL MR. with cobbles, brown, very dense,
°
moist (ADVANCE ❑UTWASH)
3
35-36-50/3"
S-9
°
313 406,29
N=86/9"
Boring Terminated at 31.3 Feet
Stratification lines are approximate In -situ. the transition may be gradual. Hammer Type: Automatic SPT Hammer
Advancement Method:
See Exhibit A-4 for description of field
Notes:
Hollow Stem Auger
procedures
j
Sea Appendix B for description of laboratory
ptaredures and additional data (if any).
Abandonment Method:
See Appendix C for explanation of symbols and
Borings backfilled with bentonite chips upon completion
abbreviations.
Elevations were interpolated from a topographic
WATER LEVEL OBSERVATIONS
rerracon
Boring Started: 10/26/2016
Boring Completed: 10/26/2016
Groundwater not encountered
Drill Rig: Track
Driller: Holocene
21905 64th Ave W Ste 100
Mountlake Terrace, WA
]Project No.: 81165135
Exhibit: A-6
BORING LOG NO. B-3
Page 1 of 1
PROJECT: StorQuest Federal Way CLIENT: William Warren Group
SITE: 298th Block Pacific Highway South
Federal Way, Washington
0o
LOCATION See Exhibit A-2
CO
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Latitude:47.3341° Longitude:-122.3127°
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DEPTH ELEVATION IFf.
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0
COw
U
a.
SILTY AND WITH GRAVEL (SM), brown, medium dense to dense,
°
moist
17
15-16-27
S-1
e
X14
16-18-27
S-2
6
3.0 43
N�5
•
V LILY WI ED SAND TH I IN P- , with
cobbles, brown, very dense, moist (ADVANCE OUTWASH)
15
20-32-46
S-3
6
v
5
9
15-26-38
S-4
N=64
a
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e
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S-5
7
8
8
19-50/6"
N=50/6"
V •
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7
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4
14-50/5"
S-6
--
N=50/5"
n
1
2
10
27-43-50/4"
S-7
417.5
N=93/10"
Boring Terminated at 21.3 Feet
Stratification lines are approximate. In -situ, the transition may be gradual.
Hammer
Type:
Automatic
SPT Hammer
Advancement Method:
Hollow Stem Auger
See Exhibit A-4 for description of field
Notes:
procedures
See Appendix B for description of laboratory
procedures and additional data (if any).
Abandonment Method:
See Appendix C for explanation of symbols and
Borings backfilled with bentonite chips upon completion
abbreviations.
Elevations were interpolated from a topographic
WATER LEVEL OBSERVATIONS
Boring Started: 10/26/2016
Boring Completed: 10/26/2016
19.5' - Perched Groundwater While Drilling
Irerracon
Driller. Holocene
Drill Rig: Track
21905 64th Ave W Ste 100
Mountlake Terrace, WA
Ptoject No.: 81165135
Exhibit: A-7
BORING LOG NO. B-4 Page 1 of 1
PROJECT: StorQuest Federal Way CLIENT: William Warren Group
SITE: 298th Block Pacific Highway South
Federal Way, Washington
0o
LOCATION See Exhibit A-2
W Z
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Latitude: 47.3342° Longitude:-122.3124°
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3 m
w
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DEPTH ELEVATION(Ft.)O
SILTY SAND WITH GRAVEL (SMI, with rootlets, brown, medium
dense, moist (FILL)
S-2
10
..3.0
4313.5
-6 inches relic t❑psoil 43DGRAVELLY
r47S-1
10
SILTY SAND (SM). brown, very loose to medium dense,S-3
moist (FILL)rj
S-4
14
16
e
- —
8
1
e
4
-12
S-5
18
29
T1,5 422.
_
r `
i
SILTY SAND wrrH GRAVEL ISM, brown, medium dense, moist
I
v'
14 0 420
SILTY SAND WITH GRAVEL (SMI, with cobbles, brown, very dense,
f
..
moist (ADVANCE OUTWASH)
15
—
3
18-36-38
S-6
•
N=74
17
12-21-29
S-7
8
18.0 416
i
Boring Terminated at 18 Feet
i
i
i
i
i
i
_ Stratification lines are approximate. In -situ, the transition may be gradual.
Hammer
Type:
Automatic P ammer
Advancement Method:
See Exhibit A-4 for description of field
Notes:
Hollow Stem Auger
i
procedures
j
See Appendix B for description of laboratory
procedures and additional data (if any).
Abandonment Method:
See Appendix C for explanation of symbols and
Borings backfilled with bentonite chips upon completion
rnlqn
abbreviations.
Elevations were interpolated from a topographic
r
r WATER LEVEL 08SERVATIONS
r _ _
Boring Started: 10/26I2016
Baring Completed: 10/26 201
Groundwater not encountered
Irerracon
Drill Rig: Track
prilter. Holocene
21905 64th Ave W Ste 100
Mountlake Terrace, WA
Project No.: 81165135
F_xhiWt: A 8
TEST PIT LOG NO. TP-1
Page 1 of 1
PROJECT: StorQuest Federal Way CLIENT: William Warren Group
SITE: 298th Block Pacific Highway South
Federal Way, Washington
0
LOCATION See Exhibit A-2
Co
w
t
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m
v
>o
a
tiro
2
LU
Z
U
Latitude:47.3344' Longitude:-122.3124°
� ¢
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w~
zu
LL
>
aLU
¢
Surface Elev.: 433 (Ft.)
p
¢ n
m
2
ai
O
U
w
LL R
J
a
3 p
U
w
DEPTH ELEVATION Ft.
O
w
�
a
SILTY GRAVELLY ,5AND, with wood, roots, brown -gray, loose to
medium dense, moist to wet (FILL)
e
b
S-1
5
S-2
6.5 426.
§u IY. 12 WITH GRAVEL. with wood and organics, brown -black,
loose, wet (FILL/TOPSOIL)
t7 424
31LU$M!b WITH GRAVEL (SM), tan -brown, medium dense, moist
1
Y.
;y
S-3
422
SILTY VEL (SMI, brown -gray, dense to very dense,
i
R121.
moist (ADVANCE OUTWASH)
5 420.5
i
i
i
Test Pit Terminated at 12.5 Feet
Stratification lines are approximate. In -situ, the transition may be gradual.
Advancement Method:
Excavator
See Exhibit A-4 for description of field
Notes:
procedures
See Appendix B for description of laboratory
procedures and additional data (if any).
Abandonment Method:
See Appendix C for explanation of symbols and
Backfilled with soil in lifts and tamped with bucket.
abbreviations.
Elevations were interpolated from a topographic
WATER LEVEL OBSERVATIONS
Test Pit Started: 12/16/2016
'Test Pit Completed: 12/16/2016
Groundwater not encountered
Irerracon
21905 64th Ave W Ste 100
Excavator.
Operator. NW Excavating
Mountlake Terrace, WA
Project No.: 81165135
Exhibit: A-9
1
J
TEST PIT LOG NO. TP-2 Page 1 of 1
PROJECT: StorQuest Federal Way
CLIENT: William Warren Group
SITE: 298th Block Pacific Highway South
Federal Way, Washington
LOCATION See Exhibit A-2
_
W o
a
r
m
o
Z
a
z
z
U
Latitude:47.3341° Longitude:-122.3125'
_
LU
Y
uj
H
H
IL
Surface Elev.: 437 (Ft.)
w
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DEPTH ELEVATION Ft.
SILTY GSAY�LLY SAND with organics, brown -gray, loose to medium
dense, moist (FILL)
°
S-1
5
°.
6.0 431
�
6.5 RELIC TOPS= with roots 430.5
0
SILTY SAND WITH GRAVEL tSM3. brown -gray, medium dense, moist
S-2
0
9.6 427.
SILTY SAND WITH GRAVEL fSMI. brown -gray, dense to very dense,
°
moist (ADVANCE OUTWASH)
11.5 425.
$-a
Test Pit Terminated at 14.5 Feet
Stratification lines are approximate. In -situ, the transition may be gradual.
Advancement Method:
See Exhibit A4 for description of field
Notes:
Excavator
procedures
j
See Appendix B for description of laboratory
procedures and additional data (if any).
Abandonment Method:
See Appendix C for explanation of symbols and
Backfilled with soil in lifts and tamped with bucket.
abbreviations.
Elevations were interpolated from a topographic
WATER LEVEL OBSERVATIONS
Irerracon
Tast Pit Started: 12/16/2016
Test Pit Completed: 12/16/2016
Groundwater not encountered
Excavator.
Operator. NW Excavating
21905 64th Ave W Ste 100
Mountlake Terrace, WA
Project No.:81165135
Exhibit: A-10
u
3
C
z
a
U.
C
LL
C7
TEST PIT LOG NO. TP-3
Page 1 of 1
PROJECT: StorQuest Federal Way
CLIENT: William Warren Group
I
SITE: 298th Block Pacific Highway South
Federal Way, Washington
.
0
LOCATION See Exhibit A-2
_ Z
ul
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Latitude: 47.3343" Longitude:-122.3125°
W
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Surface Elev.: 434 (Ft.)
o
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Q
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DEPTH ELEVATION Ft_
m
w
a
;SILTY GRAVELLY SANE. with organics, brown -gray, loose to medium
°I
dense, moist (FILL)
p
.7
BI"
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s.a 428
RELIC TOPSOIL. with roots 427.
;�1eTY SAND_WITH GRAVEL (SMI. tan -brown, medium dense, moist
S-2
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9.0 425
tf
§AND WITH SILT -AND GRAVEL (SWSM1. brown -gray, dense to very
IN
dense, moist (ADVANCE OUTWASH)
1
11.0 42
S-3
Test Pit Terminated at 11 Feet
Stratification lines are approximate. In -situ, the transition may be gradual.
Advancement Method:
See Exhibit A-4 for description of field
Notes:
Excavator
procedures
See Appendix B for description of laboratory
procedures and additional data (if any).
Abandonment Method:
See Appendix C for explanation of symbols and
Backfilled with soil in lifts and tamped with bucket.
abbreviations.
Elevations were interpolated from a topographic
ita Man
WATER LEVEL OBSERVATIONS
Test
Irerracon Excavator:
21905 64th Ave W Ste 100
Pit Started: 12/16/2016
'Test Pit Completed: 12/16/2016
Groundwater not encountered
Operator. NW Excavating
Mountlake Terrace. WA 'Project
No.: 81165135
Exhibit: A-11
TEST PIT LOG NO. TP-4
Page 1 of 1
PROJECT: StorQuest Federal Way CLIENT: William Warren Group
SITE: 298th Block Pacific Highway South
Federal Way, Washington
o LOCATION See Exhibit A-2 ^ _J a)w O
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LL U Latitude:47.3343° Longitude:-122.3126° �
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DEPTH ELEVATION Ft.
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SILTY GRAVELLY SAND. with organics, brown, loose to medium
dense, moist (FILL)
SILTY SAND WITH GRAYEL(SM), tan -brown, medium dense, moist
5
SAND WITH SILT AND GRAVEL (SQL-SM) brown -gray, dense to very
dense, moist (ADVANCE OUTWASH)
Test Pit Terminated at
S-1
Stratification lines are approximate. In -situ, the transition may be gradual.
Advancement Method:
See Exhibit A-4 for description of field
Notes:
Excavator
procedures
i
See Appendix B for description of laboratory
procedures and additional data (if any).
Abandonment Method:
See Appendix C for explanation of symbols and
Backfilled with soil in lifts and tamped with bucket.
abbreviations.
Elevations were interpolated from a topographic
Man
WATER LEVEL OBSERVATIONS
I rerracon
Test Pit Started: 12/16/2016
Test Pit Completed: 12116/2016
Groundwater not encountered
Excavator.
Operator. NW Excavating
i
21905 64th Ave W Ste 100
Mountlake Terrace, WA
Project No.: 81165135
Exhibit: A-12
APPENDIX B
LABORATORY TESTING
Geotechnical Engineering Report Irerracon
StorQuest Self Storage . Federal Way, Washington
January 11, 2017 Terracon Project No. 81165135
Laboratory Testing Description
As part of the testing program, all samples were examined in the laboratory by experienced
personnel and classified in accordance with the attached General Notes and the Unified Soil
Classification System based on the texture and plasticity of the soil. The group symbol for the
Unified Soil Classification System is shown in the appropriate column on the exploration logs
and a brief description of the classification system is included with this report in the Appendix.
At that time, the field descriptions were confirmed or modified as necessary and an applicable
laboratory testing program was formulated to determine index properties of the subsurface
materials.
Laboratory tests were conducted on selected soil samples and the test results are presented in
this appendix. The laboratory test results were used for the geotechnical engineering analyses,
and the development of foundation and earthwork recommendations. Laboratory tests were
performed in general accordance with the applicable ASTM, local or other accepted standards.
Selected soil samples obtained from the site were tested for the following engineering
properties:
In -situ Water Content
Grain Size Distribution
Responsive Resourceful Reliable Exhibit B-1
W
m
w
Z
LL
F-
Z
w
Of
w
il
GRAIN SIZE DISTRIBUTION
ASTM D422 / ASTM C136
U.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS I HYDROMETER
A 4 , 2 , . 1 ,,,, N2- 3 . 6 -10 . 16 __ 30 ._ 5n __ 10n .._ 9nn
MINE
1011
111111E11111110
111011s
BEENME
ism
1100111111111101
immiiiiiilmmigiiilmm
IBMMENOMINEE
N
8 N GRAIN SIZE IN MILLIMETERS
COBBLES GRAVEL SAND
z coarse fine coarse I medium fine
" Boring ID
Depth
USCS Classification
n • B-1
10 - 11.4
GRAVELLY WELL -GRADED SAND WITH SILT (SW-SM)
m B-1
20 - 21.4
GRAVELLY POORLY -GRADED SAND WITH SILT (SP-SM)
♦ B-2
15 - 16.5
SANDY WELL -GRADED GRAVEL (GW)
* 13-3
10 - 11
GRAVELLY WELL -GRADED SAND WITH SILT (SW-SM)
Ox 0 B-4
LL
4.5 - 6
GRAVELLY SILTY SAND (SM)
W Boring ID
Depth
D100 D60 D3o D10
• B-1
10 - 11.4
25 2.561 0.41
n
05 m B-1
LL_
20 - 21.4
19 4.016 1.097 0.091
♦ B-2
15 - 16.5
31.5 11.944 2.807 0.372
a
F * B-3
10 - 11
25 5.668 0.632 0.116
0
z O B-4
4.5 - 6
25 5.195 0.369
PROJECT: StorOuest Federal Way
SITE: 298th Block Pacific Highway South Irerracon
L2 Federal Way, Washington
21905 64th Ave W Ste 100
a
Mountlake Terrace, WA
SILT OR CLAY
1
WC (0/6)
ILL
PL
PI
Cc
Cu
8
1.12
43.74
10
3.29
44.04
16
1.77
32.12
7
0.61
48.73
14
%Gravel
%Sand
%Silt %Fines %Clay
31.1
57.3
11.6
35.4
55.3
9.2
61.5
33.8
4.7
42.4
49.3
8.3
41.5
42.5
16.0
PROJECT NUMBER:
81165135
CLIENT: William Warren Group
EXHIBIT: B-2
APPENDIX C
SUPPORTING DOCUMENTS
GENERAL NOTES
Water Initially
N Standard Penetration Test
Encountered
Resistance (Blows/Ft.)
Water Level After a
(HP) Hand Penetrometer
Specified Period of Time
�
J
y,l
� Water Level After
�
(� Torvane
Z
Modified
eCalifornia Grab
W
J
a Specified Period of Time
N
W
d
Ring Sample
�
Water levels indicated on the soil boring
G
(DCP) Dynamic Cone Penetrometer
�
Sampler
W
logs are the levels measured in the
J
N
Q
borehole at the times indicated.
W
Detector
Split Spoon?
Groundwater level variations will occur
LL
(PID) Photo -Ionization
over time. In low permeability soils,
accurate determination of groundwater
(OVA) Organic vapor Analyzer
levels is not possible with short term
water level observations.
DESCRIPTIVE SOIL CLASSIFICATION
Soil classification is based on the Unified Soil Classification System. Coarse Grained Soils have more than 50% of their dry
weight retained on a #200 sieve; their principal descriptors are: boulders, cobbles, gravel or sand. Pine Grained Soils have
less than 50% of their dry weight retained on a #200 sieve; they are principally described as clays if they are plastic, and
silts if they are slightly plastic or non -plastic. Major constituents may be added as modifiers and minor constituents may be
added according to the relative proportions based on grain size. In addition to gradation, coarse -grained soils are defined
on the basis of their in -place relative density and fine-grained soils on the basis of their consistency.
LOCATIQN AND EL9MQN NOTES
Unless otherwise noted, Latitude and Longitude are approximately determined using a hand-held GPS device. The accuracy
of such devices is variable. Surface elevation data annotated with +/- indicates that no actual topographical survey was
conducted to confirm the surface elevation. Instead, the surface elevation was approximately determined from topographic
maps of the area.
RELATIVE PROPORTION!5 OF SAND AND GRAVEL GRAJIN TERMINOLOGY
Descriptive Term(s) Percent off Maior Component Particle Size
of other constituents Du yye�pht of Sample
Trace < 15 Boulders Over 12 in. (300 mm)
With 15 - 29 Cobbles 12 in. to 3 in. (300mm to 75mm)
Modifier > 30 Gravel 3 in. to #4 sieve (75mm to 4.75 mm)
Sand #4 to #200 sieve (4.75mm to 0.075mm
Silt or Clay Passing #200 sieve (0.075mm)
RELATIVE PROPORTIONS PLASTICITY DESCRIPTION
Descriptive Term(s) Percent of Tenn Plasticity Index
of other constituents DryWeiaht Non -plastic 0
Trace < 5 Low 1 - 10
I With 5-12 Medium 11 - 30
Modifier > 12 High > 30
IrerraconExhibit: C-1
5-9
RELATIVE DENSITY OF COARSE -GRAINED SOILS
CONSISTENCY OF FINE�aRAINED SOILS
(50°/o or more passing the No. 200 sieve.]
(More than 50°Iv retained an No. 200 sieve.)
Consistency determined by laboratory shear strength testing, field
Density determined by Standard Penetration Resistance
visual -manual procedures or standard penetration resistance
N
Descriptive Term
Standard Penetration or
Ring Sampler
Descriptive Tenn
i Unconfined Compressive
Standard Penetration or
Ring Sampler
�
(Density)
BI was/�Ft
Blows/Ft
(Consistency)
Strength Qu, (psi)
Blowas/�Ft
Blows/Ft
�
—
Very Loose
�
0-3
0-6
Very Soft
less than 3.50
0 -1
< 3
Soft
2-4
H
4-9
7-18
3-4
ZLoose
10 - 29
19 - 58
—
4-8
W
Medium Dense
Medium -Stiff
UNIFIED SOIL CLASSIFICATION SYSTEM
T
Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests A
_
Gravels: Clean Gravels: Cu ? 4 and 1 <_ Cc <_ 3 E
More than 50% of Less than 5% fines c Cu < 4 and/or 1 > Cc > 3 E
coarse fraction retained Gravels with Fines: Fines classify as ML or MH
Coarse Grained Soils: on No. 4 sieve More than 12% fines ° Fines classifyas CL or CH
More than 50%
Soil Classification
Group B
Group Name
Symbol
GW
Well -graded Travel
GP
Poorly graded gravel
GM
Silty gravel F•G"'
GC
Clayey ravel
a
y y g
retained
on No. 200 sieve
Fine -Grained Soils:
50% or more passes the
No. 200 sieve
Sands:
50% or more of coarse
fraction passes No. 4
sieve
Silts and Clays:
Liquid limit less than 50
Silts and Clays:
Liquid limit 50 or more
Clean Sands:
Less than 5% fines D
Sands with Fines:
More than 12% fines °
Inorganic:
Organic:
Inorganic:
Cu >- 6 and 1 < Cc <- 3E
SW
Well -graded sand'
Cu < 6 and/or 1 > Cc > 3
SP
Poorly graded sand'
Fines classify as ML or MH
SM
Silty sandy"'
Fines classify as CL or CH
SC
Clayey sand
PI > 7 and plots on or above "A" line
CL
Lean clay"•"'
PI < 4 or plots below "A" line
ML
�
Silt K ' A
Liquid limit - oven dried
< 0.75
OL
Organic clayK"m,"
Liquid limit -not dried
q
Organic silt �L A o
PI plots on or above "A" line
CH
Fat clay"•`
PI plots below "A" line
MH
Elastic Silt" 'm
Organic:
Liquid limit - oven dried
< 0.75
Liquid limit - not dried
OH
Organic clay".IAP
Organic silt" •`,'"x
Highly organic soils:
Primarily organic matter, dark in color, and organic odor
PT
Peat
A Based on the material passing the 3-inch (75-mm) sieve
B If field sample contained cobbles or boulders, or both, add "with cobbles
or boulders, or both" to group name.
Gravels with 5 to 12% fines require dual symbols: GW-GM well -graded
gravel with silt, GW-GC well -graded gravel with clay, GP -GM poorly
graded gravel with silt, GP -GC poorly graded gravel with clay.
Sands with 5 to 12% fines require dual symbols: SW -SM well -graded
sand with silt, SW -SC well -graded sand with Gay, SP-SM poorly graded
sand with silt, SPSC poorly graded sand with clay
E Cu = D60/1310 Cc = (D30) 2
0)2
131. x De0
F If soil contains > 15% sand, add "with sand" to group name.
c If fines classify as CL-ML, use dual symbol GC -GM, or SC-SM.
a
60
50
10
7
4
0
0
" If fines are organic, add "with organic fines" to group name.
' If soil contains ? 15% gravel, add "with gravel" to group name-
'' If Atterberg limits plot in shaded area, soil is a CL-ML., silty clay.
K If soil contains 15 to 29% plus No. 200, add "with sand" or "with gravel,"
whichever is predominant.
If soil contains >_ 30% plus No. 200 predominantly sand, add "sandy" to
group name.
M If soil contains >_ 30% plus No. 200, predominantly gravel, add
"gravelly" to group name.
" PI >_ 4 and plots on or above "A" line.
° PI < 4 or plots below "A" line.
P PI plots on or above "A" line.
PI plots below "A" line.
For classification atfine-grained
sails and tlne-grained fraction �•'�
of coarse -grained sails
Equation of "A"- line .ti] ,• I rp
Horizontal at PI=4 to LL=25.5. r
then PI=0.73 (LL-20) O�
t
Equation of "U" - line ��°
Vertical at LL=16 to PI=7.
then PI=0.9 (LL-8)
I f °4OL
MH or OH
-- ML or OL
10 16 20 30 40 50 60 70 80 90 100 110
LIQUID LIMIT (LL)
Irerracon
Exhibit C-2
x -uD-0
INFORMATION
TECHNICALm
m mom
° 0 m
�c�
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'Q
REPORT
cDCnN
Z�
j CD CO
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mF3•�.cn
StorQuest Premium Self -Storage
�'�' = o
Federal Way, WASHINGTON
o
cn
RESUBMITTED
SEP 2 2 2017
CITY OF FEDERAL WAY
GOMMUNf iY DEVELOPMENT
TECHNICAL INFORMATION REPORT
TABLE OF CONTENTS
PIGF
SECTION
PROJECTOVERVIEW................................................................................................................
1. TIR WORKSHEET...........................................................................................................
2. SITE LOCATION............................................................................................................
3. DRAINAGE BASIN, SUBBASINS, AND SITE CHARACTERISTICS ......................................
4. SOILS............................................................................................................................
CONDITIONS AND REQUIREMENTS SUMMARY.................................................................................15
OFFSITEANALYSIS...............................................................................................................................19
FLOW CONTROL, LID, AND WATER QUALITY FACILITY ANALYSIS AND DESIGN ............................... 24
1. EXISTING SITE HYDROLOGY.....................................................................................................24
2. DEVELOPED SITE HYDROLOGY................................................................................................. 25
3. FLOW CONTROL FACILITY........................................................................................................26
4. WATER QUALITY FACILITY.......................................................................................................33
5. 100-YEAR FLOOD FIRM MAP/OVERFLOW CONDITION...........................................................36
CONVEYANCE SYSTEM ANALYSIS AND DESIGN................................................................................. 37
SPECIALREPORTS AND STUDIES......................................................................................................... 40
OTHER PERMITS ...
..................... I ... . 41
CSWPPANALYSIS AND DESIGN...........................................................................................................42
ESC PLAN ANALYSIS AND DESIGN (PART A)...................................................................................42
1. EROSION RISK ASSESSMENT..............................................................................................42
2. CONSTRUCTION SEQUENCE AND PROCEDURE.................................................................42
3. TRAPPING SEDIMENT........................................................................................................42
4. WET WEATHER TESC.........................................................................................................43
SWPPSPLAN DESIGN (PART B).....................................................................................................43
BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT ............................. 48
OPERATION AND MAINTENANCE GUIDELINES.................................................................................. 51
APPENDIX: A— EXISTING CONDITIONS AND PROPOSED CONDITIONS EXHIBITS
B — SPECIAL REPORTS AND STUDIES
C — CSWPPP WORKSHEETS
NAVIX StorQuest Federal Way Page 1
TECHNICAL INFORMATION REPORT
PROJECT OVERVIEW
DESIGN CRITERIA
The stormwater management facilities have been designed to the 2016 King County Surface Water
Design Manual (2016 Manual) per City of Federal Way Requirements.
Duration Analysis: Conservation Flow Control
2-year:
10-year:
Water Quality Menu:
Downstream Analysis:
Match existing site conditions
Match existing site conditions
Enhanced Basic
X mile
Since the project proposes more than 2,000 SF of new impervious area, a Full Drainage Review will be
required.
EXISTING CONDITIONS
The proposed project is located at 29600 Pacific Ave S in Federal Way (King County), Washington. The
site is approximately 1.05 acres and is currently undeveloped with trees and sparse vegetation. The
site is rectangular in shape and is bordered to the north by an existing motel, to the east by Pacific Hwy
S, to the south by an undeveloped parcel, and to the west by 16th Ave S. The existing conditions are
shown in Figure 1 below:
NAVIX StorQuest Federal Way Page 2
TECHNICAL INFORMATION REPORT
Drainage
Swale
I �
a I �
Depression outlet
culvert to municipal
! storm system
I �
Depression
Figure 1: Existing Conditions Map
Per the Geotechnical Engineering Report by Terracon Consultants, Inc., dated January 11, 2017, the on -
site soils consist of granular recessional outwash deposits in the central and western portions of the
site and undocumented fill underlain by recessional outwash in the eastern portion of the site.
Previous grading activities created an approximately 1.5H:1V to 2HAV slope that extends from the
western property line down to a 4' high existing rockery in the western portion of the site. The
remainder of the site is a relatively flat pad, which gently slopes to the east. A drainage swale from
previous grading and erosion control efforts directs surface runoff to a depression at the southeast
corner of the site.
The project site is in a Level 2 Flow Control Area, and per the requirements of the 2016 Manual, the
pre -developed conditions were modeled as fully forested.
The ground surface varies from approximately elevation 475 feet in the southwest corner, elevation
464 feet in the northeast corner, and elevation 428 feet along the eastern perimeter. The site slopes
down 20' to 30' at approximately 3:1 from the western property line to the existing rock wall. A
second rockery extends along the northern property line and varies from 3' to 10' in height. Site
grades slope toward an existing shallow Swale that directs runoff to a depression at the southeast
corner of the site.
NAVIX StorQuest Federal Way Page 3
TECHNICAL INFORMATION REPORT
PRE -DEVELOPMENT STORMWATER RUNOFF
Runoff from the site sheet flows to an existing on -site drainage ditch, which conveys the runoff to a
small depression at the southeast corner of the project site. The depression extends to the adjacent
property to the south and collects runoff from approximately 0.5 acres from the adjacent parcel. The
depression drains to an existing 12" on -site culvert that is routed to the municipal storm system in
Pacific Hwy S via a catch basin in the ROW sidewalk in front of the project site.
A small portion of the runoff from the undeveloped portion sheet flows onto Pacific Hwy S and enters
the municipal storm system directly.
DEVELOPED CONDITIONS
The project proposes to construct a 3-story plus grade -plane basement self -storage building with
associated parking, stormwater management facilities, utilities, and on -site landscaping. The building
footprint is approximately 20,568 SF, and the gross floor area is approximately 83,000 SF. The western
rockery and existing stormwater culvert will be demolished as part of this development. The total
NAVIX StorQuest Federal Way Page 4
TECHNICAL INFORMATION REPORT
proposed building area is approximately 0.47 acres, and the proposed pollution -generating impervious
area is 0.18 acres. The developed conditions are shown in Figure 2 below:
Shotcrete gutter
along top of _
shoring (Typ.)
I'
I I
I
I
I
II !
a II i
i
II
f
II I
L__.
Figure 2: Developed Conditions Map
StormFilter 48"
Manhole
Water Quality
Facilitv
f
'r
�i
I d
CMP system
overflow to
municipal
storm system
Catch Basin
(Typ•)
Per the 2016 Manual, enhanced water quality treatment is required for all pollution generating
surfaces prior to discharge from the project site as specified in Core Requirement #8 and Special
Requirement #5. Site stormwater runoff is comprised of Non -Pollution Generating Impervious
Surfaces (NPGIS) and Pollution Generating Impervious Surfaces (PGIS). NPGIS areas include sidewalk
and roof runoff. PGIS areas include all paved roadway surfaces.
POST -DEVELOPMENT STORMWATER RUNOFF
Stormwater will be managed on the project site in accordance with the standards of the 2016 Manual.
Stormwater runoff will be managed by the following stormwater facilities:
This project is subject to Enhanced Basic Water Quality treatment. However, per Exception 2 of
Section 1.2.8.1 of the 2016 Manual, all runoff that is fully infiltrated in accordance with the 2016
Manual may be treated Basic Water Quality facility in lieu of Enhanced Basic. The stormwater runoff
from the proposed PGIS areas totals approximately 0.18 acres. This runoff will be captured and
conveyed through a series of catch basins and closed conveyance pipes to a single StormFilter 48"
NAVIX StorQuest Federal Way Page 5
TECHNICAL INFORMATION REPORT
Manhole facility for Basic Water Quality treatment before discharging to the proposed on -site 96"
perforated CMP infiltration facility for flow control. The proposed NPGIS roof area will be routed
directly to the 96" perforated CMP infiltration facility.
The 96" perforated CMP infiltration facility is designed to meet Conservation Flow Control in
accordance with the 2016 Manual. The CMP infiltration will infiltrate the 100-year peak developed
flow. For flows larger than the 100-year event, the facility will include an emergency overflow
structure that will connect to the municipal storm system in Pacific Hwy S at the site's natural
discharge location.
To meet Core Requirement #9, this project is subject to the Large Lot BMP Requirements for projects
that will result in an impervious surface coverage of greater than 65% on the buildable portion of the
site. For this project, the target impervious surface for this requirement is 10% of the total site area
(0.10 acres). Full Dispersion was not determined to be feasible for this project due to inadequate flow
path length. Infiltration was determined to be feasible for this project, per the Preliminary Stormwater
Infiltration Addendum by Terracon Consultants, Inc., dated February 3, 2017.
The minimum required target impervious surface (0.1 acres) for Core Requirement #9 was met by
routing runoff from the entire site (1.05 acres) to the CMP infiltration facility, which was sized using
WWHM per the requirements of the 2016 Manual.
NAVIX StorQuest Federal Way Page 6
TECHNICAL INFORMATION REPORT
KING COUNTY. WASHINGTON. SURFACE WATER DESIGN MANUAL
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
Part 1 PROJECT OWNER AND
PROJECT ENGINEER
Project Owner William Warren Grouo
Phone
Address
Project Engineer Jenelie Tallin. P.E.
Company Navix Engineering
Phone 425-453.9501 x1515
Part 3 TYPE OF PERMIT APPLICATION
❑ Landuse Services
Subdivison / Short Subd. / UPD
0 Buiid rvices
M/F ammerica SFR
❑ Clearing and Grading
❑ Right -of -Way Use
❑ Other
Part 5 PLAN AND REPORT INFORMATION
Technical Information Report
Type of Drainage Review Full 1 Targeted !
(circle): Large Site
Date (include revision
dates):
Date of Final:
Part 2 PROJECT LOCATION AND
DESCRIPTION
Project Name StorQuest Federal Way___
DDES Permit # NIA
Location Township 21 N
Range 4E
Section 4
Site Address 29600 Pacific Hwy S
Federal Way, WA 98003
Part 4 OTHER REVIEWS AND PERMITS
❑
DFW HPA
❑ Shoreline
❑
COE 404
Management
❑
DOE Dam Safety
❑ Structural
Rockery/VaulU
❑
FEMA Floodplain
El Section 7
❑
COE Wetlands
❑
Other
Site Improvement Plan (Engr. Plans)
Type (circle one): Full 1 Modified
/
mali Site
Date (include revision
dates):
Date of Final:
Part 6 ADJUSTMENT APPROVALS
Type (circle one): Standard / Complex / Preapplication / Experimental / Blanket
Description: (include conditions in TIR Section 2)
Date of Approval:
2009 Surface Water Design Manual
1 /9/2009
NAVIX StorQuest Federal Way Page 7
TECHNICAL INFORMATION REPORT
KING COUNTY. WASHINGTON. SURFACE WATER DESIGN MANUAL
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
Part 7 MONITORING REQUIREMENTS
Monitoring Required: Yes No Describe:
Start Date:
Completion Date: -----
Part 8 SITE COMMUNITY AND DRAINAGE BASIN
Community Plan . NIA
Special District Overlays:
Drainage Basin: Lower Puget Sound Basin
Stormwater Requirements: No additional requirements.
Part 9 ONSITE AND ADJACENT SENSITIVE AREAS
❑ River/Stream NIA f ® Steep Slope Located along western property line
❑ Lake N/A _ ❑ Erosion Hazard _ NIA
❑ Wetlands N/A ❑ Landslide Hazard N/A
❑ Closed Depression _ N/A ❑ Coal Mine Hazard _ _ NIA
❑ Floodplain N/A - ❑ Seismic Hazard _ _ _ _ NIA
❑ Other _ _- ❑ Habitat Protection NIA
Part 10 SOILS
Soil Type Slopes Erosion Potential
Undocumented Fill NIA Low
Recessional Outwash Steep Low - well vegetated and stable
High Groundwater Table (within 5 feet)
Other
Additional Sheets Attached
2009 Surface Water Design Manual
2
❑ Sole Source Aquifer
❑ Seeps/Springs
1 /9/2009
NAVIX StorQuest Federal Way Page 8
TECHNICAL INFORMATION REPORT
KING COUNTY. WASHINGTON. SURFACE WATER DESIGN MANUAL
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
Part 11 DRAINAGE DESIGN LIMITATIONS
REFERENCE
❑ Core 2 — Oftsite Analysis
❑ ensi ive/Critical Areas
❑ EPA
❑ Other
❑ Additional Sheets Attached
LIMITATION / SITE CONSTRAINT
N/A
N/A
N/A
N/A
Part 12 TIR SUMMARY SHEET(provide
one TIR Summary Sheet per Threshold Discharge Area
Threshold Discharge Area:
name or description)
Gore Requirements (all S apply)
Discharge at Natural Location
Number of Natural Discharge Locations: 2 tMttlirawn and 0ty sysiern)
Offsite Analysis
Level: 1 1 2 1 3 daied: 10`2512016
Flow Control
Level: 1 1 2 l 3 or Exemption Number
inct. facility summa sheet
Small Site BMPs
Conveyance System
Spill containment located at: N/A
Erosion and Sediment Control
ESC Site Supervisor: TBD
Contact Phone:
After }lours Phone:
Maintenance and Operation
Responsibility; Private Public
If Private. Maintenance Lon Required: Yes No
Financial Guarantees and
Provided: Yes No
Liability
Water Ouality
Type: Basic 1 Sens. Lake I nhanced Basic 1 Bog
(include facility summary sheet)
or Exemption No.
Landscape Management Plan: Yes No
Special Requirements as applicable)
Area Specific Drainage
Type: CDA J SDO 1MDF0 BP LMP 1 Shared Fat. / None
Requirements
Name: Lower Pu a un sin Plan - no sRiRcific requirements
FlovdplainlFloodway Delineation
Type: Major / Minor / Exemption /None
100-year Base Flood Elevation (or range):
Datum:
Flood Protection Facilities
Describe: N/A
Source Control
Describe landuse: Commercial
(comm.riindustrial landuse)
Describe any structural controls:
2009 Surface Water Design Manual
1 /9/2009
NAVIX StorQuest Federal Way Page 9
TECHNICAL INFORMATION REPORT
KING COUNTY. WASHINGTON. SURFACE WATER DESIGN MANUAL
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
Oil Control High -use Site: Yes No
Treatment BMP:
Maintenance Agreement: Yes No
Part 13 EROSION AND SEDIMENT CONTROL REQUIREMENTS
MINIMUM ESC REQUIREMENTS
MINIMUM ESC REQUIREMENTS
DURING CONSTRUCTION
AFTER CONSTRUCTION
0 Clearing Limits
0 Stabilize Exposed Surfaces
0 Cover Measures
0 Remove and Restore Temporary ESC Facilities
0 Perimeter Protection
x❑ Clean and Remove All Silt and Debris, Ensure
0 Stabilization
Operation of Permanent Facilities
Traffic Area
❑ Flag Limits of SAO and open space
0 Sediment Retention
preservation areas
preservation
0 Surface Water Collection
❑ Dewatering Control
_
0 Dust Control
❑ Flow Control
Part 14 STORMWATER
FACILITY DESCRIPTIONS
Note: Include Facili Summa
and Sketch
Flow Control
Type/Description
Water Quality
T /Descrition
❑ Detention
x❑ Infiltration
❑ Regional Facility
❑ Shared Facility
❑ Flow Control
BMPs
❑ Other
❑ Biofiltration
❑ Wetpool
0 Media Filtration
❑ Oil Control
❑ Spill Control
❑ Flow Control BMPs
❑ Other
CMP infiltration gallery
StormFilter Catch Basin
2009 Surfacc Water Dcsign Manual
1!9/2009
NAVIX StorQuest Federal Way Page 10
TECHNICAL INFORMATION REPORT
KING COUNTY. WASHINGTON. SURFACE- WATER DESIGN MANUAL
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
Part 15 EASEMENTSITRACTS
Part 16 STRUCTURAL ANALYSIS
❑ Drainage Easement
❑ Cast in Place Vault
❑ Covenant
❑ Retaining Wall
❑ Native Growth Protection Covenant
❑ Rockery ;- 4' High
❑ Tract
❑ Structural on Steep Slope
❑ Other
❑ Other
Part 17 SIGNATURE OF PROFESSIONAL ENGINEER
I, or a civil engineer under my supervision, have visited the site. Actual site conditions as observed were
incorporated into this worksheet and the attached Technical Information Report To the best of my
knowledge the information provided here is a curate
2/10/2017
5 ate .
2009 Surface Water Design Manual
119+2009
NAVIX StorQuest Federal Way Page 11
SITE LOCATION
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to
S 293rd St
g 2950
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S7
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i r/?
Sacajavlea n
paw0.
_
_ W
PROJECT n
SITE
m
'�� u' S 303rd St
a�
0
TECHNICAL INFORMATION REPORT
��se-
If .?gr1st 5t
2�nd St
S 296th St
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S 296th St
GO �
5 304th St
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4
Figure 3: Vicinity Map
Location: 29600 Pacific Hwy S in Federal Way, WA.
Section, Township, Range: SW 1/4, SEC. 4, TOWNSHIP 21N, RANGE 4E, W.m.
Parcel/Tax Lot: 0421049035
Size: Approximately 1.05 acres
City, County, State: Federal Way, King County, Washington
Governing Agency: City of Federal Way
NAVIX
StorQuest Federal Way
3
S 300th St
N
w
a -
� m
V
� to
4 0
S 304th St
Steef Lai:e
Page 12
TECHNICAL INFORMATION REPORT
DRAINAGE BASIN, SUBBASINS, AND SITE CHARACTERISTICS
DRAINAGE BASIN
The projects site is located within the Lower Puget Sound Basin and is subject to Level 2 Flow Control
and Enhanced Basic water quality treatment. The Hylebos Creek and Lower Puget Sound Basin Plan
contains area -specific regulations. The proposed development meets all stormwater management
requirements for this drainage basin as described in the Basin Plan and noted below.
SUBBASINS
A single basin is present in the existing conditions, which will be maintained in the developed
conditions.
SOILS
Per the Geotechnical Engineering Report by Terracon Consultants, Inc., dated January 11, 2017, the on -
site soils consist of granular recessional outwash deposits in the central and western portions of the
site and undocumented fill underlain by recessional outwash in the eastern portion of the site. On the
eastern side of the site, silty sand with gravel extends approximately
underlain by recessional outwash. The undocumented fill layer extends nds from 0.5 deep in the central
portion of the site to 11.5' deep at: the western portion of the site.
NAVIX StorQuest Federal Way
Page 13
TECHNICAL INFORMATION REPORT
The project proposes to cut into the steep slope along the western property line and reduce the
existing slope to a proposed slope of 2H:1V maximum
, pr the recommendions in the
Report and requested in the Modification Request Letter included in he and Use Submittal for thisl
project. To protect the existing steep slopes during construction, the recommendations of the
Geotechnical Report include keeping vegetation in
place, providing erasion protection matting, and
providing other TESC measures to limit the potential for erosion. Vegetation shall be reestablished
immediately after bringing the surface to final grades to stabilize the slope.
Groundwater was observed on -site at a depth of 19.5' in one boring (B-3). However, groundwater was
not observed in the full depth boring (B-4), which extended approximately 5.5' below the elevation of
the proposed infiltration facility.
Per the Geotechnical Engineering Report Addendum — Stormwater Infiltration and Landslide Hazard
Assessment by Terracon Consultants, Inc., dated March 9, 2017, a design infiltration rate of 3 inches
per hour may be used for the sizing of the proposed on -site infiltration facility.
NAVIX StorQuest Federal Way
Page 14
TECHNICAL INFORMATION REPORT
CONDITIONS AND REQUIREMENTS SUMMARY
As required by the 2016 King County Surface Water Design Manual, this project is subject to a Full
Drainage Review. Therefore, the storm drainage design for this project is required to comply with, or
explain exemptions for, all nine (9) Core Requirements as well as all five (5) Special Requirements. The
applicable requirements have been met as follows:
CORE REQUIREMENTS
Core Requirement #1: Discharge at Natural Location
All surface and storm water runoff from a project must be discharged at the natural location so as not
to be diverted onto or away from downstream properties. The manner in which runoff is discharged
from the project site must not create a significant adverse impact to downhill properties or drainage
systems.
Response: On -site runoff will be treated and fully infiltrated on -site by means of a CMP infiltration
facility. An emergency overflow structure will be provided for the facility and will discharge higher
flows at the natural discharge location of the municipal storm system in Pacific Highway S east of the
project site. No downstream impacts are anticipated.
Core Requirement #2: Offsite Analysis
All proposed projects must submit an offsite analysis report that assesses potential offsite drainage
impacts associated with development of the project site and propose appropriate mitigations of those
impacts. The initial permit submittal shall include, at a minimum, a Level 1 downstream analysis as
described in Section 1.2.2.1 of the 2016 Manual.
Response: A Level 1 Downstream Analysis was completed for this project. See the Offsite Analysis
section for details.
Core Requirement #3: Flow Control Facilities
All proposed projects, including redevelopment projects, must provide onsite flow control facilities to
mitigate the impacts of storm and surface water runoff generated by new impervious surface, new
pervious surface, and replaced impervious surface targeted for flow mitigation as specified in the
following sections. Flow control facilities must be provided and designed to perform as specified by
the area -specific flow control facility requirement in Section 1.2.3.1 and in accordance with the
applicable flow control facility implementation requirements in Section 1.2.3.2.
Response: This project is located in the Level 2 Flow Control Area. A CMP infiltration facility wrements of the 2016 Manual. An emergency
as
designed to fully infiltrate the 100-year flow, per the requirements
overflow structure will be provided for the infiltration facility and will connect to the municipal storm
system in Pacific Highway S east of the project site. See the Flow Control and Water Quality Facility
Analysis and Design section for detailed calculations.
NAVIX StorQuest Federal Way
Page 15
TECHNICAL INFORMATION REPORT
Core Requirement #4: Conveyance System
All engineered conveyance system elements for proposed projects must be analyzed, designed, and
constructed to provide a minimum level of protection against overtopping, flooding, erosion, and
structural failure as specified in Sections 1.2.4.1, 1.2.4.2, and 1.2.4.3 of the 2016 Manual.
Response: Please see the Conveyance System Analysis and Design section of this report.
Core Requirement #S: Construction Stormwater Pollution Prevention
All proposed projects that will clear, grade, or otherwise disturb the site must provide erosion and
sediment controls to prevent, to the maximum extent practicable, the transport of sediment from the
project site to downstream drainage facilities, water resources, and adjacent properties_ All proposed
projects that will conduct construction activities onsite or offsite must provide stormwater pollution
prevention and spill controls to prevent, reduce, or eliminate the discharge of pollutants to onsite or
adjacent Stormwater systems or watercourses. To prevent sediment transport and pollutant
discharges as well as other impacts related to land -disturbing and construction activities, Erosion and
Sediment Control (ESC) measures and Stormwater Pollution Prevention and Spill Control (SWPPS)
measures that are appropriate to the project site must be applied through a comprehensive
Construction Stormwater Pollution Prevention (CSWPP) plan as described in Sections 1.2.5.1 and
1.2.5.3 and shall perform as described in Section 1.2.5.2. In addition, these measures, both temporary
and permanent, shall be implemented consistent with the requirements in Section 1.2.5.3 that apply
to the proposed project.
Response: Construction storm water pollution prevention measures as outlined in the 2016 Manual are
an integral part of the project construction documents. These measures will include methods to reduce
erosion of on site soils and to prevent sediment from inadvertently leaving the project site, such a
sediment trap, silt fence, straw wattles, inlet protection, and marking clearing limits_ Eraion and
s
W
sediment control measures will be designed in conformance with City of Federal
Manual requirements. ay and the 2016
and
Core Requirement #6: Maintenance and Operations
Maintenance and operation of all drainage facilities is the responsibility of the applicant or property
owner, except those facilities for which the City of Federal Way is granted an easement, tract, or right-
of-way and officially assumes maintenance and operation. Drainage facilities must be maintained and
operated in compliance with King County Maintenance Standards,
Response: An Operations and Maintenance Manual is located in Appendix B of this report.
Core Requirement #7: Financial Guarantees and Liability
All drainage facilities constructed or modified for projects (except flow control facilities to be privately
maintained) must comply with the financial guarantee requirements and the liability requirements of
the City of Federal Way. There are two types of financial guarantees for projects constructing or
modifying drainage facilities; the drainage facilities restoration and site stabilization guarantee, and the
drainage defect and maintenance guarantee.
Response: A Bond Quantity worksheet will be provided in the next submittal of the storm report.
NAVIX StorQuest Federal Way
Page 16
TECHNICAL INFORMATION REPORT
Core Requirement #8: Water Quality
All proposed projects, including redevelopment projects, must provide water quality (WQ) facilities to
treat the runoff from new and replaced pollution -generating impervious surfaces and pollution -
generating pervious surfaces targeted for treatment. These facilities shall be selected from one of the
area -specific WQ menus described in Section 1.2.8.1 and implemented according to the applicable WQ
implementation requirements in Section 1.2.8.2 of the 2016 Manual.
Response: This site is subject to Enhanced Water Quality Treatment. However, per Exception 2 of
Section 1.2.8.1 of the 2016 Manual, the Enhanced Basic WQ menu may be reduced to the Basic WQ
menu for treatment of any runoff that is infiltrated per Section 5.2 of the 2016 Manual_ Full infiltration
of on -site runoff is proposed for this project in accordance with Section 5.2, and soil infiltration
properties will be confirmed by the geotechnical engineer in accordance with the requirements of the
2016 Manual. Therefore, Basic water quality treatment will be provided for this site by means of a
StormFilter 48" Manhole facility, which has GOLD approval from DOE. See the Water quality section
for estimated facility sizing calculations.
Core Requirement #9: Flow Control BMPs
All proposed projects, including redevelopment projects, must provide onsite flow control BMPs to
mitigate the impacts of storm and surface water runoff generated by new impervious surface, new
pervious surface, existing impervious surfaces, and replaced impervious surface targeted for mitigation
as specified in the following sections. Flow control BMPs must be selected and applied according to
the basic requirements, procedures, and provisions detailed in this section and the design
specifications for each BMP in Appendix C, Section C.Z.
Flow control BMPs are methods and designs for dispersing, infiltrating, or otherwise reducing or
preventing development -related increases in runoff at or near the sources of those increases. Flow
control BMPs include, but are not limited to, preservation and use of native vegetated surfaces to fully
disperse runoff, use of other pervious surfaces to disperse runoff; roof downspout infiltration;
permeable pavements; bioretention; limited infiltration systems; and reduction of development
footprint.
Response: This project is subject to Large Lot BMP requirements. The feasibility and applicability of full
dispersion, full infiltration, and other Flow Control BMPs were evaluated. Infiltration was determined
to be the most feasible Flow Control BMP for this project; a CMP infiltration facility is proposed to meet
Core Requirement ##9.
SPECIAL REQUIREMENTS
Special Requirement #1: Other Adopted Area -Specific Requirements
The drainage requirements of adopted CDAs, MDPs, BPs, SCPs, SFDPs, LMPs, FHMPs, l!
and SFDPs shall
be applied in addition to the drainage requirements of the 2016 Manual unless otherwise specified in
ll the adopted regulation. Where conflicts occur between the two, the drainage requirements of the
adopted area -specific regulation shall supersede those in the 2016 Manual.
NAVIX StorQuest Federal Way
Page 17
TECHNICAL INFORMATION REPORT
Response: This project is subject to the Lower Puget Sound Executive Proposed Basin Plan. The
proposed development and storm water management facilities are in compliance with the Basin Plan.
No additional area -specific requirements are applicable to this project site.
Special Requirement #2: Flood Hazard Area Delineation
Floodplains and floodways are subject to inundation during extreme events. The 100-year floodplains
are delineated in order to minimize flooding impacts to new development and to prevent aggravation
of existing flooding problems by new development. Regulations and restrictions concerning
development within a 100-year floodplain are found in the Sensitive Areas Ordinance.
Response: Per the king County iMAP viewer, shown on page 34 of this report, the project site does not
lie within the 100-year floodplain.
Special Requirement #3: Flood Protection Facilities
Developing sites protected by levees and revetments require a high level of confidence in their
structural integrity and performance. Proper analysis, design, and construction are necessary to
protect against the potentially catastrophic consequences if such facilities should fail.
Response: The project site does not contain any levees or revetments
Special Requirement #4: Source Controls
Water quality source controls prevent rainfall and runoff water from coming into contact with
pollutants, thereby reducing the likelihood that pollutants will enter public waterways and violate
water quality standards and County stormwater discharge permit limits. The County may require
mandatory source controls at any time through formal code enforcement if complaints or studies
reveal water quality violations or problems.
Response: Since the project proposes a building and pollution generating impervious surfaces, water
quality source control is proposed as part of the redevelopment. The on -site trash enclosure will be
covered and routed to sanitary sewer.
Special Requirement #S: Oil Control
Projects proposing to develop or redevelop a high -use site must provide oil controls in addition to any
other water quality controls required by the 2016 Manual. Such sites typically generate high
concentrations of oil due to high traffic turnover or the frequent transfer of oil.
Response: Per the 2016 Manual, commercial developments with an expected average daily traffic
(ADT) count of 100 or more vehicles per 1,000 square feet of gross building area are considered high
use sites. This project is not considered a high -use site.
NAVIX StorQuest Federal Way Page 18
TECHNICAL INFORMATION REPORT
OFFSITE ANALYSIS
TASK 1: STUDY AREA DEFINITION AND MAPS
Available resources such as the survey and topographic maps were utilized to prepare the downstream
analysis. The study area extended 1/4-mile downstream ❑f the project site, at which point the site
discharge is contained within Redondo Creek. There is a small amount upstream tributary flow to the
project site from the adjacent property to the south, which drains to the existing on -site culvert and is
routed to the municipal system in Pacific Hwy S.
Figure 4 shows the general location of the critical areas relative to the proposed project site. No
sensitive/critical areas are located on -site. An erosion hazard area is located in the vicinity of Redondo
Creek to the north of the project site. However, this project does not propose to develop within the
erosion hazard area or creek; therefore, these sensitive/critical areas will not be impacted by the
Proposed development.
Figure 4: Critical Areas Map
TASK 2: RESOURCE REVIEW
The following resources were reviewed for existing/potential problems within the study area:
• Site Survey
■ Basin Plan
• FEMA F.I.R.M.
Federal Way Critical Area Map
« Reported Drainage Complaints
« Current DOE 303(d) List
NAVIX StorQuest Federal Way
Page 19
TECHNICAL INFORMATION REPORT
A review of drainage complaints from the last 10 years within one -quarter mile around the project site,
as supplied by King County, indicates that there have been no relevant complaints related to drainage
or water quality concerns that would impact or be impacted by the development of this site. The only
complaints are records of storm water audits.
Drainage compiainFs
Complaint
2013-0131
number
Sacajawea
Complaint type
WQAL
Park
Date received
Problem
WQAI
Date closed
6/11/2013
Address
29805 PACIFIC HWY
5
Parcel
0421049157
Comments
' Tracker ID
38019.00
Zoom to
TASK 3: FIELD INSPECTION
Drainage complaints
�Ct
Complaint number 2013-0129
Complaint type
WQAL
Date received
Problem
WQAI
Date closed
611112013
-4.
+ Address
r
29645 18TH AVE 5 .
r
Parcel
6453450000
Comments
-
�^ Tracker ID
38017.00
tiQ
Zoom to
UPSTREAM ANALYSIS
Runoff from approximately 0.5 acres of the adjacent southern property sheet flows to a depression at
the southeast of the project site that straddles the southern property line. The depression drains to an
existing on -site culvert, which routes the runoff to the municipal storm system in Pacific Hwy S. The
culvert will be reconstructed as part of the proposed development, and the ultimate discharge point
will be maintained in the developed condition.
DOWNSTREAM ANALYSIS
downstream analysis was completed on October 25, 2016
A formal downstream analysis has been completed in accordance with the 2016 Manual. The
. The temperature was approximately 50
degrees, and it was partly sunny. A map of the downstream path and an analysis of this system for
nearly % mile from the site are provided below.
Figure 5 shows the downstream analysis path from the project site to % mile downstream.
NAVIX StorQuest Federal Way
Page 20
TECHNICAL INFORMATION REPORT
Figure 5: Downstream Path
As previously discussed, runoff from the site sheet flows to an existing drainage ditch, which conveys
the runoff to a small depression at the southeast corner of the project site. The depression extends to
the adjacent property to the south and collects runoff from approximately 0.5 acres from the adjacent
parcel. The depression drains to an existing 12" on -site culvert that is routed to the municipal storm
system in Pacific Hwy S via a catch basin in the ROW sidewalk in front of the project site.
T # Photo
1
❑escription
Looking north at the
southwest property
corner.
On -site stormwater
runoff flows from the
on -site drainage ditch
the project site to the
depression at the
southwest property
corner. The
depression discharges
to an existing 12" CMP
culvert with CM
P
riser.
NAVIX StorQuest Federal Way
Page 21
3
4
2
TECHNICAL INFORMATION REPORT
Looking north at the
site driveway on
Pacific Hwy S.
The 12" culvert enters
an existing catch basin
in the ROW along
Pacific Hwy S. Runoff
is routed north along
Pacific Hwy S via a 30"
closed conveyance
pipe•
Looking west at the
intersection of Pacific
Hwy S and S Dash
Point Road.
The municipal system
continues north within
Pacific Hwy S and
turns to flow west in S
Dash Point Road in a
30" conveyance pipe.
Looking north at the
intersection of
Redondo Way S and S
Dash Point Road.
The municipal system
continues west within
S Dash Point Road and
turns to flow north in
Redondo Way S,
where it transitions to
a 36" conveyance
pipe.
NAVIX StorQuest Federal Way
Page 22
TECHNICAL INFORMATION REPORT
Looking south at the
36" culvert outfall to
Redondo Creek.
The municipal system
in Redondo Way S
discharges by means
of a 36" culvert into
Redondo Creek.
Looking north at
Redondo Creek.
Redondo Creek
continues to flow
approximately
downstream to the
mile downstream
location.
TASK 4: DRAINAGE SYSTEM DESCRIPTION AND PROBLEM DESCRIPTIONS
There are no known problems with the drainage paths around the site. No downstream impacts from
the proposed project are anticipated.
TASK 5: MITIGATION OF EXISTING OR POTENTIAL PROBLEMS
No existing or potential problems were identified as discussed in Task 4 above; therefore, additional
mitigation is not warranted.
NAVIX StorQuest Federal Way Page 23
TECHNICAL INFORMATION REPORT
FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN
EXISTING SITE HYDROLOGY
The site is approximately 1.05 acres of a vacant parcel with trees and vegetation. Rockeries extend
along the northern property line and at the toe of the steep slope along the western property line. The
site generally slopes from west 'to east, and sheet flows to a drainage swale. The swale directs runoff
south to the depression at the southeast corner of the project site, where the runoff flows into an
existing culvert and is conveyed to the municipal storm system in Pacific Hwy S.
Approximately 0.5 acres of the adjacent property to the south appears to contribute upstream run-on
to the project site. The adjacent property is vacant and moderately vegetated with significant tree
cover. This run-on flows to the depression at the southeast of the project site and enters into a
culvert. The culvert discharges to the municipal storm system in Pacific Hwy S. The existing pipe will
be reconstructed in the proposed conditions, and this flow path will be maintained. No impacts to the
downstream or upstream conditions are anticipated.
The pre -developed conditions are shown in Table 1 and Figure 6.
Table 1
Area (AC) Description
1.05 Landscape
1.05 Total Basin Area
NAVIX StorQuest Federal Way
Page 24
TECHNICAL INFORMATION REPORT
PERVIOUS SURFACE
1.05 AC
L
. . . .
. . . . . . . . d
. .'. . . . i
Figure 6: Existing Surface Conditions Map
DEVELOPED SITE HYDROLOGY
The project proposes to construct a 3-story plus grade -plane basement, approximately 83,000 SF self -
storage building with associated parking and loading areas, sidewalks, utilities, and stormwater
management facilities. The existing western rockery will be demolished as part of this redevelopment.
Per the 2016 Manual, water quality treatment will be provided for all PGIS prior to infiltration as
specified in Core Requirement #8 and Special Requirement #5. The 0.18 acres of proposed pavement
is considered PGIS and will be routed through a StormFilter 48" Manhole facility prior to the CMP
infiltration facility. Runoff from the 0.02 acres of sidewalks is directed to the pavement and will be also
be routed to the water quality facility. The 0.47 acres of proposed roof area is considered NPGIS and
will be routed directly to the CMP infiltration facility.
See Table 2 and Figure 7 for the Proposed Conditions.
Area (AC)
Table 2
Description
0.20
Pavement and Sidewalks (PGIS)
0.47
Building (NPGIS)
0.38
Landscape (Lawn)
1.05
Total Basin Area
NAVIX StorQuest Federal Way Page 25
TECHNICAL INFORMATION REPORT
®PGIS AREA
0.20
0.20 AG
NPGIS AREA
0.47
0.47 AC
PERVIOUS SURFACE
0.38 AC
I
V� _ .J. V
................
Figure 7: Proposed Surface Conditions Map
FLOW CONTROL FACILITY
A 140 LF 96" perforated CMP pipe was designed to meet Conservation (Level 2) Flow Control Standards
per the 2016 Manual. The CMP facility was designed to infiltrate runoff from the entire site. An
infiltration rate of 3 inches per hour was utilized as recommended in the Geotechnical Engineering
Report Addendum — Stormwater Infiltration and Landslide Hazard Assessment by Terracon
Consultants, Inc., dated March 9, 2017.
The infiltration facility was sized using WWHM2012. The project site was modeled in WWHM with a
single point of compliance (POC #1). The predeveloped conditions were modeled as fully forested.
The developed (mitigated) conditions were modeled as noted in Table 2 with a single basin that routes
to POC #1. The infiltration facility was modeled as a 75' x 18' x 7' vault with a total live storage volume
of 9,450 CF. The WWHM model inputs (Predeveloped Conditions and Developed Conditions) and
model output are described below:
NAVIX StorQuest Federal Way Page 26
TECHNICAL INFORMATION REPORT
PREDEVELOPED CONDITIONS
Name : Predeveloped
Bypass: No
GroundWater: No
Pervious Land Use
Acres
C, Forest, Flat
1.05
Pervious Total
1.05
Impervious Land Use
Acres
Impervious Total
0
Basin Total
1.05
Element Flows To:
Surface Interflow
DEVELOPED CONDITIONS
Project Name: SQ FW_LU_170727
Site Name:
Site Address:
City
Report Date: 7/27/2017
Gage : Seatac
Data Start : 1948/10/01
Data End : 2009/09/30
Precip Scale: 1.00
Version Date: 2016/02/25
Version : 4.2.12
Groundwater
Low Flow Threshold for POC 1 : 50 Percent of the 2 Year
High Flow Threshold for POC 1: 50 year
MITIGATED LAND USE
Name : Developed
Bypass: No
GroundWater: No
Pervious Land Use acre
NAVIX StorQuest Federal Way Page 27
TECHNICAL INFORMATION REPORT
C, Lawn, Flat
.38
Pervious Total
0.38
Im ervious Land Use
acre
ROADS FLAT
0.2
ROOF TOPS FLAT
0.47
Impervious Total
0.67
Basin Total
1.05
Element Flows To:
Surface Interflow Groundwater
CMP Facility CMP Facility
Name : CMP Facility
Width 18 ft.
Length : 75 ft.
Depth: 7 ft.
Infiltration On
Infiltration rate: 3
Infiltration safety factor: 1
Total Volume Infiltrated (ac-ft.): 135.4
Total Volume Through Riser (ac-ft.): 0
Total Volume Through Facility (ac-ft.): 135.4
Percent Infiltrated: 100
Total Precip Applied to Facility: 0
Total Evap From Facility: 0
Discharge Structure
Riser Height: 6.5 ft.
Riser Diameter: 12 in.
Element Flows To:
Outlet 1 Outlet 2
Flow Frequency Return Periods for Predeveloped. POC #1
Return Period
Flow(cfs)
2 year
0.030871
5 year
0.048484
10 year
0.058466
25 year
0.06904
50 year
0.075584
100 year
0.081149
Flow Frequency
Return Periods for Mitigated. POC #1
Return Period
Flow(cfs)
2 year
0
5 year
0
10 year
0
25 year
0
50 year
0
100 year
0
NAVIX
StorQuest Federal Way Page 28
TECHNICAL INFORMATION REPORT
Vault
Hydraulic
Table
Stage(feet)
Area(ac.)
volume(ac-ft.) Discharae(efs)
Infilt(cfs)
0.0000
0.031
0.000
0.000
0.000
0.0778
0.031
0.002
0.000
0.093
0.1556
0.031
0.004
0.000
0.093
0.2333
0.031
0.007
0.000
0.093
0.3111
0.031
0.009
0.000
0.093
0.3889
0.031
0.012
0.000
0.093
0.4667
0.031
0.014
0.000
0.093
0.5444
0.031
0.016
0.000
0.093
0.6222
0.031
0.019
0.000
0.093
0.7000
0.031
0.021
0.000
0.093
0.7778
0.031
0.024
0.000
0.093
0.8556
0.031
0.026
0.000
0.093
0.9333
0.031
0.028
0.000
0.093
1.0111
0.031
0.031
0.000
0.093
1.0889
0.031
0.033
0.000
0.093
1.1667
0.031
0.036
0.000
0.093
1.2444
0.031
0.038
0.000
0.093
1.3222
0.031
0.041
0.000
0.093
1.4000
0.031
0.043
0.000
0.093
1.4778
0.031
0.045
0.000
0.093
1.5556
0.031
0.048
0.000
0.093
1.6333
0.031
0.050
0.000
0.093
1.7111
0.031
0.053
0.000
0.093
1.7889
0.031
0.055
0.000
0.093
1.8667
0.031
0.057
0.000
0.093
1.9444
0.031
0.060
0.000
0.093
2.0222
0.031
0.062
0.000
0.093
2.1000
0.031
0.065
0.000
0.093
2.1778
0.031
0.067
0.000
0.093
2.2556
0.031
0.069
0.000
0.093
2.3333
0.031
0.072
0.000
0.093
2.4111
0.031
0.074
0.000
0.093
2.4889
0.031
0.077
0.000
0.093
2.5667
0.031
0.079
0.000
0.093
2.6444
0.031
0.082
0.000
0.093
2.7222
0.031
0.084
0.000
0.093
2.8000
0.031
0.086
0.000
0.093
2.8778
0.031
0.089
0.000
0.093
2.9556
0.031
0.091
0.000
0.093
3.0333
0.031
0.094
0.000
0.093
3.1111
0.031
0.096
0.000
0.093
3.1889
0.031
0.098
0.000
0.093
3.2667
0.031
0.101
0.000
0.093
3.3444
0.031
0.103
0.000
0.093
3.4222
0.031
0.106
0.000
0.093
3.5000
0.031
0.108
0.000
0.093
3.5778
0.031
0.110
0.000
0.093
3.6556
0.031
0.113
0.000
0.093
3.7333
0.031
0.115
0.000
0.093
3.8111
0.031
0.118
0.000
0.093
3.8889
0.031
0.120
0.000
0.093
3.9667
0.031
0.122
0.000
0.093
4.0444
0.031
0.125
0.000
0.093
4.1222
0.031
0.127
0.000
0.093
NAVIX
StorQuest Federal Way Page 29
TECHNICAL INFORMATION REPORT
4.2000
0.031
0.130
0.000
0.093
4.2778
0.031
0.132
0.000
0.093
4.3556
0.031
0.135
0.000
0.093
4.4333
0.031
0.137
0.000
0.093
4.5111
0.031
0.139
0.000
0.093
4.5889
0.031
0.142
0.000
0.093
4.6667
0.031
0.144
0.000
0.093
4.7444
0.031
0.147
0.000
0.093
4.8222
0.031
0.149
0.000
0.093
4.9000
0.031
0.151
0.000
0.093
4.9778
0.031
0.154
0.000
0.093
5.0556
0.031
0.156
0.000
0.093
5.1333
0.031
0.159
0.000
0.093
5.2111
0.031
0.161
0.000
0.093
5.2889
0.031
0.163
0.000
0.093
5.3667
0.031
0.166
0.000
0.093
5.4444
0.031
0.168
0.000
0.093
5.5222
0.031
0.171
0.000
0.093
5.6000
0.031
0.173
0.000
0.093
5.6778
0.031
0.176
0.000
0.093
5.7556
0.031
0.178
0.000
0.093
5.8333
0.031
0.180
0.000
0.093
5.9111
0.031
0.183
0.000
0.093
5.9889
0.031
0.185
0.000
0.093
6.0667
0.031
0.188
0.000
0.093
6.1444
0.031
0.190
0.000
0.093
6.2222
0.031
0.192
0.000
0.093
6.3000
0.031
0.195
0.000
0.093
6.3778
0.031
0.197
0.000
0.093
6.4556
0.031
0.200
0.000
0.093
6.5333
0.031
0.202
0.064
0.093
6.6111
0.031
0.204
0.389
0.093
6.6889
0.031
0.207
0.838
0.093
6.7667
0.031
0.209
1.318
0.093
6.8444
0.031
0.212
1.736
0.093
6.9222
0.031
0.214
2.029
0.093
7.0000
0.031
0.216
2.203
0.093
7.0778
0.031
0.219
2.394
0.093
7.1556
0.000
0.000
2.550
0.000
Stream Protection Duration
POC #1
The Facility PASSED
The Facility PASSED.
Flow(cfs) Predev Mit Percentage Pass/Fail
0.0154
17567
0
0
Pass
0.0160
16166
0
0
Pass
0.0167
14964
0
0
Pass
0.0173
13860
0
0
Pass
0.0179
12818
0
0
Pass
0.0185
11813
0
0
Pass
0.0191
10898
0
0
Pass
0.0197
10123
0
0
Pass
NAVIX
StorQuest Federal Way Page 30
0.0203 9388 0 0 Pass TECHNICAL INFORMATION REPORT
`
0.0209 8733 0 0
0.0215 8143 p Pass
p Pass
0.0221 7602 0 0 Pass
0.0227 7063 0 0
0.0233 6590 p Pass
0 Pass
0.0239 6145 p
0 Pass
0.0245 5781 p
p Pass
0.0252 5433 0 0
Pass
0.0258
5099 0 0 Pass
0.0264 4808 0 0
0.0270 4528 p Pass
p Pass
0.0276 4254 0 0 Pass
0.0282 4017 0 0
0.0288 3782 p Pass
p Pass
0.0294 3551 0 0 Pass
0.0300 3339 0 0
0.0306 3138 p Pass
0 Pass
0.0312 2950 p
0.0318 2787 p 0 Pass
0 Pass
0.0324 2599
0 p Pass
0.0331 2447 0 0
0.0337 2304 p Pass
0 Pass
0.0343 2162 p
0 Pass
0.0349 2027 p
0 Pass
0.0355 1898 p
p Pass
0.0361 1790 0 0
0.0367 1687 Pass
0 p Pass
0.0373 1587 0 0
0.0379 1483 p Pass
p Pass
0.0385 1379 0 0 Pass
0.0391 1292 0 0
0.0397 1221 p Pass
0 Pass
0.0403 1155 p
0 Pass
0.0410 1098 p
0.0416 1048 p 0 Pass
0 Pass
0.0422 997 p
0.0428 930 0 Pass
0 p Pass
0.0434 883 p p
0.0440 837 p Pass
0.0446 789 p Pass
0 p Pass
0.0452 743 0 0
0.0458 713 Pass
p 0 Pass
0.0464 668 0 0
0.0470 631 Pass
0 0 Pass
0.0476 596 0 0 Pass
0.0482 565 0 0 Pass
0.0489 539 0 0
0.0495 497 p Pass
0.0501 473 0 Pass
p 0 Pass
0.0507 434 0 0
0.0513 399 p Pass
0.0519 366 0 Pass
p p Pass
0.0525 348 0 0 Pass
0.0531 323 0 0 Pass
0.0537 296 0 0 Pass
NAVIX StorQuest Federal Way
Page 31
TECHNICAL INFORMATION REPORT
0.0543
272
0
0
0.0549
256
0
Pass
0.0555
235
0
0
Pass
0.0561
217
0
0
Pass
0.0567
195
0
0
Pass
0.0574
180
0
0
Pass
0.0580
158
0
0
Pass
0.0586
145
0
0
Pass
0.0592
129
0
0
Pass
0.0598
119
0
0
Pass
0.0604
109
0
0
Pass
0.0610
97
0
0
Pass
0.0616
91
0
0
Pass
0.0622
82
0
0
Pass
0.0628
76
0
0
Pass
0.0634
69
0
0
Pass
0.0640
61
0
0
Pass
0.0646
54
0
0
Pass
0.0653
48
0
0
Pass
0.0659
41
0
0
Pass
0.0665
38
0
0
Pass
0.0671
33
0
0
Pass
0.0677
27
0
0
Pass
0.0683
22
0
0
Pass
0.0689
21
0
0
Pass
0.0695
20
0
0
Pass
0.0701
19
0
0
Pass
0.0707
17
0
0
Pass
0.0713
13
0
0
Pass
0.0719
12
0
0
Pass
0.0725
g
0
0
Pass
0.0732
4
0
0
Pass
0.0738
3
0
0
Pass
0.0744
3
0
0
Pass
0.0750
3
0
0
Pass
0.0756
3
0
0
Pass
0
Pass
CMP INFILTRATION FACILITY
A 142 LF 96" perforated CMP infiltration facility has been designed by Contech that will provide 9,466
CF of storage volume, which meets the required storage volume of 9,450 CF. To account for flows
larger than the 100-year peak, the infiltration facility includes an emergency overflow structure, which
connects to the municipal system in Pacific Hwy S.
A summary of the CMP infiltration facility sizing has been provided below:
NAVIX StorQuest Federal Way
Page 32
TECHNICAL INFORMATION REPORT
ASSEAAELY
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DYODS' 28431-01-D
PROJECTNRME-574rOutril
Federal way. WA SM3
0ESCRiPV0N;CMFSYS7EM Di
WATER QUALITY FACILITY
This project is subject to the Enhanced Water Quality requirements. Per Exception 2 of Section 1.2.8.1
of the 2016 Manual, the Enhanced Basic WQ menu may be reduced to the Basic WQ menu for
treatment of any runoff that is infiltrated per Section 5.2 of the 2016 Manual. Full infiltration of on -
site runoff is proposed for this project in accordance with Section S.2, and soil infiltration properties
will be confirmed by the geotechnical engineer in accordance with the requirements of the 2016
Manual. Therefore, this project will be subject only to the basic water quality treatment menu.
Basic water quality treatment will be provided by means of a StormFilter 48" Manhole facility. The
runoff from pollution -generating parking lot surface will be routed to a StormFilter 48" Manhole
facility for water quality treatment prior to entering the CMP infiltration facility.
The water quality design flow for preceding detention is equal to 91% of the developed water quality
volume, as determined using WWHM2012. The PGIS has been See below for a summary of the
WWHM2012 input and output:
Project Name:sm_WQ 170727
Site Name:
Site Address:
City
Report Date: 7/27/2017
NAVIX StorQuest Federal Way
Page 33
TECHNICAL INFORMATION REPORT
Gage : Seatac
Data Start : 1948/10/01
Data End : 2009/09/30
Precip Scale: 1.00
Version Date: 2016/02/25
Version : 4.2.12
Low Flow Threshold for POC 1 : 50 Percent of the 2 Year
High Flow Threshold for POC 1: 50 year
PREDEVELOPED LAND USE
Name : Predeveloped
Bypass: No
GroundWater: No
Pervious Land Use acre
C, Forest, Flat .2
Pervious Total 0.2
impervious Land Use acre
Impervious Total U
Basin Total 0.2
Element Flows To:
Surface Interflow
MITIGATED LAND USE
Name : Basin 1
Bypass: No
GroundWater: No
Pervious Land Use acre
Pervious Total U
Impervious Land Use acre
ROADS FLAT 0.2
Impervious Total 0.2
Basin Total 0.2
Groundwater
NAVIX StorQuest Federal Way Page 34
TECHNICAL INFORMATION REPORT
Element Flows To:
Surface Interflow
ANALYSIS RESULTS
Stream Protection Duration
Predeveloped Landuse Totals for POC #1
Total Pervious Area:0.2
Total Impervious Area:O
Mitigated Landuse Totals for POC #1
Total Pervious Area:O
Total Impervious Area:0.2
Flow Frequency Return Periods for
Return Period
Flow(cfs)
2 year
0.00588
5 year
0.009235
10 year
0.011136
25 year
0.013151
50 year
0.014397
100 year
0.015457
Groundwater
Predeveloped. POC #1
Flow Frequency Return Periods for Mitigated. POC #1
Return Period
Flow(cfs)
2 year
0.076253
5 year
0.096316
10 year
0.109948
25 year
0.12763
Sear
0.141164
1100 year
0.155026
Water Quality BMP Flow and Volume for POC #1
on-line facility volume: 0.0246 acre-feet
on-line facility target flow: 0.0324 cfs
Adjusted for 15 min: 0.0324 cfs.
Off-line facility target flow: 0.0183 cfs.
Adjusted for 15 min: 0.0183 cfs.
The Storm Filter 48" Manhole was sized to accommodate the on-line water quality flow rate, per
Department of Ecology's GULD approval. The Storm Filter has an internal bypass with a capacity of 1.0
cfs, which is larger than the 100-year developed peak flow rate of the tributary area that is routed to
the Storm Filter facility (0.1550 cfs). A summary of the Storm Filter 48" Manhole facility design and
sizing estimate is provided below:
NAVIX StorQuest Federal Way Page 35
TECHNICAL INFORMATION REPORT
PLAN VIEW
CARTPoDGES AND FLOW IUT NOT SHOWN
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ELEVATION NEW
100-YEAR FLOOD/OVERFLOW CONDITION
SECTION A -A
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Review of the most recent FIRM maps indicates that the development area on the project site does not
lie within the 100-year flood plain. The portion of FIRM containing the subject property is included
below.
NAVIX StorQuest Federal Way Page 36
TECHNICAL INFORMATION REPORT
High Flow Threshold for POC 1: 50 year
PREDEVELOPED LAND USE
Name : Basin 1
Bypass: No
GroundWater: No
Pervious Land Use
acre
C, Forest, Flat
1.05
Pervious Total
1.05
Impervious Land Use
acre
Impervious Total
0
Basin Total
1.05
Element Flows To:
Surface Interflow Groundwater
MITIGATED LAND USE
Name : Predeveloped
Bypass: No
GroundWater: No
Pervious Land Use
acre
C, Lawn, Flat
•38
Pervious Total
0.38
Impervious Land Use
acre
ROADS FLAT
0.2
ROOF TOPS FLAT
0.47
Impervious Total
0.67
Basin Total
1.05
ANALYSIS RESULTS
Stream Protection Duration
Predeveloped Landuse Totals for POC #1
Total Pervious Area:1.05
Total Impervious Area:O
NAVIX StorQuest Federal Way Page 38
TECHNICAL INFORMATION REPORT
Mitigated Landuse Totals for POC #1
Total Pervious Area:0.38
Total Impervious Area:0.67
Flow Frequency Return Periods for Predeveloped.
Return Period
Flow(cfs)
2 year
0.030871
5 year
0.048484
10 year
0.058466
25 year
0.06904
50 year
0.075584
100 year
0.081149
Flow Frequency Return Periods for Mitigated.
Return Period
Flow(cfs)
2 year
0.280022
5 year
0.363783
10 year
0.421937
25 year
0.498664
50 year
0.558271
100 year
0.620043
Manning's Calculation
Twelve -Inch Pipe
set units: I m I rnm I ft I in
12
Pipe diameter, do
in v
Manning roughness, n ? 0.013
Pressure slope (possibly ? equal to 1 _005
pipe slope), So rise/run
Percent of (or ratio toy full depth 95_83333
(100% or 1 if flowing fully % r,
POC #1
POC #1
Results
Flow, Q
2.7005
cfs
yews-ity, v
3.4883
ftlsec
Velocity head, h„
2.2694
in E
Flow area
111.4851
sq. in_
Wetted perimeter
32.7655
in
Hydraulic radius
3.4025
in
Top width, T
4.7958
in
Froude number, F
0.44
Shear stress (tractive
force), tau
02992
psf
Figure 9: Manning's Calculation for Six -Inch Pipe
NAVIX StorQuest Federal Way Page 39
TECHNICAL INFORMATION REPORT
SPECIAL REPORTS AND STUDIES
Special reports and studies for this property include the following (See Appendix Q
• Geotechnical Engineering Report by Terracon Consultants, Inc., dated January 11, 2017
■ Geotechnical Engineering Report Preliminary Stormwater Infiltration Addendum by Terracon
Consultants, Inc., dated February 3, 2017
• Geotechnical Engineering Report Addendum — Stormwater Infiltration and Landslide Hazard
Assessment by Terracon Consultants, Inc., dated March 9, 2017
NAVIX StorQuest Federal Way Page 40
TECHNICAL INFORMATION REPORT
OTHER PERMITS
Other permits required for this project include the following:
■ Utility Developer Extension through Lakehaven Utility District
Commercial Building Permit and building -related permits, including Engineering Review
■ Type III Land Use Review with SEPA Environmental Review
• NPDES
NAVIX StorQuest Federal Way Page 41
TECHNICAL INFORMATION REPORT
CSWPP ANALYSIS AND DESIGN
ESC Plan Analysis and Design (Part A)
All erosion and sediment control measures shall be governed by the requirements of the King County.
A temporary erosion and sedimentation control plan has been prepared to assist the contractor in
complying with these requirements. The Erosion and Sediment Control (ESC) plan is included with the
construction plans.
1. Erosion Risk Assessment
The degree of erosion risk on the proposed project site is minimal. The following factors contribute to
a low degree of erosion risk:
• Slope across the site is slight to moderate. Runoff will not travel at high velocities across the
site and, therefore, will not cause noticeable erosion impacts.
■ The site is already stabilized with hard surfaces and the portions that will be removed will
generally create temporary closed depression areas that will trap stormwater runoff.
2. Construction Sequence and Procedure
The proposed development will include an erosion/sedimentation control plan designed to prevent
sediment -laden run-off from leaving the site during construction. The erosion potential of the site is
influenced by four major factors: soil characteristics, vegetative cover, topography and climate.
Erosion/sedimentation control is achieved by a combination of structural measures, cover measures,
and construction practices that are tailored to fit the specific site.
Prior to the start of any grading activity upon the site, all erosion control measures, including stabilized
construction entrances, shall be installed in accordance with the construction documents.
The best construction practice will be employed to properly clear and grade the site and to schedule
construction activities. The planned construction sequence for the construction of the site will be
provided with a subsequent submittal.
3. Trapping Sediment
Structural control measures will be used to reduce erosion and retain sediment on the construction
site. The control measures will be selected to fit specific site and seasonal conditions.
The following structural items will be used to control erosion and sedimentation processes:
• Compost Socks
• Filter fabric fences
• Catch Basin Inlet Sediment Protection
• Proper Cover measures
• Sediment Trap
The proposed sediment trap was designed in accordance with the 2016 Manual. The required surface
area is:
Required Surface Area = 2 * (2 year peak developed flow) / 0.00096 = 2 * (0.3241 cfs)/0.00096 = 675 SF
NAVIX StorQuest Federal Way Page 42
TECHNICAL INFORMATION REPORT
Weekly inspection of the erosion control measures will be required during construction. Any sediment
buildup shall be removed and disposed of off -site.
Vehicle tracking of mud off -site shall be avoided. Installation of a stabilized construction entrance will
be installed at a location to enter the site. The entrances are a minimum requirement and may be
supplemented if tracking of mud onto public streets becomes excessive. In the event that mud is
tracked off site, it shall be swept up and disposed of off -site on a daily basis. Depending on the
amount of tracked mud, a vehicle road sweeper may be required.
Because vegetative cover is the most important form of erosion control, construction practices must
adhere to stringent cover requirements. More specifically, the contractor will not be allowed to leave
soils open for more than 14 days and, in some cases, immediate seeding will be required.
4. Wet Weather TESC Operating Plan
Work between October 1st and April 30th must adhere to the Wet Season Special Provisions noted in
Section D.5.2 in Appendix D of the 2016 KCSWDM.
SWPPS Plan Design (Part B)
A variety of storm water pollutant controls are recommended for this project. Some controls are
intended to function temporarily and will be used as needed for pollutant control during the
construction period. These include temporary sediment barriers such as silt fences. For most
disturbed areas, permanent stabilization will be accomplished by covering the soil with pavement,
building, or vegetation.
The CSWPPP Worksheet Forms are located in Appendix D.
A. Erosion and Sediment Controls
1. Soil Stabilization - The purpose of soil stabilization is to prevent soil from leaving
the site. In the natural condition, soil is stabilized by native vegetation. The
primary technique to be used at this project for stabilizing site soil will be to
provide a protective cover of grass, pavement, or building.
a) See 2016 KCSWDM Section D.3.2.6 for Temporary and Permanent
Seeding requirements.
b) Structural Controls — See construction plans for the T.E.S.C. Plan, D-2.0.
Inlet protection and silt fence are proposed to minimize siltation of
construction activities.
c) Silt Fence — Silt fence is a synthetic permeable mesh fabric typically
incorporating wooden support stakes at intervals sufficient to support
the fence and water and sediment retained by the fence. Silt fence is
also available with a wire mesh backing. The fence is designed to retain
sediment -laden water to allow settlement of suspended soils before
filtering through the mesh fabric for discharge downstream. Silt fence
shall be located to capture overland, low -velocity sheet flows as follows:
provide silt fence along the perimeter of the disturbed area, this site
NAVIX StorQuest Federal Way Page 43
TECHNICAL INFORMATION REPORT
does not contain sloped area that would warrant additional silt fencing.
Install silt fence at a fairly level grade (along the contour) to provide
sufficient upstream storage volume for the anticipated runoff.
d) Construction Entrance — All access points from the public street into the
construction site shall include a construction entrance composed of
course stone to the dimensions shown on the T.E.S.C. Plan, D-2.0. The
rough texture of the stone helps to remove clumps of soil adhering to
construction vehicle tires through the action of vibration and jarring
over the rough surface and the friction of the stone matrix against soils
attached to vehicle tires.
e) Clearing Limits — Clearing limits are defined by the placement of silt
fence or construction fence.
fl Storm Drain Inlet Protection — Curb and grated inlets are protected from
the intrusion of silt and sediment through a variety of measures as
shown on the Construction Drawings. The primary mechanism is to
place controls in the path of flow sufficient to slow sediment -laden
water to allow settlement of suspended soils before discharging into the
storm sewer. Controls typically provide a secondary benefit by means
of filtration. Grated inlets typically include a sturdy frame wrapped in
silt fence or crushed stone -lined perimeter to slow the flow of water.
Curb inlets typically include crushed stone barriers held in place with silt
fence material or geotextile fabric. Where inlets are located in paved
areas the contractor shall install filter fabric in the catch basin.
See 2016 KCSWDM Section D.5.5 for Final Stabilization requirements.
B. Other Pollutant Controls
Control of sediments has been described previously. Other aspects of this SWPPP are
listed below:
Dust Control - Construction traffic must enter and exit the site at the stabilized
construction entrance. The purpose is to trap dust and mud that would otherwise
be carried off -site by construction traffic.
Water trucks will be used as needed during construction to reduce dust generated
on the site. Dust control must be provided by the General Contractor to a degree
that is acceptable to the owner, and in compliance with applicable local and state
dust control regulations. After construction, the site will be stabilized (as
described elsewhere), which will reduce the potential for dust generation.
Chemical treatments have not been approved for this site. The Civil Engineer of
Record must be contacted if these are requested to be utilized.
2. Solid Waste Disposal - No solid materials, including building materials, are allowed
to be discharged from the site with stormwater. All solid waste, including
NAVIX StorQuest Federal Way Page 44
TECHNICAL INFORMATION REPORT
disposable materials incidental to the major construction activities, must be
collected and placed in containers. The containers will be emptied as necessary by
a contract trash disposal service and hauled away from the site. The location of
solid waste receptacles shall be shown on the T.E.S.C. Plan, D-2.0.
Substances that have the potential for polluting surface and/or groundwater must
be controlled by whatever means necessary in order to ensure that they do not
discharge from the site. As an example, special care must be exercised during
equipment fueling and servicing operations. If a spill occurs, it must be contained
and disposed so that it will not flow from the site or enter groundwater, even if
this requires removal, treatment, and disposal of soil. In this regard, potentially
polluting substances should be handled in a manner consistent with the impact
they represent.
3. Sanitary Facilities - All personnel involved with construction activities must comply
with state and local sanitary or septic system regulations. Temporary sanitary
facilities will be provided at the site throughout the construction phase. They
must be utilized by all construction personnel and will be serviced by a commercial
operator. The location of sanitary facilities shall be shown on T.E.S.C. Plan, D-2.0.
4. Water Source - Non -storm water components of site discharge must be clean
water. Water used for construction which discharges from the site must originate
from a public water supply or private well approved by the State Health
Department. Water used for construction that does not originate from an
approved public supply must not discharge from the site.
5. Concrete Waste from Concrete Ready -Mix Trucks — Discharge of excess or waste
concrete and/or wash water from concrete trucks will be allowed on the
construction site, but only in specifically designated diked areas that have been
prepared to prevent contact between the concrete and/or wash water and storm
water that will be discharged from the site. Waste concrete can be placed into
forms to make riprap or other useful concrete products. The cured residue from
the concrete washout diked areas shall be disposed in accordance with applicable
state and federal regulations. The jobsite superintendent is responsible for
assuring that these procedures are followed. The location of concrete washout
areas shall be shown on the T.E.S.C. Plan, D-2.0.
6. Fuel Tanks — Temporary on -site fuel tanks for construction vehicles shall meet all
state and federal regulations. Tanks shall have approved spill containment with
the capacity required by the applicable regulations. The tank shall be in sound
condition free of rust or other damage which might compromise containment.
Hoses, valves, fittings, caps, filler nozzles, and associated hardware shall be
maintained in proper working condition at all times.
Temporary on -site fuel tanks are not proposed for this project at this time.
7. Hazardous Waste Management and Spill Reporting Plan — Any hazardous or
potentially hazardous waste that is brought onto the construction site will be
handfed properly in order to reduce the potential for storm water pollution. All
NAVIX StorQuest Federal Way Page 45
TECHNICAL INFORMATION REPORT
materials used on this construction site will be properly stored, handled and
dispensed following any applicable label directions. Material Safety Data Sheets
(MSDS) information will be kept on site for any and all applicable materials.
Should an accidental spill occur, immediate action will be undertaken by the
General Contractor to contain and remove the spilled material. All hazardous
materials will be disposed of by the Contractor in the manner specified by local,
state, and federal regulations and by the manufacturer of such products. As soon
as possible, the spill will be reported to the appropriate state and local agencies.
As required under the provisions of the Clean Water Act, any spill or discharge
entering the waters of the United States will be properly reported. The General
Contractor will prepare a written record of any such spill and will provide notice to
the Owner within 24-hours of the occurrence of the spill.
Any spills of petroleum products or hazardous materials in excess of Reportable
Quantities as defined by EPA or the state or local agency regulations, shall be
immediately reported to the EPA National Response Center (1-800-424-8802) and
the Washington State Department of Ecology at (360) 407-6300 or 1-800-258-
5990. The reportable quantity for petroleum products is per the State of
Washington is any amount that contacts public waterways or public storm systems
OR equal to or greater than 1 gallon on a commercial project that does not contact
public water systems such as creeks, rivers, lakes, or storm systems and must be
reported within 24 hours.
The EPA guidelines define spills within the public water systems as those that:
violate applicable water quality standards; cause a film or "sheen" upon, or
discoloration of the surface of the water or adjoining shorelines; or cause a sludge
or emulsion to be deposited beneath the surface of the water or upon adjoining
shorelines. The reportable quantity for hazardous materials is per the
Comprehensive Environmental Response, Compensation and Liability Act
(CERCLA), and is any hazardous substance with reportable quantity that appears in
Table 302.4of 40 CFR parts 302, for other substance not found on this list, the
reportable quantity is one pound.
In order to minimize the potential for a spill of hazardous materials to come in
contact with stormwater, the following steps will be implemented:
a) All materials with hazardous properties (such as pesticides, petroleum
products, fertilizers, detergents, construction chemicals, acids, paints,
paint solvents, cleaning solvents, additives for soil stabilization,
concrete, curing compounds and additives, etc.) will be stored in a
secure location, under cover, when not in use.
b) The minimum practical quantity of all such materials will be kept on the
job site and scheduled for delivery as close to time of use as practical.
c) A spill control and containment kit (containing for example, absorbent
such as kitty litter or sawdust, acid neutralizing agent, brooms, dust
pans, mops, rags, gloves, goggles, plastic and metal trash containers,
NAVIX StorQuest Federal Way Page 46
TECHNICAL INFORMATION REPORT
etc.) will be provided at the storage site.
d) All of the product in a container will be used before the container is
disposed of. All such containers will be triple rinsed, with water prior to
disposal. The rinse water used in these containers will be disposed of in
a manner in compliance with state and federal regulations and will not
be allowed to mix with storm water discharges.
e) All products will be stored in and used from the original container with
the original product label,
fl All products will be used in strict compliance with instructions on the
product label.
9) The disposal of excess or used products will be in strict compliance with
instructions on the product label.
8. Long -Term Pollutant Controls - Storm water pollutant control measures installed
during construction, that will also provide benefits after construction, will not be
applicable to this project since most of the pollution control measures are already
in place. Those sediment barriers that do not interfere with normal operations
and appear to provide long-term benefits can be left in place after construction is
completed.
9. Source Controls — Per Section 1.3.4 of the 2016 KCSWDM, structural source control
measures, such as car was pads or dumpster area roofing, shall be applied to the
entire site containing the proposed project, not just the project site. Dumpster
area roofing is proposed as a structural source control for this project.
B. Construction Phase "Best Management Practices"
During the construction phase, the General Contractor shall implement the following
measures:
1• Materials resulting from the clearing and grubbing or excavation operations shall
be stockpiled up slope from adequate sedimentation controls. Materials removed
to an off -site location shall be protected with appropriate controls and properly
permitted.
2. The General Contractor shall designate areas on the T.E.S.C. Plan, D-2.0 for
equipment cleaning, maintenance, and repair. The General Contractor and
subcontractors shall utilize such designated areas. Cleaning, maintenance, and
repair areas shall be protected by a temporary perimeter berm, shall not occur
within 150 feet away of any waterway, and in areas located as far as practical from
storm drains.
3. Use of detergents for large scale washing is prohibited (i.e., vehicles, buildings,
pavement surfaces, etc.)
4. Chemicals, paints, solvents, fertilizers, and other toxic materials must be stored in
weatherproof containers. Except during application, the contents must be kept in
NAVIX StorQuest Federal Way
Page 47
TECHNICAL INFORMATION REPORT
trucks or within storage facilities. Runoff containing such material must be collected,
removed from the site, treated, and disposed at an approved :solid waste or chemical
disposal facility.
C. Off -Site Facilities
Whenever dirt, rock, or other materials are imoorted to the construction site or ex ❑rted
for placement in areas off of the primary construction site, the Gems ral Contractor is
responsible for determining that all stormwater permitting and pollution control
requirements are met for each and every site which receives such materials or from which
such materials are taken. Prior to the disturbance of any such site, the General Contractor
will furnish the Owner with a copy of the storm water permit issued for each such site, as
well as a copy of the off -site Owners certification statement agreeing to implement
necessary storm water pollution prevention measures. The General Contractor will also
furnish a copy of the SWPPP for each such site, including a description of the erosion
control measures, which will be applied.
At a minimum, each off -site area that provides or receives materials or is disturbed by
project activities must implement erosion control measures consisting of perimeter
controls on all down slope and side slope boundaries and must also provide for botf�
temporary stabilization measures and for permanent re -vegetation after all disturbance is
ended.
BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT
The following items are provided in this section:
■ Stormwater See A Facility Summary Sheet
� i ppendix A for Proposed Conditions Exhibit)
Site Improvement Bond Quantity Worksheet
The following item will be provided in a future submittal:
• Declaration of Covenant for Maintenance and Inspection of Flow Control BMPs
NAVIX StorQuest Federal Way
Page 48
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Public Works De artment
BOND QUANTITIES WORKSHEET
Project Name: StorQuest Self -Storage
ect No.: 17-103635-00-CO
Site Address: 29600 PE
Fill in those items which I
return to the Public Work
ROAD CONSTRUCTION
Clearing & Grubbing
Sawcutting
Excavation & Embankment
AC Pavement
CSTC
Cement Concrete Curb/Gutter
Extruded Asphalt Curb
Concrete Sidewalk
Concrete driveway approach
Monument in case
Adjust ex. monument to grade
Adjust ex. CB to grade
DRAINAGE PIPE
6" Pipe
8" Pipe
12" Pipe
18" Pipe
24" Pipe
36" Pipe
48" Pipe
54" Pipe
60" Pipe
72" Pipe
CATCH BASINS
Inlet & Grate
CB Type I & Grate
CB Type II 48" & Grate
CB Type II 54" & Grate
CB Type II 60" & Grate
CB Type II 72" & Grate
CB Type II 84" & Grate
CB Type II 96" & Grate
Round solid locking lid
Abandon existing cb
LS
LF
CY
TN
TN
LF
LF
SY
SY
EA
EA
EA
LF
LF
LF
LF
LF
LF
LF
LF
LF
LF
Me
1.30
163
18.00
70.00
10
20.00
2.5
15.00
57
5.00
45.00 21
155.00
12.0[
28.00
44.00
44.00
101.0C
94.00
117.00
143.00
235.00
EA
475.00
EA
900.00
EA
1900.00
EA
2000.00
EA
3200.00
EA
5000.00
EA
9100.00
EA Bid Estim;
EA 360.
EA 325.
$211.9C
$0.00
$700.00
$50.00
f$00:
5.00
00
$125.00
$945.00
$0.00
$0.00
$0.00 ,
$0.00
$0.00
$0.00
$0.00
$0.00
$0.00
$0.00
$0.00
$0.00
$0.00
$a 00
$0, 00
$0.00
$0.00
$0.00
$0 000
Em
B:IWashingtonlFederal Way1William Warren Groupl4ConstructionlCost EstimatelFW Bond Quantities WOorksheet Excel Spreadshee
Last Revised. txls
Page 1
CITY OF
.� Federal Way
Fill in those items which pertain to this project and
return to the Public Works Department.
RETENTION/DETENTION CONTROL
Pond Excavation & Spillway
CY
Restrictor/Separator
EA
Vault
EA
Gravel Access Road
LF
Rip Rap Outfall Protection
CY
Bollards
EA
Fencing (around pond)
LF
Infiltration Trench w/12" Perf
LF
Flow Spreader
LF
Trash Racks
EA
WATER QUALITY
Bioswale
EA
Bid
Wetvault
EA
Bid
Stormfilter Vault
EA
Bid
Stormwater wetland
EA
Bid
Sand Filter
EA
Bid
Catch basin inserts
EA
Oil/Water Separator
EA
Bid
High Flow Bypass
EA
Bid
RETAINING WALLS & STRUCTURES
Retaining Walls SF
Bridges LS
7,
750.
15.00
17.00
500.00
12.00
18.00
20.00
Public Works De artment
Public Roadway
Improvements
$0.00
$0.00
$0.00
$0.00
$0.00
$0.00
$0.00
$0.00
$0.00 .
23.001 $0.00
Bid Estimate,
TRAFFIC & LIGHTING
Signalization LS
Channelization Bid
LS Bid
Signs
EA
Streetlights (City Center) EA
Streetlights (Standard) EA
RIGHT-OF-WAY LANDSCAPING
Street Trees EA
Sod 300.00 4 $1,200.00
Shrubs (City Center) SY 10.00 21
EA $210.00
Tree Grates (City Center) EA 6.00 $0.00
700.00j _ $0.00
Private On -Site
Improvements
B IWashingtonlFederal WaylWilliam Warren Groupl4ConstructionlCost EstimatelFW Bond Quantities Worksheet Excel Spreadsheet.xls
Last Revised:
Page 2
V:�kC17Y OF
Federal Way
Fill in those items which pertain to this project and
return to the Public Works Department.
SITE STABILIZATIpN/EROSION CONTROL
Quarry Spalls
TN
Seeding/Mulch
Acre
Silt Fence
LF
Netting Jute Mesh
SY
Sediment Pond Standpipe
EA
Sensitive Area Fencing
LF
Catch basin inserts
EA
Signature
�l
Navix En ineerin
Company Name
Public Works Deartment
Public Roadway
Improvements
75.00
3000.00
4.00
13.00
200.00
3.00
70.00
Subtotal
..A..
$0.00
$0.00
$0.00
$0.00
$0.00
$210.00
9/13/2017
Date
425-453-9501
Tel—e— pI
Private On -Site
Improvements
Quantity Price
1N76200
000
300
40
000Subtotal.�..0
The following information will be completed by the City of Federal Way Public Works Department:
Public Roadway Improvements (Subtotal "A"):
Private Erosion/Sedimentation Control (Subtotal "Be'):
Subtotal ("A" + "Be'): $ 26,219.90
CONTINGENCY (20%):
TOTAL BOND AMOUNT:
Cash Deposit: 50% (Up to $20,000)
4% ($20, 001-%50, 000)
3% (°/%50,001-$100,000)
2.5% ($100,001 and up)
$ 4,506.90
$ 21,713.00
$ 5,244.00
$ 31,464.00
$0
$1.259
$0
$0
l0°/0: $22,425A0 30°/0: $9,439.00
B:IWashingtonlFederal WaylWilliam Warren Groupl4ConstructionlCost EstimatelFW Bond Quantities Worksheet Excel Spreadsheet.xls
Last Revised:
Page 3
TECHNICAL INFORMATION REPORT
OPERATIONS AND MAINTENANCE GUIDELINES
The following operations and maintenance guidelines are provided for the on -site stormwater
management system:
NAVIX StorQuest Federal Way Page 51
TECHNICAL INFORMATION REPORT
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL. CONVEYANCE. AND "IQ FACILITIES
NO.2 — INFILTRATION FACILITIES
Maintenance Defect w Problem
Component Conditions When Maintenance Is Needed
Site Trash and debris
Noxious weeds
Contaminants and
Pollution
Grass/groundcover
InfIllralion Pond.
Top or Stile slopes
Rodent holes
of Dam. Berm or
Embankment
Tree growth
Erosion
Settlement
Infiltration pond,
Tank, Vault, Trench,
or Small Basin
Storage Area
Infiltration Tank
Structure
Infiltration Vault
Structure
Sediment
accumulation
Liner damaged
If Applicable)
Plugged air vent
Tank bent out of
shape
Gaps between
sections. damaged
joints or cracks or
tears in wall
Damage to wall,
frame, bottom, andlor
lop slab
2016 Surface %%rater Design ,ienual — Appendix A
Any (rash and dsbns which exteed 1 cubic ow
per "DO square feet (this is about equal fa the
amount of trash II Would take Id fits up one
standard sire office garbage can). In general,
there should tfc no visual evidence of dumping.
Any noxious or nuisance vegetation which may
constitute a hazard to County personnel or the
public.
Any evidence of Contaminants or pollution such
as oil, gasoline, concrold slurries or Paln3.
Grass or groundcover exceeds 18 inches in
height
Any evidence of rodent holes if facilily Is acting
as a dam or berm, or any evidence of water
Piping through dam or berm via rodent holes
Tree growth threatens integrity of dams. beans
er slopes. does roe allow Mmillonance access.
Of interferes with maintertarice activity. 11 trees
are net a threat to dam. berm, w embankmenl
integnty or not interfering with access or
maintenance. they do not need to be removed,
+Eroded damage over 2 1--has deep where cause
of damage. still presenl or where there is
potential for continued erosion. Any erosion
observed on a cOmPacted slope.
Any part of a dam, berm or emban~
has settled 4 inches lower than the design
elevation
11 two inches or more sediment is present or a
Percolation test indicates facility is working at or
less than 90% of design.
Liner is visible or pond does not hold water as
designed.
Any blockage of the vent.
Any Part of tank/pipe Is bent out of shape more
than 10% of its design shape
A gap wider than Y,4nch at the joint of any lank
sections or any evidence of soil particles entering
the tank at a joint or through a wall,
Cracks wider than /Anch, any evidence or sod
entering lyre structure through cracks Of qualified
inspection personnel determines'hat the vault is
not stnicturalty sound.
A-3
NAVIX StorQuest Federal Way
Results Expected When
Maintenance is Pariwmed
Trash and debris cleared from site
Noxious and nuisance vegetation
removed according to apprirabie
�ve%etalW-
ulations. No danger of noxious
where County personnel
he public might normally be.
,Materials removed and disposed of
according to appticatde regulatmns.
Source control BMPs implemented it
aPl rWate. No contaminantS
prosonl olhar than a surfaca oil film.
Grass or groundcover mowed to a
height no greater than 6 inches.
Rodents romovad or destroyed and
dam or bean repaired
Trees do not hinder facility
performance or maintenance
activities
Stapes stabilized using apPropriale
erosion control measures, if erosion
is attuning on compacted Skrpe, a
Iitensed civil engineer should be
consulted to resolve source of
erosion.
Top or side slope restored to design
dimensions If settlement is
significant, a licensed civil engineer
should be consulted to determine
the cause of the settlement
Facility infillrales as designed
Liner repaired or replaced
Tank or vault freely vents
Tank repaired or replaced to design.
No water or soil entering tank
through joints or walls
Vault is sealed and structurally
sound
4@4 `2016
Page 52
TECHNICAL INFORMATION REPORT
•1PPENDIX A MAINTENANCE REQUIREMENTS FLOW C'OV'1'ROL, C'ON%I ANCE, AND WQ FACILITIES
NO.2 — INFILTRATION FACILMES
Maintenance
Component
Inlevoullet Pipes
Access Manhole
Large access
doorslplale
Infillratron Pond.
Tank, Vault, Trench,
or Small Basin Filter
Bags
Infiltration Pone
Tank. Vault. Trench
Or Srmaa Basin Pre.
settling Ponds and
Vaults
Infiltration Pond.
Rock Filter
Infittralion Pond
Emergency
Owe rfiow Splhvay
4 24 2016
Defect or Problem
Conditions When Maintenance
Is Needed
Sediment
accumulation
Sediment filling zu% or more of the pipe
Trash and debris
Trash and debris accumulated in
inletioutlet
pipes (includes floatables and non.floatebles).
Damaged
Cracks wider than Y inch at the
joint of the
mlet/oull
at the joints of the inletloutlel pipes.
COverlhd not in place
Coverilid Is missing or only parlfalty in place
Any open manhole requires Immediate
maintenance.
Locking mechanism
not working
Mechanism cannot bri o pentrd by one
mainntenance 17BfS[x1 Wilh pr°p$7 t°pj5 Betts
cannot be sealed. Self-locking coverAid does
work. not
Coverlkd difficult to
One maintenance YMP cannot
remove
remove
coverlkd after a 8n
l�yrrig 80 Ibs of lift
Ladder rungs unsafe
Missing rungs, misalignment, rust, or cracks
Damaged or difficult
10 open
Large access doors or plates cannot be
openedlremoved usinga normal equipment. pment.
Gaps, doesn'I cover
completely
Large access doors not flat and/or access
opening not completely covered.
Lifting Rings missing,
rusted
Lifting rings not capable of lifting weight of door
or plate.
Plugged
Filter bag more than '12 full.
Sediment
accumulation
6' or more of sediment has accumulated.
Results Expected When
Maintenance Is Performed
Inlet/oullet pipes clear of sediment
No I or debris in pipes
No cracks more than 4-In b wide at
the joint of the inletloutlol pipe.
Manhole access covered.
Mechanism opens with proper tools.
Cove d can be removed and
reinstalled by one maintenance
person
Ladder meets design standards
mows:
ows maintenance person safe
across.
Replace or repair access door so It
In opened as designed.
Doors close flat; covers access
opening completely.
Lifting rings sufficient to lift or
remove door or plate.
Replace filter bag or redesign
system
Pre -Settling occurs as designed
Plugged High water level on upstream side of filler
remains for extended period of time or little
tand replaceder evaluateneed
or no
water flows through filler during heavy fain
for filter if noft
necessary
Rock missing Only one layor of rock oldsts above
native soli in
area fire square feet or target many exposure
Spillway restored to design
Of native Soil at the top of owl now path of
standards
spillway. Rip -rap on M Wa slopes need oltil be
replaced.
Tree growth Tree growth impedes flow or threatens stability of
spillway
Trees removed
A4 2016 Surfacc Wafer Design Manual — Appcndia A
NAVIX StorQuest Federal Way
Page 53
TECHNICAL INFORMATION REPORT
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL. CONVEYANCE. AND WQ FACILITIES
NO.4 — CONTROL STRUCTURE/FLOW RESTRICTOR
Maintenance Defect or Problem
Component Condition When Maintenance is Needed
Structure Trash and debris
Trash or debris Of more than'!, cubic toot which
in located fmmedialety in front of the structure
opening or js blocking capacity of the structure
by more than 10%.
Trash or debris in the structure that exceeds '/3
the depth from the bottom of basin to mverl the
lowest pipe into or out of the basin
Deposits of garbage exceeding 1 cubic foot in
votumo.
Sediment
Damage to frame
and/or lop slab
Cracks in walls or
bottom
Settlement/
misalignment
Damaged pipe joints
Contaminants and
Pollution
Sediment exceeds 60 % of the depth from the
bottom of the structure to the invert of the lowest
pipe Into or out of the structure or the bottom of
the FROP-T section or is within 6 inches of the
invert of the lowest pipe into or out of the
structure or the bottom of the FROP-T section.
Comer of frame extends more than''/. inch past
curb face into the street (If applicable)
Top slab has holes larger than 2 square inches
or cracks wider Phan '/. inch.
Frame not sitting Flush on top slab. i.e
separation of more than'/. inch of the frame from
the lop slab.
Cracks H7tler than 'rich and longer Ina, 3 feet.
hr
any evidence Oi 5ON panicles entering structure
tough Vadcs, or ma"Onaaco person judges
that slnscture es unsound.
Cracks w+dar than V,, inch and longer than 1 foot
at the joint Of any inlellOutlel Pipe or any
evidence of $oil panicles enledog.structure
Uuough cracks.
Structure has settled more than 1 inch or has
rotated more than 2 inches out of alignment
Cracks wider than '/Anch at the joint of the
inlet/outlet Pipes or any evidence Of soil entering
the structure at the joint of the inlet/outlel pipes
Any evidence of contaminants or pollution such
as oli, gasoline, concrete slurries or paint.
Ladder rungIstructure
er is unsafe due to missing rungs, or unsafelignment rust, cracks, or shar
p edges.
FROP-T Section Damage
ction is not securely attached to structure
nd outlet pipe structure should support at
1,000 Ills of up or down pressure.
ture is not in upright position (allow up to
from Plumb).
ections to outlet pipe are not watertight or
signs of 401,Fjorated grout.
oles—other than designed holes —in the
re
2016 Surface %Paler Design Manual - Appendix A
A-7
NAVIX StorQuest Federal Way
Results Expecta' When
Maintenance Jr. Performed
No Trash or debris blocking or
Potentially blocking entrance to
slWure.
No trash or debris in the structure.
No condition present which would
attract or support the breeding of
insects or rodents.
Sump of structure contains no
sediment
Frame is even with curb.
Top slab is free of holes and cracks
Frame is sitting flush on top slab,
Structure is sealed and structurally
sound
No cracks more than '1, incli wide at
the joint of intelroullel Mpg.
Basin replaced or repaired to design
standards
No cracks more than :-eneh wide at
the joint of inleVoutfe! pipes.
Matenals removed and disposed of
according to applicable regulahpns.
Source opntrW BMPs rrnptemented if
appropriate. No contaminants
present other than a surface oil film
Ladder meols design standard8 and
allows maintenance person sate
access.
T section securely attached to wall
and Outlet pipe_
Structure in correct position
Connections to outlet pipe are water
tight; structure repaired or replaced
and works as designed,
Structure has no holes other than
designed holes
4 242016
Page 54
TECHNICAL INFORMATION REPORT
APPENDIX A MAINTENANCE REQUIREMEN I'S FLOW CONTROL, CONVEYANCE, AND WQ FAC•ILITIES
NO.4 — CONTROL STRUCTUREIFLOW
RESTRICTOR
Maintenance
Component
Defect or Problem
Condition When Maintenance is Needed
Results Expected When
Cleanoul Gate
Damaged or missing Cleanoul gate is missing.
MaYnterranca Is Performed
Replace ceanoul gale
Cleanout gate is not watertight
Gale is watertight and works as
designed,
Gate cannot be moved up and down by one
maintenance person.
Gate moves u and
P down easily and
is watertight
Chainlrod leading to gate is missing or damaged Chain is in place and works as
Orifice Plate
Damaged or missing
Control device Is not working
designed.
Property due to
missing, out of place, or bent orifice plate
Plate Is in place and works as
desi nod
g
Obstructions
Any bash, debris, sediment, or vegetation
blocking the plate
Plate is free of all obstructions and
Overflow Pi Pe
Obstructions
Any (rash or debris bl �^g is having the
works as designed.
Potential of hlocki �) the o"rflo1°r cape•
Pipe is free of ale obstructions and
Deformed or
Lip of overflow pipe Is bent or deformed.
works as designed.
damaged lip
Overflow pipe does not allow
overflow at an elevation lower than
InteVOutlet Pipe
Sediment
Sediment filling 20% or more of the
design
accumulation
pipe
InleVouteel pipes clear of sediment
Trash and debris
Trash and debris accumulated in inlet/outlet
Pipes (includes floatables and non-Iloatables).
No trash or debris in pipes
Damaged
Cracks wider than % Inch at the joint of the
intet/oullel
No cracks more than M-inch wide
Apes or eny evidence of soil entering
at the joints of the inleVoWet
at
the joint of the inleVouOet pipe
Metal Grates
(If Applicable)p
Unsafe grate openingGrate
pipes.
with opening wider than inch.
g
Grate opening meets design
Trash and debris
Trash and debris that is blocking more than 20 %
of grate surface.
standards.
Grate free of trash and debns.
Damaged or missing
Grate missing or broken
footnote to guidelines for disposal
members) o/ the grate
Grate is in place and meets design
Manhole Cover/Lid
Cover/lid not in place
CovenIttl is missingor only
standards
ty it place
Any open structure requires urgent
i es urgent
Cructurtl protects opening to
maintenance.
structure
Locking mechanism
Not Working
Mechanism cannot be opened by one
maintenance Persari +rile
Mechanism opens with proper tools.
proper IorNs. 6oRs
cannot be seated. Self'100 rig eoverAid does not
work.
Cover/lid difficult to
Remove
Ona marn(anance person cannot remove
coverArd after applying 80
pp
reinstalle can be and
ying Ibs of lift
reinstalled by one maintenance
maintenance
person
4+24.'2016
A-R 2016 Surface Water Design Manual - Appendix A
NAVIX StorQuest Federal Way
Page 55
TECHNICAL INFORMATION REPORT
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CON I'ROL. CONVEYANCE. AND "IQ FACILITIES
NO.5 — CATCH BASINS AND MANHOLES
Maintenance Defect or Problem Condition When Maintenance is Needed
Component
Results Expected When
Structure Sediment
Sediment exc seas 6035 0f the depth front
Maintenance is Performed
the
bottom of the catch basin to the Invert of the
Sump of catch basin contains no
lowest pipe into or out of the catch basin or is
sediment.
Wnlh+n 6 inches of the invert W the loxest pipe
into or out of the catch basin
Trash and debris
Trash or debris of more than % cubic foot which No Trash or debris blocking or
Is located immediately in front of the
catch basin POlonllally blocking entrance to
opening or Is blocking capacity of the catch basin calcll basin.
by more than 10 h.
Trash or debris in the catch basin that exceeds
'/, the depth from the bottom of basin
No trash or debris in the catch
to invert
the to pipe Into or out of the basin
basin.
Dead animals Or vogetauon that could penorale
odors that could cause complaints or da
No dead animals or vegetation
gases (e.g.. methane). n9erous
Present within catch basin
Deposits of garbage exceeding t cubic foot in
volume.
No condition present which would
attract or support the breeding of
Damage to frame
and/or top slab
Comer of frame extends more than 3/. inch past
insects or rodents.
Frame is
curb face into the street (If applicable)
even with curb
Top slab has holes larger than 2 square inches
Of cracks wider than Y. inch
Top slab is free of holes and cracks
Frame not sitting flush on top slab. I.e..
separation of more than Y Inch of the frame from
Frame is sitting flush on top slab.
the top slab.
Cracks in walls or
bottom
Cracks wider than '/, inch and longer than 3 feet.
any evidence of soil Particles tering
Catch basin is seated and is
catch
basin through cracks or maintenance person
structurally sound
judges that catch basin is unsound.
Cracks wider than '/, inch and longer than t fool
at the joint of any inletloutlet pipe or any
No cracks more than '/4 inch wide at
evidence of soli particles entering catch basin
the joint of inleVoutlel pipe.
through cracks
SelllemenV
misalignment
Catch basin has settled more than I inch or has
rotated more than 2 inches out
Basin replaced or repaired to design
Damaged Pipe joints
of alignment
Cracks under than % inch a the joint
standards
of the
erleVOullet pipes dr any ewdence of soft entering
g
the catch basin at the joint Iho
No cracks more than '/.-inch wide at
the joint of inleVoutlel pipes.
of mleVougal
P"Pes.
Contaminants and
Pollution
Any evidence of contaminants Or Pollution such
as oil, gasoline, concrete slurries
Materials removed and disposed of
or
or paint
according tp applicable ations
Source con BMpjmpteml enled if
aPPropnate. No conWninahls
Inlet/Outlet Pipe Sediment
Sediment filling 20% or more of the
Present other than a surtace cif film.
accumulation
pipe.
Inlet/outlet pipes clear of sediment.
Trash and debris
Trash and debris accumulated in inleVoutlet
Pipes (includes floalablas and
No trash or debris in pipes.
Damaged
non-Ooalables)
Cracks wider than I/Anch at the pint of the
inletloutlet tapes or any evidence of soil entering
at the joints of the inleVoutlet Apes
No cracks more than :-inch wide at
ene
the joint of thillfoutlet pipe.
2016 Surface Water Design Manual — ;Appendix A
A_q
4'24:2016
NAVIX StorQuest Federal Way
Page 56
TECHNICAL INFORMATION REPORT
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL. CONVEYANCE. AND WQ FACILITIES
NO. S — CATCH BASINS AND MANHOLES
Maintenance Defect or Problem Condition When Maintenance is Needed
Component
Melel Grates Unsafe grate opening Grate with r
(Catch Basins) opening wider than J6 Inch.
4t24-+2016
Trash and debris that is blocking more than 20%
of grate surface.
Grate missing or broken memtxr(s) of the grate
Any open structure requires urgent
maintenance
Cover:l,d -5 m:55rng Or only Partially in place
Any open structure requires urgent
maintenance
Mechanism cannot be opened by one
maintenance person w th proper tools Bolls
cannot be seated Self-locking coverAid does not
work
OR(- maintenance Pe+son cannot remove
coverAld after applrng 80 lbs. of IIR.
A-10
Results Expected When
Maintenance Is Performed
Grate opening meets design
standards.
Grate free of trash and debris
footnote to guidelines for disposal
Grate is in place and meets design
standards.
Coverrlid protects Opening to
struclufe
Mechanism opens with proper tools.
CoverAid can be removed and
reinstalled by one maintenance
person
2016 Surface Water Design Manual --Appendix A
NAVIX StorQuest Federal Way
Page 57
TECHNICAL INFORMATION REPORT
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW COMIROL. CONVEYANCE. AND WQ FACILITIES
NO.6 — CONVEYANCE PIPES AND DITCHES
Maintenance Defect or Problem Conditions When
Component Maintenance is Needed
Pipes Sediment & debris Accumulated sediment or debris that exceeds
accumulation 20% of the diameter of the pipe
Vegetationfroots Vegetationlroots that reduce free movement of
water through pipes
Contaminants and Any evidence of contaminants or pollution such
polluas oil, gasoline, concrete slurries a paint.
Damage to protective
coaling or corrosion
Damaged
Ditches Trash and debris
Sediment
accumulation
Noxious weeds
Contaminants and
pollution
Vegetation
Erosion damage to
slopes
Rock lining out of
placr or missing (If
Applicable)
2016 Surfacc Waicr Dcsign Manual - Appendix A
Protective coaling Is damaged; rust or corrosion
is weakening the structural integrity of any part of
pipe.
Any dent that decreases the Cross section area
of pipe by more than 20% or is determined to
have weakened structural integrity of the pipe
Trash and debris exceeds t cubic foot per 1.000
square feet of ditch and slopes
Accumulated sediment that exceeds 20% of the
design depth
Any noxious or nuisance vegetation which may
constitute a hazard to County personnel or the
Public
Any evidence of contaminants or pollution such
as oil, gasoline, concrete slurries or paint.
Results Expected When
Maintenance Is Performed
Water flours freely through pipes
Water flows freely through pipes.
Matenafs removed and disposed of
according to applicable regulations.
Source conl"A BMps implemented if
appropriate. Nocomaminanls
Present other than a surface oil film
Pipe repaired or replaced
Pipe repaired or replaced.
Trash and debris cleared from
ditches
Ditch cleaned/flushed of all
sediment and debris so that it
matches design.
Noxious and nuisance vegetation
removed according to applicable
regulations No danger of noxious
vegetation where County personnel
or the public might normally be.
Materials removed and disposed of
according 10 applicable regulations.
Source control BMP$ imptomenlod if
APproPrble No contaminants
Present other than a surface oil film,
Vegetation that reduces free movement �SloPesare
gh ditches
through ditches.
Any erosion observed on a ditch slope.
One layer or less of rock exists above native soil
area 5 square feet or more, any exposed native
soil
A-11
Replace rocks to design standards.
4'24r2016
NAVIX StorQuest Federal Way
Page 58
TECHNICAL INFORMATION REPORT
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL. CONVEYANCE,
AND
WQ FACILITIES
NO. 11 —GROUNDS (L 4MSCMNG)
Maintenance Defect or problem
I Conditions When Maintenance is Needed
Results Exp
ected pected When
Site
Maintenance Is Performed
Trash or litter
Any bash and debris Which exceed 1 cuhhc foul
Trash and debris cleared from site
per f.DDO square feet it" is about equal to the
amount of trash It WOO lake Io Oil up Oft
slandatd size office garbage Can]- In general,
there should be no visual evidence of dumpiV.
Noxious weeds
Any noxious or nuisance vegetation which may
Noxious and nuisance vegetation
Con shtule a hazard to Courtly perSOMoI or the
public-
removed according to apphcobie
regulations. No danger of noxious
vegetation where County personnel
or the public might normally b4
Contaminants and
pollution
Any evidence of contaminants or pollution such
as oil, gasoline, concrete slurries or
Malenals removDd and disposed of
paint.
according to a pplicaWe ragufat,ons.
Source cortlrof OMPs implemented if
appropriate- No contaminants
present other than a surface oil ram
Grasslgroundcover
Grass or groundcover exceeds 18 inches in
Grass or groundcover mowed to a
he ght.
height no greater than 6 inches.
Trees end Shrubs Hazard
Any tree or limb of a tree identified as having a
No hazard trees in facility.
poient.,al to fall and Cause property damage or
threaton human rife, A hazard tree identified by
a qualified aeborist must be removed as soon
as possible.
Damaged
Limbs or parts of trees or shrubs that are split or
broken which affect more than 25% of the total
Trees and Shrubs with loss titan 5%
foMge of the tree or shrub
of total foliage wilh split or brokon
limbs.
Trees or shrubs that have been blown down or
knocked over.
No blown down vegetation or
knocked over vegetation Trees or
shrubs free of Injury.
Trees or shrubs which are not adequately
Tree or shrub in place and
supposed or are leaning over, causing exposure
of the ,Dots.
adequately supported; dead or
diseased trees removed.
4, 24-r2016
A-I6 2016 Surface 1Vater Design Manual - Appendix A
NAVIX StorQuest Federal Way Page 59
Orvoi-NTECH"
ENGINEERED SOLUTIONS
CatchBasin StormFilter"'
Important: These guidelines should be used as a part of your site
stormwater plan.
Overview
The ColchBosin StormFilter" (CBSF) consists of a multi -chamber
steel, concrete, or plastic catch basin unit that can contain up to
four StormFilter cartridges, The steel CBSF is offered both as a
standard and as a deep unit.
The CBSF is installed flush with the finished grade and is
applicable for both constrained lot and retrofit applications. It
can also be fitted with an inlet pipe for roof leaders or similar
applications.
The CBSF unit treats peak water quality design Flows up to 0.13
cis, coupled with an internal weir overflow capacity of 1.0 cfs for
the standard unit, and 1.8 cfs for the deep steel and concrete
units. Plastic units have on internal weir overflow capacity of 0.5
cfs.
Design Operation
The CBSF is installed as the primary receiver of runoff, similar
to a standard, grated catch basin. The steel and concrete CBSF
units have an H-20 rated, traffic bearing lid that allows the filter
to be installed in parking lots, and for oil practical purposes,
takes up no land area. Plastic units can be used in landscaped
areas and for other non -traffic -bearing applications.
The CBSF consists of a sumped inlet chamber and a cartridge
chamber{s). Runoff enters the sumped inlet chamber either
by sheet flow from a paved surface or from an rolel pipe
discharging directly to the unit vault. The inlet chomber is
equipped with an internal baffle, which traps debris and floating
Oil and grease, and an overflow weir. While in the inlet chamber,
heavier solids are allowed to settle into the deep sump, while
lighter solids and soluble pollutants are directed under fhe baffle
and into the cartridge chamber through p port between the
baffle and the overflow weir.
URBANGREEN`:`''
SMrm .' solufi_ tram ennr—h-
TECHNICAL INFORMATION REPORT
OPERATION AND
MAINTENANCE
Croce in she cartridge chamber, polluted water ponds and
percolates horizontally through the media in the filter cartridges.
Treated water collects in the cartridges center tube from where it
is directed by on under -drain rnanifold to the outlet pipe on the
downstream side of the overflow weir and discharged.
When flows into file CBSF exceed the water quality design
value, excess water spills over the overflow weir, bypassing the
cartridge boy, and discharges to the outlet pipe.
Applications
The CBSF is particularly useful where small flows ore being
treated or for sites ]hot we Flo] and hove little available hydraulic
head to spare. The unit is ideal For appli[olions in which
standard catch basins are so be used. Both water quality and
colchmenl issues can be resoived with the use of the CBSF
Retro-Fit
The retrofit market has many possible applications for the CBSF
The CBSF con be installed by replacing on existing catch basin
without having to "chase the grade," thus reducing the high cost
of re piping the storm system.
Page 1
www. ContechES. ca m/sto rmwaf er
-1122
�' 2013 Conterh E g- �re3d Sntutiais
NAVIX StorQuest Federal Way Page 60
C1%7 0 VTECH
ENGINEERED SOLUTIONS
CotchBasin StormFilterTM
Maintenance Guidelines
MOIRIsnonce procedures for typical catch basins can be applied
to the CatchBasin StormFitter (CBSF). The filter cartridges
contained in the CBSF are easily removed and replaced during
maintenance ociivities according to the following guidelines,
1. Establish a safe working area as per typical catch basin
service activity_
2. Remove steel grate and diamond plate cover (weight 100
lbs. each).
3. Turn cortricige(s) counter -clockwise to disconnect from pipe
manifold.
4. Remove 4" center cap from cartridge and replace with
lifting cap.
5. Remove cortridge(s) from catch basin by hand or with vactor
truck boom.
6. Remove accumulated sediment via vactor truck (min.
clearance 13" x 24").
7. Remove accumulated sediment from cartridge bay. (min.
clearance 9.25" x 11 ").
8. Rinse interior of both bays and vactor remaining water and
sediment.
9. Install fresh cortridge(s) threading clockwise to pipe
manifold.
10. Replace cover and grate.
11. Return original cartridges to Contech for cleaning.
Media may be removed from the filter cartridges using the
vactor truck before the cartridges are removed from the catch
basin structure. Empty cartridges tan be easily removed from
the catch basin structure by hand. Empty cartridges should be
reassembled and returned to Contech as appropriate.
Materials required include a lifting cap, vactor truck and
fresh filter cartridges. Contact Contech for specifications and
availability of the lifting cap. The valor truck must be equipped
with a hose capable of reaching areas of restricted clearance.
the owner may refresh spent cartridges. Refreshed cartridges are
also available from Contech on an exchange basis. Contact the
maintenance department of Contech of 503-258-3157 for more
information.
Maintenance is estimated at 26 minutes of site time. For units
with more than one cartridge, add approximately 5 minutes for
each additional cartridge. Add travel time as required.
URBANCREEN'
srwmwoec. sewr yam e"nrcch" y7.r
TECHNICAL INFORMATION REPORT
OPERATION AND
MAINTENANCE
Mosquito Abatement
In certain areas of the United States, mosquito abatement is
desirable to reduce the incidence of vectors.
In BMPS with standing water, which could provide mosquito
breeding habitat, certain abatement measures can be taken.
1. Periodic observation of the standing water to determine if
the facility is harboring mosquito larvae.
Regular catch basin maintenance.
3. Use of larvicides containing Bacillus thuringiensis israelensis
(BTI). BTI is a bacterium toxic to mosquito and black fly
larvae.
In some cases, the presence of petroleum hydrocarbons may
interrupt the mosquito growth cycle.
Using I.atvkkles In the Catchaosin s►ormFilter
Larvicides should be used according to manufacturer's
recommendations.
Two widely available products are Mosquito Bunks and
Summit 13.11 Briquets. For more information, visit htip://Kww.
summitchamicol.com/mos ctrt/d efoulf.him.
The larvicide must be. in contact with the permanent pool. The
larvicide should also be fastened to the CatchBosin SlormFiller
by string or wire to prevent displacement by high flows. A
magnet con be used with a sleet catch basin.
For more information on mosquito abatement in starmwater
BMPs, refer to the following; http://www_ucmrp.ucdovis.edu/
publicalians/monogingmosqui oesstormwater8125.pdf
Page 2
www. Contech E$.cons/stormwate r
800-338-1122
x' 2013 Confech Enginetred Sotutiany
NAVIX StorQuest Federal Way
Page 61
-r-
TECHNICAL INFORMATION REPORT
Maintenance
ii,l rT- 11 -7,• r .71 pe
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StorQuest Federal Way
CMP DETENTION SYSTEMS
C4'r,NTECH'
ENGINEEMID SOLUTIONS
Page 62
TECHNICAL INFORMATION REPORT
APPENDIX A
EXHIBITS
EXHIBIT A — EXISTING CONDITIONS EXHIBIT
EXHIBIT B — PROPOSED CONDITIONS EXHIBIT
NAVIX StorQuest Federal Way
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TECHNICAL INFORMATION REPORT
APPENDIX B
SPECIAL REPORTS AND STUDIES
NAVIX StorQuest Federal Way
Geotechnical Engineering Report
StorQuest Self Storage
Federal Way, Washington
January 11, 2017
Terracon Project No. 81165135
Prepared for:
William Warren Group
Denver, Colorado
Prepared by:
Terracon Consultants, Inc.
Mountlake Terrace, Washington
Irerracon
January 11, 2017
William Warren Group
4301 DTC Blvd.
Greenwood Village, CO 80111
Attn: Mr. Jon Suddarth
P: [303] 842-5690
E: juddarth@williamwarren.com
Re: Geotechnical Engineering Report
StorQuest Self Storage
Federal Way, Washington
Terracon Project Number: 81165135
Dear Mr. Suddarth:
Terracon Consultants, Inc. (Terracon) has completed the geotechnical engineering services
for the above referenced project. This study was performed in general accordance with our
proposal number P81165135 dated September 22, 2016 and the supplemental agreement
dated December 2, 2016. This report presents the findings of the subsurface exploration and
provides geotechnical recommendations concerning earthwork and the design and
construction of foundations, floor slabs, pavement, retaining walls, and temporary shoring for
the proposed project.
We appreciate the opportunity to be of service to you on this project. If you have any
questions concerning this report, or if we may be of further service, please contact us.
Sincerely,
Terracon Consultants, Inc.
// llZ/i�
�pr Ryan M. ScKeffier, P.E. Dennis R. Stettler, P.E.
Project Engineer Senior Engineering Consultant
Terracon Consultants, Inc. 21905 64th Avenue, Suite 100 Mountlake Terrace, Washington 98043
TABLE OF CONTENTS
Page
.......... ..............................................
i
EXECUTIVESUMMARY
1.0
.....................................................
INTRODUCTION.............................................................................................................1
2.0
PROJECT INFORMATION.............................................................................................1
2.1
Project Description ..............................................................................................
A
2.2
Site Location and Description..............................................................................2
3.0
SUBSURFACE CONDITIONS........................................................................................2
3.1
Geology...............................................................................................................2
3.2
Typical Profile......................................................................................................2
3.3
Groundwater
4.0
........................................................................................................3
RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION......................................3
4.1
Geotechnical Considerations...............................................................................3
4.2
Earthwork...........................................................................................................14
4.2.1 Site Preparation. .....................................................................................
- 4
4.2.2 Temporary Cut Slopes..............................................................................5
4.2.3 Existing Steep Slopes...............................................................................5
4.2.4 Permanent Cut and Fill Slopes.................................................................6
4.2.5 Material Requirements.............................................................................6
4.2.6 Compaction Requirements...........................................................
... I ........ 7
4.2.7 Grading and Drainage..............................................................................7
4.2.8 Earthwork Construction Considerations....................................................7
4.3
Foundations.........................................................................................................
9
4.3.1 Foundation Design Recommendations.....................................................9
4.3.2 Foundation Construction Considerations................................................10
4.4
Floor Slabs.........................................................................................................11
4.4.1 Floor Slab Design Recommendations....................................................11
4.4.2 Floor Slab Construction Considerations.................................................12
4.5
Seismic Considerations.....................................................................................12
4.5.1 Fault Zones............................................................................................13
4.5.2 Liquefaction............................................................................................13
4.5.3 Seismic Surcharge.................................................................................13
4.6
Lateral Earth Pressures.....................................................................................13
4.7
Pavements.........................................................................................................16
4.7.1 Subgrade Preparation............................................................................17
4.7.2 Design Considerations ...................................... ..................•••.•.•.•
.........17
4.7.3 Estimates of Minimum Pavement Thickness............................................18
4.7.4 Pavement Drainage ......... .........................................................................
19
4.7.5 Pavement Maintenance...........................................................................20
4.8
Temporary Shoring...........................................................................................20
4.8.1 Soil Nail Wall Design Recommendations................................................20
4.8.2 Soil Nail Shoring Installation...................................................................21
4.8.3 Soldier Piles...........................................................................................22
4.8.4 Soldier Pile Shoring Installation..............................................................23
4.8.5 Monitoring of Temporary Shoring...........................................................24
Responsive -: Resourceful Reliable
TABLE OF CONTENTS (continued)
5.0 GENERAL COMMENTS...............................................................................................24
APPENDIX A — FIELD EXPLORATION
Exhibit A-1 Site Location Map
Exhibit A-2 Site and Exploration Plan
Exhibit A-3 Section A -A'
Exhibit A-4 Field Exploration Description
Exhibits A-5 through A-8 Boring Logs B-1 through B-4
Exhibits A-9 through A-12 Test Pit Logs TP-1 through TP-4
APPENDIX B — LABORATORY TESTING
Exhibit B-1 Laboratory Testing Description
Exhibit B-2 and B-3 Grain Size Distributions
APPENDIX C — SUPPORTING DOCUMENTS
Exhibit C-1 General Notes
Exhibit C-2 Unified Soil Classification System
Responsive ■ Resourceful ■ Reliable
Geotechnical Engineering Report Irerracon
StorQuest Self Storage Federal Way, Washington
January 11, 2017 vi Terracon Project No. 81165135
EXECUTIVE SUMMARY
A geotechnical exploration program has been performed for the proposed project located in the
298th block of Pacific Highway South (SR 99) in Federal Way, Washington. Terracon's
geotechnical scope of services included the advancement of four test pits and four soil test
borings to approximate depths of 9'/2 to 50 feet below the existing ground surface (bgs). The
site appears suitable for the proposed construction based upon geotechnical conditions
encountered in the explorations and our current understanding of the proposed development.
The following geotechnical considerations were identified:
In our explorations we encountered undocumented fill or reworked soil, sometimes including
organic soil or a buried topsoil horizon, to depths of '/2 to 11'/z feet, primarily in the eastern
portion of the site. We recommend complete removal of the undocumented fill and
reworked soil below and immediately adjacent to the building footprint. An allowable
bearing pressure of 3,500 pounds per square foot (psf) can be used for shallow footings
bearing on medium dense native material or structural fill extending to medium dense to
very dense native soil.
Explorations in the central and western portion of the site disclosed dense to very dense
gravelly sand or sandy gravel with variable silt content at shallow depths and at deeper depths
below fill in the eastern portion of the site. This soil is interpreted to be Advance Outwash,
which is a glacially -overridden soil that is typically found in a dense to very dense condition.
Foundations bearing on dense to very dense, glacially -overridden native soil can be designed
for an allowable soil bearing pressure of 8,000 psf.
Assuming the owner is willing to accept the risk of unpredictable settlement response in the
pavement areas by leaving some of the undocumented fill below the pavement section, we
recommend removal of at least the upper 12 inches of pavement subgrade, scarification and
compaction of the exposed subgrade, and replacement of the removed material with
structural fill.
The western portion of the site slopes up steeply to 16th Avenue South. Given the planned
location and floor elevation of the building, sufficient room is not available to construct the
building with a temporary excavation and shoring will be required. Shoring will likely require
temporary ground anchors to extend into the 16th Avenue South right-of-way and a construction
easement to allow these anchors would be required from the City of Federal Way.
The on -site soil typically appears suitable for reuse as structural fill if placed at a moisture
content near the optimum value. However, this soil contains a significant fraction of fines
(silt and clay passing the No. 200 mesh sieve) and will quickly become unstable, soft and
unsuitable for reuse as structural fill when exposed to excessive moisture. If work is
planned for the winter months, the site soil will likely not be suitable for reuse on the site.
Responsive Resourceful Reliable
Geotechnical Engineering Report Irerracon
StorQuest Self Storage =- Federal Way, Washington
January 11, 2017 Terracon Project No. 81165135
Groundwater seepage was observed at a depth of 19'/2 feet bgs in boring B-3 while drilling.
Groundwater level fluctuations occur due to seasonal variations in the amount of rainfall,
runoff, and other factors not evident at the time the explorations were performed. Based on
our understanding of the proposed development, we do not expect groundwater to affect
construction. If encountered, typical construction dewatering methods such as trench and
sump pumping should be used.
The seismic site classification for this site is C, based on the conditions encountered in our
explorations.
Close monitoring of the construction operations discussed herein will be critical in achieving the
design subgrade support. We therefore recommend that Terracon be retained to monitor this
portion of the work. This summary should be used in conjunction with the entire report for
design purposes. It should be recognized that details were not included or fully developed in this
section, and the report must be read in its entirety for a comprehensive understanding of the items
contained herein. The section titled GENERAL COMMENTS should be read for an understanding
of the report limitations.
Responsive : Resourceful F- Reliable
GEOTECHNICAL ENGINEERING REPORT
StorQuest Self Storage
Federal Way, Washington
Terracon Project No. 81165135
January 11, 2017
1.0 INTRODUCTION
Terracon Consultants, Inc. (Terracon) is pleased to present the results of our geotechnical
engineering services for the proposed storage facility. The site is located in the 2981h block of
Pacific Highway South in Federal Way, Washington at the general location shown on the Site
Location Map, Exhibit A-1. Terracon's geotechnical scope of services included the
advancement of four test pits and four soil test borings to approximate depths of 9'/2 to 50 feet
below the existing ground surface (bgs).
The purpose of these services is to provide information and geotechnical engineering
recommendations relative to:
subsurface soil conditions
groundwater conditions
earthwork
pavement design recommendations
temporary shoring recommendations
2.0 PROJECT INFORMATION
2.1 Project Description
Item
a foundation design and construction
■ slab design and construction
■ seismic considerations
ni lateral earth pressures
Description
Site layout See Appendix A, Exhibit A-2: Site and Exploration Plan
The proposed project would consist of a single, 3-story+daylight
basement, fully enclosed self -storage facility with roughly 101,950
gross square feet of total building area and a building footprint
Proposed improvements taking up most of the site with the exception of a 15 foot setback on
three sides and a 40 foot setback that will contain a parking area
between the building and Pacific Highway South.
Approximate elevation of 432 feet based on Site Section developed
Finished floor elevation by Magellan Architects.
Responsive -- Resourceful Reliable 1
Geotechnical Engineering Report
StorQuest Self Storage Federal Way, Washington
January 11, 2017 - Terracon Project No. 81165135
2.2 Site Location and Description
Item
Location
Existing improvements
Irerracon
Description
This project is located in the 298th block of Pacific Highway South
(SR 99) in Federal Way, Washington. The site encompasses tax
parcel 0421049035.
The site consists of a primarily undeveloped lot with bushes and
trees. A short rockery lies at the base of the relatively steep slope
on the west side of the site, and along the north side of the site
separating the site from the Federal Way Motel to the north.
Site grades up slightly east to west and north to south. The
Existing topography property rises very steeply near the west edge of the property. The
east side of the property slopes down to Pacific Highway South.
3.0 SUBSURFACE CONDITIONS
3.1 Geology
The geologic map of the area, Geologic Map of the Poverty Bay 7.5' Quadrangle, King and
Pierce Counties, Washington (USGS, Booth et al, 2004), shows the surficial geology for the site
is mapped as Qva — Advance outwash deposit. Advance outwash consists of well -bedded sand
and less common gravel deposited subaqueously or by streams and rivers in front of the
advancing ice sheet. Advance outwash is typically overridden by a glacial till soil deposited
beneath advancing glaciers. Glacial till is mapped near the site. Our interpretation of the soil
disclosed in the explorations is that the soil is advance outwash, although glacial till is mapped
nearby and could be present near the ground surface over higher elevation portions of the site.
3.2 Typical Profile
Soil conditions on the site were explored by advancing four test pits and four soil test borings to
approximate depths of 9'/2 to 50 feet bgs. Logs of the explorations and a description of the field
exploration procedures are presented in Appendix A. The locations of the explorations on the site
are shown on Exhibit A-2 in Appendix A.
Conditions encountered at each exploration location are indicated on the individual exploration
logs. Stratification boundaries on the exploration logs represent the approximate location of
changes in soil types; in situ, the transition between materials may be gradual. .
Responsive r-- Resourceful - Reliable 2
Geotechnical Engineering Report Irerracon
StorQuest Self Storage Federal Way, Washington
January 11, 2017 Terracon Project No. 81165135
Based on the results of the explorations, a generalized subsurface profile is presented along
section A -A' in Exhibit A-3. The subsurface conditions on the project site can be generalized as
follows:
Approximate Depth to
Consistency/
Stratum Bottom of Stratum
Material Description
Density
(feet)
Uncontrolled fill' or reworked soil consisting
Very loose to
1
I 1/2 to 11'h
of silty sand with gravel with organics.
medium dense
22 14
Silty sand with gravel
Medium dense
Gravelly sand with variable silt and gravel
Dense to very
3 Undetermined3
content (Advance Outwash)
dense
1. Uncontrolled fill is material that was placed without moisture and density control.
This material is
typically variable in composition, consistency, density, moisture, and depth and in some locations
could include organic materials and clearing debris.
2. Stratum 2 was only encountered on the east side of the site.
3. Borings and test pits were terminated at their planned depths within this stratum.
3.3 Groundwater
The eight on -site explorations were observed while drilling/excavating for the presence and level
of groundwater. Groundwater seepage was encountered in boring B-3 at a depth of
approximately 19'/2 feet bgs. The seven other explorations did not encounter groundwater at
the time of exploration.
Groundwater level fluctuations occur due to seasonal variations in the amount of rainfall, runoff,
and other factors not evident at the time the explorations were performed. In addition, perched
water can develop over low -permeability soil. Therefore, groundwater levels during construction
or at other times in the life of the structure may be higher or lower than the levels indicated on
the exploration logs.
4.0 RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION
4.1 Geotechnical Considerations
Based on the results of the subsurface exploration, laboratory testing, and our geotechnical
engineering analyses, it is our opinion that the proposed building can be supported on shallow
foundations bearing on medium dense to very dense native soil or compacted structural fill
extending to medium dense to very dense native soil. Geotechnical engineering
recommendations for foundation systems and other earth -connected phases of the project are
Responsive Resourceful Reliable 3
Geotechnical Engineering Report Irerracon
StorQuest Self Storager. Federal Way, Washington
January 11, 2017 Terracon Project No. 81165135
outlined below. The recommendations contained in this report are based upon the results of
data presented herein, engineering analyses, and on our current understanding of the proposed
project.
ASTM and Washington State Department of Transportation (WSDOT) specification codes cited
herein respectively refer to the current manual published by the American Society for Testing &
Materials and the 2016 edition of the WSDOT Standard Specifications for Road, Bridge, and
Municipal Construction (Publication M41-10).
We encountered undocumented fill or reworked soil to depths of '/2 to 11'/2 feet in our
explorations. Fill depths encountered in the explorations were deepest in the northeast corner
of the site and were observed to be shallower in the explorations to the south and west. Fill,
especially undocumented fill, by nature can be highly variable and could vary greatly between
sample locations. There is an inherent risk for the owner that compressible fill or unsuitable
material within or buried by the fill will not be discovered. This risk of unforeseen conditions
cannot be eliminated without completely removing the undocumented fill. For the purposes of
this report, we assume complete removal of the fill and replacement with structural fill will be
limited to the area under and adjacent to the building pad. In addition to the fill soil, any loose or
organic -rich soil should be removed and replaced in a similar manner. The lateral extent of
undocumented fill removal and replacement beyond the building pad footprint is defined later in
this report.
4.2 Earthwork
Based on the subsurface conditions encountered in our exploration, we expect that all of the on -
site soil within the limits of construction can be removed with conventional excavation
equipment. Cobbles and boulders may have been encountered in our explorations based on
our interpretation of drilling action and are commonly found in glacial soil. The contractor should
be prepared to deal with cobbles and boulders. Recommendations for site preparation,
structural fill, and permanent slopes are presented below
4.2.1 Site Preparation
Prior to equipment arriving onsite, clearing and grading limits should be established and
marked. Silt fences should be constructed along the downslope side of all areas planned for
clearing and grading. Preparation for site grading and construction should begin with
procedures intended to control surface water runoff. The sandy soil on site is moderately
susceptible to erosion by flowing water. We anticipate that the use of shallow ditches, with
sumps and pumps as needed, will be adequate for surface water control during wet weather
and wet site conditions.
Stripping efforts should include removal of vegetation, organic materials, and any deleterious
debris from the proposed structure's footprint. It appears that up to about 6 inches of stripping
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will be necessary in areas with light vegetation. Greater depths of stripping and grubbing may
be necessary in areas with thick vegetation and tree roots. These materials are not suitable for
reuse as structural fill. Site disturbance beyond the work area should be limited to reduce the
potential for erosion and off -site sediment transport. Disturbance of existing vegetation and soil
structure on the slope up to 16th Avenue South should be avoided if at all practical until
temporary shoring is installed.
Areas that are stripped or excavated to the design subgrade elevation, or that are to receive
structural fill, should be proofrolled with heavy rubber -tired construction equipment (e.g. loaded
dump truck). Any soft, loose, or otherwise unsuitable areas identified during proofrolling should
be recompacted if practical or removed and replaced with structural fill. We recommend that
proofrolling of the subgrade be observed by a representative of our firm to assess the adequacy
of the subgrade conditions and identify areas needing remedial work. We recommend that this
procedure not be performed during wet weather. During wet conditions, systematic probing
should be used to evaluate the subgrade.
4.2.2 Temporary Cut Slopes
We anticipate that temporary open cuts and/or trenches will be utilized during construction of
the project. Temporary slope stability is a function of many factors, including the following:
The presence and abundance of groundwater
The type and density of the various soil strata
The depth of cut
Surcharge loading adjacent to the excavation
The length of time the excavation remains open
It is exceedingly difficult under the variable circumstances to pre -establish a safe and
"maintenance -free" temporary cut slope angle. Therefore, it should be the responsibility of the
contractor to maintain safe slope configurations since the contractor is continuously at the job
site, able to observe the nature and condition of the cut slopes, and able to monitor the
subsurface materials and groundwater conditions encountered. It may be necessary to drape
temporary slopes with plastic or to otherwise protect the slopes from the elements and minimize
sloughing and erosion. We do not recommend vertical slopes or cuts deeper than 4 feet if
worker access is necessary. The cuts should be adequately sloped or supported to prevent
injury to personnel from local sloughing and spalling. The excavations should conform to
applicable Federal, State, and local regulations.
4.2.3 Existing Steep Slopes
Relatively steep slopes are present along the west side of the site sloping down from the west
property line along 16th Avenue South to the general grade of the site. A rockery is present at
the toe of the slope along all of the slope except within about 30 feet of the south property line.
Ground surface elevations along the west property line range from about 464 to 474 feet. The
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ground surface elevation near the toe of the rockery (or toe of slope where a rockery is not
present) is about 440 feet.
Based on the topography of this site and the surrounding area, it is evident that the relatively
steep slope along the west side of the site was created by cutting into the existing topography at
some time in the past to create a relatively level portion of the site and construction of a rockery
at the toe of the slope. Presumably this cut slope and rockery was constructed under some
previous grading permit. The existing cut slope above the rockery appears to have a slope of
approximately 1.5H:1 V to 1.7H:1 V (horizontal:vertical) for most of the slope above the rockery
based on site topography provided to us. The rockery is not present within about 30 feet of the
south property line and the slope extends more into the site to the east with an average slope of
about 1.8H:1V to 2H:1V based on topography provided to us.
The existing cut slope is highly vegetated with brush and trees. Significant blackberry bushes
obscure much of the ground surface on the steep slope. To the extent that the slope is visible,
we were not able to identify indications of past slope failures or existing slope instability features
on the existing cut slope. The boring advanced at the top of the slope and the geologic
mapping of the site indicate the presence of dense to very dense, glacially -consolidated soil
composed primarily of gravelly sand with variable silt content and some cobbles. Existing cut
slopes as steep as 1.5H:1 V are expected to be stable with an appropriate factor of safety in
these soil conditions.
Steep slopes can be subject to erosion if not protected. We recommend that the vegetation be
kept in place on the existing cut slope. To the extent that vegetation is removed on this slope,
we recommend specific attention to erosion protection including placement of erosion protection
matting and other features to limit the potential for erosion followed by prompt planting on the
slope to reestablish a suitable vegetative protective slope cover.
4.2.4 Permanent Cut and Fill Slopes
We recommend newly constructed permanent cut and fill slopes be constructed at 2H:1 V or
flatter. Any exposed slopes should be protected from erosion during construction and by
establishment of appropriate permanent vegetative cover to limit the potential for erosion.
4.2.5 Material Requirements
Compacted structural fill should meet the following material property requirements:
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WSDOT Standard
Fill Type I Specification
Structural Fill
Trench Backfill
9-03.12(1)A Gravel Backfill for
Foundations Class A
9-03.9(1) Ballast
9-03.9(3) Crushed Surfacing
Base Course
Native gravelly sand with silt'
Native gravelly sand with silt'
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Acceptable Location for Placement
Beneath and adjacent to the structure's slab
and foundation; beneath pavement sections
Utility Trenches
Fines content of near -surface native gravelly sand with silt make this material moisture
sensitive and therefore likely unsuitable for use during periods of wet weather.
4.2.6 Compaction Requirements
Item Description
8 inches or less in loose thickness when heavy, self-
propelled compaction equipment is used
Fill Lift Thickness
4 inches in loose thickness when hand -guided equipment
(i.e. jumping jack or plate compactor) is used
Minimum 95% of the material's modified Proctor maximum
Minimum Compaction Requirements dry density (ASTM D 1557)
Moisture Content — Granular Material Workable moisture levels'
1. Typically within 2% of optimum
4.2.7 Grading and Drainage
Adequate positive drainage of exposed subgrades should be provided during construction and
maintained throughout the life of the development to prevent an increase in moisture content of
the foundation and pavement subgrades and excavation backfill materials. Surface water
drainage should be controlled to prevent undermining of structures during and after
construction. Additionally, surface water should be directed away from steep slopes on the site
to the extent feasible to reduce the risk of erosion and instability.
Roof gutters and downspouts should be routed into tightline pipes that discharge into a
municipal storm drain or other suitable location. Splash -blocks should also be considered below
hose bibs and water spigots if the area is not paved.
4.2.8 Earthwork Construction Considerations
It is anticipated that excavations for the proposed construction can be accomplished with
conventional earthmoving equipment. Advance outwash can contain cobbles and occasionally
boulders. The contractor should be prepared to remove cobbles and boulders from excavations
if encountered.
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Upon completion of filling and grading, care should be taken to maintain the subgrade moisture
content prior to construction of floor slabs and pavements. Construction traffic over the
completed subgrade should be avoided to the extent practical. The site should also be graded
to prevent ponding of surface water on the prepared subgrades or in excavations. If the
subgrade should become frozen, desiccated, saturated, or disturbed, the affected material
should be removed or these materials should be scarified, moisture conditioned, and
recompacted prior to floor slab and pavement construction and observed by Terracon.
Surface water should not be allowed to pond on the site and soak into the soil during
construction. Construction staging should provide drainage of surface water and precipitation
away from the building and pavement areas. Any water that collects over or adjacent to
construction areas should be promptly removed, along with any softened or disturbed soil.
Surface water control in the form of sloping surfaces, drainage ditches and trenches, and sump
pits and pumps will be important to avoid ponding and associated delays due to precipitation
and seepage.
Groundwater seepage was encountered at a depth of 19'/2 feet bgs in boring B-3. Based on our
understanding of the proposed development, we do not expect groundwater to affect
construction. If groundwater is encountered during construction, some form of temporary
dewatering may be required. Conventional dewatering methods, such as pumping from sump
pits, should likely be adequate for temporary removal of groundwater encountered during
excavation at the site.
Temporary excavations will probably be required during grading operations. The grading
contractor, by his contract, is usually responsible for designing and constructing stable,
temporary excavations and should shore, slope or bench the sides of the excavations as
required to maintain stability of both the excavation sides and bottom. All excavations should
comply with applicable local, state and federal safety regulations, including the current
Occupational Health and Safety Administration (OSHA) Excavation and Trench Safety
Standards. All excavations should be sloped or braced as required by OSHA regulations to
provide stability and safe working conditions.
Construction site safety is the sole responsibility of the contractor who controls the means,
methods and sequencing of construction operations. Under no circumstances shall the
information provided herein be interpreted to mean that Terracon is assuming any responsibility
for construction site safety or the contractor's activities; such responsibility shall neither be
implied nor inferred.
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4.3 Foundations
We encountered undocumented fill or reworked soil to depths of '/2 to 11'/z feet in our
explorations. Due to the unpredictability of undocumented fill, we recommend complete
removal of undocumented fill below the proposed building pad. Any loose or organic soil
observed below the fill should also be removed. The lateral extent of removal and replacement
for the building pads should be at least two-thirds of the depth of excavation beyond the building
pad footprint at the perimeter footing location.
In our opinion, after these overexcavations are completed, the proposed building can be
supported by a shallow, spread footing foundation system bearing on compacted structural fill
extending to medium dense to dense native soil. Since the finished floor elevation of 432 feet
requires excavation below existing site grades, we expect foundations for the central and
western thirds of the proposed building will likely bear on dense to very dense, glacially -
consolidated, advance outwash soil. For foundations bearing on the dense to very dense
outwash, a higher allow soil bearing pressure could be used, if desired. Design
recommendations for shallow foundations for the proposed structures are presented in the
following paragraphs.
4.3.1 Foundation Design Recommendations
Description
Column
Wall
Net allowable bearing pressure'
- Compacted structural fill or medium
3,500 psf
3,500 psf
dense to dense native soil
Dense to very dense Advance Outwash
8,000 psf
1
8,000 psf
Minimum dimensions
24 inches
18 inches
Minimum embedment below finished floor
18 inches
18 inches
grade for perimeter footings2
Minimum embedment below finished floor
12 inches
12 inches
grade for interior footings
Approximate total settlement from foundation
<1 inch
<1 inch
loads3
Estimated differential settlement from <'/2 inch between <+/2 inch over 40 feet
foundation loads3 columns
Ultimate coefficient of sliding friction 0.5
Ultimate passive earth pressure 400 pcf
1. The recommended net allowable bearing pressure is the pressure in excess of the minimum
surrounding overburden pressure at the footing base elevation. Assumes any unsuitable
undocumented fill or soft soil, if encountered, will be undercut and replaced with compacted
structural fill. Based upon a minimum Factor of Safety of 3.
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- IDescription Column Wall
2. For frost protection and to reduce the effects of seasonal moisture variations in the subgrade soil.
For perimeter footing and footings beneath unheated areas.
3. The foundation settlement will depend upon the variations within the subsurface soil profile, the
structural loading conditions, the embedment depth of the footings, the thickness of compacted fill
and the quality of the earthwork operations.
The allowable foundation bearing pressures apply to dead loads plus design live load
conditions. The design bearing pressure may be increased by one-third when considering total
loads that include wind or seismic conditions. The weight of the foundation concrete below
grade may be neglected in dead load computations.
Footings, foundations, and masonry walls should be reinforced as necessary to reduce the
potential for distress caused by differential foundation movement. The use of joints at openings
or other discontinuities in masonry walls is recommended.
Foundation excavations should be observed by a Terracon representative. If the soil conditions
encountered differ from those presented in this report, supplemental recommendations may be
required. Confirmation of the soil conditions in the foundation excavations is required at the
time of construction for the allowable soil bearing pressures provided in this report to be valid.
We recommend that the building be encircled with a perimeter foundation drain to collect
exterior seepage water. This drain should consist of a 4-inch-diameter perforated pipe within an
envelope of pea gravel or washed rock, extending at least 6 inches on all sides of the pipe. The
gravel envelope should be wrapped with filter fabric (such as Mirafi 140N) to reduce the
migration of fines from the surrounding soil. Ideally, the drain invert would be installed no more
than 8 inches above or below the base of the perimeter footings. The perimeter foundation
drain with cleanouts should not be connected to roof downspout drains and should be
constructed to discharge into the site storm water system or other appropriate outlet.
4.3.2 Foundation Construction Considerations
We recommend that the existing fill or reworked and organic soil disclosed in the eastern portion
of the site be totally excavated and removed from beneath and immediately adjacent to the
building footprint as recommended previously in this report. Following removal of the existing fill
or reworked and organic soil, we recommend the excavation be backfilled with compacted
structural fill as recommended in the Earthwork section of this report. The actual horizontal and
vertical extent of the recommended removal of unsuitable soil will require visual observation by
Terracon at the time of construction.
In the event that unsuitable soil is disclosed at the planned foundation level at localized areas in
other portions of the site at the time of construction, overexcavation and removal of the
unsuitable soil will be required in those areas as well. Overexcavation below footings should
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extend laterally beyond all edges of the footings at least 8 inches per foot of overexcavation
depth below footing base elevation. The overexcavation should then be backfilled up to the
footing base elevation with well -graded granular material placed in lifts of 8 inches or less in
loose thickness and compacted to at least 95 percent of the material's modified Proctor
maximum dry density (ASTM D 1557). In areas where overexcavation is required for use of the
higher bearing pressure associated with the dense to very dense advance outwash, we
recommend that the foundation either be deepened or the foundation overexcavation be
backfilled with lean concrete. The overexcavation and backfill procedure is described in the
figure below.
Design
Footing L
Recommi
Excavatic
s'iiJ I i-1 I
Design 2/313 1V
Fooling Level
COMPACTED
STRUCTURAL D
FILL
Recommended
Excavation Level
2I3D
Lean Concrete Backfill Overexcavation / Backfill
NOTE: Excavations in sketches shown vertical for convenience. Excavations should be sloped as necessary for safety.
4.4 Floor Slabs
We recommend complete removal of undocumented fill encountered below the proposed
building floor slab, as described above for the foundation subgrade. Removed soil should be
replaced with structural fill placed and compacted in accordance with the Earthwork section of
this report. A subgrade prepared and tested as recommended in this report should provide
adequate support for a moderately loaded floor slab.
4.4.1 Floor Slab Design Recommendations
Item Description
Interior floor system Slab -on -grade concrete.'
Floor slab support Structural fill placed and compacted in accordance with
the Earthwork section of this report.
Aggregate base course/capillary break'
Minimum 4-inch thickness compacted layer of free
draining, uniform gravel
1. Floor slabs should be structurally independent of any building footings or walls to reduce floor
slab cracking caused by differential movements between the slab and foundation. The slabs
should be appropriately reinforced to support the proposed loads.
2. The base course serves as a capillary break layer, a drainage layer, a leveling layer, and a
bearing layer.
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We recommend subgrades be maintained at the proper moisture condition until floor slabs are
constructed. If the subgrade should become desiccated prior to construction of floor slabs, the
affected material should be removed or the materials scarified, moistened, and recompacted.
Upon completion of grading operations in the building areas, care should be taken to maintain
the recommended subgrade moisture content and density prior to construction of the building
floor slabs.
Where appropriate, saw -cut control joints should be placed in the slab to help control the
location and extent of cracking. For additional recommendations refer to the ACI Design
Manual.
The use of a vapor retarder or barrier should be considered beneath concrete slab -on -grade
floors that will be covered with wood, tile, carpet or other moisture -sensitive or impervious
coverings, or when the slab will support equipment sensitive to moisture. When conditions
warrant the use of a vapor retarder, the slab designer and slab contractor should refer to ACI
302 and ACI 360 for procedures and cautions regarding the use and placement of a vapor
retarder/barrier.
4.4.2 Floor Slab Construction Considerations
On most project sites, the site grading is generally accomplished early in the construction phase.
However as construction proceeds, the subgrade may be disturbed due to utility excavations,
construction traffic, desiccation, rainfall, etc. As a result, the floor slab subgrade may not be
suitable for placement of the base course and concrete slab, and corrective action may be
required.
All floor slab subgrade areas should be moisture conditioned and properly compacted to the
recommendations in this report and then thoroughly proofrolled prior to final grading and
placement of the base course. Particular attention should be paid to high traffic areas that were
rutted and disturbed earlier and to areas where backfilled trenches are located. Areas where
unsuitable conditions are located should be repaired by removing and replacing the affected
material with properly compacted structural fill.
4.5 Seismic Considerations
Description
International Building Code (IBC) and 2010
ASCE 7'
Site Latitude
Site Longitude
SS — Short Period Spectral Acceleration for Site
Value
C2
47.3344° N
122.3124°W
1.306 g
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Class C
S, — 1-Second Period Spectral Acceleration for 0.499 g
Site Class C
Fa — Short Period Site Coefficient 1.000
F —1-Second Period Site Coefficient 1.301
1. The 2010 ASCE 7 document indicates that the seismic site classification is based on the average
soil and bedrock properties in the top 100 feet. The current scope does not include a 100-foot
soil profile determination. This seismic site class definition considers that soil encountered at
depth in our explorations continue below the termination depths. Additional exploration to deeper
depths would be required to confirm the conditions below the current depth of exploration.
2. Site Class C applies to an average soil profile within the top 100 feet consisting predominantly of
very dense soil and soft rock. This soil is characterized by Standard Penetration Test blow counts
in exceedance of 50, a shear wave velocity of between 1,200 and 2,500 feet per second, and an
undrained shear strength in exceedance of 2,000 pounds per square foot.
4.5.1 Fault Zones
Risk of damage from onsite fault rupture appears to be low based on review of the Washington
State Department of Natural Resources Geologic Hazards interactive map accessed on
December 20, 2016. The site is located within the Tacoma fault zone. The closest estimation
of the trace of this fault lies approximately 1,000 feet to the north.
4.5.2 Liquefaction
The term liquefaction refers to a phenomenon by which saturated soil develops high pore water
pressures during seismic shaking and, as a result, loses its strength characteristics. This
phenomenon generally occurs in areas of high seismicity, where groundwater is relatively
shallow and where loose granular soil (mainly sands) or non -plastic fine-grained soil (mainly
silts) is present. Considering the likely depth to groundwater and the dense to very dense
glacially -consolidated soil encountered at depth in our explorations, our opinion is that risk from
liquefaction is very low.
4.5.3 Seismic Surcharge
For backfilled walls or walls cast directly against shoring, we recommend a uniform seismic
lateral surcharge pressure equal to 12H, where H is equal to the wall height in feet, and
pressure is in pounds per square foot (psf). Basement walls between floors can be designed for
80% of the factored seismic load combination to account for the concentration of load at the
relatively stiff floor slabs.
4.6 Lateral Earth Pressures .
Reinforced concrete walls with unbalanced backfill levels on opposite sides should be designed
for earth pressures at least equal to those indicated in the following table. Earth pressures will
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be influenced by structural design of the walls, conditions of wall restraint, methods of
construction and/or compaction and the strength of the materials being restrained. Two wall
restraint conditions are shown. Active earth pressure is commonly used for design of
free-standing cantilever retaining walls and assumes wall movement. The "at -rest" condition
assumes no wall movement. The recommended design lateral earth pressures do not include a
factor of safety and do not provide for possible hydrostatic pressure on the walls.
For active pressure movement
S = Surcharge (0.002 H to 0.004 H)
S For at -rest pressure
- No Movement Assumed
Horizontal
Finished ALGrade
H
Earth Pressure
Conditions and
backslope
Active (Ka)
Horizontal
2:1 Slope
At -Rest (Ko)
Horizontal
2:1 Slope
Horizontal
Finished Grade
�_pz--114 p,--+l - Retaining Wall
Earth Pressure Coefficients
Coefficient for Equivalent Fluid Surcharge Earth Pressure,
Backfill Type Density (pcf) Pressure, p, (psf) I pz (psf)
0.31
40 (0.31)S
(40)H
0.45
60 (45)S
(60)H
0.47
60
(0.47)S
(47)H
0.68
90
(0.68)S
(90)H
Passive (Kp) I 3.25 I 400
Applicable conditions to the above include:
For active earth pressure, wall must rotate about base, with top lateral movements of about
0.002 H to 0.004 H, where H is wall height
For passive earth pressure to develop, wall must move horizontally to mobilize resistance
Uniform surcharge, where S is surcharge pressure
In -situ soil backfill weight a maximum of 135 pcf
Backfill compacted between 92 and 95 percent of modified Proctor maximum dry density
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• Loading from heavy compaction equipment not included
■ No hydrostatic pressures acting on wall
■ No dynamic loading
R No safety factor included
■ Ignore passive pressure in frost zone
Backfill placed against structures should consist of granular soil as described in Section 4.2.3.
For these values to be valid, the granular backfill must extend out and up from the base of the
wall at an angle of at least 45 and 60 degrees from vertical for the active and passive cases,
respectively. To calculate the resistance to sliding, a value of 0.50 should be used as the
ultimate coefficient of friction between the footing and the underlying soil.
A perforated rigid plastic or metal drain line installed behind the base of walls that extend below
adjacent grade is recommended to prevent hydrostatic loading on the walls. The invert of a
drain line around a below -grade building area or exterior retaining wall should be placed near
foundation bearing level. The drain line should be sloped to provide positive gravity drainage or
to a sump pit and pump. The drain line should be surrounded by clean, free -draining granular
material having less than 5 percent passing the No. 200 sieve. The free -draining aggregate
should be encapsulated in a filter fabric and should extend to within 2 feet of final grade, where
it should be capped with compacted low permeability fill to reduce infiltration of surface water
into the drain system.
Layer of `
cohesive fill
Foundation wall
Free draining graded
granular filter material or
non -graded free -draining
material encapsulated in
an appropriate filter
I fabric (see report)
— Slope to drain
away from building
---- 4
1167
r
Baddll (see report
1 B I requirements)
/ '_=
— Native, undisturbed
l•' soil or engineered fill
Perforated drain pipe (Rigid PVC
! 11-11L=1 l unless stated otherwise in report)
As an alternative to free -draining granular fill, a pre -fabricated drainage structure may be used.
A pre -fabricated drainage structure is a plastic drainage core or mesh which is covered with
filter fabric to prevent soil intrusion, and is fastened to the wall prior to placing backfill.
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If controlling hydrostatic pressure behind the wall as described above is not possible, then
combined hydrostatic and lateral earth pressures should be calculated using an equivalent fluid
weighing 85 and 90 pcf for active and at -rest, respectively. These pressures do not include the
influence of surcharge, equipment, or pavement loading, which should be added as applicable.
Heavy equipment should not operate within a distance closer than the exposed height of
retaining walls to prevent lateral pressures more than those provided.
We recommend that permanent basement walls constructed flush against shoring be designed
to withstand uniform rectangular lateral pressure equal to 22 H, in psf, where H equals the wall
height in feet. Permanent walls should be provided with drainage as described subsequently in
this report.
A surcharge load should be added to the lateral pressure if traffic or other loading is anticipated
within a zone extending back from the wall a distance equal to the wall height. A traffic
surcharge equal to 2 feet of retained soil is recommended for traffic loading. A seismic
surcharge, as discussed in Section 4.5.3 should also be considered in the design. For other
loads adjacent to the basement wall, such as adjacent building foundations, please, contact
Terracon to estimate appropriate surcharge pressures.
These equivalent fluid pressures are based on the assumption of a uniform backfill and no
buildup of hydrostatic pressures behind the wall. To prevent the buildup of lateral earth
pressures in excess of the above designed pressures, over compaction of fill behind the walls
should be avoided. This can be accomplished by placing the backfill within 24 inches of the wall
in lifts not exceeding 4 inches in loose depth and compacting with hand -operated or self-
propelled equipment.
Care should be taken where utilities penetrate through basement walls. Minor settlement of the
backfill can put significant soil loading on utilities, and some form of flexible connection may be
appropriate at backfilled wall penetrations.
4.7 Pavements
We encountered undocumented fill soil to depths of/z to 11'/z in our explorations. Provided the
owner is willing to accept the risk of unpredictable settlement response of the undocumented fill
under pavement sections, we recommend limited risk mitigation measures including removal of
at least the upper 12 inches of pavement subgrade, scarification and compaction of the exposed
subgrade, and replacement of the removed material with structural fill in accordance with the
earthwork section of this report. Based on the results of our explorations, the undocumented fill
soil is generally in a very loose to medium dense condition and represents a moderate risk of
excessive settlements due to traffic loading after completion of the recommended
improvements, though areas of unsuitable or compressible fill may be present within the fill
areas that were not observed in our explorations.
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4.7.1 Subgrade Preparation
On most project sites, the site grading is accomplished relatively early in the construction phase.
However, as construction proceeds, excavations are made into these areas, rainfall and surface
water saturates some areas, heavy traffic from concrete trucks and other construction vehicles
disturbs the subgrade, and many surface irregularities are filled in with loose soil to temporarily
improve driving conditions. As a result, the pavement subgrades, initially prepared early in the
project, should be carefully evaluated as the time for pavement construction approaches.
We recommend that the moisture content and density of the top 12 inches of the subgrade be
evaluated and that the pavement subgrades be proofrolled within two days prior to
commencement of actual paving operations. Areas not in compliance with the required ranges of
moisture or density should be moisture conditioned and recompacted. Particular attention should
be paid to high traffic areas that were rutted and disturbed earlier and to areas where backfilled
trenches are located. Areas where unsuitable conditions are located should be repaired by
removing and replacing the materials with properly compacted structural fills. If a significant
precipitation event occurs after the evaluation or if the surface becomes disturbed, the subgrade
should be reviewed by qualified personnel immediately prior to paving. The subgrade should be
in its finished form at the time of the final review.
4.7.2 Design Considerations
We anticipate that traffic loads will be produced primarily by automobile and light traffic and by
occasional larger moving trucks and trash -removal trucks. The thickness of pavements
subjected to heavy truck traffic should be determined using expected traffic volumes, vehicle
types, and vehicle loads and should be in accordance with local, city or county ordinances.
Pavement thickness were determined using AASHTO methods based on assumed values of
maximum ESAL loading of 100,000 (ESAL = equivalent 18-kip single axle load) for standard
duty car and light truck parking areas over a 20-year design life. For heavy duty truck traffic
areas, we used an assumed traffic loading of 250,000 ESALs in our analysis. If traffic loading
developed by the civil engineer differs significantly from these assumed values, the pavement
thickness design should be revisited.
The minimum pavement sections outlined below were determined based on the estimated
subgrade support and post -construction traffic loading conditions. These pavement sections do
not account for heavy construction traffic during development. A partially constructed structural
section may be subjected to heavy construction traffic that can result in pavement deterioration
and premature failure. Our experience indicates that this pavement construction practice can
result in pavements that will not perform as intended. Considering this information, several
alternatives are available to mitigate the impact of heavy construction traffic on the pavement
construction. These include using thicker sections to account for the construction traffic; using
some method of soil stabilization to improve the support characteristics of the pavement
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Geotechnical Engineering Report
StorQuest Self Storage Federal Way, Washington
January 11, 2017 Terracon Project No. 81165135
Irerracon
subgrade; routing heavy construction traffic around paved areas; or delaying paving operations
until as near the end of construction as is feasible.
Pavement performance is affected by its surroundings. In addition to providing preventive
maintenance, the civil engineer should consider the following recommendations in the design
and layout of pavements:
Final grade adjacent to parking lots and drives should slope down from pavement edges at
a minimum 2 percent;
The subgrade and the pavement surface should have a minimum 114 inch per foot slope to
promote proper surface drainage;
Install pavement drainage surrounding areas anticipated for frequent wetting (e.g.,
landscaping areas, etc.);
Install joint sealant and seal cracks immediately;
Seal all landscaped areas in, or adjacent to pavements to reduce moisture migration to
subgrade soil, and;
Place compacted, low permeability backfill against the exterior side of curb and gutter
Our pavement design was conducted using an assumed CBR value of 20 percent. To obtain
this CBR value in the field, the pavement subgrade must be thoroughly compacted to at least 95
percent of the modified Proctor density within 2 percent of its optimum moisture. Any imported
structural fill placed below proposed pavement areas should have a CBR value of at least 20
percent.
4.7.3 Estimates of Minimum Pavement Thickness
MINIMUM STANDARD -DUTY PAVEMENT SECTION FOR
CAR AND LIGHT TRUCK -ONLY AREAS
Layer
Asphalt Surface
Crushed Aggregate Base
Compacted Structural Fill
Subgrade
Total Pavement Section
Thickness Compaction/Material
(inches) Specification
WSDOT: 9-03.8(2) %-inch HMA
WSDOT: 9-03.8(6) %-inch Aggregate
WSDOT: 9-03.9(3) Base Course
95% of Modified Proctor MDD, -2 to
+2% OMC
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Geotechnical Engineering Report
StorQuest Self Storage - Federal Way, Washington
January 11, 2017 :: Terracon Project No. 81165135
Irerracon
MINIMUM HEAVY DUTY -PAVEMENT SECTION FOR TRUCK AREAS
` Thickness
Layer I (inches) 1
Asphalt Surface Course 4.0
Crushed Aggregate Base 6.0
Compacted Structural Fill 12
Subgrade
Total Pavement Section 10.0
Compaction/Material
Specification
WSDOT: 9-03.8(2) %-inch HMA
WSDOT: 9-03.8(6) %-inch Aggregate
WSDOT: 9-03.9(3) Base Course
95% of Modified Proctor MDD, -2 to
+2% OMC
The abbreviations MDD, OMC, and HMA in the tables above refer to Maximum Dry Density,
Optimum Moisture Content, and Hot Mix Asphalt, respectively. The graded crushed aggregate
base should be compacted to a minimum of 95 percent of the material's modified Proctor
(ASTM D 1557, Method C) maximum dry density. We recommend that asphalt be compacted
to a minimum of 92 percent of the Rice (theoretical maximum) density or 96 percent of Marshall
(maximum laboratory) density.
We recommend that a Portland cement concrete pavement (CCP) be utilized in entrance and
exit sections, dumpster pads, loading dock areas, or other areas where extensive wheel
maneuvering or repeated loading are expected. The dumpster pad should be large enough to
support the wheels of the truck which will bear the load of the dumpster. We recommend a
minimum of 6 inches of CCP underlain by 4 inches of crushed aggregate base. Although not
required for structural support, the base course layer is recommended to help reduce potentials
for slab curl, shrinkage cracking, and subgrade "pumping" through joints. Proper joint spacing
will also be required to prevent excessive slab curling and shrinkage cracking. All joints should
be sealed to prevent entry of foreign material and dowelled where necessary for load transfer.
Portland cement concrete should be designed with proper air -entrainment and have a minimum
compressive strength of 4,000 psi after 28 days of laboratory curing. Adequate reinforcement
and number of longitudinal and transverse control joints should be placed in the rigid pavement
in accordance with ACI requirements. The joints should be sealed as soon as possible (in
accordance with sealant manufacturer's instructions) to minimize water infiltration into the soil.
4.7.4 Pavement Drainage
Pavements should be sloped to provide rapid drainage of surface water. Water allowed to pond
on or adjacent to the pavements could saturate the subgrade and contribute to premature
pavement deterioration. In addition, the pavement subgrade should be graded to provide positive
drainage within the crushed aggregate base section.
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StorQuest Self Storage :.: Federal Way, Washington
January 11, 2017 Terracon Project No. 81165135
We recommend drainage be included at the bottom of the crushed aggregate base layer at the
storm structures to aid in removing water that may enter this layer. Drainage could consist of
small diameter weep holes excavated around the perimeter of the storm structures. The weep
holes should be excavated at the elevation of the crushed aggregate base and soil interface.
The excavation should be covered with crushed aggregate which is encompassed in Mirafi
140NL or approved equivalent which will aid in reducing fines from entering the storm system.
4.7.5 Pavement Maintenance
The pavement sections provided in this report represent minimum recommended thicknesses.
Therefore preventive maintenance should be planned and provided for through an on -going
pavement management program. Preventive maintenance activities are intended to slow the rate
of pavement deterioration, and to preserve the pavement investment. Preventive maintenance
consists of both localized maintenance (e.g., crack and joint sealing and patching) and global
maintenance (e.g., surface sealing). Preventive maintenance is usually the first priority when
implementing a planned pavement maintenance program. Prior to implementing any
maintenance, additional engineering observation is recommended to determine the type and
extent of a cost-effective program. Even with periodic maintenance, some movements and
related cracking may still occur and repairs may be required.
4.8 Temporary Shoring
Based on the soil conditions observed at the exploration locations and the proposed floor slab
elevation, we recommend that either soldier pile or soil nail shoring be considered to temporarily
support the excavation during construction. Provided adequate distance is available, temporary
slope cuts can be combined with the shoring system to reduce the height retained by the
shoring. The shoring required to support the excavation is typically used as back forms for the
permanent basement walls.
Terracon is in discussions with the design team regarding design of temporary shoring systems
for this project at the time of this report. The following design and construction parameters are
provided for preliminary planning purposes.
4.8.1 Soil Nail Wall Design Recommendations
The basic concept of soil nailing is to reinforce and strengthen the existing ground by installing
closely spaced steel bars commonly referred to as "nails" into a slope or excavation as
construction proceeds from the top, downward. This produces a reinforced zone that is itself
stable and helps to support the un-reinforced ground behind it. The nails are considered
passive as tension is applied as they resist the deformation of the adjacent soil. The nail
reinforcement improves stability in two ways. First, soil nailing reduces the driving force along
the potential failure surfaces. Second, in frictional soil, nailing increases the normal force and
hence the soil shear resistance along potential failure surfaces. If required, vertical elements
typically consisting of closely spaced steel beams or pipes placed in augered holes and
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StorQuest Self Storage Federal Way, Washington
January 11, 2017 Terracon Project No. 81165135
backfilled with lean concrete can be installed to improve face stability and temporary conditions
during nail installation.
Based on the subsurface conditions encountered during our site investigation, the portion of the
site where shoring will likely be required consists of glacially -consolidated deposits of advance
sand composed of dense to very dense gravelly sand with variable silt and cobble content. At
the time of this report, shoring is not anticipated within the uncontrolled fill soil in the eastern
portion of the site. If future plans require shoring within the fill, Terracon should be consulted to
provide additional design recommendations.
The following parameters are recommended for design of soil nail walls:
Advance Outwash
Friction Angle: 38 degrees
Cohesion: 100 psf
Moist Unit Weight: 135 pcf
Ultimate Pullout Strength (minimum 6-inch diameter soil nail): 6 kip/ft.
Allowable Pullout Strength (minimum 6-inch diameter soil nail): 3 kip/ft.
The actual adhesion value will depend on the materials and installation methods and should be
confirmed by testing. Larger diameter drill holes and/or secondary grouting may be required to
achieve the recommended pull out capacity. Installation methods should be the responsibility of
the contractor. The location and presence of existing features should be checked during the
design as these may affect the location and lengths of the soil nails.
Vertical elements may be used to provide cantilever support where utilities or adjacent
structures prevent installation of soil nails in the upper portion of the shoring wall. The vertical
elements should be designed using the recommendations presented in the soldier pile sections
of this report. The allowable passive resistance can be represented as an equivalent fluid
weight of 350 pcf above the groundwater table and 200 pcf below and can be assumed to act
over three times the concrete pile diameter or pile spacing, whichever is less.
We recommend that soil nail shoring be designed in general accordance with local standard of
practice and soil surcharge pressures from slopes, construction loads, and traffic be included in
the analysis and design, where appropriate.
4.8.2 Soil Nail Shoring Installation
Cased holes may be required to prevent caving and loss of ground within any surficial fill and
sandy zones within the glacially overridden deposits. The soil nail grout should be pumped into
the soil nail holes by tremie methods in order to force grout up from the bottom of the hole and
to provide a continuously grouted soil nail.
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StorQuest Self Storage -:. Federal Way, Washington
January 11, 2017 m Terracon Project No. 81165135
A minimum of two sacrificial, 200 percent verification tests should be performed in each soil type
to be nailed in order to evaluate the ultimate soil friction capacity and the load deformation
performance of the soil nail. Verification testing should be accomplished as soon as each soil
type is encountered and prior to installation of production nails. The location of the verification
tests should be selected by the contractor and approved by the engineer of record. The drilling
method, hole diameter, and depth of soil nail should be identical to the production soil nails.
Additionally, 5 percent of production soil nails should be proof tested to 150 percent of design
load to confirm the design capacity and appropriate construction methods.
4.8.3 Soldier Piles
Soldier piles for shoring are typically set in drilled holes and backfilled with lean or structural
concrete. Soldier pile installation may involve casing the holes and/or drilling with a mud slurry
to cut-off groundwater seepage. Passive earth pressures acting on the embedded portion of the
soldier piles resist horizontal loads on the shoring system. We recommend using an allowable
equivalent fluid unit weight of 350 pcf. The passive earth pressure will act over three diameters
of the concreted soldier pile section or the pile spacing, whichever is less. The active earth
pressures act over the concreted pile diameter below the base of the excavation.
For a cantilevered shoring system or shoring with one row of tieback anchors or internal
bracing, we recommend the following:
Use an equivalent fluid unit weight of 30 pounds per cubic foot (pcf) for active earth
pressures and 50 pcf for at -rest earth pressures;
For the case of street loads adjacent to the shoring, add a uniform surcharge load
equivalent to 2 additional feet of soil;
For the case of a slope above the shoring, add a uniform surcharge that is the product of the
appropriate equivalent fluid unit weight (e.g., 30 pcf) and one-half the height of the cut slope;
and
For other loads adjacent to the shoring (e.g., heavy construction loads and building
foundations), contact Terracon to estimate appropriate surcharge pressures.
For tieback anchors, the anchor portion of the tieback should be located sufficiently far behind
the excavation shoring to stabilize the excavation face. The no "load" zone limits is the area
behind the soldier pile equal to a lateral distance from the base of the excavation equal to the
exposed wall height (H in feet) divided by four, or five feet, whichever is greater, and a line
sloping up and back at 60 degrees from horizontal.
The selection of the tieback materials and installation methods should be the responsibility of
the contractor. The actual adhesion values will depend on the materials and installation method
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StorQuest Self Storage : Federal Way, Washington
January 11, 2017 Terracon Project No. 81165135
and should be confirmed by testing. For non -pressure grouted anchors, the allowable design
concrete/soil adhesion value of 2,000 psf can be used for preliminary design and cost
estimating purposes. For pressure grouted anchors, this value can typically be increased by
two to three times. We recommend all tieback anchors be proof tested to at least 130% of the
design capacity prior to locking off at the specified post tensioned design load. Prior to
installation of production anchors, two verification tests to 200% of the design pull out capacity
are recommend for each soil type in order to confirm the design capacity.
A minimum anchor spacing of four feet center to center is recommended for tieback anchors.
The anchor holes should be drilled at an angle of 15 to 30 degrees down from horizontal. A
minimum anchor bond of 10 feet is recommended. The location and presence of existing
features such as utilities and foundation should be checked during the design as these may
affect the location and length of tieback anchors.
Vertical capacity of the soldier piles may be provided by a combination of end bearing and side
friction below the base of the excavation. The piles can be designed for an allowable end
bearing resistance of 20 ksf with an allowable side friction of 2 ksf for that portion of the pile
embedded into the dense to very dense glacially consolidated soil. A factor of safety of 3 and 2
apply to the allowable end bearing and side friction, respectively.
We recommend timber lagging, or some other form of protection, be installed in all areas. Due
to soil arching effects, lagging may be designed for 40 percent of the lateral earth pressure used
for shoring design. Prompt and careful installation of lagging would reduce potential loss of
ground. The requirements for lagging should be made the responsibility of the shoring
subcontractor to prevent soil failure, sloughing, and loss of ground. Proper installation of
lagging is critical to provide safe working conditions. We recommend that any voids between
the lagging and soil be backfilled promptly. However, the backfill should not allow potential
hydrostatic pressure to build-up behind the wall. Drainage behind the wall must be maintained.
4.8.4 Soldier Pile Shoring Installation
The contractor should be required to prevent caving and loss of ground in all soldier pile drill
holes. The shoring contractor will need to use methods to minimize caving and sloughing of the
drill holes, such as the use of augercast methods or installation of casing. If more than one foot
of water is present in the bottom of the hole, placement of concrete from the bottom of the hole
will be required.
When drilling tieback anchor holes, casing may be required to prevent caving and loss of
ground. The anchor grout should be pumped into the anchor zone by tremie methods in order
to remove water from the hole and to provide a continuous grouted anchor.
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StorQuest Self Storage Federal Way, Washington
January 11, 2017 :- Terracon Project No. 81165135
Voids behind the lagging should be backfilled immediately with a permeable granular soil
material or lean concrete. The excavation height prior to lagging installation should not exceed
5 feet to maintain stability of the cut face.
4.8.5 Monitoring of Temporary Shoring
Any time an excavation is made below the level of existing buildings, utilities, or other
structures, there is risk of damage even if a well -designed shoring system has been planned.
We recommend, therefore, that a systematic program of observations be conducted on adjacent
facilities and structures. The monitoring program should include measurements of the
horizontal and vertical movements of the adjacent structures and the shoring system itself. At
least two reference lines should be established adjacent to the excavation at horizontal
distances back from the excavation space of about 1 /3H and H, where H is the final excavation
height. Monitoring of the shoring system should include measurements of horizontal
movements at the top of every other soldier pile. If local wet areas are noted within the
excavation, additional monitoring points may be recommended by Terracon.
The measuring system used for shoring monitoring should have an accuracy of at least 0.01-
feet. All reference points on the existing structures should be installed and readings taken prior
to commencing the excavation. All reference points should be read prior to and during critical
stages of construction. The frequency of readings will depend on the results of previous
readings and the rate of construction. As a minimum, readings should be taken about once a
week throughout construction until the basement walls are completed. All readings should be
reviewed by Terracon.
In order to establish the condition of existing facilities prior to construction, we recommend that
William Warren Group makes a complete inspection and evaluation of pavements, structures,
utilities, and other facilities near the project site. This inspection should be directed towards
detecting any existing signs of damage, particularly those caused by settlement or lateral
movement. The observations should be documented by pictures, notes, survey drawings, or
other means of verification. The contractor should also establish for their own records the
existing conditions prior to construction.
5.0 GENERAL COMMENTS
Terracon should be retained to review the final design plans and specifications so comments
can be made regarding interpretation and implementation of our geotechnical recommendations
in the design and specifications. Terracon also should be retained to provide observation and
testing services during grading, excavation, foundation construction and other earth -related
construction phases of the project.
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Geotechnical Engineering Report lFerracon
StorQuest Self Storage Federal Way, Washington
January 11, 2017 :- Terracon Project No. 81165135
The analysis and recommendations presented in this report are based upon the data obtained
from the explorations performed at the indicated locations and from other information discussed
in this report. This report does not reflect variations that may occur between explorations,
across the site, or due to the modifying effects of construction or weather. The nature and
extent of such variations may not become evident until during or after construction. If variations
appear, we should be immediately notified so that further evaluation and supplemental
recommendations can be provided.
The scope of services for this project does not include either specifically or by implication any
environmental or biological (e.g., mold, fungi, bacteria) assessment of the site or identification or
prevention of pollutants, hazardous materials or conditions. If the owner is concerned about the
potential for such contamination or pollution, other studies should be undertaken.
This report has been prepared for the exclusive use of William Warren Group and their design
consultants for specific application to the project discussed and has been prepared in
accordance with generally accepted geotechnical engineering practices. No warranties, either
express or implied, are intended or made. Site safety, excavation support, and dewatering
requirements are the responsibility of others. In the event that changes in the nature, design, or
location of the project as outlined in this report are planned, the conclusions and
recommendations contained in this report shall not be considered valid unless Terracon reviews
the changes and either verifies or modifies the conclusions of this report in writing.
Responsive Resourceful .. Reliable 25
APPENDIX A
FIELD EXPLORATION
Projen Mope Project No, SITE LOCATION MAP EXHIBIT
SGP 81165135
oramroy: AMP wale: ASSHOWN I C StorQuest Federal Way
chocked By: mie No, Consulting Engineers and Scientists
sGP ExhibitA-1 298th Block Pacific HWY S. A-1
Approved&: Date: 2190564a,Avenue W..sr100 Moundakel'errace,WA98043 Federal Way, King County, Washington
DRS January Z017 All OM 771 3304 FAX (425) 771 3549
VACANT LAND
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LEGEND:
B-3 Exploration Number
S 70' Exploration offset direction and distance from
section
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THE SUBSURFACE CONDITIONS SHOWN ON THE GENERALIZED SUBSURFACE PROFILE ARE BASED UPON INTERPOLATION BETWEEN WIDELY SPACED
EXPLORATIONS AND MAY NOT REPRESENT ACTUAL SUBSURFACE CONDITIONS. SIMPLIFIED NAMES ARE SHOWN FOR SOIL DEPOSITS, BASED ON
N-5p 5'
'1
,®GM'+u'
Gravel
S.
LOGS AND REPORT TEXT FOR MORE DETAILED SOIL AND GROUNDWATER DESCRIPTION
Water Level Reading at time of drillingtl
GENERALIZATIONS OF SOIL DESCRIPTIONS. SEE EXPLORATION
27— 4- ;
N`110'ar-2,3rl Borin Termination depth
p
EXHIBIT
s
NOTES:
Pf0JCC1Mnsr SGP
ProjeaNu 81165135
1rerracon
SECTION A -A
Drawn 6y'
Sale:
StorQuest Federal Way
2:1 Vertical Exaggeration
See ExhibitA-2 for orientation of soil profile.
AMP
cheekedBy:
AS SHOWN
FdeNu
Consulting Engineers and Scientists
298th Block Pacific HWY S.
A_3
SGP
Exhbit3.dw
See General Notes in Appendix C for symbols and soil classifications.
App,oved13,
Daze:
216D564thAvenueW,S1e160 Nleue(lakeTeeaCL,M08043
Federal Way, King County, Washington
Soil profile provided for illustration purposes only.
DRSIJ
January 2017
1 P11. (425) 771 3304 F,1k (125) 77135,19
Soil between borings may differe.
1
Geotechnical Engineering Report Irerracon
StorQuest Self Storage ; Federal Way, Washington
January 11, 2017 .: Terracon Project No. 81165135
Field Exploration Description
The subsurface exploration consisted of drilling and sampling four borings and excavating four
test pits at the site to depths ranging from about 9'/2 to 50 feet below existing grade. The boring
and test pit locations were laid out by Terracon personnel. Distances from these locations to
the reference features indicated on the attached diagram are approximate and were estimated.
The locations of the borings should be considered accurate only to the degree implied by the
means and methods used to define them. Horizontal boring locations were determined using a
handheld GPS instrument. The boring elevations were interpolated from the topographic survey
provided by Magellan Architects.
Field logs of each boring and test pit were prepared by the engineer or geologist on site. These
logs included visual classifications of the materials encountered during drilling/excavating as
well as the engineer or geologist's interpretation of the subsurface conditions between samples.
Final boring and test pit logs included with this report represent an interpretation of the field logs
and include modifications based on laboratory observation and tests of the samples obtained in
the field. The enclosed boring and test pit logs indicate the vertical sequence of soil and
materials encountered in each exploration. Where a soil contact was observed to be
gradational, our logs indicate the average contact depth.
The samples were classified in the laboratory based on visual observation, texture and
plasticity. The descriptions of the soil indicated on the boring logs are in general accordance
with the enclosed General Notes and the Unified Soil Classification System. Estimated group
symbols according to the Unified Soil Classification System are given on the boring logs. A brief
description of this classification system is attached to this report.
Soil Boring Procedures
The borings were drilled with a track -mounted rotary drill rig using hollow stem augers to
advance the boreholes. Representative soil samples were obtained by the split -barrel sampling
procedure. In the split -barrel sampling procedure, the number of blows required to advance a
standard 2-inch O.D. split -barrel sampler the last 12 inches of the typical total 18-inch
penetration by means of a 140-pound hammer with a free fall of 30 inches, is the standard
penetration resistance value (N). These values are indicted on the borings logs at the depths of
occurrence. This value is used to estimate the in -situ relative density of cohesionless soil and
the consistency of cohesive soil. The sampling depths and penetration distance, plus the
standard penetration resistance values, are shown on the boring logs. The samples were
sealed and taken to the laboratory for testing and classification.
An automatic SPT hammer was used to advance the split -barrel sampler in the borings
performed on this site. A greater efficiency is typically achieved with the automatic hammer
compared to the conventional safety hammer operated with a cathead and rope. Published
correlations between the SPT values and soil properties are based on the lower efficiency
Responsive - Resourceful Reliable Exhibit A-4
Geotechnical Engineering Report Irerracon
StorQuest Self Storage - Federal Way, Washington
January 11, 2017 -- Terracon Project No. 81165135
cathead and rope method. This higher efficiency affects the standard penetration resistance
blow count (N) value by increasing the penetration per hammer blow over what would obtained
using the cathead and rope method. The effect of the automatic hammer's efficiency has been
considered in the interpretation and analysis of the subsurface information for this report.
Test Pit Procedures
Test pits were excavated with a tracked excavator operated by an excavation company
(Northwest Excavating) working under subcontract to Terracon. A geologist from our firm
continuously observed the test pits, logged the subsurface conditions that were encountered,
and obtained disturbed representative soil samples. The samples were stored in moisture -tight
containers and transported to our laboratory for visual classification and testing.
After completion of the test pits, the resulting excavations were backfilled with the excavated
material. The backfill was compacted in lifts by means of bucket tamping with the excavator.
Some settlement of the backfill should be expected
Responsive ■ Resourceful a Reliable Exhibit A-4
BORING LOG NO. B-1
Page 1 of 3
PROJECT:
StorQuest Federal Way CLIENT: William
298th Block Pacific Highway South
Warren Group
SITE:
Federal Way, Washington
0LOCATION
See Exhibit A-2
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8
12
s
N=74/11"
a
i
455
1
GRAVELLY RQOE�LY-GRAdEB SAND WITH S ISP�11, with
16
24-42-46
S-3
6
m.
cobbles, tan -brown, very dense, moist (ADVANCE OUTWASH)
N=88
gym:
(blowcount on gravel may be overstated)
s.
'a
20—
d
17
19-36-50/5"
S 4
10
9
C"
N=86/11
D
u ..'®.
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u
Strdti5ca11on lines are approximate. In�ilu, the transition may be gradual.
Hammer Type: Automallc SPT Hammer
YP
x
i
7) Advancement
Method: See Exhibit A-4 for description of field
Notes:
1 Hollow
Stem Auger procedures
See Appendix 8 for description of laboratory
j
�
procedures and additional data (if any).
Method: See Appendix C for explanation of symbols and
Abandonment
z
n Borings
backfilled with bentonite chips upon completion abbreviations.Elevations were interpolated from a topographic
WATER LEVEL OBSERVATIONS
Groundwater not encountered Irerracon
Baring Started: 10/25I2016
Drill Rig: Track
Boring Completed:
Driller: Holocene
10125/201
6
�
X
p
m
21905 64th Ave W Ste 100
Mountlake Terrace, WA
Project No.: 81165135 Exhibit:
A-5
L
=
BORING LOG NO. B-1
PROJECT: StorQuest Federal Way CLIENT: William Warren Group
SITE: 298th Block Pacific Highway South
Federal Way, Washington
o LOCATION See Exhibit A-2
U_ Latitude:47.3343° Longitude:-122.3133'
2
<L
DEPTH
I
.-.
J Z
w z
O
v
_a
Surface Elev.: 470 (Ft.)
_
o
M
O
[,r?4VELLY POORLY -GRADED SAND WITH SILT_(SPSM), with
cobbles, tan -brown, very dense, moist (ADVANCE OUTWASH)
® (continued)
-.4.
58Nt}Y GRAVEL WITH SILT tGW-GM), brown, dense, moist
(ADVANCE OUTWASH)
are approximate. In -situ, the transition may be gradual.
ivamr aiq ertt Method:
Hollow Stem Auger
IAbandonment Method:
Borings backfilled with bentonite chips upon completion
Groundwater not encountered
2 of 3
w
t
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c
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rr
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26-5016"
S-5
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32-50/3"
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4
50/6"
S 7
N=50/6"
3
40-5011"
S 8
N=50l1"
1
5012"
S-9
N=50/2"
ype- Automatic'!- I rummer
See Exhibit A-4 for description of field
Notes:
procedures
See Appendix B for description of laboratory
procedures and additional data (if any).
See Appendix C for explanation of symbols and
abbreviations.
Elevalions were interpolated from a topographic
�Op Man
Boring Started: 10/25I2016
Irerracon
Drill Rig: Track
21905 64th Ave W Ste 100
Mountlake Terrace, WA
Project No.: 81165135
Boring Completed: 10125/2016
Driller: Holocene
Exhibit: A-5
BORING LOG NO. B-2
PROJECT: StorQuest Federal Way , CLIENT: William Warren Group
SITE: 298th Block Pacific Highway South
Federal Way, Washington
o LOCATION See Exhibit A-2
O Latitude:47.33430 Longitude:-122.3129'
2
a
J Z
wZ
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w of
Surface Elev.: 438 (Ft.)
_ _..._
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SILTY SAND WITH GRAVEL SM , brown, medium dense, moist
(FILL)
SANDY WELL GRADED GRAVEL ME with cobbles, trace silt,
brown, very dense, moist (ADVANCE OUTWASH)
(blowcount on gravel may be overstated) I 5
(blowcount on gravel may be overstated) f 1
SILTY-CLAYEY_SAND WITH GRAVE L6Mj brown, very dense,
moist to wet (ADVANCE OUTWASH)
itificatlon lines are approximate. In -situ, the transition may be gradual.
vancement Method:
Hollow Stem Auger
IAbandonment Method:
Borings backfilled with bentonite chips upon completion
Groundwater not encountered I
1
1 of 2
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9
25-28-30
S-6
16
5
N=58
13
15-31-36
S-7
N=67
I ype: Rummauc ar i hammer
See Exhibit A-4 for description of field Notes:
procedures
See Appendix B for description of laboratory
procedures and additional data (if any).
See Appendix C for explanation of symbols and
abbreviations.
Elevations were interpolated from a topographic
Irerracon Wrq Started: 10126/2016
Drill Rig: Track
21905 64th Ave W Ste 100
Mountlake Terrace, WA Project No.: 81165135
Boring Completed: 10/26/2016
Driller: Holocene
Exhibit: A-6
BORING LOG NO. B-2
PROJECT: StorQuest Federal Way I CLIENT: William Warren Group
SITE: 298th Block Pacific Highway South
Federal Way, Washington
o LOCATION See Exhibit A-2
J
U_ Latitude:47.3343' Longitude:-122.3129'
x
a.
9
LL
x
a
Surface Elev.: 438 (Ft.) o
IL LAYEY SANP NTH GRAVRLM , brown, very dense,
moist to wet (ADVANCE OUTWASH) (continued)
.o
SILTY SAND WITH GRAVEL I'SM), with cobbles, brown, very dense,
moist (ADVANCE OUTWASH)
Boring Terminated at 31.3 Feet
lines are approximate. In -situ, the transition may
IAdvancement Method:
Hollow Stem Auger
IAbandonment Method:
Borings backflled with bentonite chips upon completion
Groundwater not encountered I
See Exhibit A-4 for description of field
procedures
See Appendix B for description of laboratory
procedures and additional data (if any).
See Appendix C for explanation of symbols and
abbreviations.
Elevations were interpolated from a topographic
Irerracan
21905 64th Ave W Ste 100
Mountlake Terrace. WA
2 of 2
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19-23-35
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35-36-50/3"
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N=86/9"
Hammer type: wnamancarr narnrner
Notes:
Boring Started: 10/26/2016 Boring Completed: 10/26/2016
Drill Rig: Track Driller: Holocene
Prolect No.: 81165135 Exhibtl: A-6
BORING LOG NO. B-3
Page 1 of 1
PROJECT: StorQuest Federal Way CLIENT: William Warren Group
SITE: 298th Block Pacific Highway South
Federal Way, Washington
cn LOCATION See Exhibit A-2
W z a
i-
L
m
o
Z
o v
U Latitude: 47.3341 ° Longitude:-122.3127° H
w� S
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w� a
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o.
❑ ELEVATION Ft.
SILTY SAND WITH GRAVEL ISM) brown, medium dense to dense,
17
15-16-27
S-1
° moist
14
16-18-27
S-2
6
N=45
3.n 436
�. G ELLY POO LY ❑ N❑ WITH with
cobbles, brown, very dense, moist (ADVANCE OUTWASH)
15
20-32-46
S-3
6
5
9
15-26 38
S-4
°•
N=64
B'
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A
°
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19-50/6"
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7
8
i
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.
i B
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:1
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•
10
27-43-50/4"
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a1�.
N=93/10"
C 21.3
Boring Terminated at 21.3 Feet
C
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7
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e
L
7
u
Stratificasian lines are approaimat>9. In -situ, the transition may be gradual.
Hammer Type: Automatic SPT Hammer
yp
r
L
o Advancement Method: See Exhibit A-4 for description of field
Notes:
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j See Appendix B for description of laboratory
= procedures and additional data (if any).
Abandonment Method: See Appendix C for explanation of symbols and
z abbreviations.
n Borings backfilled with bentonite chips upon completion Elevations were interpolated from a topographic
WATER LEVEL OBSERVATIONS
j
Boring Started: 10/26/2016 Boring Completed: 10/2612016
r 19.5' - Perched Groundwater While Drilling
Irerracon
Drill Rig: Track
Driller: Holocene
n 21905 64th Ave W Ste 100
= Mountlake Terrace, WA
r
Project No.: 81165135 Exhibit:
A-7
i
BORING LOG NO. I
PROJECT: StorQuest Federal Way CLIENT: Wi
I
SITE: 298th Block Pacific Highway South
Federal Way, Washington
LOCATION See Exhibit A-2
J
v Latitude:47.3342' Longitude:-122.3124°
d
Surface Elev.: 434 (Ft.)
(7
DEPTH ELEVATION Fl.
SILTY SAND WITH GRAVEL L_M]. with rootlets, brown, medium
dense, moist (FILL)
3.i7 431
3,5 -6 inches relic topsoil 430.6
GRAVELLY SILTY SAND (SMI, brown, very loose to medium dense,
moist (FILL)
11.5 422.5
SILTY SAND WITH GRAVEL (SMI, brown, medium dense, moist
140 420
�ILT( SAN12 WITH GRAVEL fSMI, with cobbles, brown, very dense,
moist (ADVANCE OUTWASH)
•
c
G
I :
416
�8.n
Boring Terminated at 18 Feet
i
Stratification lines are approximate. In -situ, the transition may he gradual.
� Advancement Method: See Exhibit A-4 for description of field
Hollow Stem Auger procedures
See Appendix B for description of laborato
procedures and additional data (if any).
Abandonment Method: See Appendix C for explanation of symbol.
Borings backfilled with bentonite chips upon completion abbreviations.
! Elevations were interpolated from a topogi
' WATER LEVEL OBSERVATIONS
Groundwater not encountered
Irerracoi
i
, 21905 64th Ave W Ste 100
Mountlake Terrace, WA
3-4
Iliam Warren Group
W ° CL
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Notes:
14
12
9
8
7-8-19
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N=14
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3 S-6
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17 12-21-29 S-7 8
Automalic
Y
;and
aphic
Boring Started:10/26/2016
41 Drill Rig: Track
Praw No.:81165135
Boring Completed: 10/26/2016
Driller: Holocene
Exhibit, A-8
TEST PIT LOG NO. TP-1
Page 1 of 1
PROJECT: StorQuest Federal Way CLIENT: William Warren Group
SITE: 298th Block Pacific Highway South
Federal Way, Washington
c� LOCATION See Exhibit A-2
N
> Z CL
LU
o
LU
z
OU Latitude: 47.3344' Longitude:-122.3124°
W ¢ Y
> K
W J
p
7 W Z
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WI a
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3: m Q 0
LL
¢
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DEPTH ELEVATION F1.
Cn
rr
rn
-
ISILTY VEL Y SAND, with wood, roots, brown -gray, loose to
° medium dense• moist to wet (FILL)
r
l
a•
5
_
S-2
n
6.s 426.5
SIM SAND WITH GRAVEL, with wood and organics, brown -black,
b� loose, wet (FILL/TOPSOIL)
n 9.0 424
�+ SILTY SAND WITH GRAVEL_(SM), tan -brown, medium dense, moist
� 10—
S-3
- e 11.0 422
SILTY D WIT VE brown -gray, dense to very dense,
> ° moist (ADVANGE OUTWASH)
420.5
12.5
Test Pit Terminated at 12.5 Feet
0
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¢
(D Advancement Melnod: See Exhibit A-4 for description of field
Notes:
LL Excavator procedures
See Appendix B for description of laboratory
procedures and additional data (if any).
r See Appendix C for explanation of symbols and
o Abandonment Method:
Z Backfilled with loll in lifts and tamped with bucket. abbreviations.
m Elevations were interpolated from a topographic
ceci
WATER LEVEL OBSERVATIONS
Yes! Pit Started: 12/16/2016
Test Pit Completed: 12/16/2016
O
z Groundwater not encountered
Irerracon
Excavator:
Operator: NW Excavating
0
m 21905 64th Ave W Ste 100
Mountlake Terrace. WA
Project No.: 81165135
I
Exhibit: A-9
=
f-
TEST PIT LOG NO. TP-2
PROJECT: StorQuest Federal Way CLIENT: William Warren Group
SITE: 298th Block Pacific Highway South
Federal Way, Washington
LOCATION See Exhibit A-2
J
v_ Latitude:47.3341' Longitude:-122.3125'
o_
I
--.
J z
w z
O
v>
J Q
w
aU)Surface
Elev.: 437 (Ft.)
-- -
o
� m
O
SILTY GRAVELLY SAND, with organics, brown -gray, loose to medium
dense, moist (FILL)
5
RELIC TOPSt]IL, with roots
SILTY SAND WITH GRAVEL (SM), brown -gray, medium dense, moist
r SILTY SAND WITH GRAVEL (SM), brown -gray, dense to very dense,
moist (ADVANCE OUTWASH)
Test Pit Terminated at 11.5 Feet
lines are apprwumate. In -situ, the transition may be
1 of 1
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5-1
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S-3
Advancement Method: See Exhibit A-4 for description of field Notes:
Excavator procedures
j See Appendix B for description of laboratory
procedures and additional data (if any).
Abandonment Method: See Appendix C for explanation of symbols and
Backf Iled with soil in lifts and tamped with bucket. abbreviations.
Elevations were interpolated from a topographic
WATER LEVEL oBSERVATIONS Test Pit Started: 12/16/2016
Groundwater not encountered Irerracon Excavator:
i
� 21905 64th Ave W Ste 100
Mountlake Terrace, WA Project No.: 81165135
Test Pit Completed: 12/16/2016
Operator: NW Excavating
Exhibit: A-10
TEST PIT LOG NO. TP-3
PROJECT: StorQuest Federal Way CLIENT: William Warren Group
SITE: 298th Block Pacific Highway South
Federal Way, Washington
o LOCATION See Exhibit A-2
J
v Latitude:47.3343° Longitude:-122.3125'
a
1
-,
J
w Z
LL
J Q
W
�
Surface Elev.: 434 (Ft.)
_
o
Quj
< m
o
SILTY GRAVELLY SAND, with organics, brown -gray, loose to medium
dense, moist (FILL)
5
RELIC TOPSOIL. with roots
SILTY SAND WITH GRAVEL (SM), tan -brown, medium dense, moist
AND WIj1j SILT AND GRAVEL , brown -gray, dense to very
dense, moist (ADVANCE OUTWASH) I 1
Test Pit Terminated at 11 Feet
lines are approximate. In-sllu, the transition may be gradual.
e1of1
W
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Advancement Method:
See Exhibit A-4 for description of field
Notes:
Excavator
procedures
j
See Appendix B for description of laboratory
procedures and additional data (if any).
See Appendix C for explanation of symbols and
Abandonment Method:
Backfilled with soil in lifts and tamped with bucket.
abbreviations.
Elevations were interpolated from a topographic
WATER LEVEL OBSERVATIONS
1rerracon
Test Pit Started: 12/16/2016
Groundwater not encountered
F�rcavalar.
21905 64th Ave W Ste 100
Mountlake Terrace, WA
Project No.: 81165135
>
rest Pit Completed: 12/16/2016
Operator NW Excavating
Exhibit: A-11
TEST PIT LOG NO. TP-4
PROJECT: StorQuest Federal Way CLIENT: William Warren Group
SITE: 298th Block Pacific Highway South
Federal Way, Washington
0 LOCATION See Exhibit A-2
LL
o Latitude:47.3343' Longitude:-122.3126' _
a. w
ga Surface Elev.: 436 (Ft.) o
0
ELEVATION Ft.
SILTY GRAVELLED, with organics, brown, loose to medium
dense. moist (FILL)
�o
S. 432.5
SILTY SAND WITH GRAVEL (SMI, tan -brown, medium dense, moist
5—
6.5 429.5
SAND WITH SILT AND GRAVEL lSIflI_ NI), brown -gray, dense to very
6 dense, moist (ADVANCE OUTWASH)
s
Test Pit Terminated at 9.5 Feet
lines are approximate.
WnW neat Method:
Excavator
andonment Method:
Backfilled with soil in lifts and tamped with bucket.
transition may be gradual.
See Exhibit A-4 for description of field
procedures
See Appendix B for description of laboratory
procedures and additional data (if any).
See Appendix C for explanation of symbols and
abbreviations.
Elevations were interpolated from a topographic
1 of 1
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Notes:
WATER LEVEL OBSERVATIONS Test Pit Started: 12/16/2016 Test Pit Completed: 12i16/2016
Groundwater not encountered Irerracon Excavator. Operator. NW Excavating
21905 64th Ave W Ste 100
Mountlake Terrace, WA Project No.: 81165135 Exhibit: A-12
APPENDIX B
LABORATORY TESTING
Geotechnical Engineering Report Irerracon
StorQuest Self Storage Federal Way, Washington
January 11, 2017 - Terracon Project No. 81165135
Laboratory Testing Description
As part of the testing program, all samples were examined in the laboratory by experienced
personnel and classified in accordance with the attached General Notes and the Unified Soil
Classification System based on the texture and plasticity of the soil. The group symbol for the
Unified Soil Classification System is shown in the appropriate column on the exploration logs
and a brief description of the classification system is included with this report in the Appendix.
At that time, the field descriptions were confirmed or modified as necessary and an applicable
laboratory testing program was formulated to determine index properties of the subsurface
materials.
Laboratory tests were conducted on selected soil samples and the test results are presented in
this appendix. The laboratory test results were used for the geotechnical engineering analyses,
and the development of foundation and earthwork recommendations. Laboratory tests were
performed in general accordance with the applicable ASTM, local or other accepted standards.
Selected soil samples obtained from the site were tested for the following engineering
properties:
In -situ Water Content
Grain Size Distribution
Responsive ■ Resourceful N Reliable Exhibit B-1
m
N
U)
U
w
U)
z
GRAIN SIZE IN MILLIMETERS
COBBLES GRAVEL SAND SILT OR CLAY
coarse fine coarse medium fine
ng ID Depth USCS Classification we N LL PL PI Cc Cu
1 12 43 74
o i
B-1
10 - 11.4
GRAVELLY WELL -GRADED SAND WITH SILT (SW-SM)
8
IL
a m
B-1
20 - 21.4
GRAVELLY POORLY -GRADED SAND WITH SILT (SP-SM)
10
3.29
44.04
J
A
B-2
15 - 16.5
SANDY WELL -GRADED GRAVEL (GW)
16
1.77
32.12
c�
o *
B-3
10 - 11
GRAVELLY WELL -GRADED SAND WITH SILT (SW-SM)
7
0.61
48.73
0 O
B-4
4.5 - 6
GRAVELLY SILTY SAND (SM)
14
LL
w Boring
ID
Depth
D1oo Dso D30 D10
%Gravel
%Sand
%Siit %Fines
%Clay
0
B-1
10 - 11.4
25 2.561 0.41
31.1
57.3
11.6
EL
n M
B-1
20 - 21.4
19 4.016 1.097 0.091
35.4
55.3
9.2
o A
B-2
15 - 16.5
31.5 11.944 2.807 0.372
61.5
33.8
4.7
J
10 - 11
25 5.668 0.632 0.116
42.4
49.3
8.3
w J
B-4
4.5 - 6
25 5.195 0.369
41.5
42.5
16.0
a
PROJECT:
StorQuest Federal
Way
PROJECT
NUMBER:
81165135
r SITE: 298th Block Pacific Highway South Irerracon
CLIENT: William Warren Group
oFederal Way, Washington
21905 64th Ave W Ste 100
Mountlake Terrace, WA EXHIBIT: B-2
a
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a PROJECT: StorQuest Federal Way PROJECT NUMBER: 81165135
LU
> SITE: 298th Block Pacific Highway South Irerraca
n CLIENT: William Warren Group
o Federal Way, Washington
21905 64th Ave W Ste 100
o Mountlake Terrace, WA EXHIBIT: B-3
5
APPENDIX C
SUPPORTING DOCUMENTS
GENERAL NOTES
DESCRIPTION OF SYMBOLS AND ABBREVIATIONS
Water Initially N Standard Penetration Test
Encountered Resistance (Blows/Ft.)
Water Level After a (HP) Hand Penetrometer
Specified Period of Time
J
W �` Water Level After H (T) Torvane
0 9 a Specified Period of Time CO)
California Grab J W
W
d e Ring Sample w Water levels Indicated on the soil boring G (DCP) Dynamic Cone Penetrometer
Sampler W logs are the levels measured in the J
borehole at the times indicated. W
Q ®(PID) Photo -Ionization Detector Split Spoon � Groundwater level variations will occur li
over time. In low permeability soils,
accurate determination of groundwater (OVA) Organic vapor Analyzer
levels is not possible with short term
water level observations.
DESCRIPTIVE SOIL CLASSIFICATION
Soil classification is based on the Unified Soil Classification System. Coarse Grained Soils have more than 50% of their dry
weight retained an a #200 sieve, their principal descriptors are: boulders, cobbles, gravel Or sand. Fine Grained Soils have
less than 50% of their dry weight retained on a #200 sieve; they are principally described as clays if they are plastic, and
silts if they are slightly piastic or non -plastic. Major constituents may be added as modifiers and minor constituents may be
added according to the relative proportions based on grain size. In addition to gradation, coarse -grained soils are defined
on the basis of their in -place relative density and fine-grained soils on the basis of their consistency.
LOCATION AND ELEVATION NOTES
Unless otherwise noted, Latitude and Longitude are approximately determined using a hand-held GPS device. The accuracy
of such devices is variable. Surface elevation data annotated with +/- indicates that no actual topographical survey was
conducted to confirm the surface elevation. Instead, the surface elevation was approximately determined from topographic
maps of the area.
RELATIVE DENSITY OF COARSE -GRAINED SOILS CONSISTENCY OF FINE-GRAINED SOILS
(50% or more passing the No. 200 sieve.)
(More than 50% retained on No. 200 sieve.) Consistency determined by laboratory shear strength testing, field
Density determined by Standard Penetration Resistance visual -manual procedures or standard penetration resistance
N Standard Penetration or
� Descriptive Term Standard Penetration or Ring Sampler Descriptive Term Unconfined Compressive Ring Sampler
N-Value Blows/Ft. (Consistency) Strength Qu, (psi) N-Value Blows/Ft.
IX (Density) Blows/Ft. Blows/Ft.
(—
Very Loose 0-3 0-6 Very Soft less than 3.50 0-1 < 3
2
H
(9 Loose 4-9 7-18 Soft 2-4 3-4
Z — —
W Medium Dense 10 - 29 19 - 58 Medium -Stiff 4-8 5 9
N Dense 30 - 50 59 - 98 Stiff 8 - 15 10 -18
Very Dense > 50 > 99 Very Stiff 15 - 30 19 - 42
Hard > 55.5 > 30 > 42
ELAT P F VEL GRAIN SIZE TERMINOLOGY
Descriptive Term(s) Percent of Maior Component Particle Size
of other constituents Dry Weight of Sample
Trace < 15 Boulders Over 12 in. (300 mm)
With 15 - 29 Cobbles 12 in. to 3 in. (300mm to 75mm)
Modifier > 30 Gravel 3 in. to #4 sieve (75mm to 4.75 mm)
Sand #4 to #200 sieve (4.75mm to 0.075mm
Silt or Clay Passing #200 sieve (0.075mm)
BgLATIVE_PBQPORTIONS QF FINES P ICITY DUCRIPTION
Descrigtive Term(s) Pe Term Plasticity Index
of other constituents Dry Waight Non -plastic 0
Trace a 5 Low 1 - 10
With 5-12 Medium 11 - 30
Modifier > 12 High > 30
Exhibit: C-1
UNIFIED SOIL CLASSIFICATION SYSTEM
Soil Classification
Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests A Group Group Name B
. Symbol
Gravels:
More than 50% of
coarse fraction retainer
Coarse Grained Soils:
on No. 4 sieve
More than 50% retained
on No. 200 sieve
Sands:
50% or more of coarse
fraction passes No. 4
sieve
Silts and Clays:
Liquid limit less than 51
Fine -Grained Soils:
50% or more passes the
No. 200 sieve
Silts and Clays:
Liquid limit 50 or more
Highly organic soils- I Prima
Clean Gravels:
Cu >_ 4 and 1 <_ Cc < 3E
GW Well -graded gravel'
Less than 5% fines c
Cu < 4 and/or 1 > Cc > 3 E
GP
Poorly graded gravel
I Gravels with Fines:
Fines classify as ML or MH
GM
Silty gravel
More than 12% fines c
Fines classify as CL or CH
GC
FAH
Clayey gravel
Clean Sands:
Cu >_ 6 and 1 < Cc < 3
SW
Well -graded sand
Less than 5% fines °
Cu < 6 and/or 1 > Cc > 3 E
SP
Poorly graded sand
Sands with Fines:
Fines classify as ML or MH
SM
Silty sand
More than 12% fines °
Fines classify as CL or CH
SC
Clayey sand -"`
PI > 7 and plots on or above "A" line
CL
Lean clay K.LrM
Inorganic:
PI < 4 or plots below "A" line
ML
SiltrILM
Liquid limit - oven dried
Organic clay
Organic:
< 0.75
OL
Liquid limit -not dried
Organic siltK'h"M'
PI plots on or above "A" line
CH
Fat clayIUA
Inorganic:
PI plots below "A" line
MH
.M
Elastic Silt
Liquid limit - oven dried
Organic clay KLKP
Organic:
< 0.75
Liquid limit -not dried
OH
M
Organic silt
-ily organic matter, dark in color, and organic odor
PT
Peat
" Based on the material passing the 3-inch (75-mm) sieve
B If field sample contained cobbles or boulders, or both, add "with cobbles
or boulders, or both" to group name.
c Gravels with 5 to 12% fines require dual symbols: GW-GM well -graded
gravel with silt, GW-GC well -graded gravel with clay, GP -GM poorly
graded gravel with silt, GP -GC poorly graded gravel with clay.
° Sands with 5 to 12% fines require dual symbols: SW-SM well -graded
sand with silt, SW -SC well -graded sand with clay, SP-SM poorly graded
sand with silt, SP-SC poorly graded sand with clay
z
E Cu = D60010 Cc = (D 30)
D10 x D60
F If soil contains >_ 15% sand, add "with sand" to group name.
c If fines classify as CL-ML, use dual symbol GC -GM, or SC-SM.
" If fines are organic, add "with organic fines" to group name.
If soil contains >_ 15% gravel, add "with gravel" to group name.
If Atterberg limits plot in shaded area, soil is a CL-ML, silty clay.
K If soil contains 15 to 29% plus No. 200, add "with sand" or "with gravel,"
whichever is predominant.
L If soil contains >_ 30% plus No. 200 predominantly sand, add "sandy" to
group name.
M If soil contains >_ 30% plus No. 200, predominantly gravel, add
"gravelly" to group name.
" PI >_ 4 and plots on or above "A" line.
c PI < 4 or plots below "A" line.
P PI plots on or above "A" line.
° PI plots below "A" line.
60
i
For classification of fine-grained
ell
soils and fine-grained fraction
50
of coarse -grained soils
�� •'!
�
�4
Equation of "A" - line
Horizontal at PI=4 to LL=25.5.
then PI=0.73
` •
X
40
(LL-20) - — ,
0
W/onli.ned�
p
- line
z_
6 to PI=7.
}
30LL-8)
—
rMH
or OH
a-'10Fa
; ML or OL
0
10 16 20 30 40 50
60 70
80 90 100 110
LIQUID LIMIT (LL)
Irerracon Exhibit C-2
Irerracon
February 3, 2017
William Warren Group
4301 DTC Blvd.
Greenwood Village, CO 80111
Attn: Mr. Jon Suddarth
P: (303) 842-5690
E: suddarth@williamwarren.com
Re: Geotechnical Engineering Report — Preliminary Stormwater Infiltration Addendum
StorQuest Self Storage
2981h Block Pacific Highway South (SR 99)
Federal Way, Washington
Terracon Project Number: 81165135
Dear Mr. Suddarth:
This letter is an addendum to, and should be used in conjunction with, our Geotechnical
Engineering Report for the project that was submitted to you on January 11, 2017. This report
addendum has been completed in accordance with our Supplemental Scope and Fee Proposal
dated February 2, 2017. The purpose of this addendum is to provide preliminary
recommendations for sizing of stormwater infiltration facilities for the above referenced site.
Field infiltration testing at the location of the proposed gallery is scheduled for February 16,
2017 and final design rates and will be provided upon completion of the field testing.
Project Information
Based on discussions with the architect and the project civil engineer, we understand the
current development plan includes the use of a below -grade infiltration gallery below the eastern
parking lot for infiltration of stormwater. The proposed parking lot grades in the area generally
range from about elevation 429 to 431 feet and the base of the infiltration gallery would be
located at an approximate elevation of 4211/2 feet.
Subsurface Conditions
As a part of our original scope, we advanced four borings and four test pits on the site. One of
the borings and three of the test pits were located in the lower, east side of the site
approximately within the extents of the proposed infiltration gallery. Based on the conditions
encountered in these explorations, soil at the estimated infiltration depths in this area appears to
generally consist of dense to very dense sand with silt and gravel Advance Outwash deposits.
Terracon Consultants, Inc. 21905 641h Avenue, Suite 100 Mountlake Terrace, Washington 98043
P [425] 771 3304 F [4251 771 3549 terracon.com
Geotechnical Engineering Report — Stormwater Infiltration Addendum Irerracon
Proposed StorQuest Self Storage Facility ■ Federal Way, Washington
February 3, 2017 ■ Terracon Project No. 81165135
Above the Advance Outwash deposits, we encountered existing fill soil above elevations
ranging from about 422'h feet to 430Y2 feet.
Groundwater was observed at a depth of about 19'/z feet in Boring B-3, southwest of the
proposed infiltration gallery. Groundwater was not observed within the full depth Boring B-4,
however, which is located near the east -central portion of the proposed infiltration gallery and
extended to a depth of approximately 5'/z feet below the elevation of proposed infiltration.
Preliminary Design Stormwater Infiltration Rate
Based on the results of the subsurface explorations and laboratory testing completed as a part
of our original scope, we calculated a design infiltration rate of 8 to 9 inches per hour using the
Soil Grain Size Analysis Method as described in Section 3.3.6 of Volume III of the 2014
Department of Ecology (DOE) Stormwater Management Manual for Western Washington.
Correction Factors of 0.4, 0.8, and 0.9 were applied to the calculated rate to account for test
type, site variability, and siltation and buildup, respectively. However, the Soil Grain Size
Analysis Method does not adequately account for the glacially consolidated nature of the
Advance Outwash and lower actual infiltration rates are expected. We recommend a lower rate
of 3 inches per hour be used in preliminary design of the proposed infiltration gallery to
account for the glacially consolidated nature of the Advance Outwash. A final design infiltration
rate recommendation will be provided upon completion of our field infiltration testing.
General Comments
The recommendations presented in this addendum are based upon the data obtained from the
borings and test pits at the locations indicated in the original Geotechnical Engineering Report
and from other information discussed in the report and the above paragraphs. The letter does
not reflect variations that may occur between explorations, across the site, or due to the
modifying effects of construction or weather. The nature and extent of such variations may not
become evident until during or after construction. If variations appear, we should be
immediately notified so that further evaluation and supplemental recommendations can be
provided.
Responsive Resourceful Reliable
Geotechnical Engineering Report — Stormwater Infiltration Addendum
Proposed StorQuest Self Storage Facility m Federal Way, Washington I rerracur-i
February 3, 2017 ■ Terracon Project No. 81165135
We appreciate the opportunity to perform these services for you. Please contact us if you have
questions regarding this information or if we can provide any additional services.
Sincerely,
Terracon Consultants, Inx
Ryan M. Scheffler,
Project Engineer
�t� k L
NVA
49529 w4
ST'P-
A
Cc: John Kay, Magellan Architects
Responsive Resourceful Reliable
Dennis R. Stettler, PE
Senior Engineering Consultant
Irerracan
March 9, 2017
William Warren Group
4301 DTC Blvd.
Greenwood Village, CO 80111
Attn: Mr. Jon Suddarth
P: (303) 842-5690
E: iuddarth williamwarreii.com
Re: Geotechnical Engineering Report Addendum — Stormwater Infiltration and Landslide
Hazard Assessment
StorQuest Self Storage
298th Block Pacific Highway South (SR 99)
Federal Way, Washington
Terracon Project Number: 81165135
Dear Mr. Suddarth:
This letter is an addendum to, and should be used in conjunction with, our Geotechnical
Engineering Report for the project that was submitted to you on January 11, 2017. This report
addendum has been completed in accordance with our Supplemental Scope and Fee Proposal
dated February 2, 2017. The purpose of this addendum is to provide recommendations for
design of stormwater infiltration facilities and discussion of landslide hazard areas for the above
referenced site. The recommendations provided in this letter supersede the preliminary
infiltration recommendations contained in our previously completed addendum letter, dated
February 3, 2017.
Project Information
Based on discussions with the architect and the project civil engineer, we understand the
current development plan includes a 4-story self -storage building to be located in approximately
the western three quarters of the site. Due to existing grades, the lower two floors of the
proposed building will be below grade on the west side of the building and will daylight on the
east. A below -grade infiltration gallery will be utilized below the eastern parking lot for infiltration
of stormwater runoff. The proposed parking lot grades in the area generally range from about
elevation 429 to 431 feet and the base of the infiltration gallery would be located at an
approximate elevation of 421'h feet.
Terracon Consultants, Inc. 21905 64th Avenue, Suite 100 Mountlake Terrace, Washington 98043
P [425] 771 3304 F [425] 771 3549 terracon.com
Geotechnical Engineering Report — Stormwater Infiltration Addendum Irerracon
Proposed StorQuest Self Storage Facility Federal Way, Washington
March 14, 2017 : Terracon Project No. 81165135
Subsurface Conditions
As a part of our original scope, we advanced four borings and four test pits on the site. One of
the borings and three of the test pits were located in the lower, east side of the site
approximately within the extents of the proposed infiltration gallery. Two additional test pits were
advanced within the proposed infiltration gallery to perform infiltration testing. Based on the
conditions encountered in these explorations, soil at the proposed infiltration depths in this area
appears to generally consist of dense to very dense sand with silt and gravel Advance Outwash
deposits. Above the Advance Outwash deposits, we encountered existing fill soil above
elevations ranging from about 422Y2 feet to 430'/z feet.
Groundwater was observed at a depth of about 19'/2 feet in Boring B-3, southwest of the
proposed infiltration gallery. Groundwater was not observed within the full depth Boring B-4,
however, which is located near the east -central portion of the proposed infiltration gallery and
extended to a depth of approximately 5'/2 feet below the elevation of proposed infiltration.
Groundwater was also not observed within our test pits or infiltration test excavations.
Stormwater Infiltration Rate
Two infiltration tests (IT-1 and IT-2) were completed within the area of the proposed infiltration
facility at the locations shown on Exhibit A-1. Logs of the soil conditions encountered in IT-1 and
IT-2 are attached to the end of this letter. The infiltration test pits were excavated by a
subcontractor to Terracon to the approximate elevation of the base of the proposed infiltration
facility. A metal ring with a diameter of 6 feet was placed at the base of the excavations to
prevent sidewall cave-ins during testing. Infiltration tests were completed within the excavations
in general accordance with the requirements of Section 5.2.1 of the 2016 King County Surface
Water Design Manual (KCSWDM).
We observed measured short-term infiltration rates of 20 and 12 inches per hour in IT-1 and IT-
2, respectively. In accordance with the KCSWDM, correction Factors of 0.3, 0.8, and 0.9 were
applied to the measured rate to account for test type, facility geometry, and soil type,
respectively. After applying these factors to the measured rates, we recommend an allowable
infiltration rate of 3 inches per hour be used in design of the proposed infiltration gallery.
Landslide Hazard Areas
As described in our geotechnical report, relatively steep slopes are present along the west side
of the site sloping down from the west property line along 16th Avenue South to the general
grade of the site. A rockery is present at the toe of the slope along all of the slope except within
about 30 feet of the south property line. Ground surface elevations along the west property line
range from about 464 to 474 feet. The ground surface elevation near the toe of the rockery (or
toe of slope where a rockery is not present) is about 440 feet.
Responsive Resourceful r� Reliable 2
Geotechnical Engineering Report — 5tormwater Infiltration Addendum Irerraccin
Proposes! StorQuest Self Storage Facility Federal Way, Washington
March 14, 2017 Terracon Project No. 81165135
Based on the topography of this site and the surrounding area, it is evident that the relatively
steep slope along the west side of the site was created by cutting into the existing topography at
some time in the past to create a relatively level portion of the site and construction of a rockery
at the toe of the slope. Presumably this cut slope and rockery was constructed under some
previous grading permit. The existing cut slope above the rockery appears to have a slope of
approximately 1.5H:1 V to 1.7H:1 V (horizontal:vertical) for most of the slope above the rockery
based on site topography provided to us. The rockery is not present within about 30 feet of the
south property line and the slope in this area extends more into the site to the east with an
average slope of about 1.8H:1V to 2H:1V based on topography provided to us.
The existing cut slope is highly vegetated with brush and trees. Significant blackberry bushes
obscure much of the ground surface on the steep slope. To the extent that the slope is visible,
we were not able to identify indications of past slope failures or existing slope instability features
on the existing cut slope.
With a slope greater than 40 percent and a vertical relief of over 10 feet, this slope is classified
as a Landslide Hazard Area according to Section 19.05.070 of the City of Federal Way Revised
Code. Section 19.145.220 of the code regulates development activities on or within 50 feet of
Landslide Hazard Areas. However, Section 19.145.230(4) notes that buffers and setbacks may
be reduced or improvements may be located within a Landslide Hazard Area when a qualified
professional determines the improvements will not create an increased slide hazard or be at risk
of damage by the landslide hazard.
As a part of our original scope, we advanced one boring (B-1) atop the slope near 16th Avenue
South to a depth of approximately 50 feet. We encountered very dense Advance Outwash sand
and gravel within the full depth of boring B-1 and did not encounter groundwater seepage at the
time of our exploration. The boring advanced at the top of the slope and the geologic mapping
of the site indicate the presence of dense to very dense, glacially -consolidated soil composed
primarily of gravelly sand with variable silt content and some cobbles. Existing cut slopes as
steep as 1.5H:1V are expected to be stable with an appropriate factor of safety in these soil
conditions.
The proposed site layout indicates the new building will extend approximately 20 feet into the
base of the slope. Current building plans include the use of temporary soldier pile with tieback
anchors or soil nail shoring along the west building wall and the western ends of the south and
north walls to facilitate construction. Once complete, the below -grade portions of the building
walls are designed to support the retained soil. The current plans show that the slope above the
building will be flattened to a 2H:1V slope. The slope along the south and north sides of the
planned building will be graded to a 2H:1V or flatter slope and a two-tier retaining wall will be
constructed near the northwest corner of the building. In our opinion, cut slopes in the natural
soil at the site or fill slopes composed of properly placed and compacted structural fill sloped at
2H:1V or flatter will be stable with an appropriate factor of safety against slope instability.
Responsive Resourceful -.: Reliable 3
Geotechnical Engineering Report — 5tormwater Infiltration Addendum 1 rem con
Proposed StorQuest Self Storage Facility Federal Way, Washington
March 14, 2017 n Terracon Project No. 81165135
Construction of the building as currently planned will reduce the exposed height of the western
slope from approximately 30 feet to approximately 15 feet. Provided the temporary shoring and
permanent building walls are designed and constructed in accordance with the
recommendations provided in our original geotechnical report, the building will act as a buttress
to the slope and will work to significantly improve the stability of the slope as compared to
existing conditions. Regrading the existing slope to a 21-1:1 V or flatter slope as compared to the
existing slope will also improve slope stability. As currently proposed, the development will
reduce the existing landslide hazard and improve the overall stability of the slope. The
development would not be at risk of damage by the remaining slope, in our opinion.
General Comments
The recommendations presented in this addendum are based upon the data obtained from the
borings and test pits at the locations indicated in the original Geotechnical Engineering Report
and the attached Exhibit A-1, and from other information discussed in the report and the above
paragraphs. This letter does not reflect variations that may occur between explorations, across
the site, or due to the modifying effects of construction or weather. The nature and extent of
such variations may not become evident until during or after construction. If variations appear,
we should be immediately notified so that further evaluation and supplemental
recommendations can be provided.
We appreciate the opportunity to perform these services for you. Please contact us if you have
questions regarding this information or if we can provide any additional services.
Sincerely,
Terracon Consi
Ryan M. Scheffl
Project Enginee,
cc: John Kay, Magellan Architects
Attachments: Exhibit A-1
Exhibits A-2 to A-3
Responsive Resourceful Reliable
Dennis R. Stettler, PE
Senior Engineering Consultant
Site and Exploration Plan
Test Pit Logs IT-1 to IT-2
4
VACANT LAND
— — — — PACIFIC HWY S. / HWY 99--
HinoS kVMHOH OWIOVci
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Win' r^ f 3 a W cc a
ty S
n
TEST PIT LOG NO. IT-1
PROJECT: StorQuest Federal Way CLIENT: William Warren Group
SITE: 298th Block Pacific Highway South
Federal Way, Washington
Q LOCATION See Exhibit A-1
OLatitude:47.33427' Longitude:-122.32154' _
a a.
Approximate Surface Elev: 435 (Ft) +/- o
SILTY GRAVELLY SAND, with organics, brown -gray, loose to medium -
dense, moist (FILL)
431+r _
RELIC
TOPMIL, with roots 430.5+1-
SILTY SAND WITH GRAMEL_(SM1, tan -brown, medium dense, moist 5 —
427.54
AND WITH SILT AND G&AVEL(SW-S, brown -gray, dense to very
dense. moist (ADVANCE OUTWASH)
424.5+i- 1 o-
Test Pit Terminated at 10.5 Feet
lines are approximate. In -situ, the transition may be
S IAdvancement Method:
Excavator
> I Abandonment Method:
I Backf Iled with soil in lifts and tamped with bucket.
Groundwater not encountered I
Elevations were interpolated from a topographic
irerracyll
21905 64th Ave W Ste
Mountlake Terrace, WA
1 of 1
o
WH
w�
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W
w
w
Notes:
Test Pit Started: 2/16/2017 Test Pit Completed: 2/16/2017
Excavator: Operator: NW Excavating
Project No.: 81165135 Exhibit: A-2
TEST PIT LOG NO.
IT-2
Page 1 of 1
PROJECT:
StorQuest Federal Way CLIENT: William
Warren
Group
SITE:
298th Block Pacific Highway South
Federal Way, Washington
c9
LOCATION See Exhibit A-1
w
a
it
155 m o z
O
U
Latitude: 47.33415' Longitude:-122.31248'
v
=
w�
J Q
w
-
1
J Z) w~ W
~ Z z I w z
0_
W
>
Ful
2
Ill
0 w
J
WX d �0
Approximate Surface Elev: 436 (Ft.) +l-
o
CO
co
U
X
i ¢ v a
i]>=i'TH ELEVATION F .
o
ua
m
0 5 TOPSC0IL 435.5+1
SILTY GRAVELLY SAND, with organics, brown -gray, loose to medium
dense, moist (FILL)
5
6.o aaa+/
a--•
RELIC TOPSOIL, with roots
SILTY SAND WITH GRAVEL (SMI, tan -brown, medium dense, moist
❑
c�
Lu
9.fl 427+I
{ D wr[H GRAyEL ME, brown -gray, dense to very dense,
a
w
moist (ADVANCE OUTWASH)
a,
❑I '$
11.5 424.5�1-
Test Pit Terminated at 11.5 Feet
a
c7
m
J
W
O
z
0
O
U)
rn
O
CW7
H
0
O
w
z
T
X
0
7
0
LL
❑
Stratification lines are approximate. In -situ, the transition may be gradual.
a
a
u) Advancement
Method:
Notes:
11 Excavator
J
a
~O Abandonment
Method:
z Backfilled
co
with soil in lifts and tamped with bucket.
Elevations were interpolated from a topographic
0
°
WATER LEVEL OBSERVATIONS
iaSt
Pit
Started:
2/16/2017
Teal Pit Completed: 2116/2017
Groundwater not encountered
Irerracon
Excavator.
Operator: NW Excavating
O
Project
No.:
81165135
Exhibit: A-3
m
CO
=
21905 64th Ave W Ste 100
Mountlake Terrace, WA
TECHNICAL INFORMATION REPORT
APPENDIX C
CSWPP WORKSHEETS
NAVIX StorQuest Federal Way
BMP In
Develop a plan
construction or
implementation
BMPs
Good
Housekeeping
Preventive
Maintenance
Spill
Prevention
and
Emergency
Cleanup
Inspections
TECHNICAL INFORMATION REPORT
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
Completed by:
rplementation Title:
Date:
for implementing each BMP. Describe the steps necessary to implement the BMP (i.e.. any
design), the schedule for completing those steps (list daces), and the person(s) responsible for
Scheduled Milestone and Person
Description of Action(s) Required for Completion Date(s) Responsible for
Implementation Action
1.
2.
3
1.
2.
3.
4.
1.
2.
3.
1.
2.
3.
2016Surface Water Design Manual — Appendix D CSWPP Forms 4/24/2026
NAVIX StorQuest Federal Way
TECHNICAL INFORMATION REPORT
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
BMps
Source Control
Bill
Treabnent BMps
Description of Action($) Required for Implementation
1.
Schedule Milestone and
Completion Date($)
Person
Responsible for
Action
2.
3
4.
5.
6.
7.
8.
1.
2.
3.
4.
Emerging
technologies
Flow Control
BMps
1
2.
3.
4.
2016 Surface Water Design Manual - Appendix D CSWPP Forms 4/24/2016
NAVIX StorQuest Federal Way
TECHNICAL INFORMATION REPORT
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
pleted by:
Pollution Prevention Team
:
LDate:
Responsible Official:
Title:
Team Leader:
Office Phone:
Cell Phone #:
Pager #:
Responsibilities:
Title:
Office Phone:
Pager#.
Cell Phone:
Responsibilities:
(2)
Tine:
Office Phone:
Pager #
Cell Phone K:
Responsibilities:
2016 Surface Water Design Manual — Appendix D CSWPP Forms 4/24/2016
NAVIX StorQuest Federal Way
TECHNICAL INFORMATION REPORT
KING COUNTY, WASHINGTON, SURPACE WATER DESIGN MANUAL
LCorndplothd try:Fmployee Training
Describe the annual tralni Of Om i a en Uw SWPPP. ad drossino s 'R res onsa, good housekee In . and matonal mana omens ides.
Training Topics Brief Description of Training ProgramAtiaterials SeWule for Training
(e.g., film, nOWSTOttar COUrse) (Met dates) Aftwiclow
1. LINE WORKERS
Spill prevention and
Response
Good Housekeeping
Material Management
Practices
2. P2 TEAM:
SWPPP Irnpie me Mal i on
Monitoring Procedures
2026 Surface Water Design Manual - Appendix 0 CSWPP forms
NAVIX StorQuest Federal Way
4/24/2026
TECHNICAL INFORMATION REPORT
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
Completed Iry:
Title -
List of Significant Spills and Leaks Date:
List all spills and leaks of toxic or hazardous pollutants that were significant but are =limited to, release of 2jL or h-jUrd ous tsubs to ncsc in excels of ivovAabk
auarr<ities. Although not required, we suggest you list spills and leaks of nor hazardous materials.
Description Response Procedure
Date Location Type of puarrtlt Soure Reason for Amount of Material No Preventive Measure Taken
(montiJdaylye (as Material y e, if SpNllLeak Material longer
Indicated Known Recovered exposed to
ar) on site Stormwater
map) (YeslNo)
2016 Surface Water Design Manual — Appendix D CSWPP Forms 4/24/2026
NAVIX StorQuest Federal Way
TECHNICAL INFORMATION REPORT
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
completed w.
TRIO
Date:
Material Inventory
List materials handled, treated, stored, or disposed of at the project site that may potentially be exposed to precipitation or runoff.
Quantity (Units) Likelihood of contact with stormwater Past Spill or
Used Produced I Stored If Yes, describe reason Leak
Material 'u oselLecation indicate rlwk. or r. Yes No
2016 Surface Water Design Manual — Appendix D CSW PP Forms 4/24/2016
NAVIX StorQuest Federal Way
2016 Surface Water Design Manual — Appendix D CSW PP Forms 4/24/2016
NAVIX StorQuest Federal Way