2010-01-27 HEX #10-001 Exhibit HEXHIBIT 0 _
PAGE 0 lr-!�
P-
NORPOINT HEIGHTS
SUBDIVISION
Preliminary Technical Information Report
December 2007
Revised: June 26, 2009
Prepared for
Landmark Homes, Inc.
PO Box 26116
Federal Way, WA 98039
Submitted by
ESM Consulting Engineers, LLC
33915 1' Way South, Suite 200
Federal Way, WA 98003
253.838.6113 tel
253.838.7104 fax
RESUBMITTED
JUN 2 6 2009 www.esmcivii.com
CITY OF FEDERAL WAY
BUILDING DEPT.
E X H I I i"I - -Y -- - -
PAGE-0-1-OF-5
TECHNICAL INFORMATION REPORT
FOR
Norpoint Heights Subdivision
Prepared for:
Landmark Homes Inc.
PO Box 26116
Federal Way, WA 98093-3116
Prepared by:
ESM Consulting Engineers
33915 1gt Way South, Suite 200
Federal Way, WA 98003
7
June 26, 2009
Approved By:
Job No. 1453-002-007
City of Federal Way Date
EXHI t
TABLE OF CONTENTS cDAGE—I—C)F—Sp�_.
PROJECTOVERVIEW................................................................................................................................................................. 1-1
Project Overview
Vicinity Map (Figure 1)
Review of 8 Core Requirements and 5 Special Requirement of 1998 KCSWDM
Summary
Overall Summary of Mitigation
Basin Map
Soils Map
2. PRELIMINARY CONDITIONS SUMMARY............................................................................................................ 2-1
3. OFF -SITE ANALYSIS.................................................................................................................................................................... 3-1
Off -Site Analysis
Figure III - A, Basin Map
Figure III - B, Downstream Flow Path
Figure III - C, Conveyance System
Pipe Summary Sheet
4. WATER QUANTITY & QUALITY FACILITY ANALYSIS AND DESIGN ................................. 4-1
Water Quantity Design
Water Quality Design/Worksheet
5. SPECIAL REPORTS AND STUDIES........................................................................................................................... 5-1
Geotechnicai Report
6. ESC ANALYSIS AND DESIGN........................................................................................................................................... 6-1
Erosion Control Plan
APPENDIX
L i 1. 1 L�
SECTION I PAGE q (DF v0
PROJECT OVERVIEW
The Norpoint Heights Subdivision is located west of 25th Avenue SW, south of SW
352"d Street, east of Norpoint Way in Tacoma and bordering the King County and
Pierce County line. The north side of the property abuts residential developments and a
small park. The east side of the property abut a residential subdivisions, the south side
abuts a single family home and a apartment complex and west sides abuts Norpoint
Way NE located within the City of Tacoma, Section 24, Township 21 North, Range 3
East.
The project contains just over 3 acres. The site does not have any buildings to remove.
It is currently covered with heavy underbrush and trees. There is one power pole on the
site which is in a 50 foot wide power line easement. The property generally slopes in a
westerly direction, with slopes generally around 14 percent or less on the site. The
access to the site will come from Norpoint Way NE in Tacoma, with an interior road
probably named SW 353rd St.
The proposal is to develop 14 single-family residential lots add an access road with
curb, gutter and sidewalks off Norpoint Way, and add a pedestrian access to 25fh
Avenue SW The sanitary sewer and water will come from Lakehaven Utility District.
There is a small sewer pump station near the northwest corner of this site which this site
will utilize. Access will be from an existing utility easement. Water will run though the
site, from south to north, connecting to an existing water system along the south
property line and running north though the site and extending though an existing park
over to 25th Ave. SW.
The site is located within Federal Way's "Lower Puget Sound" drainage basin. The
entire site will flow to a combination detention water quality facility before discharging to
the City of Tacoma's conveyance system which discharges straight down Norpoint Way
to Commencement Bay. The system design will be guided by both the City of Federal
Way and the City of Tacoma stormwater design guidelines.
Both jurisdictions generally allow continuous rainfall runoff modeling, which since the
site is in King County, will be KCRTS along with other requirements set forth in the 1998
King County Surface Water Design Manual (KCSWDM) and in the 2003 City of Tacoma
Surface Water Management Manual. A water quality facility will be part of the detention
pond creating a combined detention wetpool facility using the requirements set forth in
the 1998 King County Surface Water Design Manual (KCSWDM). This site is in the City
of Federal Way's Basic Water Quality Area. The downstream conveyance system will
be analysis using the 2003 City of Tacoma Surface Water Management Manual, which
in this case will be the rational method.
See Section III for Overall Summary of Conclusions and Proposed Mitigation
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DESCRIPTIONS OF THE SOILS
This section describes the soil series and map-
ng units in the King County Area. Each soil
ries is described and then each mapping unit in
:hat series. Unless it is specifically mentioned
)therwise, it is to be assumed that what is stated .
,out the soil series holds true for the mapping
;its in that series. Thus, to get full information
about any one mapping unit, it is necessary to read
)oth the description of the mapping unit and the
ascription of the soil series to which it belongs.
An important part of the description of each
soil series is the soil profile, that is, the
sequence of layers from the surface downward to
)ck or other underlying material. Each series
intains two descriptions of this profile. The
first is brief and in terms familiar to the layman.
The second, detailed and in technical terms, is for
:ientists, engineers, and others who need to make
zorough and precise studies of soils. Unless it
is otherwise stated, the colors given in the
descriptions are those of a moist soil..
As mentioned in the section "How This Survey Was
ade," not all mapping units are members of a soil
series_ Urban land, for example, does not belong
to a soil series, but nevertheless, is listed in
1phabetic order along with the soil series.
Following the name of each mapping unit is a
symbol in parentheses. This symbol identifies the
mapping unit on the detailed soil map. Listed at
he end of each description of a mapping unit is the
apability unit and woodland group in which the
mapping unit has been placed, The woodland desig-
nation and the page for the description of each
apability unit can be found by referring to the
Guide to Mapping Units" at the back of this survey.
The acreage and proportionate extent of each
mapping unit are shown in table 1. Many of the
terms used in describing soils can be found in the
;lossary at the end of this survey, and more de-
tailed information about the terminology and methods
of soil mapping can be obtained from the Soil Survey
lanual (19) -
Alderwood Series
The Alderwood series is made up of moderately
cell drained soils that have a weakly consolidated
to strongly consolidated substratum at a depth of
24 to 40 inches. These soils are on uplands. They
ormed under conifers, in glacial deposits. Slopes
ire 0 to 70 percent. The annual precipitation is
35 to 60 inches, most of which is rainfall, between
October- and May. The mean annual air temperature is
about 50' F. The frost -free season is 150 to 200
Says. Elevation ranges from 100 to 800 feet.
In a representative profile, the surface layer
and subsoil are very dark brown, dark -brown, and
grayish -brown gravelly sandy loam about 27 inches
thick. The substratum is grayish -brown, weakly
consolidated to strongly consolidated glacial till
that extends to a depth of 60 inches and more.
a
Alderwood soils are used for timber, pasture,
berries, row crops, and urban development. They
are the most extensive soils in the survey area.
Alderwood gravelly sandy loam, 6 to 15 percent
slopes (AgC)•--This soil is rolling- Areas are
irregular in shape and range from 10 to about 600
acres in size.
Representative profile of Alderwood gravelly
sandy loam, 6 to 15 percent slopes, in woodland,
450 feet east and 1,300 feet south of the north
quarter corner of sec. 15, T. 24 N., R, 6 E.:
A1--0 to 2 inches, very dark brown (10YR 2/2)
gravelly sandy loam, dark grayish brown
(10YR 4/2) dry; weak, fine, granular struc-
ture; slightly hard, friable, nonsticky,
nonplastic; many roots; strongly acid;
abrupt, wavy boundary. 1 to 3 inches thick.
B2--2 to 12 inches, dark -brown (10YR 4/3) gravelly
sandy loam, brown (10YR 5/3) dry; moderate,
medium, subangular blocky structure; slightly
hard, friable, nonsticky, nonplastic; many
roots; strongly acid; clear, wavy boundary.
9 to 14 inches thick.
B3--12 to 27 inches, grayish -brown (2.5Y 5/2)
gravelly sandy loam, light gray (2,5Y 7/2)
dry; many, medium, distinct mottles of light
olive brown (2.5Y 5/6); hard, friable, non -
sticky, nonplastic; many roots; medium acid;
abrupt, wavy boundary. 12 to 23 inches thick.
IIC--27 to 60 inches, grayish -brown (2.5Y 5/2),
weakly to strongly consolidated till, light
gray (2.5Y 7/2) dry; common, medium, distinct
mottles of light olive brown and yellowish
brown (2.5Y S/6 and 10YR 5/6); massive, no
roots; medium acid. Many feet thick.
The A horizon ranges from very dark brown to
dark brown. The B horizon is dark brown, grayish
brown, and dark yellowish broom. The consolidated
C horizon, at a depth of 24 to 40 inches, is mostly
grayish brown mottled with yellowish brown. Some
layers in the C horizon slake in water. In a few
areas, there is a thin, gray or grayish -brown A2
horizon. In most areas, this horizon has been
destroyed through logging operations.
Soils included with this soil in mapping make up
no more than 30 percent of the total acreage. Some
areas are up to 3 percent the poorly drained Norma,
Bellingham, Seattle, Tukwila, and Shalcar soils;
some are up to 5 percent the very gravelly Everett
and Neilton soils; and some are up to 15 percent
Alderwood soils that have slopes more gentle or
steeper than 6 to 15 percent. Some areas in New-
castle Hills are 25 percent Beausite soils, some
northeast of Duvall. are as much as 25 percent Ovall
soils, and some in the vicinity of Dash Point are
10 percent Indianola and Kitsap soils. Also
included are small areas of Alderwood soils that
have a gravelly loam surface layer and subsoil.
Permeability is moderately rapid in the surface
layer and subsoil and very slow in the substratum_
Roots penetrate easily to the consolidated substra-
tum where they tend to mat on the surface. Some
roots enter the substratum through cracks. Water
moves on top of the substratum in winter. Available
water capacity is low. Runoff is slow to medium,
and the hazard of erosion is moderate.
This soil is used for timber, pasture, berries,
and row crops, and for urban development. Capability
unit IVe-2; woodland group 3dl.
Aldenvood gravelly sandy loam, 0 to 6 percent
slopes (AgB)_--This soil is nearly level and
undulating. It is similar to Aldenvood gravelly
sandy loam, 6 to 15 percent slopes, but in places
its surface layer is 2 to 3 inches thicker. Areas
axe irregular in shape and range from 10 acres to
slightly more than 600 acres in size.
Some areas are as much as 15 percent included
Norma, Bellingham, Tukwila, and Shalcar soils, all
of which are poorly drained; and some areas in the
vicinity of Enumclaw are as much as 10 percent
Buckley soils..
Runoff is slow, and the erosion hazard is
slight.
This Alderwood soil is used for timber, pasture,
berries, and row crops, and for urban development.
Capability unit IVe-2; woodland group 3d2.
Alderwood gravelly sandy loam, 15 to 30 percent
slopes (AgD).--Depth to the substratum in this soil
varies within short distances, but is commonly
about 40 inches. Areas are elongated and range
from 7 to about 250 acres in size.
Soils included with this soil in mapping make
up no more than 30 percent of the total acreage.,
Some areas are up to 25 percent Everett soils that
have slopes of 15 to 30 percent, and some areas are
up to 2 percent Bellingham, Norma, and Seattle soils,
which are in depressions. Some areas, especially
on Squak Mountain, in Newcastle Hills, and north of
Tiger Mountain, are 25 percent Beausite and Ovall
soils. Beausite soils are underlain by sandstone,
and Ovall soils by andesite.
Runoff is medium, and the erosion hazard is
severe. The slippage potential is moderate.
This Alderwood soil is used mostly for timber.
Some areas on the lower parts of slopes are used
for pasture. Capability unit VIe-2; woodland group
3dl.
Aldenvood and Kitsap soils, very steep fAkF).--
This mapping unit is about 50 percent Aldenvood
gravelly sandy loam and 25 percent Kitsap silt
loam. Slopes are 25 to 70 percent. Distribution
of the soils varies greatly within short distances.
About 15 percent of some mapped areas is an
included, unnamed, very deep, moderately coarse
textured soil; and about 10 percent of some areas
is a very deep, coarse -textured Indianola soil.
Drainage and permeability vary. Runoff is rapid
to very rapid, and the erosion hazard is severe to
very severe. The slippage potential is severe.
These soils are used for timber. Capability
unit VIIe-1; woodland group 2dl.
10
Arents, Aldenvood Material
Arents, Aldenvood material consists of Aldenvood
soils that have been so disturbed through urban-
ization that they no longer can be classified with
the Alderwood series. These soils, however, have
many similar features. The upper part of the soil,
to a depth of 20 to 40 inches, is brown to dark -
brown gravelly sandy loam. Below this is a grayish -
brown, consolidated and impervious substratum.
Slopes generally range from 0 to 15 percent.
These soils are used for urban development-
Arents, Aldenvood material, 0 to 6 percent slopes
(AmB)._-In many areas this soil is level, as a
result of shaping during construction fox, urban
facilities. Areas are rectangular in shape and
range from 5 acres to about 400 acres in size.
Representative profile of Arents, Alderwood
material, 0 to 6 percent slopes, in an urban area,
1,300 feet west and 350 feet south of the northeast
corner of sec. 23, T. 25 N., R. 5 E.:
0 to 26 inches, dark -brown (10YR 4/3) gravelly
sandy loam, pale brown (10YR 6/3) dry;
massive; slightly hard, very friable, non -
sticky, nonplastic; many roots; medium acid;
abrupt, smooth boundary. 23 to 29 inches
thick.
26 to 6❑ inches, grayish -brown (2.5Y 5/2) weakly
consolidated to strongly consolidated glacial
till, light brownish gray (2.5Y 6/2) dry;
common, medium, prominent mottles of yellowish
brown (10YR 5/6) moist; massive; no Toots;
medium acid. Many feet thick.
The upper, very friable part of the soil extends
to a depth of 20 to 40 inches and ranges from dark
grayish brown to dark yellowish brown.
Some areas are up to 30 percent included soils
that are similar to this soil material, but either
shallower or deeper over the compact substratum;
and some areas are 5 to 10 percent very gravelly
Everett soils and sandy Indianola soils.
This Arents, Alderwood soil is moderately well
drained. Permeability in the uppex, disturbed soil
material is moderately rapid to moderately slow,
depending on its compaction during construction.
The substratum is very slowly permeable, Roots
penetrate to and tend to mat on the surface of the
consolidated substratum. Some roots enter the
substratum through cracks. Water moves on top of
the substratum in winter. Available water, capacity
is low. Runoff is slow, and the erosion hazard is
slight.
This soil is used for urban development. Ca-
pability unit IVe-2; woodland group 3d2.
Arents, Aldenvood material, 6 to 15 percent
slopes AmC ---This soil has convex slopes. Areas
are rectangular in shape and range from 10 acres to
about 450 acres in size.
PAGE 10F 50
REVIEW OF STORMWATER REQUIREMENTS FROM
CITY OF FEDERAL WAY AND THE CITY OF TACOMA
Since this project is within the City of Federal Way but discharges stormwater to the City
of Tacoma's system, this review will focus on both Cities' stormwater manuals. The City
of Federal Way follows the 1998 KCSWDM, which has eight core requirements and five
special requirements. The City of Tacoma's 2003 Surface Water Management Manual
has ten minimum requirements and two additional requirements.
KCSWDM - Core Requirement No. 1 — Discharge at the Natural Location
TSWMM - Minimum Requirement No. 4 - Preservation of Natural Drainage
Systems and Outfalls
City of Federal Way:
The entire site drains west to the City of Tacoma under existing and proposed
conditions. It will drain to an existing conveyance system which flows straight south in
Norpoint Way all the way to Commencement Bay.
City of Tacoma:
The entire site generally drains west eventually discharging to a catch basin at the start
of the City of Tacoma's stormwater conveyance system in Norpoint Way. Flows stay in
the City of Tacoma and continue in a conveyance system to Commencement Bay.
KCSWDM - Core Requirement No. 2 - Offsite Analysis
TSWMM - Additional Requirement No. 1 - Off -Site Analysis and Mitigation
City of Federal Way:
"All proposed projects must submit an offsite analysis report that assesses potential
offsite drainage impact associated with development of the project site and proposes
appropriate mitigation of those impacts." (See Section 111 of this report)
City of Tacoma:
Since the site flows to Tacoma, this submittal includes a downstream analysis as
described in Volume 111 Chapter 4 of the City of Tacoma's Surface Water management
Manual. (See Section III of this report, Offsite Analysis, for this information).
KCSWDM - Core Requirement No. 3 - Flow Control
TSWMM -Additional Requirement No. 7 - Flow Control
City of Federal Way:
The flow control facility will be located within the City of Federal Way. Based on the City
of Federal Way standards, the proposed onsite improvements (buildings, driveways and
the private access road) will introduce more than 10,000 square feet of new impervious
area; therefore, onsite storm water flow control is required. The project would propose
1-5 i :) ;
��
AUE
to design a detention pond to a Level 1 Flow Control standard as set forth in the 1998
KCSWDM.
City of Tacoma:
Although the flow control facility will be located in the City of Federal Way, it will
discharge to the City of Tacoma's conveyance system; therefore the flow control needs
to be designed with this in mind. Per the TSWMM, Figure 3-4, the proposed onsite
improvements (buildings, driveways and the private access road) will introduce more
than 10,000 square feet of effective impervious area; but not to Leach Creek or Flett
Creek Watershed, nor does it discharge to fresh water. It does not discharge to an open
system so a qualitative downstream analysis in required. (See downstream analysis)
This analysis indicates that the existing conveyance system will contain the design
flows, so flow control, per the City of Tacoma may not be required. However, since it is
in Federal Way, it is required. The project proposes to design a detention pond using a
"continues rainfallrunoff modeling", which, since the site is in King County, will be
KCRTS. It will discharge at a Level 1 per the KCSWDM, which means it matches the
existing site conditions 2 and 10 year peaks.
KCSWDM - Core Requirement No. 4 - Conveyance System
TSWMM - Additional Requirement No. 1 - Off -Site Analysis
City of Federal Way:
"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".
The City of Federal Way's conveyance requirements for a new system are per Section
1.2.4.1. The conveyance system must be designed with sufficient capacity to convey
and contain (at a minimum) the 25-year storm peak flow, assuming developed
conditions for onsite tributary areas and existing conditions for any offsite tributary
areas. The means to check the capacity of the proposed conveyance system for the
Norpoint Heights Subdivision was Table 3.2, page 3-10 of the 1998 KCSWDM. Insofar
as the project Natural Discharge Area is less than 10 acres and the majority of the
tributary area is detained, the King County Runoff Time Series (KCRTS) with 15-minute
time steps runoff computation method will be used for the capacity analysis of the site.
The new conveyance system analysis and design will be done during the final stage of
this project.
City of Tacoma:
The City of Tacoma's conveyance requirements for a new system are per Volume 111,
Chapter 4. All public and private pipe systems less than 24 inches in diameter shall be
designed to convey the 10-year 24-hour peak flow rate without surcharge.
All conveyance systems shall be designed for the full -developed conditions. The fully
developed conditions for the project site shall be derived from the percentage of
proposed and existing impervious area. For off -site tributary areas, typical percentage of
1-6 EXHIBIT-4-
PAG V�—P>
impervious area for fully developed conditions is provided in Table 4.1. Conveyance
systems shall be modeled as if no detention is provided upstream.
KCSWDM - Core Requirement No. 5- TemporaEy Erosion and Sedimentation
Control
TSWMM - Minimum Requirement No. 2 - Construction Stormwater Pollution
Prevention
Will apply during the final design review.
KCSWDM - Core Requirement No. 6 - Maintenance and Operations
TSWMM - Minimum Requirement No. 10 - Operation and Maintenance
Will apply during the final design review.
KCSWDM - Core Requirement No. 7 - Financial Guarantees and Liabilitv
TSWMM - Additional Requirement No. 2 - Financial Liabilitv
Will apply during the final design review.
KCSWDM - Core Requirement No. 8 - Water Quality
TSWMM - Minimum Requirement No. 6 - Runoff Treatment
Since this project is in the City of Federal Way, but discharges to the City of Tacoma, it
needs to be developed for both jurisdictions. It appears both will accept a combined
detentionlwetpond facility.
City of Federal Way:
All proposed projects must provide water quality (WQ) facilities to treat the runoff from
new and/or replace pollution -generating impervious surfaces and pollution -generating
pervious surfaces. The site is located within a Basic Water Quality Treatment Area as
identified on the City of Federal Way Water Quality Applications Map.
City of Tacoma:
The following projects require construction of stormwater treatment facilities (See Table
3.1
TSWMM)
Projects in which the total of the effective pollution -generating impervious surface
(PGIS) is 5,000 square feet or more in a threshold discharge area of the project, or
Projects in which the total of pollution -generating pervious surface (PGPS) is three-
quarters (314) of an acre or more in a threshold discharge area, and from which there is
a surface discharge in a natural or man-made conveyance system from the site.
1-7
PPG E WC� F -5 0
The Norpoint Heights Subdivision proposal will utilize the proposed combined
detention/wetpool facility as mitigation for water quality.
KCSWDM -Special Requirement No. 1 - Other Adopted Area -Specific
Requirements
No other specific requirements are known for this site.
KCSWDM -Special Requirement: No. 2 - Fioodplain/Floodwa- Delineation
The 100-year Flood Plain does not enter this site.
KCSWDM -Special Requirement No. 3 - Flood Protection Facilities
This requirement does not apply since the project is outside any defined floodplains.
KCSWDM Special Requirement No. 4 - Source Controls
"Water quality source controls prevent rainfall and runoff from coming into contact
with pollutants, thereby reducing the likelihood that pollutants will enter public
waterways and violate water quality standards." A combined detention and wetpool
facility is proposed for water quality treatment of runoff from the paved surface
subject to vehicular traffic, prior to discharge into the downstream public drainage
system.
KCSWDM -Special Requirement No. 5 - Oil Control
After reviewing Section 1.3.5 of the KCSWDM, this site will not be classified as a
high use site, and oil control will not be required.
TSWMM - Minimum Requirement No. 1 - New Development
All new development shall be required to comply with Minimum Requirement # 2. In
addition, new development that exceeds certain thresholds shall be required to
comply with additional minimum requirements as follows:
The following new development shall comply with Minimum Requirements # 1
through #5:
Creates or adds 2,000 square feet, or greater, of new, replaced, or new plus
replaced impervious surface area, or
Has land disturbing activity of 7,000 square feet or greater.
In addition to complying with the Minimum Requirements #1 through #5, the
following new development shall comply with Minimum Requirements # 6 through
10. r, 11,/r r`^iT
1-8
PA G E _--_O F �=Q
or
or
Creates or adds 5,000 square feet, or more, of new impervious surface area,
Converts % acres, or more, of native vegetation to lawn or landscaped area,
Converts 2.5 acres, or more, of native vegetation to pasture.
The - Norpoint Heights Residential Subdivision proposal will utilize a combined
detention and wetpool facility as mitigation for stormwater impacts.
TSWMM -Minimum Requirement No.2-�Const. Stormwater Pollution Prevention
SWPP
All new developments and redevelopments shall comply with Construction SWPP
Elements # 1 through 12. These requirements will apply during the final design
review.
TSWMM - Minimum Requirement No. 3 - Source Control of Pollution
All known available and reasonable source control BMP's shall be applied to all
projects. Source control BMP's shall be selected, designed, and maintained according
to this manual.
These requirements will apply during the final design review.
TSWMM - Minimum Requirement No. 5 - On -Site Stormwater Management
The infiltration and disposal systems described in this Minimum Requirement shall only
be used with the pre -approval of the City.
The soils under the Norpoint Heights Project are Alderwood soils which are generally
not too good for infiltration systems. No infiltration systems are proposed.
TSWMM - Minimum Requirement No. 8 - Wetland Protection
The Norpoint Heights site does not contain any recorded wetlands.
TSWMM - Minimum Requirement No._9 - Basin Plan_rfin_g;
No geographic specific requirements are known to exist downstream of this project.
1-9 PAGE
SUMMARY
Since this site is within the City of Federal Way but access and stormwater discharges
to the City of Tacoma, any design would have to accommodate the requirements of
both jurisdictions. The standards established for the two jurisdictions are similar enough
to provide an acceptable design for both Cities.
The stormwater runoff from the project site will be collected from the access road, roof,
grass and landscaped areas, and conveyed through a pipe system to a combined
detention wetpond facility and then discharge to the City of Tacoma conveyance
system.
OVERALL SUMMARY OF CONCLUSIONS & PROPOSED MITIGATION
The summary of Section III "Off -Site Analysis", within this TIR indicates this system is
adequate for the discharge from the proposed combined detention /wet pond facility
design using the level 1 design parameters. No other mitigation is proposed.
Soils Information
The King County Soils Survey by the US Soils Conservation Service (1973)
generalizes the soils in the vicinity of this project as Alderwood Series; AgC. These
soils are made up of mostly poorly draining soils that have a weakly consolidated to
strongly consolidated substratum at a depth of 24 to 40 inches.
1-10 FAGE-0F�
SECTION III
OFFSITE ANALYSIS
This off -site review will follow both the City of Federal Way and City of Tacoma
guidelines.
City of Federal Way:
(This portion follows the KCSW DM)
The following is a Preliminary Level I Downstream Analysis, which looks at the drainage
system 1/4 mile downstream of the site along with the five tasks outlined under the
Level I Downstream Analysis. (See Overall Drainage Map in Appendix).
The five Tasks are: Task 1 - Study Area Definition and Maps
Task 2 - Resource Review
Task 3 - Field Inspection
Task 4 - Drainage System Description and Problem Screening
Task 5 — Mitigation
Task 1 - Study Area Definitions and Maps
See Figure 111 - A within this report is an overall map showing the project site and the
downstream drainage path going south.
Task 2 - Resource Review
Since the site discharges to the City of Tacoma a review of their downstream system
was conducted. From this review, flows go immediately into a conveyance system
which goes directly to main storm line which goes directly to Commencement Bay.
There is no area which will have adverse affects or problems downstream of the project
site.
Task 3 - Field Inspection
A site inspection was conducted on 11-30-07 of the downstream system and the study
area. The inspection revealed that this area is generally a mixture of older homes with
some newer homes and developments scattered through -out the study area. Starting at
the Pierce County/King County line, any flows would generally start in the new
conveyance system built with the new Norpoint Way roadway improvements just a
couple of years ago in the City of Tacoma. Flows will stay within this closed conveyance
system for the entire 1/4 mile downstream review, and on to Commencement Bay.
Task 4 - Drainage System Description and Problem Screening
At the end of this proposal in Norpoint Way there is a new storm system built with this
new road. The system starts with a couple of catch basins on either side of the new
3-1 EX H I B
PAGE 02 -59
road. From these catch basins there are 8" storm lines going northerly to a Type 2
manhole. From this manhole there is a new 10" main storm line running in a northwest
direction to a second type 2 manhole. A 12" line continues in a westerly direct to a cast -
in -place manhole over an existing 36" storm line. This line runs in a north -south
direction. Flows go south in this 36" main line to 29th Street NE were it turns east over
to Norpoint Way were it turns again and continues south in Norpoint Way .
Task 5 — Mitigation
Since there are no known drainage issues with the downstream system, the proposed
mitigation would be to follow Federal Way's "Level 1" detention and their "Basic" water
quality requirements in the 1 998 KCS WDM.
City of Tacoma:
(This portion follows the TSWMM)
The following is a Qualitative Analysis under "Additional Requirement #1 - Off -Site
Analysis and Mitigation" as defined in the TS WMM, page 3-33.
This Quantitative Analysis has five tasks that are:
Task 1 - Define and map the study area,
Task 2 - Review all available information on the study area,
Task 3 - Field inspect the study area,
Task 4 - Describe the drainage system, and its existing and predicted
problems through observations and hydraulic modeling of the City
specified design storm event described in Chapter 4 Volume III.
Task 1 -Define and Map the Study Area
See Figure 111 - B within this report represents an overall map showing the project site
and the downstream drainage path going generally south. This map generally shows
the drainage basins that flow into this system. The study area is generally residential
with a few roads.
Task 2 - Review all available information on the study area.
A review of the available information was conducted within the City of Tacoma Surface
Water Management Manual along with the City of Tacoma's Public Works web site.
Per the TSWMM, this area is within the "Northeast Tacoma" watershed area, which on
page 2- 13 describes this area as generally residential with open spaces and
undeveloped land. Most of this watershed discharges directly to Commencement Bay.
The sub -basin this project flows to discharges directly to Commencement Bay.
Flow control requirements, as defined in this section, call for projects which do not
discharge to a creek or gulch, which would include this project, but are instead piped all
3-2
the way to a marine outfall, require an offsite analysis for capacity. (This is done under
Task 4) This section also indicates that none of the stormwater discharges in this area
are to fish bearing streams. This would indicate that enhanced treatment for water
quality is not required.
Task 3 - Field Inspect the study area.
A site inspection was conducted on 11-30-07 of. the downstream system and the
study area. The inspection revealed that this area is generally a mixture of older
homes with some newer homes and developments scattered throughout the study
area.
Starting at the Pierce County/King County line, any flows would generally start in the
new conveyance system built with the new Norpoint Way roadway improvements
just a couple of years ago in the City of Tacoma.
Flows will stay within this closed conveyance system for the entire ?4 mile
downstream review, and on to Commencement Bay:
The enclosed conveyance system generally starts at the new access road for this
Norpoint Heights Subdivision. Flows continue in a northwest direction until it enters the
main 36" line running north/south in 59th Ave. NE . NE. Flows continue flowing south in
59th Ave . NE until it reaches 29& St. E. where it turns east and then south again in
Norpoint Way NE. Flows stay in Norpoint Way NE almost all the way to
Commencement Bay. The conveyance system veers off this road near the bottom of the
hill and discharges in a small cove next to Commencement Bay.
There did not appear to be any excessive erosive areas along the conveyance
system's path.
Task 4 - Describe the drainage system, and its existing and predicted problems
through observations and hydraulic modeling of the City specijied design
storm event described in Chapter 4 Volume 111
The following section reviews the existing conveyance system with developed
basins using Stormshed a hydraulic modeling programs.
It appears the downstream conveyance system is sized correctly for the developed
drainage basin in a 10 year storm event, see printout. Per City of Tacoma
requirements, only the conveyance system between a project and a 24" or larger
main line needs to be reviewed, which is what is enclosed.
3-3
'` JJC�-O F
Conveyance Basin =
229,332 sf or 5.26 acres
14 new horses x 4,000 sf each =
56,000 sf or 1.29 acres
I existing home x 2,876 sf or
0.066 acres
Roadway/sidewalks 29,268 sf. or•
0.67 acres
Total impervious surface Is t$b,144 st
or 2.02 acres
Total grass area = 141,188 sf
or 3.24 acres
w*} l aeovos[n
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DRAINAGE BASIN FOR
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CONSULTING ENGINEERS LLC
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JOB N❑. 1453-002
DRAWING NAME I DRAINAGE BASINS
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Federal way, WA e80o3
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DATE 1 1-8-08
www.esmcIvIL.com
BBTHELL 4125, 415-614+
ELLENSBURG (509) 962-2600
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1 I o � H1
SECTION IV
WATER QUANTITY AND QUALITY
ANALYSIS AND DESIGN
As indicted in previous sections, this project proposes to provide flow control as
required by both the City of Federal Way and the City of Tacoma.
WATER QUANTITY
Area -Specific Flow Control Standards
Under the City of Federal Way, this project would be subject to Core Requirement #3
(Flow Control) which, at a minimum, would need to comply with one of the three area -
specific flow control standards: Level 1, Level 2, or Level 3, whichever applies per the
threshold information detailed in Section 1.2.3.1 of the 1998 KCSWDM. King County
Department of Natural Resources has determined by the King County Flow Control
Applications Map that a Level 1 Flow Control application would be appropriate for this
area. The City of Federal Way's Flow Control Map also shows this area as a Level 1.
KCRTS will be used for flow control modeling of the development.
Under the City of Tacoma, per the Figure 3-4 of the TSWMM, the proposed onsite
improvements (buildings, driveways and the private access road) will introduce more
than 10,000 square feet of effective impervious area. However, it does not discharge to
Leach Creek or Flett Creek Watersheds, nor does it discharge to fresh water, so only a
qualitative downstream analysis in required. The analysis in the previous section shows
the existing conveyance system will contain the proposed flows, so the only control
required from Tacoma is a level 1.
The proposal is to design a detention pond using a "continues rainfall/runoff modeling",
which, since the site is in King County, will be KCRTS. It will discharge, per Table
1.2.3.A of the KCSWDM, "match the existing 2-year to 10-year peak flow, which is
generally a Level 1.
Existing Site Hydrology
Existing conditions on the Norpoint Heights Subdivision site consists of underbrush,
trees, one power pole, no buildings and gravel driveway all in a forest condition. There
is only basin, Basin A (See Figure IV -A). Using KCRTS the site will be modeled as till
forest including a portion of Norpoint Way NE right-of-way, as detailed in the area
delineation table below:
TABLE IV.1
Pre-Deve[Wed Pond Tributary Area
BASIN
TOTAL
IMPERV.
TILL
TILL
AREA
(Ac)
GRASS
FOREST
(Ac)
(Ac)
(Ac)
BASIN A
3.13
0.00
0.00
3.13
4-1
EM.-
Runoff files for the existing conditions were performed using KCRTS software in the
SeaTac Region with:
1.0 Scale Factor,
1-hour Time Step, and
Reduced Rainfall Data.
The results of the analysis are shown as follows:
Flow Frequency Analysis (Existing Conditions)
Flow Frequency Analysis
Time Series File:predev.tsf
Project Location:Sea-Tac
---Annual
Peak
Flow Rates ---
Flow Rate
Rank
Time of
Peak
(CFS)
0.197
2
2/09/01
18:00
0.054
7
1/06/02
3:00
0.147
4
2/28/03
3:00
0.005
8
3/24/04
20400
0.087
6
1/05/05
8:00
0.151
3
1/18/06
21:00
0.128
5
11/24/06
4:00
0.252
1
1/09/08
9-:00
Computed Peaks
Developed Conditions
-----Flow
Frequency Analysis
-------
- - Peaks
- - Rank
Return
Prob
(CFS)
Period
0.252
1
100.00
0.990
0.197
2
25.00
0.960
0.151
3
10.00
0.900
0.147
4
5.00
0.800
0.128
5
3.00
0.667
0.087
6
2.00
0.500
0.054
7
1.30
0.231
0.005
8
1.10
0.091
0.234
50.00
0.98C
The developed conditions will consist of the Norpoint Heights Subdivision, new
roadway, pond, and landscape areas in Basin A. (See Figure IV) The sizing will use a
4,000 s.f. roof area for each of the homes along with about 5,300 sf of impervious
private driveway. Developed land use types are delineated in the table below:
TABLE IV.2
riou,minnari Pnnri Trihritary Area
BASIN
TOTAL
IMPERV.
TILL
TILL
BYPASS
AREA
(AC)
GRASS
FOREST
IMPERV.
(Ac)
(AC)
(AC)
(Ac)
BASIN A
3.13
2.03
1.05
0.00
0.05
Runoff files for the proposed conditions were performed using KCRTS software in the
SeaTac Region with:
Scale Factor = 1,
1-hour Time Step, and
Reduced Rainfall Data.
The results of the analysis are shown as follows:
E%HI� oT..
4-2
Flow Frequency Analysis (Developed Conditions and Bypass Flow Rate)
Flow Frequency Analysis
Time Series File:dev.tsf
Project Location:Sea-Tac
---Annual
Peak
Flow Rates ---
Flow Rate
Rank
Time of
Peak
(CFS)
0.586
6
2/09/01
2:00
0.461
8
1/05/02
16:00
0.704
3
2/27/03
7:00
0.525
7
8/26/04
2:00
0.632
4
10/28/04
16:00
0.623
5•
1/18/06
16:00
0.764
2
10/26/06
0:00
1.18
1
1/09/08
6:00
Computed Peaks
Flow Frequency Analysis
Time Series File:bypass.tsf
Project Location:Sea-Tac
---Annual
Peak
Flow Rates ---
Flow Rate
Rank
Time of
Peak
(CFS)
0.012
7
2/09/01
2:00
0.011
8
1/05/02
16:00
0.015
3
12/08/02
18:00
0.012
6
8/26/04
2:00
0.015
4
10/28/04
16:00
0.013
5
1/18/06
16:00
0.018
2
10/26/06
0:00
0.023
1
1/09/08
6:00
Computed Peaks
-----Flow
Frequency Analysis-------
- - Peaks
- - Rank
Return
Prob
(CFS)
Period
1.18
1
100.00
0.990
0.764
2
25.00
0.960
0.704
3
10.00
0.900
0.632
4
5.00
0.800
0.623
5
3.00
0.667
0.586
6
2.00
0.500
0.525
7
1.30
0.231
0.481
8
1.10
0.091
1.04
50.00
0.980
-----Flow
Frequency Analysis-------
- - Peaks
- - Rank
Return
Prob
(CFS)
Period
0.023
1
100.00
0.990
0.018
2
25.00
0.960
0.015
3
10.00
0.900
0.015
4
5.00
0.800
0.013
5
3.00
0.667
0.012
6
2.00
0.50C
0.012
7
1.30
0.231
0.011
8
1.10
0.091
0.022
50.00
0.98C
The allowable release rates from the pond for Basin A per the Level 1 Flow Control are
shown below:
TABLE IV.3
Dnnd Trihi ann► Flnw Antrac
BASIN A
EXISTING
DEVELOPED
BYPASS
ALLOWED
STORM EVENTS
FLOW RATE
FLOW RATE
FLOW RATE
RELEASE RATE
(CFS)
(CFS)
(CFS)
(CFS)
2 Year
0.09
0.59
0.01
0.09
10 Year
0.15
0.70
0.02
1 0.15
The data shown below demonstrate the required sizing for the detention pond per the
Level 1 Flow Control analysis.
Basin A
Pond Bottom Length: 88.5 ft
Pond Bottom Width: 29.5 ft
Side Slope: 3 H: 1V
Orifice #1: Ht = 0.0', Dia. = 1.32"
-_gip.
Orifice #2: Ht = 4.0', Dia. = 1.26"
Effective Storage Depth: 5.00 ft
Storage Volume: 23,427 ft3
Type of Facility: Detention Pond
To
Effec
Side Slope:
3.00
H:1V
Pond Bottom Length:
88.56
ft
Pond Bottom Width:
29.52
ft
Pond Bottom Area:
2614.
sq. ft
p Area at 1 ft. FB:
8161.
sq. ft
0.187
acres
tive Storage Depth:
5.00
ft
Stage 0 Elevation:
901.00
ft
Storage Volume:
23427.
cu. ft
0.538
ac-ft
Riser Head:
5.00
ft
Riser Diameter:
12.00
in ches
Nu ber of orifices:
2
Full Head Pipe
Orifice
# Height
Diameter
Discharge Diameter
(ft)
(in)
(C FS)
(in)
1
0.00
1.32
0.105
2
4.00
1.26
0.043
4.0
Top Notch Weir:
None
Outflow
Rating Curve:
None
Stage
Elevation
Storage Discharge
Percolation
Surf Area
(ft)
(ft) (cu. ft)
(ac-ft)
(cfs)
(cfs)
(sq. ft)
0.00
901.00
0.
0.000
0.000
0.00
2614.
0.01
901.01
26.
0.001
0.005
0.00
2621.
0.03
901.03
79.
0.002
0.008
0..00
2636.
0.04
901.04
105.
0.002
0.010
0.00
2643.
0.05
901.05
132.
0.003
0.011
0.00
2650.
0.07
901.07
185.
0.004
0.012
0.00
2664.
0.08
901.08
211.
0.005
0.01.3
0.00
2671.
0.10
901.10
265.
0.006
0.015
0.00
2685.
0.11
901.11
292.
0.007
0.016
0.00
2693.
0.21
901.21
565.
0.013
0.022
0.00
2765.
0.31
901.31
845.
0.019
0.026
0.00
2837.
0.41
901.41
1132.
0.026
0.030
0.00
2911.
0.51
901.51
1427.
0.033
0.034
0.00
2985.
0.61
901.61
1729.
0.040
0.037
0.00
3060.
0.71
901.71
2039.
0.047
0.040
0.00
3135.
0.81
901.81
2356.
0.054
0.042
0.00
3212.
0.91
901.91
2681.
0.062
0.045
0.00
3289.
1.01
902.01
3014.
0.069
0.047
0.00
3367.
1.11
902.11
3355.
0.077
0.049
0.00
3445.
1.21
902.21
3703.
0.085
0.052
0,00
3524.
1.31
902.31
4060.
0.093
0.054
0.00
3604.
1.41
902.41
4424.
0.102
0.056
0.00
3685.
1.51
902.51
4797.
0.110
0.058
0.00
3766.
1.61
902.61
5177.
0.119
0.060
0.00
3848.
1.71
902.71
5566.
0.128
0.061
0.00
3931.
1.81
902.81
5963.
0.137
0.063
0.00
4015.
1.91
902.91
6369.
0.146
0.065
0.00
4099.
2.01
903.01
6783.
0.156
0.067
0.00
4184.
2.11
903.11
7206.
0.165
0.068
0.00
4269.
2.21
903.21
7637.
0.175
0.070
0.00
4356.
2.31
903.31
8077.
0.185
0.071
0.00
4443.
2.41
903.41
8526.
0.196
0.073
0.00
4531.
2.51
903.51
8983.
0.206
0.074
0.00
4619.
4-4
EXHIBIT
PAGE OF -
2.61
903.61
9450.
0.217
0.076
0.00
4709.
2.71
903.71
9925.
0.228
0.077
0.00
4799.
2.81
903.81
10409.
0.239
0.079
0.00
4889.
2.91
903.91
10903,
0.250
0.080
0.00
4981.
3.01
904.01
11406.
0.262
0.081
0.00
5073.
3.11
904.11
11917.
0.274
0.083
0.00
5166.
3.21
904.21
12439.
0.286
0.084
0.00
5259.
3.31
904.31
12969.
0.298
0.085
0.00
5354.
3.41
904.41
13509.
0.310
0.087
0.00
5449.
3.51
904.51
14059.
0.323
0.088
0.00
5544.
3.61
904.61
14618.
0.336
0.089
0.00
5641.
3.71
904.71
15187.
0.349
0.090
0.00
5738.
3.81
904.81
15766.
0.362
0.092
0.00
5836.
3.91
904.91
16355.
0.375
0.093
0.00
5935.
4.00
905.00
16893.
0.388
0.094
0.00
6024.
4.01
905.01
16953.
0.389
0.094
0.00
6034.
4.03
905.03
17074.
0.392
0.095
0.00
6054.
4.04
905.04
17134.
0.393
0.097
0.00
6064.
4.05
905.05
17195.
0.395
0.100
0.00
6074.
4.07
905.07
17317.
0.398
0.103
0.00
6094.
4.08
905.08
17378.
0.399
0.107
0.00
6104.
4.09
905.09
17439.
0.400
0.108
0.00
6114.
4.11
905.11
17561.
0.403
0.109
0.00
6134.
4.12
905.12
17623.
0.405
0.110
0.00
6144.
4.22
905.22
18242.
0.419
0.117
0.00
6245.
4.32
905.32
18872.
0.433
0.122
0.00
6347.
4.42
905.42
19512.
0.448
0.127
0.00
6449.
4.52
905.52
20162.
0.463
0,131
0.00
6552.
4.62
905.62
20822.
0.478
0.135
0.00
6656.
4.72
905.72
21493.
0.493
0.139
0.00
6760.
4.82
905.82
22174.
0.509
0.142
0.00
6865.
4.92
905.92
22866.
0.525
0.146
0.00
6971.
5.00
906.00
23427.
0.538
0.148
0.00
7057.
5.10
906.10
24138.
0.554
0.460
0.00
7164.
5.20
906.20
24860.
0.571
1.030
0.00
7272.
5.30
906.30
25592.
0.588
1.760
0.00
7380.
5.40
906.40
26336.
0.605
2.550
0.00
7490.
5.50
906.50
27090.
0.622
2.840
0.00
7600.
5.60
906.60
27856.
0.639
3.100
0.00
7711.
5.70
906.70
28633.
0.657
3.330
0.00
7822.
5.80
906.80
29420.
0.675
3.550
0.00
7934.
5.90
906.90
30219.
0.694
3.760
0.00
8047.
6.00
907.00
31030.
0.712
3.960
0.00
8161.
6.10
907.10
31852.
0.731
4.150
0.00
8275.
6.20
907.20
32685.
0.750
4.320
0.00
8391.
6.30
907.30
33530.
0.770
4.500
0.00
8506.
6.40
907.40
34386.
0.789
4.660
0.00
8623.
6.50
907.50
35254.
0.809
4.820
0.00
8740.
6.60
907.60
36134.
0.830
4.970
0.00
8858.
6.70
907.70
37026.
0.850
5.120
0.00
8977.
6.80
907.80
37930.
0,871
5.270
0.00
9096.
6.90
907.90
38846.
0.892
5.410
0.00
9217.
7.00
908.00
39773.
0.913
5.550
0.00
9338.
Hyd
Inflow
Outflow
Peak
Storage
Stage
Elev
(Cu-Ft)
(Ac-Ft)
1
1.18
0.89
5.18
906.18
24687.
0.567
2
0.59
0.42
5,09
906.09
24048.
0.552
3
0.59
0.15
5.00
906.00
23424.
0.538
4
0.62
0.14
4.70
905.70
21338.
0.490
5
0.70
0.13
4.56
905.56
20456.
0.470
6
0.37
0.09
3.65
904.65
14858.
0.341
7
0.48
0.08
2.70
903.70
9901.
0.227
4-5
8
0.53
0.07
2.18 903.18
7527.
0.173
Hyd
R/D Facility
Tributary
Reservoir
POC Outflow
Outflow
Inflow
Inflow
Target
Calc
1
0.89
0.02
********
*******
0.91
2
0.42
0.01
********
*******
0.43
3
0.15
0.01
********
0.15
0.15
4
0.14
0.01
********
*******
0.14
5
0.13
0.01
********
*******
0.14
6
0.09
0.01
********
0.09
0.09
7
0.08
0.01
********
*******
0.08
8
0.07
0.01
********
*******
0.07
----------------------------------
Route Time Series through Facility
Inflow Time Series File:dev.tsf
Outflow Time Series File:rdout
POC Time Series File:dsout
Inflow/Outflow Analysis
Peak Inflow Discharge: 1.18 CFS at 6:00 on Jan 9 in Year 8
Peak Outflow Discharge: 0.893 CFS at 9:00 on Jan 9 in Year 8
Peak Reservoir Stage: 5.18 Ft
Peak Reservoir Elev: 906.18 Ft
Peak Reservoir Storage: 24687. Cu-Ft
0.567 Ac-Ft
Add Time Series:bypass.tsf
Peak Summed Discharge: 0.912 CFS at 9:00 on Jan 9 in Year 8
Point of Compliance File:dsout.tsf
Flow Frequency Analysis
Time Series File:dsout.tsf
Project Location:Sea-Tac
---Annual
Peak
Flow Rates ---
Flow Rate
Rank
Time of
Peak
(CFS)
0.426
2
2/09/01
16:00
0.079
7
12/28/01
16:00
0.135
5
2/28/03
6:00
0.072
8
8/26/04
4:00
0.092
6
1/05/05
8:00
0.140
4
1/18/06
21:00
0.152
3
11/24/06
6:00
0.912
1
1/09/08
9:00
Computed Peaks
-----Flow
Frequency Analysis-------
- - Peaks
- - Rank
Return
Prob
(CFS)
Period
0.912
1
100.00
0.990
0.426
2
25.00
0.960
0.152
3
10.00
0.900
0.140
4
5.00
0.800
0.135
5
3.00
0.667
0.092
6
2.00
0.500
0.079
7
1.30
0.231
0.072
8
1.10
0.091
0.750
50.00
0.980
TABLE IVA
Pond Flow 5ummary
BASIN A
ALLOWED
CALCULATED
STORM EVENTS
RELEASE RATE
RELEASE RATE
(CFS)
(CFS)
2 Year
0.09
0.09
10 Year
0.15
0.15
Also see Appendix for complete computer printouts for Basin A.
�D
4-6
WATER QUALITY
As indicted in previous sections, this project also proposes to provide water quality
control as required by both the City of Federal Way and the City of Tacoma.
Reviewing the Federal Way Surface Water Resources Map, the "basic water quality" is
required for this project.
Under the City of Tacoma, since this project does not discharge to fish bearing stream,
it would not need enhanced treatment for water quality, but it will be a project with a
total of 5,000 square feet or more of pollution -generating impervious surface (PGIS) in a
threshold discharge area, so it would be subject to the "Basic Treatment" options.
The proposed Norpoint Heights Residential Subdivision will utilize a combined
detention/wetpool facility as mitigation for water quality. Since the bottom of the
proposed detention/wetpool facility is less than 1,500 SF, no access road to the bottom
is proposed.
The following is a wet pond calculation sheet from King County;
IV F--
47 AG
KING COUNTY, WASHINGTON, SURFACE WTER DESIGN MANUAL
WETPOND SIZING WORKSHEET
Summary of the 1998 Surface Water Design Manual Requirements
Project Name: Norpoint Heights 1453-002-007
METHOD OF ANALYSIS (see p. 6-68)
Step 1) Determine Volume factor, f
Basic Size? f = _
Large Size? f =
3 Consult WQ requirement(Section 1.2.8)
4.5 to determine if basic or large size needed
Step 2) Determine rainfall R for mean annual storm
Rainfall (R) 0.039 (feet) Required from Figure 6.4. LA
Step 3) Calculate runoff from mean annual storm
Vr = (0.9Ai+ 0.25At9+ 0.1OAtf+ 0.01 AoJ * R
A;
tributary area of impervious surface
88293 (ft)
Determine now
Ats
tributary area of till grass
45588 (ftZ)
Determine now
Atf=
tributary area of till forest
0 (ftZ)
Determine now
Aog
tributary area of outwash grass
0 (ftZ)
Determine now
R=
rainfall from mean annual storm
0.039 (ft)
From Step 2
Vr=
volume of runoff from mean annual storm
3544 (ft)
Step 4) Calculate wetpool volume
Vb=fV,
f = Volume factor
Vr = volume runoff, mean annual storm
Vb = Volume of the wetpool
3 (unitless) From Step 1
3544 (W) From Step 3
10631
Step 5) Determine wetpool dimensions
a) Determine geometry of first cell
Volume in first cell 3189 (ft3)
Depth h 1st cell (minus sed. Stor.) 3 (ft)
Determine horizontal xs-area at surface at mid -depth using Amid = V,rt/h
Amid = 1063 (ftZ)
Mid -width 33 (ft)
Mid -length 33 (ft)
Z = Side slope length: _ (H): 1(V)
2(h/2 * Z) _
Find top dimensions by adjusting for shape geometrics
Top width
Top Length
A,op _
N WIA
25-35% of total
See Section 6.4.1.2
2 (ft) 3:1 recommended
6 (ft)
39 (ft)
39 (ft)
1490 (ftZ)����
PA -
1998 Surface Water Design Manual I:\esm jobs\l025\documents\CALC-003.xls
b) Determine gemoetry of second cell
Volume in second cell 7441 (ft') Must be 65-75%
Depth h of 2nd cell 3 (ft) See Section 6.4.1.2
Determine horizontal xs-area at mid depth using Am,d = V2mJ/h
Amid =
Mid -width
Mid -length
Determine xs-area at surface
Z = Side slope length: _ (H): 1(V)
2(h/2 * Z) _
Top width
T,. length
Atop =
Adjust Cell 2 width to match cell 1
Adjust Cell 2 length using Atop
Geometry check: overall pond L : W at mid depth = 3 : I.
Pond width (mid -depth)
Cell 1 length (mid -depth)
Cell 2 length (mid -depth)
Pond length (mid -depth) = cel 1+2
Lmid • Wmid
1860 (ft')
43 (ft)
43 (ft)
1 (ft)
3 (ft)
46 (ft)
46 (ft)
2128 (ft2)
39 (ft)
55 (ft)
33 (ft)
33 (ft)
52 (ft)
85 (ft)
2.60
Step 6) Adjust shape of pond to blend into site (recommeneded)
Use the same side -slopes and depth as above
March pond surface area for each cell
Make sure L:W ratio still 3:1, or if one -celled, 4:1
Step 7) Design rest of pond (see Criteria p. 6-72)
Internal Berm
Inlet & Outlet
Primary overflow
Access
Other Design Details (Sections 6.2.2, p. 6-18, 6.2.3, p.20 and 6.2.4, p. 6-22)
Sequence of Facilities
Setbacks
Sideslopes, fencing, embankment
Total wetland surface area estimate
Surface area 1 st cell + 2nd cell + area for internal berm + area for access ramp
(ft')
Used to check L:W
3:1 recommended
Plus setbacks, access roads, 100-yr conveyance
77,
1998 Surface Water Design Manual IAesm jobs\1025\documents\CALC-003.xls
SECTION V
SPECIAL REPORTS AND STUDIES
Enclosed a soils report and infiltration report is part of this preliminary Technical
Information Report.
5-1
PL.253.896-1011
Px.253-896-2633
GeoResourees, LLC
5007 Pacific Hwy. E, Suite 20
Fife, Washington 98424-2649
January 16, 2008
Landmark Homes, Inc.
PO Box 26116
Federal Way, WA OM-2116
Attention: Mr. Larry King
Mr. David Litawitz
Geotechnical Engineering Services
Proposed Residential Development
Norpoint Residential Plat
Browns Point Area
Federal Way, Washington
Job: LandmarkHm.Norpolnt.RG
INTRODUCTION AND SCOPE
This report summarizes our site observations and provides geotechnical
recommendations and design criteria for the proposed Norpoint Residential Plat to be located
north of Norpoint Way In the Browns Point area of Federal Way, Washington. The general
location of the site is shown on the Vicinity Map, Figure 1.
Our understanding of the project is based on our discussions with you and Mr. Stuart
Schouerrnan of ESM (civil engineer), a review of the preliminary plans provided, and on our
experience in the area. We understand that current plans call for creating a new roadway for
approximately 14 residential lots with associated driveways and utilities. Thu site
configuration and topography is illustrated on the Site Plan, Figure 2.
The purpose of our services Is to evaluate the surface and subsurface conditions at
the site as a basis for addressing the Federal Way Critical Areas Ordinance as well as
addressing the potential of the site soils for supporting a stormwater detention pond. We have
also included geotechnical recommendations and design criteria for the project. We received
your written authorization on December 28, 2007. Speclficaily, the scope of services for this
project will include the following:
1. Reviewing the available geologic, hydrogeologic and geotechnical data for the site
•area.
2. Evaluating the shallow subsurface conditions at the site by observing open test pits at
the site.
3. Addressing the appropriate geotechnical regulatory requirements for the proposed site
development, per any City of Federal Way CAO requirements.
4. Providing geotechnlcal recommendations for site grading Including site preparation,
subgrade preparation, till placement criteria, suitability of on -site soils for use as
structural fill, temporary and permanent cut and fill slopes, and drainage and erosion
control measures.
5. Providing recommendations and design criteria for conventional foundation and floor
slab support, including allowable bearing capacity, subgrade modulus, lateral
resistance values and estimates of settlement.
E
EX I-1 C
Landmarkilm.NorpointAG
January 16, 2008
Page 2
6. Providing recommendations and design criteria for the design of conventional
subgradetretaining wails, Including backfill and drainage requirements, lateral design
loads, and lateral resistance values.
7. Providing recommendations for pavement subgrade preparation.
8. Providing appropriate IBC seismic design parameters for the proposed residential
structures.
SITE CONDITIONS
Surface Conditions
The proposed Norpoint residential plat Is located In an area of established residential
development. The subject property consists of two adjoining tax parcels that are generally
rectangular in shape. The site Is bounded by Norpoint Way NE on the West, existing residential
development on the east, north, and south. The King — Pierce County line bisects extreme
southwest comer of the site. The site configuration for proposed development is illustrated on
the Site Plan, Figure 2.
The project site is situated on the west margin of a local topographic ridge. The ground
surface at the site is generally fiat to gently sloping in the northeast portion of the site and gently
to moderately sloping to the west in the remaining area. Slopes at the site range from
approximately 5 percent to 20 percent
The site is currently vegetated with young alder and maple, and scattered small conifers
with a low understory of vine maple, native wandering blackberry, and occasional huckleberry,
holly and salal. Localized areas of invasive blackberry and grasses occur. No evidence of
standing water, seeps or springs were observed on the site. No evidence of erosion or slope
instability was observed at the site or the adjacent areas.
Site Solis
Although the subject property is located In an area that is not mapped by the Soil
Survey for Pierce County (USDA Natural Resource Conservation Service web soil survey),
the adjacent properties to the north are mapped as being underlain by the Alderwood gravelly
sandy loam (1 C) soils that form on 6 to 15 percent slopes. The Alderwood soils are derived
from glacial till and are classified as having a °moderate" potential for erosion when exposed.
An excerpt from the NROS soils map for the site area Is Included as Figure 3.
As previously stated, we observed no evidence of significant erosion at the site at the
time of our site visit.
Site Geology
According to the Geologic map of the Tacoma North 7.5-minute Quadrangle Pierce
County, Washington in review (Troost, K,G., Booth, D.E., and Borden, IRX), the site is in an
area underlain by glacial outwash deposits (10vr) and glacial till (Cvt). The outwash and till
deposits were deposited during the Vashon stade of the Fraser Glaciation, approximately
12,000 to 15,O00 years ago. The outwash deposits generally consist of a poorly stratified
mixture of sand and gravel that may locally contain silt, cobbles or boulders. The Vashon
glacial till was deposited at the base of the advancing glacial Ice and subsequently overridden
by the glacial ice. As such, the glacial till Is considered densely consolidated offer high
strength characteristics. The outwash deposits are considered normally consolidated and
offer moderate strength characteristics. An excerpt of the Geologic Map Is attached as
Figure 4.
LandmarkHm.Norpolnt. RO
January 16, 2008
Page 3
Subsurface Conditions
Our interpretation of the subsurface conditions at the site are based on our site
observations, data review and experience in the area. The existing open test pits observed at
the site ranged from 4.5 to 7 feet in depth and generally confirmed the mapped stratigraphy. In
general, the test pits encountered % to 1-foot of forest duff and topsoil mantling sand and gravel
with variable amounts of sift and cobbles. We interpret this sand and gravel material to be
recessional outwash deposits. The test pits on the southwest portion of the site encountered
the sand and gravel to depths of up to 6 feet. Glacial till was encountered at depths of 5 to 6
feet below the ground surface. Test pits in the northeast portion of the site encountered
between 3 and 4 feet of outwash sand and gravel over glacial till.
The recessional outwash sand with gravel soils were in a medium dense to dense condition.
The outwash was underlain by dense to very dense glacial till. Although no groundwater
seepage was observed, localized mottling was observed In the upper porlion of the glacial till in
several of the test pits in the west portlon of the site. This would suggest a seasonal perched
groundwater condition, likely above the dense glacial till. Perched groundwater typically
develops when the vertical infiltration of precipitation through a more permeable soil Is slowed
at depth by a deeper, less permeable soil type. The greatest volume of perched water will
likely occur in late spring or early summer, following the wet weather season.
Landslide Hazard Indicators — per City of Federal Way Municipal Code, Chapter 18.24
The City of Federal Way Municipal Code, Chapter 18.24 defines geologically
hazardous areas because of their susceptibility to erosion, landsliding, seismic or other
geological events are not suited to commercial, residential or industrial development
consistent with public health or safety concerns. Landslide hazard areas are those areas
potentially subject to episodic downslope movement of a mass of soil or rock including but not
limited to the following areas:
a. Any area with a combination of:
1. Slopes greater than 15 percent;
2. Permeable sediment (predominately sand and gravel) overlying relatively
Impermeable sediment or bedrock (typically sift and clay); and
3. Springs or groundwater seepage.
b. Any area which has shown movement during the Holocene epoch, from 10,000 years ago
to the present, or which Is underlain by mass wastage debris of that epoch.
c. Any area potentially unstable as a result of rapid stream incision, stream bank erosion or
undercutting by wave action.
d. Any area located in a ravine or on an active alluvial fan, presently or potentially subject to
inundation by debris flows or flooding.
e. Those areas Identified by the United States Department of Agriculture Soil Conservation
Service as having a severe limitation for building site development.
f. Those areas mapped as Class U (unstable), UOS (unstable old slides), and URS (unstable
recent slides) by the Department of Ecology.
g. Slopes having gradients greater than 80 percent subject to rockfall during seismic shaking.
Erosion Hazards — per City of Federal Way Chapter 18.24
The City of Federal Way Municipal Code, Chapter 18.24 defines erosion hazard areas
as generally consisting of areas having severe to very severe erosion hazard due to natural
agents such as wind, rain, splash, frost action or stream flow. The Everett and Harsiine soils
mapped in the site area are listed as having a "moderate" potential for erosion when exposed.
These soils are also listed as being well drained to moderately well dralned and having a
rapid to moderately rapid permeability, respectively.
LendmarkHmAorpoint.RG
January 1 e, 200E
Page 4
No evidence of erosion or slope instability was observed at the site at the time of our
site visit.
Seismic Hazards — per City of Federal Way Chapter 18.24
The City of Federal Way Municipal Code, Chapter 18.24 defines seismic hazard areas
as those areas subject to severe risk of earthquake damage as a result of seismically
Induced ground shaking, slope failure, settlement or soil liquefaction, or surface faulting.
These conditions occur in areas underlain by cohesionless Solis of low density usually in
association with a shallow groundwater table.
According to the Seismic Zone Map of the United States contained in Figure 16-2 of
the 1997 IBC (Intemational Building Code), the project site is located within Seismic Risk
Zone 3. Based on the subsurface conditions observed at the site, we interpret the structural
site conditions to corresponds with a seismic Soil Profile type So, (Site Class "D") as defined
by Table 1615.1.1 in the 2003 iBC documents. This Is based on the likely range of equivalent
SPT (Standard Penetration Test) blow counts for the soil types observed in the site area.
These conditions were assumed to be representative for the conditions beyond the depths
explored. Structures located at the site that are constructed in accordance with the appropriate
seismic criteria will have the same risk as other designed structures in the Puget Sound area.
CONCLUSIONS
Based on the results of our data review, site reconnaissance, subsurface explorations
and our experience in the area, it Is our opinion that the site is suitable for the proposed
residential plat development. Grading at the site is expected to be limited to localized cuts
and fills to meet the design grades. Conventional footings may be utilized in areas of medium
dense to dense native soil, or where the old fill material Is recompacted following removal of
the large organic debris. The infiltration of stormwater runoff from the roadways will not likely
be feasible at this site. The Infiltration of roof runoff Is feasible based on the amount of
grading that occurs at the site.
Pertinent conclusions and geotechnical recommendations regarding the design and
construction of the proposed development are presented below.
Landslide Hazards— per City of Federal Way Chapter 18.24
The City of Federal Way Municipal Code, Chapter 18.24 uses the above reierenced
checklist to define a landslide hazard area.
Slopes greater than 15 percent were observed on the site, but no impermeable
sediment or groundwater seepage were observed. No areas of historic mass movement Is
mapped or observed on the site. No areas of stream Incision, stream bank erosion or
undercutting by wave action were observed at the time of our site visit. No ravines or on an
active alluvial fan were observed on or adjacent to the site at the time of our site visit. The
USDA SCS maps the Everett and Harstine soils on the site as having °moderate" limitations
for building site development. No slopes greater than 80 percent were observed on the site at
the time of our visit.
Based on our observations of the site and review of published Information, the site
does not have any above listed indicators and therefore Is not classified as an active landslide
hazard area.
Steep Slope Hazard Indicators — per City of Federal Way Municipal Code, Chapter 18.24
The City of Federal Way Municipal Code, Chapter 18.24 defines steep slope hazard
areas as those areas with a slope of 40 percent or greater and with a vertical relief of 10 or
more fleet, a vertical rise of 10 feet or more for every 25 feet of horizontal distance. A slope is
PAGEJL0E-,5-V--
LandmarkHm.NorpolnIAG
January 16, 2006
Page 5
delineated by established Its toe and top and measured by averaging the Inclination over at
least 10 feet of vertical relief.
We did not observe any slopes of 40 percent or greater on the site.
Erosion Hazards — per City of Federal Way Chapter 18.24
Based on our site observations and explorations, it Is our opinion that conventional
erosion control measures will provide adequate erosion mitigation at this site. We recommend
that temporary and permanent erosion control measures be Installed and maintained during
construction or as soon as practical thereafter, to limil the influx of water onto exposed soils
and/or disturbed areas. Erosion control measures should include, but should not be limited
to, berms and swales with check dams to direct surface water runoff, ground cover/protection
In exposed areas and silt fences where appropriate. Graded areas should be shaped to
avoid concentrations of runoff onto cul or fill slopes, natural slopes or other erosion -sensitive
areas. Temporary ground cover/protection such as Jute matting, excelsior matting, wood
chips or clear plastic sheeting may be used until the permanent erosion protection is
established.
Seismic Hazards — per City of Federal Way Chapter 18.24
The City of Federal Way Municipal Code, Chapter 18.24 defines seismic hazard areas
as those areas subject to severe risk of earthquake damage as a result of seismically
Induced ground shaking, slope failure, settlement or soil liquefaction, or surface faulting.
These conditions occur in areas underlain by cohesionless soils of low density usually in
association with a shallow groundwater table.
Based on our review of the subsurface conditions, we conclude that the site soils are not
susceptible to liquefaction. The near -surface soils are generally in a medium dense to condition
and the static water table is located below the soils encountered at the site. Shaking of the
already dense soil Is not apt to produce a denser configuration and subsequently excess pore
water pressures are not likely to be produced.
Liquefaction Is a phenomenon where there is a reduction or complete loss of soil
strength due to an increase in water pressure. The increase in pore water pressure Is
induced by seismic vibrations. Liquefaction malnly affects geologically recent deposits of
loose, fine-grained sands that are below the groundwater table. Based on the density and
coarse-gralned nature of the glacially derived lolls observed on the site, and the lack of a
groundwater table, it is our opinion that the risk for liquefaction to occur at this site during an
earthquake Is negligible.
Site Preparation
Areas to be graded should be cleared of deleterious matter including any existing
structures, foundations, abandoned utility lines, debris and vegetation. The portions of the
site still covered with vegetation should be stripped of any forest duff and organic -laden soils.
These materials can be stockpiles and later used for erosion control or should be removed
from the site.
Where placement of fill material is required, the strippedlexposed subgrade areas
should be compacted to a firm and unyielding surface prior to placement of any fill.
Excavations for debris removal should be backfllled with structural fill compacted to the
densities described in the "Structural Fill" section of this report.
We recommend that a member of our staff evaluate the exposed subgrade conditions
after removal of vegetation and topsoil stripping is completed and prior to placement of
structural fill, The exposed subgrade soil should be proof -rolled with heavy rubber -tired
i-,)A
LandmarkHm.Norpolnt.RG
January 16. 2008
Page 6
equipment during dry weather or probed with a 1/2-inch-diameter steel rod during wet
weather conditions.
Any soft, loose or otherwise unsuitable areas delineated during proofrolling or probing
should be recompacted, if practical, or over -excavated and replaced with structural fill, based
on'the recommendations of our site representative. The areas of old fill material should be
evaluated during grading operations to determine If they need mitigation; recompaction or
removal.
Structural Fill
All material placed as fill associated with mass grading, as utility trench backfill, under
building areas, or under roadways should be placed as structural fill. The structural fill should
be placed In horizontal lifts of appropriate thickness to allow adequate and uniform
compaction of each iifi. Fill should be compacted to at least 95 percent of MDD (maximum
dry density as determined In accordance with ASTM D-1557).
The appropriate lift thickness will depend on the fill characteristics and compaction
equipment used. We recommend that the appropriate lift thickness be evaluated by our field
representative during construction. We recommend that our representative be present during
site grading activitiss to observe the work and perform field density tests.
The suitability of material for use as structural fill will depend on the gradation and
moisture content of the soil. As the amount of fines (material passing US No. 200 sieve)
increases, soil becomes increasingly sensitive to small changes In moisture content and
adequate compaction becomes more difficult to achieve. During wet weather, we
recommend use of well -graded sand and gravel with less than 5 percent (by weight) passing
the US No. 200 sieve based on that fraction passing the 3/4-Inch sieve, such as Gravel
Backfill for Walls (9-03.12(2)). If prolonged dry weather prevails during the earthwork and
foundation installation phase of construction, higher fines content (up to 10 to 12 percent) will
be acceptable.
Material placed for structural fill should be free of debris, organic matter, trash and
cobbles greater than 6-Inches in diameter. The moisture content of the fill material should be
adjusted as necessary for proper compaction.
Suitability of On-SI#e Materials as Fill
During dry weather construction, any non -organic on -site soil may be considered for
use as structural fill; provided it meets the criteria described above In the structural fill section
and can be compacted as recommended. If the soil material is over -optimum in moisture
content when excavated, it will be necessary to aerate or dry the soil prior to placement as
structural fill. We generally did not observe the site soils to be excessively moist at the time
of our subsurface exploration program.
The native outwash soils at the site generally consist of sand with varying amounts of
gravel, cobbles and silt. These soils are generally comparable to °common pit run" material
and will be suitable for use as structural fill provided the moisture content is maintained within
4 percent of the optimum moisture level. The underlying glacial till soils contain a higher fines
content and will likely be unsuitable for use as structural fill during or fallowing extended
periods of wet weather.
111i'e recommend that completed graded -areas be restricted from traffic or protected
prior to wet weather conditions. The graded areas may be protected by paving, placing
asphalt -treated base, a layer of free -draining material such as pit run sand and gravel or
clean crushed rock material contalning less than 5 percent fines, or some combination of the
above.
A�n I-1
�o
Landmarkft.Norpoint.RG
January 16, 2008
Page 7
Cud and Fill Slopes
All job site safety issues and precautions are the responsibility of the contractor
providing services/work. The following cuttfill slope guidelines are provided for planning
purposes only.
Temporary cut slopes will likely be necessary during grading operations or utility
installation. As a general guide, temporary slopes of 1.51-1:1 V (Horizontal:Vertical) or flatter
may be used for temporary cuts in the upper 3 to 4 feet of the soils that are weathered to a
loose/medium dense condition, where as temporary slopes as steep as 3/4H:1V can be used
In the very dense unweathered glacial till. Where ground water seepage is encountered,
flatter temporary slopes may be required. These guidelines assume that all surface loads are
kept at a minimum distance of at least one half the depth of the cut away from the top of the
slope and that significant seepage is not present on the slope face. Flatter cut slopes will be
necessary where significant raveling or seepage occurs.
We recommend a maximum slope of 2HA V for permanent cut and fill slopes in areas
of medium dense sand and gravel. It should be recognized that slopes of this nature do ravel
and require occasional maintenance. Where raveling or maintenance Is unacceptable, we
recommend that flatter slopes or retaining systems be considered. Where 2HAV slopes are
not feasible in these soils, retaining structures should be considered. Where retaining
structures are greater than 4-feet in height (bottom of footing to top of structure) or have
slopes of greater than 15 percent above them, they should be engineered.
Foundation Support
Based on the encountered subsurface soil conditions encountered across the site, we
recommend that spread footings for the new residences be founded on dense to very dense
native glacial till or on structural fill that extends to suitable native soils.
The soil at the base of the excavations should be disturbed as little as possible. All
loose, soft or unsuitable material should be removed or recompacted, as appropriate. A
representative from our firm should observe the foundation excavations to determine if
suitable bearing surfaces have been prepared, particularly In the areas where the foundation
will be situated on fill material.
We recommend a minimum width of 2 feet for isolated footings and at least 16 Inches
for continuous wail footings. All footing elements should be embedded at least 18 inches
below grade for frost protection. Footings founded as described above can be designed
using an allowable soil bearing capacity of 2,600 psf (pounds per square foot) for combined
dead and long-term live loads. The weight of the footing and any overlying backfill may be
neglected. The allowable bearing value may be increased by one-third for transient loads
such as those induced by seismic events or wind loads.
Lateral loads may be resisted by friction on the base of footings and floor slabs and as
passive pressure on the sides of footings. We recommend that an allowable coefficient of
friction of 0.35 he used to calculate friction between the concrete and the underlying soil.
Passive pressure may be determined using an allowable equivalent fluid density of 300 pcf
(pounds per cubic foot). Factors of safety have been applied to these values.
We estimate that settlements of footings designed and constructed as recommended
will be less than 1 inch, for the anticipated load conditions, with differential settlements
between comparably loaded footings of 1/2 inch or less. Most of the settlements should
occur essentially as loads are being applied. However, disturbance of the foundation
subgrade during construction could result In larger settlements than predicted.
Floor Slab Support`
LandmarkHrn.Norpolnl.RG
January 16, 2008
Page 8
Slabs -on -grade, If constructed, should be supported on the medium dense native soils
or on structural fill prepared as described above. Any areas of old fill material should be
evaluated during grading activity for suitability of structural support. Areas of significant
organic debris should be removed.
We recommend that floor slabs be directly underlain by a capillary break material with
minimum 6-inch thickness of coarse sand, pea gravel, or gravel containing less than 3
percent fines. The drainage material should be placed In one lift and compacted to an
unyielding condition.
A synthetic vapor barrier is recommended to control moisture migration through the
slabs. This Is of particular Importance where moisture migration through the slab is an issue,
such as where adhesives are used to anchor carpet or tile to the slab. A thin layer of sand
may be placed over the vapor barrier and Immediately below the slab to protect the liner
during steel and/or concrete placement.
A subgrade modulus of 400 kcf (kips per cubic foot) may be used for floor slab design.
We estimate that settlement of the floor slabs designed and constructed as recommended,
will be 1/2 Inch or less over a span of 50 feet.
Pavement Subgrades
Pavement subgrade areas should be prepared as previously described in the site
preparation section of this report. The prepared subgrade should be evaluated by proofrolling
with a fully -loaded damp truck or equivalent point load equipment. Soft, loose or wet areas
that are disclosed should be recompacted or removed, as appropriate. Over -excavated areas
should be backfilled with compacted structural fill and sub -base material.
Site Drainage
All ground surfaces, pavements and sidewalks at the site should be sloped away from
the structure. Surface water runoff should be controlled by a system of curbs, berms,
drainage swales, and or catch basins, and conveyed to an appropriate discharge point.
Based on our site evaluation, It is our opinion that the infiltration of stormwater at the site
should be limited to roof water from the individual residence, if appropriate. We understand
that run-off from the new residential driveways and roadway areas will be collected and
conveyed to an engineered stormwater detention pond to be located in the southwest comer
of the subject property. Any embankment construction required should be completed with
suitable silty soils (greater than 25 percent fines by weight or minus No. 200 US Sieve).
Alternatively, the embankment may be lined with a suitable non -permeable liner material.
Where infiltration is utilized for the individual residences, we recommend an infiltration
rate of 15 minutes per inch for the sandy soils. An appropriate factor of safety should be
utilized.
LIMITATIONS
We have prepared this report for use by Landmark Homes, Inc. and other members of
the design team, for use in the design of a portion of this project. The data used in preparing
this report and this report should be provided to prospective contractors for their bidding or
estimating purposes only. Our report, conclusions and interpretations are based on data from
others and limited site reconnaissance, and should not be construed as a warranty of the
subsurface conditions.
Variations In subsurface conditions are possible between the explorations and may also
occur with time. A contingency for unanticipated conditions should be included in the budget
and schedule. Sufficient monitoring, testing and consultatlon should be provided by our firm
during construction to confirm that the conditions encountered are consistent with those
r,
PAGE OF
LandmarkHm.NorpointAG
January 16, 2008
Page 9
indicated by the explorations, to provide recommendations for design changes should the
conditions revealed during the work differ from those anticipated, and to evaluate whether
earthwork and foundation Installation activities comply with contract plans and specifications.
The scope of our services does not Include services related to environmental
remediation and construction safety precautions. Our recommendations are not intended to
direct the contractor's methods, techniques, sequences or procedures, except as specifically
described in our report for consideration in design.
It there are any changes in the loads, grades, locations, configurations or type of
facilities to be constructed, the conclusions and recommendations presented In this report may
not be fully applicable. If such changes are made, we should be given the opportunity to review
our recommendations and provide written modifications or verifications, as appropriate.
We have appreciated the opportunity to be of service to you on this project. If you have
any questions or comments, please do not hesitate to call at your earliest convenience.
Respectfully submitted,
GeoResources, LLC
Brad Biggerstaff, LEG Glen Coad, PE
Principal Principal
RIRES 10131 10
SPB.'WW..bpb
D=XPLWWn *"MN0"MRO
Almdimft: Plgum I -8b Vid* Map
Fig=2-SA* and Eglomdm Plan
Rgum$- USDA SM8dW Map
Rgum4-US08 Map
ftre 6-Bog OwlAedtlan SMwn
Rgum 6 - Teel PR Lops
GeoAesources, LLC
5007 Pacific Highway East, Suite 20
Fife, Washington 98424
Phone: 253-896-1011
Fax: 253-696-2633
Approximate Site Location
Not to Scale
Site Vicinity Map
Norpolnt Residential Plat
Browns Point Area
Federal Way, Washington
File: Landmarli-Im.Norpoint.SVAA I January 2008 1 Figure 1
3"Vwo-
`xtile� 1r!!K
pw
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s�ast� s>rs
APPROXIMATE LOCATION 8-1 1b
OF BORING,
APPROXIMATE LOCATION TP-1 m
OF TEST PIT
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GeoResoulrces, LLC FIGURE 2 - Site Plan
i 5 to 39 PERCENT SLOPE AREA SOOT Paeft Highway East, Suite 28 Froieci : W okrt his
40 PERCENT OR GREATER File, Washington 98A24 Lecalion : Nor0ntV1ay & 2e A►0
SLOPE AREA Phone: 2M.896-1011 i�edsr�t way, wa
Fad 253-8166 2633 33 ClIeM : Lwxknw c K maa
Dejo ; DIP&% Job M: lanfta* t 14wpc"
EXH I B 6
PAGE-3t0F,.VV-
�Jmw-.46;
!iRLssnureas- LLE; I USDA SGS SC
orowns roint Area
fin a! Wav- Wachinc
Approximate Site Location
Excerpts from the
Geologic map of the Tacoma North 7.5-minute Quadrangle, Washington: il.S
Troost, KG., Booth, D.B., and Borden, R K
IW+.� ,
5 Not to Scale
GeoResources, LLC
5007 Pacific Highway East, Suite 20
Fife, Washington 98424
Phone: 253-896-1011
Fax: 253-896-2633
USGS Geologic Map
Norpoint Residential Plat
Browns Point Area
Federal Way, Washington
File: LandmarkHm.NorpolnLUSGS I January 2008 1 Figure 4
SOIL CLASSIFICATION SYSTEM
MAJOR DIVISIONS
GROUP
SYMBOL
GROUP NAME
GRAVEL
CLEAN
GW
WELL -GRADED GRAVEL, FINETO COARSE
GRAVEL
GRAVEL
GP
�—
POORLY -GRADED GRAVEL
COARSE
GRAINED
More than 50%
-
SOILS
Of Coarse Fraction
Retained on
No. 4 Sieve
GRAVEL
WITH FINES
GM
SILTY GRAVEL
GC
CLAYEY GRAVEL
SAND
CLEAN SAND
SW
WELL -GRADED SAND, FINE TO COARSE SAND
More than 50%
Retained on
No. 200 Sieve
SP
POORLY -GRADED SAND
More than 50°%
Of Coarse Fraction
SAND
SM
SILTY SAND
Passes
WITH FINES
No. 4 Sieve
Sc
CLAYEY SAND
SILT AND CLAY
INORGANIC
MIL
SILT
FINE
GRAINED
I
CL
CLAY
SOILS
Liquid Limit
Less than 50
ORGANIC
OL
ORGANIC SILT, ORGANIC CLAY
SILT AND CLAY
INORGANIC
MH
SILT OF HIGH PLASTICITY, ELASTIC SILT
More than 50%
Passes
CH
CLAY OF HIGH PLASTICITY, FAT CLAY
No. 200 Sieve
Liquid Limit
50 or more
ORGANIC
OH
ORGANIC CLAY, ORGANIC SILT
HIGHLY ORGANIC SOILS
PT
PEAT
NOTES:
1.
2.
S.
Field oiaselfioatlon Is based on visual examination of soil
In general accordance with ASTM D2488-80.
Soil classification using laboratory tests Is based on
ASTM D2487-90.
Description of soil density or consistency are based on
Interpretation of blow count date, visual appearance of
soils, and or test data.
GeoResources, LLC
5007 Paciflc Highway East, Suite 20
File, Washington 98424
Phone: 253-896-1011
Fax: 253-896-2633
SOIL MOISTURE MODIFIERS:
Dry- Absence of moisture, dry to the touch
Moist- Damp, but no visible water
Wet. Visible free water or saturated, usually soil is
obtained from below water table
AGE--7
Soil Classification System
Norpolnt Residential Plat
Browns Point Area
Federal Way, Washington
JOB# LandrnrarkHm.Norpolnt.USC8 I January 2008 -- _ i Figures
Test Pit TP 1 Location: northwest site area (SEE Figure 2)
Depth (fib, Soll Tune Descrlotlon
0.0 - 0.5 Duffiiopsoli.
0.5 - 3.5 SP Org brown SAND with gravel (loose to medium dense, moist)
3.6 - 4.5 SM Brown silty SAND with gravel, occasional cobbles (medium dense
to dense, moist). (wea till?)
4.5 - 6.6 SM Bm Gry silty SAND w/ gvl, cobbles (dense, moist to damp) (wea till?)
Minor caving observed.
No groundwater seepage observed.
I Test Pit TP-2 Location: western property line (SEE Figure 2)
_ Depth (ft.) Soil Type _ . Description
0.0 - 3.6 SP Org brown SAND with gravel, min. sift, occasional cobbles, organics (roots)
(loose to med. dense, moist)
3.5 - 4.0 SM Gray brown silty SAND with gravel, occasional cobbles, (dense, moist)
(local mottling)
4.0 - 6.0 SM Brown/Gray silty SAND w/ gravel, cobbles (dense, moist)
Minor caving observed.
No groundwater seepage observed
1 Test Pit TP-3 Location: east of TP-1 (SEE Figure 2)
Deoth-(ft.) Soli Tune Descr pilon _
0.0- 0.6 Duff/ropsoll
0.5 - 3.5 SP Org brown SAND with gravel, occasional cobbles, organics
(loose to med. dense, moist).
3.5 - 5.0 SM Gray brown silty SAND with oxidized gravel, Interbedded coarse sand lenses
j (dense, moist).
Minor caving observed.
No groundwater seepage observed.
Test Pit TP-4 Location: SW site area (SEE Figure 2)
I Depth (fQ Soil Type Description„ „ . --
0.0 - 0.5 Du ffropsoil.
0.5 - 5.5 SP Org brown SAND with sift, gravel, occ. boulders (loose to med. dense,
moist)
5.6 - 6.5 SM Gray silty SAND with gravel, (dense to v. dense, moist) (till?)
Terminated ai 101h feet bgs.
No caving observed. _
-, q
No groundwater seepage observed. ► - ;
Sample (S-3) taken at 10 feet below ground surface. ° '01
GeoResources, LLC
5007 Pacific Highway East, Suite 20
Fife, Washington 98424
Phone: 253-896-1011
Fax 253-896-2633
Test Pit Logs
Norpoint Residential Site
Federal Way, Washington
JOB# LandmarWrn.NoMdInLTP I January 2008 1 Figure 6
SECTION VI
EROSION & SEDIMENTATION CONTROL ANALYSIS AND DESIGN
Any proposed TESP facilities will be designed per City of Federal Way's requirements
during the final design phase of the project.
6-1
APPENDIX
KCRTS Output
Pond Sizing per KCSWDM Section 3.2.2
Pre -Developed Land Use Condition
3.13
0.00
0.000000
Till Forest
0.00
0.00
0.000000
Till Pasture
0.00
0.00
0.000000
Till Grass
0.00
0.00
0.000000
Outwash Forest
0.00
0.00
0.000000
Outwash Pasture
0.00
0.00
0.000000
Outwash Grass
0.00
0.00
0.000000
Wetland
0.00
0.00
0.000000
Impervious
predev.tsf
ST 1.00000
Flow Frequency Analysis
Time Series File:predev.tsf
Project Location:Sea-Tac
---Annual Peak
Flow Rates---
-----Flow
Frequency
Analysis-------
FlowRate Rank
Time of
Peak -
- Peaks - - Rank
Return
Prob
(CFS)
(CFS)
Period
0.197 2
2/09/01
18:00
0.252
1
100.00
0.990
0.054 7
1/06/02
3:00
0.197
2
25.00
0.960
0.147 4
2/28/03
3:00
0.151
3
10.00
0.900
0.005 8
3/24/04
20:00
0.147
4
5.00
0.800
0.087 6
1/05/05
8:00
0.128
5
3.00
0.667
0.151 3
1/18/06
21:00
0.087
6
2.00
0.500
0.128 5
11/24/06
4:00
0.054
7
1.30
0.231
0.252 1
1/09/08
9:00
0.005
8
1.10
0.091
Computed Peaks
0.234
50.00
0.980
Developed Land Use Condition
0.00
0.00
0.000000
Till Forest
0.00
0.00
0.000000
Till Pasture
1.05
0.00
0.000000
Till Grass
0.00
0.00
0.000000
Outwash Forest
0.00
0.00
0.000000
Outwash Pasture
0.00
0.00
0.000000
Outwash Grass
0.00
0.00
0.000000
Wetland
2.03
0.00
0.000000
Impervious
dev.tsf
ST 1.00000
Flow Frequency Analysis
Time Series File:dev.tsf
Project
Location:Sea-Tac
---Annual
Peak
Flow Rates ---
Flow Rate
Rank
Time of Peak
(CFS)
0-.586
- -6---2/09/01
2:00
0.481
8
1/05/02 16:00
0.704
3
2/27/03 7:00
0.525
7
8/26/04 2:00
0.632
4
10/28/04 16:00
0.623
5
1/18/06 16:00
0.764
2
10/26/06 0:00
1.18
1
1/09/08 6:00
Computed Peaks
-----Flow
Frequency
Analysis-------
- - Peaks
- - Rank Return
Prob
(CFS)
Period
1.18
1
100.00
0.990
0.764
2
25.00
0.960
0.704
3
10.00
0.900
0.632
4
5.00
0.800
0.623
5
3.00
0.667
0.586
6
2.00
0.500
0.525
7
1.30
0.231
0.481
8
1.10
0.091
1.04
50.00
0.980
A-1
Bypass Land Use Condition
0.00
0.00
0.000000
Till Forest
0.00
0.00
0.000000
Till Pasture
0.00
0.00
0.000000
Till Grass
0.00
0.00
0.000000
Outwash Forest
0.00
0.00
0.000000
Outwash Pasture
0.00
0.00
0.000000
Outwash Grass
0.00
0.00
0.000000
Wetland
0.05
0.00
0.000000
Impervious
bypass.tsf
ST 1.00000
Flow Frequency Analysis
Time Series
File:bypass.tsf
Project
Location:Sea-Tac
---Annual
Peak
Flow Rates ---
Flow Rate
Rank
Time of Peak
(CFS)
0.012
7
2/09/01 2:00
0.011
8
1/05/02 16:00
0,015
3
12/08/02 18:00
0.012
6
8/26/04 2:00
0.015
4
10/28/04 16:00
0.013
5
1/18/06 16:00
0.018
2
10/26/06 0:00
0.023
1
1/09/08 6:00
Computed Peaks
Retention/Detention Facility
-----Flow Frequency Analysis-------
- - Peaks -
- Rank
Return
Prob
(CFS)
Period
0.023
1
100.00
0.990
0.018
2
25.00
0.960
0.015
3
10.00
0.900
0.015
4
5.00
0.800
0.013
5
3.00
0.667
0.012
6
2.00
0.500
0.012
7
1.30
0.231
0.011
8
1.10
0.091
0.022
50.00
0.980
Type of Facility:
Detention Pond
Side Slope:
3.00 H:lV
Pond Bottom Length:
88.56 ft
Pond Bottom Width:
29.52 ft
Pond Bottom Area:
2614. sq. ft
Top Area at 1 ft. FB:
8161. sq. ft
0.187 acres
Effective Storage Depth:
5.00 ft
Stage 0 Elevation:
901.00 ft
Storage Volume:
23427. cu. ft
0.538 ac-ft
Riser Head:
5.00 ft
Riser Diameter:
12.00 inches
Number of orifices:
2
Full Head Pipe
_
E X H
Orifice # Height
Diameter Discharge Diameter
(ft)
(in) (CFS) (in)
A r � -
P'
1 0.00
1 . 32 0. 105
° `�" S TO
2 4.00
1.26 0.043 4.0
Top Notch Weir:
None
Outflow Rating Curve:
None
Stage Elevation
Storage Discharge
Percolation Surf Area
(ft) (ft) (cu. ft) (ac-ft) (cfs)
(cfs)
(sq. ft)
0.00 901.00
0. 0.000 0.000
0.00
2614.
0.01 901.01
26. 0.001 0.005
0.00
2621.
0.03 901.03
79. 0.002 0.008
0.00
2636.
0.04 901.04
105. 0.002 0.010
0.00
2643.
0.05 901.05
132. 0.003 0.011
0.00
2650.
A-2
0.07
901.07
185.
0.004
0.012
0.08
901.08
211.
0.005
0.013
0.10
901.10
265.
0.006
0.015
0.11
901.11
292.
0.007
0.016
0.21
901.21
565.
0.0.13
0.022
0.31
901.31
845.
0.019
0.026
0.41
901.41
1132.
0.026
0.030
0.51
901.51
1427.
0.033
0.034
0.61
901.61
1729.
0.040
0.037
0.71
901.71
2039.
0.047
0.040
0.81
901.81
2356.
0.054
0.042
0.91
901.91
2681.
0.062
0.045
1.01
902.01
3014.
0.069
0.047
1.11
902.11
3355.
0.077
0.049
1.21
902.21
3703.
0.085
0.052
1.31
902.31
4060.
0.093
0.054
1.41
902.41
4424.
0.102
0.056
1.51
902.51
4797.
0.110
0.058
1.61
902.61
5177.
0.119
0.060
1.71
902.71
5566.
0.128
0.061
1.81
902.81
5963.
0.137
0.063
1.91
902.91
6369.
0.146
0.065
2.01
903.01
6783.
0.156
0.067
2.11
903.11
7206.
0.165
0.068
2.21
903.21
7637.
0.175
0.070
2.31
903.31
8077.
0.185
0.071
2.41
903.41
8526.
0.196
0.073
2.51
903.51
8983.
0.206
0.074
2.61
903.61
9450.
0.217
0.076
2.71
903.71
9925.
0.228
0.077
2.81
903.81
10409.
0.239
0.079
2.91
903.91
10903.
0.250
0.080
3.01
904.01
11406.
0.262
0.081
3.11
904.11
11917.
0.274
0.083
3.21
904.21
12439.
0.286
0.084
3.31
904.31
12969.
0.298
0.085
3.41
904.41
13509.
0.310
0.087
3.51
904.51
14059.
0.323
0.088
3.61
904.61
14618.
0.336
0.089
3.71
904.71
15187.
0.349
0.090
3.81
904.81
15766.
0.362
0.092
3.91
904.91
16355.
0.375
0.093
4.00
905.00
16893.
0.388
0.094
4.01
905.01
16953.
0.389
0.094
4.03
905.03
17074.
0.392
0.095
4.04
905.04
17134.
0.393
0.097
4.05
905.05
17195.
0.395
0.100
4.07
905.07
17317.
0.398
0.103
4.08
905.08
17378.
0.399
0.107
4.09
905.09
17439.
0.400
0.108
4.11
905.11
17561.
0.403
0.109
4.12
905.12
17623.
0.405
0.110
4.22
905.22
18242.
0.419
0.117
4.32
905.32
18872.
0.433
0.122
4.42
905.42
19512.
0.448
0.127
4.52
905.52
20162.
0.463
0.131
4.62
905.62
20822.
0.478
0.135
4.72
905.72
21493.
0.493
0.139
4.82
905.82
22174.
0.509
0.142
4.92
905.92
22866.
0.525
0.146
5.00
906.00
23427.
0.538
0.148
5.10
906.10
24138.
0.554
0.460
5.20
906.20
24860.
0.571
1.030
A-3
0.00 2664.
0.00 2671.
0.00 2685.
0.00 2693.
0.00 2765.
0.00 2837.
0.00 2911.
0.00 2985.
0.00 3060.
0.00 3135.
0.00 3212.
0.00 3289.
0.00 3367.
0.00 3445.
0.00 3524.
0.00 3604.
0.00 3685.
0.00 3766.
0.00 3848.
0.00 3931.
0.00 4015.
0.00 4099.
0.00 4184.
0.00 4269.
0.00 4356.
0.00 4443.
0.00 4531.
0.00 4619.
0.00 4709.
0.00 4799.
0.00 4889.
0.00 4981.
0.00 5073.
0.00 5166.
0.00 5259.
0.00 5354.
0.00 5449.
0.00 5544.
0.00 5641.
0.00 5738.
0.00 5836.
0.00 5935.
0.00 6024.
0.00 6034.
0.00 6054.
0.00 6064.
0.00 6074.
0.00 6094.
0.00 6104.
0.00 6114.
0.00 6134.
0.00 6144.
0.00 6245.
0.00 6347.
0.00 6449.
0.00 6552.
0.00 6656.
0.00 6760.
0.00 6865.
0.00 6971.
0.00 7057.
0.00 7164.
PAGE 0 � �
5.30
906.30
25592.
0.588
1.760
0.00
7380.
5.40
906.40
26336.
0.605
2.550
0.00
7490.
5.50
906.50
27090.
0.622
2.840
0.00
7600.
5.60
906.60
27856.
0.639
3.100
0.00
7711.
5.70
906.70
28633.
0.657
3.330
0.00
7822.
5.80
906.80
29420.
0.675
3.550
0.00
7934.
5.90
906.90
30219.
0.694
3.760
0.00
8047.
6.00
907.00
31030.
0.712
3.960
0.00
8161.
6.10
907.10
31852.
0.731
4.150
0.00
8275.
6.20
907.20
32685.
0.750
4.320
0.00
8391.
6.30
907.30
33530.
0.770
4.500
0.00
8506.
6.40
907.40
34386.
0.789
4.660
0.00
8623.
6.50
907.50
35254.
0.809
4.820
0.00
8740.
6.60
907.60
36134.
0.830
4.970
0.00
8856.
6.70
907.70
37026.
0.850
5.120
0.00
8977.
6.80
907.80
37930.
0.871
5.270
0.00
9096.
6.90
907.90
38846.
0.892
5.410
0.00
9217.
7.00
908.00
39773.
0.913
5.550
0.00
9338.
Hyd
Inflow
Outflow
Peak
Storage
Stage
Elev
(Cu-Ft)
(Ac-Ft)
1
1.18
0.89
5.18
906.18
24687.
0.567
2
0.59
0.42
5.09
906.09
24048.
0.552
3
0.59
0.15
5.00
906.00
23424.
0.538
4
0.62
0.14
4.70
905.70
21338.
0.490
5
0.70
0.13
4.56
905.56
20456.
0.470
6
0.37
0.09
3.65
904.65
14858.
0.341
7
0.48
0.08
2.70
903.70
9901.
0.227
8
0.53
0.07
2.18
903.18
7527.
0.173
Hyd
R/D Facility
Tributary Reservoir
POC Outflow
Outflow
Inflow Inflow Target
Calc
1
0.89
0.02 ******** *******
0.91
2
0.42
0.01 ******** *******
0.43
3
0.15
0.01 ********
0.15
0.15
4
0.14
0.01 ******** *******
0.14
5
0.13
0.01 ******** *******
0.14
6
0.09
0.01 ********
0.09
0.09
7
0.08
0.01 ******** *******
0.08
8
0.07
0.01 ******** *******
0.07
---------------------
Route
Time
-------------
Series through
Facility
Inflow
Time
Series File:dev.tsf
�-
µ
Outflow
Time
Series File:rdout
POC Time
Series File:dsout
°
Inflow/Outflow Analysis
Peak Inflow Discharge:
1.18
CFS at 6:00 on Jan 9 in Year 8
Peak Outflow Discharge:
0.893
CFS at 9:00 on Jan 9 in Year 8
Peak Reservoir Stage:
5.18
Ft
Peak Reservoir Elev:
906.18
Ft
Peak Reservoir Storage:
24687.
Cu-Ft
0.567
Ac-Ft
Add Time Series:bypass.tsf
Peak Summed Discharge:
0.912
CFS at 9:00 on Jan 9 in Year 8
Point of Compliance File:dsout.tsf
A-4
Flow Frequency Analysis
Time Series File:rdout.tsf
Project Location:Sea-Tac
---Annual Peak Flow Rates ---
Flow Rate Rank Time of Peak
(CFS)
0.420
2
2/09/01
16:00
0.077
7
12/28/01
17:00
0.133
5
2/28/03
7:00
0.069
8
8/26/04
6:00
0.089
6
1/05/05
15:00
0.138
4
1/18/06
23:00
0.148
3
11/24/06
8:00
0.893
1
1/09/08
9:00
Computed
Peaks
Flow Frequency Analysis
Time Series
File:dsout.tsf
Project
Location:Sea-Tac
---Annual
Peak
Flow Rates
---
Flow Rate
Rank
Time of
Peak
(CFS)
0.426
2
2/09/01
16:00
0.079
7
12/28/01
16:00
0.135
5
2/28/03
6:00
0.072
8
8/26/04
4:00
0.092
6
1/05/05
8:00
0.140
4
1/18/06
21:.00
0.152
3
11/24/06
6:00
0.912
1
1/09/08
9:00
Computed
Peaks
-----Flow Frequency Analysis-------
- - Peaks - - Rank Return Prob
(CFS) (ft) Period
0.893 5.18 1 100.00 0.990
0.420 5.09 2 25.00 0.960
0.148 5.00 3 10.00 0.900
0.138 4.70 4 5.00 0.800
0.133 4.56 5 3.00 0.667
0.089 3.65 6 2.00 0.500
0.077 2.70 7 1.30 0.231
0.069 2.18 8 1.10 0.091
0.735 5.15 50.00 0.980
-----Flow Frequency Analysis-------
- - Peaks -
- Rank
Return
Prob
(CFS)
Period
0.912
1
100.00
0.990
0.426
2
25.00
0.960
0.152
3
10.00
0.900
0.140
4
5.00
0.800
0.135
5
3.00
0.667
0.092
6
2.00
0.500
0.079
7
1.30
0.231
0.072
8
L.10
0.091
0.750
50.00
0.980
i'AGF f]D--
so
A-5