11-102455L/ �V/
PERRONE CONSULTING, INC., P.S.
Geotechnical & Underground Engineering 11220 Fieldstone Lane NE
Bainbridge Island, WA 98110
Tel. 206-778-8074 Fax 206-780-5669
Jude 16, 2011 www.perroneconsulting.com
City of Federal Way
Community and Economic Development - Building Permit Department
33325 8t' Ave S.
Federal Way, WA 98003
Subject: Doman/Johnson Landslide Remediation
1445 SW 296" St.
Federal Way, Washington
Perrone Consulting, Inc. Project #11105
Perrone Consulting, Inc., P.S. has completed a geotechnical engineering investigation of the recent
landslide at 1445 SW 296th St. in Federal Way, Washington. The results of our investigation have
been presented in a report dated May 27, 2011. Based on the results of our investigation, we are
requesting a waiver of the SEPA permit due to the potential for imminent danger to the existing house.
The landslide occurred in December 2010 and destroyed the existing decks that were attached to the
house at the top of the slope. The upper portions of the landslide were covered with plastic to
minimize additional ground movements. However, over the past several months, additional ground
movements have occurred at the top of the landslide and the headscarp has moved closer to the
house which is supported on shallow spread footings. The movements are a result of on -going
subsurface groundwater seepage and from rainfall infiltration on the lower portions of the slope which
cannot be effectively covered due to dense vegetation.
In our opinion, the proposed slope repairs consisting of a soldier pile wall, groundwater interceptor
trench drains, and slope regrading must be started without delay to prevent damage to the existing
house. The proposed construction must be completed during drier summer months when
groundwater levels are typically at lower levels. If the work is not completed before the next significant
wet weather period, there is a high probability that the house will suffer damage. Accordingly we are
requesting a waiver of the SEPA permit in order to expedite the necessary repairs.
We trust that this information suits your current needs. If you have questions or need additional
information, please contact us.
Very Truly Yours,
PERRONE CONSULTING, INC., P.S.
o � ,sszs � Ga
EXPIRES ;7
Vincent J. Perrone, Ph.D., P.E.
Principal Engineer
cc: Jacqueline Doman & Bruce Johnson
RECEIVE®
AN 17 2011
CITY OF FEDERAL WAY
CDS
CAProjects\11105 Federal Way Landslide\20 Correspondence\Letter061611_City of Federal Way.docx
A�kCITY OF
Federal Way
August 22, 2011
Jacqueline Doman
27013 Pacific Hwy South, Unit 294
Des Moines, WA 98198
RE: File #11-103201-00-SF; DOMAN/JOHNSON
1445 SW 2961h Street, Federal Way
Dear Ms. Doman:
CITY HALL
33325 8th Avenue South
Mailing Address: PO Box 9718
Federal Way, WA 98063-9718
(253) 835-7000
www.cityoffederalway.com
This letter responds to your request to intrude into a geologically hazardous area for construction of a
soldier pile retaining wall.
We understand that a portion of the slope located west of the existing residence failed in December of
2010, resulting in damage to existing decks and other landscaping features. On August 8, 2011, you
submitted a building permit application to re -grade a portion of the site, construct a soldier pile retaining
wall with maximum above grade height of 13 feet, and construct drainage features associated with the
new wall. The improvements you propose are located within a geologically hazardous area (specifically,
erosion hazard, landslide hazard, and steep slope areas).
Federal Way Revised Code (FWRC) 19.160.010(2) states the Director may permit development
activities within a geologically hazardous area if no reasonable alternative exists and only if the
development activity will not lead to or increase any slide, seismic, or erosion hazard.
The geotechnical report prepared by Perrone Consulting, Inc., P.S., dated May 27, 2011, indicates that
without repair work the slope will continue to slide and eventually endanger the existing house's
foundation. Therefore, there is no reasonable alternative to proceeding with the development activity
within the geologically hazardous area. The proposed work will not lead to or increase any slide,
seismic, or erosion hazard. It will have the effect of reducing the likelihood of further erosion and
landslide activity on the subject property.
For the reasons stated above, your request to conduct development activities, as identified in the above -
referenced geotechnical report, is hereby approved.
Please be aware that issuance of a building permit is required before commencing with any work.
Building permit application 11-103201-SF is currently under review. Please don't hesitate to contact me
if you have any questions. I can be reached at 253-835-2643 or isaac.conlen@cityoffederalway.com.
1 The project is considered to be normal maintenance and is therefore exempt from the requirement for review under the State
Environmental Policy Act.
August 22, 2011
Page 2
Sincerely,
Isaac Conlen
Planning Division Manager
for Patrick Doherty, Director
c: Scott Sproul, Plans Examiner
Matt Herrera, Associate Planner
Kevin Peterson, Engineering Plans Reviewer
11-103201
Doc. I D. 58613
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PERRONE CONSULTING, INC., P.S.
Geotechnical & Underground Engineering
Geotech n ical Investigation
1445 SW 296" St Landslide Repair
Federal Way, Washington
Prepared for:
Jacqueline Doman & Bruce Johnson
May 27, 2011
Project No. 10105
www.perroneconsulting.com
PERRONE CONSULTING, INC., P.S.
Geotechnical & Underground Engineering
May 27, 2011
Jacqueline Doman & Bruce Johnson
1445 SW 2961h St.
Federal Way, Washington 98023
Subject: Geotechnical Investigation
1445 SW 2961h St. Landslide Repair
Federal Way, Washington
Perrone Consulting Project #11105
Dear Ms. Doman and Mr. Johnson:
11220 Fieldstone Lane NE
Bainbridge Island, Washington 98110
Tel:206-778-8074 Fax:206-780-5669
www.perroneconsulting.com
We are pleased to submit three copies of our report "Geotechnical Investigation, 1445 SW 2961h St.
Landslide Repair, Federal Way, Washington." Our investigation was performed and this report was
prepared under our contract dated January 10, 2011.
In general the recent landslide can be repaired by installing a soldier pile retaining wall along the crest
of the slope, regrading the hillside to a flatter slope, and installing subsurface groundwater interceptor
trench drains. On -site construction monitoring and consultation will be required to observe the soldier
pile wall and interceptor trench drain installations.
We appreciate the opportunity to be of service to you on this project. If you have any questions about
the content of this report or need further assistance, please contact us.
Sincerely,
PERRONE CONSULTING, INC., P.S.
5/27/11
a
EXFi RES, C�' j I-'?
Vincent J. Perrone, Ph.D., P.E.
Principal Engineer
C:\Projects\11105 Federal Way Landslide\70 Reports\Final\052711_DomanUohnson.dou
Jacqueline Doman & Bruce Johnson
May 27, 2011
Page ii
TABLE OF CONTENTS
1 INTRODUCTION............................................................................................................................1
2 PROJECT AND SITE DESCRIPTION...........................................................................................1
3 FIELD PROCEDURES ............................................................................................................2
4 LABORATORY TESTING.............................................................................................................2
5 SUBSURFACE CONDITIONS.......................................................................................................2
5.1 Soils.............................................................................................................................
.....3
5.2 Groundwater..........................................................................................................................3
6 CONCLUSIONS AND RECOMMENDATIONS.............................................................................4
6.1 General..................................................................................................................................4
6.2 Slope Repairs........................................................................................................................4
6.3 Engineering Soil Properties...................................................................................................5
6.4 Seismic Design......................................................................................................................5
6.5 Cantilevered Soldier Pile Wall...............................................................................................6
6.5.1 Lateral Earth Pressures.....................................................................................................6
6.5.2 Soldier Pile Embedment....................................................................................................6
6.5.3 Lagging
6
6.5.4 Wall Drainage.............................:......................................................................................6
6.6 Groundwater Interceptor Trench Drains................................................................................7
6.7 Slope Stability........................................................................................................................7
6.8 Earthwork..............................................................................................................................
7
6.8.1 General..............................................................................................................................7
6.8.2 Site Preparation.................................................................................................................7
6.8.3 Fills....................................................................................................................................8
6.8.4 Permanent Slopes.............................................................................................................8
6.9 Surface Water and Stormwater Management....................................................................... 8
6.10 Construction Monitoring........................................................................................................8
7 ADDITIONAL GEOTECHNICAL SERVICES.................................................................................9
8 LIMITATIONS.................................................................................................................................9
9 REFERENCES...............................................................................................................................9
APPENDIX A GEOTECHNICAL EXPLORATIONS
APPENDIX B LABORATORY TESTING
APPENDIX C IMPORTANT INFORMATION ABOUT YOUR GEOTECHNICAL ENGINEERING
REPORT
PERRONE CONSULTING, INC., P.S.
Jacqueline Doman & Bruce Johnson
May 27, 2011
Page iii
TABLES
Table 1 — Top of Glacial Deposit ....................................................................................... 3
Table 2 — Engineering Material Properties............................................................................ 5
Table3 — Drain Gravel............................................................................................... 6
Table 4 — Non -Woven Drainage Geotextile...................................................................... . .... 6
FIGURES
Figure 1 — Site Vicinity Map
Figure 2 — Site and Exploration Plan
Figure 3 — Subsurface Profile Section B - B'
Figure 4 — Subsurface Profile Section D — D'
Figure 5 — Cumulative Rainfall and Groundwater Head at B-1
Figure 6 — Slope Repair Plan
Figure 7 — Slope Repair Section B-B'
Figure 8 — Slope Repair Section D — D'
Figure 9 — Cantilevered Soldier Pile Wall
Figure 10 —Surcharge Pressures
Figure 11 —Subsurface Interceptor Trench Drain
Figure 12 — Retaining Wall & Upper Slope Stability Results
Figure 13 — Lower Slope Stability Results
Figure 14 — Seismic Slope Stability Results
Figure A-1: Key to Log of Boring
Figure A-2: Boring B-1
Figure A-3: Boring B-2
Figure A-4: Boring B-3
Figure A-5: Boring B-4
Figure B-1: Atterberg Limit Test Results
Figure C-1: Important Information about Your Geotechnical Engineering Report.
PERRONE CONSULTING, INC., P.S.
Jacqueline Doman & Bruce Johnson
May 27, 2011
Page 1 of g
INTRODUCTION
This report presents the results of our geotechnical investigation for a landslide repair at 1445 SW
296th St. in Federal Way, Washington. The project site location is shown in the Vicinity Map, Figure 1.
The purpose of our investigation was to observe :subsurface conditions and to provide geotechnical
recommendations for design of the repairs. Specifically our scope of services included:
1. Drill 4 borings using hollow stem auger methods and obtaining standard penetration test
samples at 2-1/2 to 5 ft intervals. Install a vibrating wire piezometer (VWP) in one of the
borings near the top of the landslide and an observation well in a boring on the slope.
2. Coordinate the field activities, log the boreholes during drilling, obtain selected samples, and
classify the materials encountered in accordance with the Unified Soil Classification System
(ASTM D2487 and D2488) shown in figure A-1.
3. Install a data logger for monitoring groundwater pressures in one boring for about 1 month to
observe groundwater fluctuations with precipitation levels.
4. Perform laboratory tests to determine relevant soil engineering properties. The tests included
natural moisture contents, grain size analyses and Afterberg limits.
5. Evaluate subsurface soil and groundwater conditions and perform geotechnical engineering
analyses as a basis for selecting an appropriate landslide repair.
6. Provide geotechnical engineering recommendations including:
• The layout and typical sections of the proposed slope stabilization repairs;
• Construction sequencing;
• Storm water management and slope re -vegetation;
• Provide geotechnical design parameters which will be used by a structural engineer;
• Earthwork considerations including slope regrading, specifications for imported
structural fill gradation, placement and compaction, suitability of using on -site soils for
engineered fill;
7. Prepare and submit three (3) copies of our geotechnical report that summarizes the site
explorations and geotechnical engineering recommendations. The report will include a site
and exploration plan, boring logs, laboratory test results, drawings illustrating the slope
repairs.
Authorization for these services was obtained on January 30, 2011 by your signature to our proposal.
PROJECT AND SITE DESCRIPTION
The site layout and topography is shown on the Site & Exploration Plan, Figure 2. The site is
generally level at the top of the slope where the house and surrounding yard area is situated at about
elevation 134 ft to 137 ft. The lowest floor in the house is a slab on grade at about elevation 129 ft
and the garage floor at the south end of the house is at about elevation 137 ft. An elevated deck on
the west side of the house extends along the northerly half of the house, wrapping around the north
side of the house and an above -ground pool. A 10 ft tall concrete retaining wall in the northeast
corner of the property extends from the north side of the house to the City of Federal Way (City) right-
of-way on the north property line.
The upper 30 ft of the hillside sloped down to the west at about 1-3/411:1V (horizontal to vertical) to 1-
1/4H:1V, then at about 2-1/4H:1V for about 30 vertical feet down to the asphalt driveway located about
30 to 60 ft west of the property line. The total elevation change from the house to the private road was
about 65 ft. An existing 6 ft tall by 50 ft long soldier pile retaining wall was found at mid -slope
elevation 104.
PERRONE CONSULTING, INC., P.S.
Jacqueline Doman & Bruce Johnson
May 27, 2011
Page 2 of 9
The slope vegetation consisted of primarily blackberry bushes and scattered young alders near the
bottom of the slope. An older maple tree toppled near the upper slope area during the December
2010 rainstorm. A lawn covers the upland area at the south end of the house with terraced rockery
walls at the top of the slope. An in -ground sewage lift station was located at the southwest corner of
the garage below the rockery wall.
We understand that the recent landslide occurred on about December 12, 2010 during a period of
heavy precipitation. The landslide area is shown in Figure 2 and generally extends along the west
side of the house and onto the City's right-of-way. The limits of the landslide in the City's right of way
were not readily visible under the heavy cover of blackberries. The 2 to 4 ft high, near -vertical main
headscarp was located under the elevated deck and extends about 60 ft south along the crest of the
slope. Some portions of the landslide flowed downslope onto the adjacent properties creating a
distinct incised debris flow channel within the landslide mass. One of these occurred at the toppled
tree location and on the north property line.
After the December 2010 landslide event, the headscarp area was covered with plastic. Some
additional slope movement and erosion continued in the following 3 months with the headscarp
retreating a few feet upslope and dropping vertically about 1 foot. The isolated footings supporting the
west side of the deck were totally undermined causing the west side of the deck to move downward.
There was no indication of movement or damage to the house during or after the landslide event.
The City's storm water collection system discharges onto the upper portion of the slope within the
City's easement immediately to the north. The discharge system consists of a tight pipeline from the
street down to a diffuser pipe at about contour elevation 112 ft located about 25 ft west of the paved
street. Slope erosion and instability is evident downstream of the discharge. The slope above the
diffuser appeared marginally stable and was retained by a failing timber crib wall and asphalt rip rap.
Surface water runoff has eroded the slope at the northeast corner of your property and the north end
of the existing retaining wall is undermined.
3 FIELD PROCEDURES
Subsurface conditions for this project were explored by drilling 4 borings at the locations shown on
Figure 2. The boring locations and elevations were surveyed in the field. Our drilling and sampling
program is described in Appendix A. A Perrone Consulting, Inc. field representative was on site
throughout the drilling to observe the explorations, assist in sampling, and prepare descriptive logs of
the material encountered. Soils were classified in general accordance with the Unified Soil
Classification System (ASTM D-2487 and D-2488) as described in Figure A-1, "Key to Log of Borings."
The final exploration logs presented in Figures A-3 and A-6 represent our interpretation of the contents
of the soil samples, drilling conditions, and the results of laboratory testing.
4 LABORATORY TESTING
Selected soil samples were tested to develop parameters for use in evaluating subsurface conditions
and performing geotechnical engineering analyses. The tests included visual classification, moisture
contents and Atterberg limits. Laboratory testing procedures and results are presented in Appendix B.
5 SUBSURFACE CONDITIONS
The property is located on slopes classified as "intermediate stability" in the Coastal Atlas (WSDOE,
1979). Geologic maps (Booth et al, 2004) indicate that the site is underlain by glacially deposited and
over -ridden dense sand, silty sand, silt and clay with mass wastage deposits on the slope to the west
(!P PERRONE CONSULTING, INC., P.S.
Jacqueline Doman & Bruce Johnson
May 27, 2011
Page 3 of 9
of the property. Mass wastage deposits consist of undifferentiated colluvium soil and landslide debris
having indistinct morphology and include abundant discrete landslides that are feet to tens of feet in
lateral extent.
Our explorations indicated the presence of fill and colluvium (mass wastage deposits) overlying glacial
deposits as shown in the interpreted Subsurface Profiles, Figures 3 and 4. It appeared that the
property was modified for construction of the house by excavating a level bench into the east side of
the hillside slope and casting the excavation spoils onto the west facing slope. The fill, which did not
appear to have been compacted, was present on the upper portions of the slope and diminishing in
thickness further down the slope except at the existing retaining wall where the fill is at least 6 ft to 10
ft thick down to the mid -slope area.
5.1 Soils
The principal soil units encountered in the explorations consisted of the following soil types:
Fill. Brown and tan, moist to wet, fine sandy silt (ML), clayey fine to medium sand (SC) and silty fine to
coarse sand with gravel (SM), scattered organics and concrete rubble. SPT blow counts varied from 2
to 8 blows per foot with an average value of 5. The estimated fill thickness at the boring locations was
6.5 ft at B-1 and 12 ft at B-2. Fill was not encountered at borings B-3 and B-4.
Colluvium. Colluvium deposits are soils that were transported downslope to their current location by
previous landsliding, slumping and/or erosion. These deposits consisted of coarse and fine-grained
soil types: tan and mottled rust, moist to wet, silty fine sand with gravel (SM); gray and tan/mottled
rust; sandy silt (ML) and; tan and mottled rust, low plasticity clay with sand (CL), prismatic fractures
and slickensides. The SPT blow counts for the sand and silt materials varied from 3 to 28 blows per
foot indicating a very loose to medium dense consistency. The SPT's for the clay varied from 11 to 12
blows per foot indicating a medium stiff consistency. Colluvium was encountered in all of the borings
and varied in thickness from 5 ft at B-1 and B-2, 9 ft at B-3 and 4 ft at B-4.
Glacial deposits. Glacial deposits consisted of a layered sequence of sand and silt deposits that
underlie the colluvium. These deposits have been over -ridden and consolidated by 3000 ft of glacial
ice into a very dense/hard consistency. We encountered gray and tan and mottled rust, moist to wet,
silty fine sand (SM) and silty fine to coarse sand with gravel (SM); gray and tan and mottled rust, fine
sandy silt (ML) and silt (ML). SPT blow counts varied from 43 blows per ft to 50 blows for 5 inches of
penetration. The average SPT value was in excess of 50 blows per foot indicating a very dense
consistency. Table 1 summarizes the depth and elevation to the top of the glacial deposits at the
boring locations.
Table 1 — Top of Glacial Deposit
Boring
Top of Glacial Deposit
Depth (ft) Elevation (ft)
B-1
12 102
B-2
17 107
B-3
11 92
B-4
4 85
5.2 Groundwater
At the time of drilling, groundwater was encountered at a depth of 7-1/2 ft (elevation 106.5 ft) in boring
B-1; 10 ft (elevation 114 ft) in boring B-2 and; 11.8 ft in boring B-3 (elevation 91.2). No groundwater
was encountered in boring B-4 during or after drilling. Groundwater seepage was observed on the
lower portion of the slope above boring B-4 at the contact between the colluvium and glacial deposits.
PERRONE CONSULTING, INC., P.S.
Jacqueline Doman & Bruce Johnson
May 27, 2011
Page 4 of 9
Hourly groundwater measurements were made with a data logger at a depth of 18 ft (elevation 96 ft) in
boring B-1 from March 8, 2011 through April 13, 2011 while the slope was covered in plastic. The
results are plotted in Figure 5 along with cumulative precipitation quantities at SeaTac airport. The
data indicate that the groundwater head in the glacial deposit fluctuated between elevation 99.7 ft and
105.1 ft. during this time period. Groundwater levels rose about 3 ft in direct response to 3-1/2 inches
of rainfall between March 91" and March 17`h, 2011 and another 4-1/4 ft rise in groundwater levels
occurred from March 25th to April 8t". 2011 due to about 3-3/4 inches of rainfall.
6 CONCLUSIONS AND RECOMMENDATIONS
6.1 General
Our investigations indicate that the December 2010 landslide occurred within the colluvium and
overlying very loose fill soils on the upper portions of the slope. The depth of the landslide varies from
about 10 to 15 ft near the crest of the slope. Approximately 5.3 inches of rainfall occurred in the week
prior to the landslide which we estimate caused at least a 5 ft rise in the groundwater table. In our
opinion the landslide was caused by heavy precipitation which increased groundwater levels, seepage
pressures, and saturation of the very loose fill. The upslope limit of the recent landslide is west of the
house and did not appear to cause any movement of the house foundations.
We evaluated two landslide repair options including: (1) a soldier pile retaining wall from the north
property line at the north end of the existing concrete retaining wall to the south end of the house
(north side of the garage) and; (2) regrading the slope to a flatter angle and installing groundwater
interceptor trench drains. Our analyses indicated that the regrading option could not achieve the
required levels of slope safety because the recent landslide and past movements has significantly
reduced the shear strength of the clay colluvium. Given the existing house foundation elevations the
slope could not be flattened enough to accommodate the weakened clay without undermining the
existing house foundations.
In its current condition the slope will experience additional ground movements during extended
periods of heavy precipitation and the current headscarp location would retreat further upslope and
could endanger the existing house foundations. Therefore, it is critical that the repairs recommended
in this report be implemented during the upcoming seasonally drier summer months. In the interim,
the slopes should remain covered with plastic and the collected rainwater should be directed away
from the landslide area.
6.2 Slope Repairs
The soldier pile wall would retain about 5 to 13 ft of ground and create a gently sloping yard up to the
house. A concrete slab -on -grade patio or an elevated deck supported by shallow spread footings
could be constructed in this area after the soldier pile wall is constructed.
We recommend removing the existing swimming pool, wooden decks and soldier pile wall, regrading
the existing slope below the new retaining wall to 2.5HAV, and installing groundwater interceptor
trench drains downslope of the soldier pile retaining wall. The finished ground elevations at the top
and bottom of the wall and the approximate limits of the slope regrading are shown in Figure 6.
Finished slope sections with the retaining wall are illustrated in Figures 7 and 8.
Settlement points should be installed and monitored regularly (refer to Section 6.10 - Construction
Monitoring) during the work to evaluate the effects of the construction on the existing concrete
retaining wall, house foundations, sewage lift station, and utilities in the work area. If ground
movement is observed beyond the limits of the slope regrading during construction, the contractor
should stop work and backfill the excavation immediately.
PERRONE CONSULTING, INC., P.S.
Jacqueline Doman & Bruce Johnson
May 27, 2011
Page 5 of 9
We recommend that the construction proceed in the following sequence:
(1) Geotechnical engineer obtains groundwater measurements using the existing vibrating wire
piezometer at boring B-1.
(2) Contractor confirms utility locations in the field.
(3) Contractor installs settlement monitoring points on the house foundations, sewage lift
station, and concrete retaining wall.
(4) Strip the site vegetation and provide access for construction equipment to the proposed
cantilevered soldier pile wall.
(5) Install temporary erosion and sediment control facilities.
(6) Install soldier pile wall.
(7) Regrade slopes to finished contours.
(8) Install groundwater interceptor trench drains.
(9) Apply slope erosion protection and re -vegetate the slope.
(10) Reconstruct rockery walls and restore lawn area.
During the work, the contractor should provide the geotechnical engineer with daily results of the
ground movement monitoring program.
6.3 Engineering Soil Properties
Table 2 summarizes the engineering soil parameters used in our analyses. Soil strength properties
were based on correlations to SPT-N values, laboratory index test results, a back analysis of existing
slope conditions, and professional judgment.
Table 2 — Engineering Material Properties
Moist Unit
Weight
Static Strength
Dynamic Strength
Cohesion Friction
Cohesion
Friction
Soil Description
(pcf)
(psf)
(degrees)
(psf)
(degrees)
Fill (SM, SC, ML)
125
0
30
0
30
Colluvium (CL)
Intact fully softened
120
0
27
2000
0
Slickensided
120
0
18
500
0
Undisturbed Glacial
138
0
40
0
40
Deposits (SM, ML)
Due to the depositional nature of colluvium the soil engineering properties can vary widely within a
boring and between borings. Accordingly in our analyses we have assumed that colluvium is
comprised of clay (CL), which has the weakest soil engineering properties of the materials
encountered in this unit.
6.4 Seismic Design
Seismic design parameters for slope stability analyses and the retaining wall earth pressures were
based on peak horizontal ground acceleration (PHGA) of 0.34g. The specified ground motion
represents an earthquake with a 10% probability of exceedance in a 50 year period. The horizontal
seismic coefficient used for estimating seismic lateral earth pressures and for use in pseudo -static
slope stability analyses was taken as 50% of the peak ground acceleration in accordance with
standard local practice.
PERRONE CONSULTING, INC., P.S.
Jacqueline Doman & Bruce Johnson
May 27, 2011
Page 6 of 9
6.5 Cantilevered Soldier Pile Wall
6.5.1 Lateral Earth Pressures
Design lateral earth pressures are shown in Figure 9 for the cantilevered soldier pile wall. Passive
pressures include a factor of safety equal to 1.5. We recommend including a surcharge load
equivalent to an additional 2 ft of wall height (area load of 240 psf)._ Any additional surcharge loads
from heavy equipment should be added to the 2 ft surcharge in accordance with the surcharge
recommendations presented in Figure 10.
6.5.2 Soldier Pile Embedment
Lateral resistance for cantilevered soldier piles should be applied at elevation "C" in Figure 9 which is
below the regraded slope surface (elevation "B"). Assuming that the soldier piles are 3.0 ft diameter
and spaced at 8 ft centers, the soldier piles tips should be embedded at least 20 ft into the dense
glacial soils. If other pile diameters and spacings are used, we should re-evaluate the minimum pile
embedment depth required for overall (global) wall stability.
6.5.3 Lagging
Lagging may consist of treated wood planks, concrete panels, or metal sheets attached to the inside
flange adjacent to the excavation or on the face of the flange. Lagging may be designed using 50
percent of the lateral earth pressure and 100 percent of any lateral surcharge pressures. The design
pressures are assumed to act uniformly across the lagging between the soldier piles.
6.5.4 Wall Drainage
The soldier pile wall should be constructed with a wall drainage system installed on the back of the
lagging. A geo-composite drainage board such as Mirafl G100N or equivalent should be applied to
the back of the lagging such that it provides 100% lagging coverage. A 4-inch diameter perforated
rigid collection pipe (such as PVC or an approved equivalent) should be placed at the base
(downslope side) of the lagging in a blanket of drain gravel meeting the gradational requirements
specified in Table 3. The width of the openings (slots or round holes) in the pipe should not exceed '/
inch. The pipe should be placed with the perforations downward and surrounded by at least 6 inches
of drain gravel wrapped in non -woven filter fabric (see Table 4). The Contractor should take care to
protect drainage pipe from damage by equipment and from clogging during construction.
Table 3 — Drain Gravel
U.S. Standard Sieve
Percent Passing by
Size
Dry Weight
3/8 inch
100
'/< inch
30 — 50
No.8
0-5
Table 4— Non -Woven Drainage Geotextile
Property
Recommended
Value
Minimum
0.01 cm/sec
permeability
Percent open area
Greater than 4%
Porosity
Greater than 30%
(�p PERRONE CONSULTING, INC., P.S.
Jacqueline Doman & Bruce Johnson
May 27, 2011
Page 7 of 9
Collected water from the retaining wall drains should be tight lined to the bottom of the slope using a 6-
inch diameter pipe.
6.6 Groundwater Interceptor Trench Drains
The trench drains should extend at least 1 ft into the very dense glacial deposits and sloped to drain to
the discharge area. Figure 11 illustrates the trench drain materials and dimensions. The drain should
consist of 4-inch diameter perforated PVC pipe with slots or holes no wider than '/ inch. Convenient
cleanouts should be provided along the interceptor drain and the discharge pipe. Flexible, corrugated
drain pipe should not be used for the interceptor drain or the discharge line.
6.7 Slope Stability
Slope stability analyses of the regraded hillside and new retaining walls were performed using a
computer program to evaluate the overall factor of safety of the new retaining wall against deep seated
slope instability. The computer program models the subsurface soil and groundwater conditions and
the soldier pile wall and searches for the most critical (lowest factor of safety) failure surface.
In general terms, the calculated factor of safety is the ratio of available soil shear resistance to the
existing gravitational forces tending to produce landsliding. When the soil strength is exactly equal to
the slide producing forces, the factor of safety is 1.0 and the slope would be on the verge of
movement. Uncertainties and inaccuracies are usually associated with the assumed subsurface
conditions, soil strength, groundwater levels and location of the most critical failure surface. To
provide a margin of safety against these uncertainties, a factor of safety of approximately 1.3 to 1.5 for
static (non -seismic) conditions and 1.0 to 1.1 for seismic conditions is usually considered desirable in
generally accepted engineering practice.
The retaining wall and upper slope is stable with a computed factor of safety is 1.6 for a deep seated
slope failure. The results are illustrated in Figure 12. The regraded lower slope between the new
retaining wall and the property line has a computed factor of safety of 1.3 for shallow surficial failure as
shown in Figure 13. Due to the shallow nature of the critical failure surface, we anticipate that this
factor of safety will increase as the slope vegetation becomes established.
Figure 14 illustrates the results of our seismic slope stability analyses. The design earthquake was
simulated by applying a seismic coefficient of 0.17 which is equal to '/z the peak ground acceleration.
Our analyses indicate an adequate factor of safety of 1.1.
6.8 Earthwork
6.8.1 General
Site grading will generally involve the areas behind and below the new soldier pile wall. The area
behind the soldier pile wall will generally be cut and filled to provide construction equipment access for
wall construction., Upon completion of the wall, some final regrading will be required behind the wall to
establish site grades compatible with the existing house and concrete retaining wall foundation
elevations.
The slope below the new retaining wall will be regraded to a flatter configuration. This will generally
require excavation and removal of site soils to achieve the desired slope angles. Site regrading will
extend into the City's right-of-way and will require City approval.
6.8.2 Site Preparation
After clearing trees and brush from the site, the Contractor should remove roots and stumps from all
areas to be graded. The topsoil and root zone which mantles the site is loose and organic, and should
be removed from new fill areas. Topsoil is not considered suitable for reuse as structural fill but may
be stockpiled and later spread as topsoil on the finished slopes.
PERRONE CONSULTING, INC., P.S.
Jacqueline Doman & Bruce Johnson
May 27, 2011
Page 8 of 9
6.8.3 Fills
All fills should be placed in uniformly thick lifts and thoroughly compacted with vibratory plate
compactors, self-propelled vibratory rollers or a HoPac vibratory plate attached to a backhoe. All
compaction standards specified in this report referto modified Proctor compaction (ASTM D1557).
Granular fill should consist of clean sand and gravel meeting the specifications for "Gravel Backfill for
Walls" (WSDOT Standard Specification 9-03.12(2)). Granular fill should be placed in 9 inch thick
loose lifts and compacted to 95% of maximum dry density.
6.8.4 Permanent Slopes
We recommend planting permanent slopes with relatively fast-growing vegetation to reduce surficial
sloughing and erosion. In non -growing and wet weather seasons, vegetative mats, jute matting, or
plastic sheeting should be used until permanent vegetation can be established.
6.9 Surface Water and Stormwater Management
We recommend installing a new stormwater collection system for all of the roof downspouts. The
system should consist of rigid PVC pipe with conveniently located cleanouts. The storm drain pipeline
should discharge at an approved location at the bottom of the slope. In addition, we recommend that
you contact the City and request that they improve the storm drainage collection system at the
northwest corner of your property. Surface water runoff from the road is currently eroding the north
end of the existing retaining wall and the pavement and the slope is being eroded/destabilized by the
diffuser discharge. We recommend that the City remove the diffuser and convey the stormwater in a
tight pipeline to a more appropriate and stable discharge location.
6.10 Deck Foundations
Wood decks constructed between the retaining wall and the house could be supported on shallow
spread footings. The footings should have a minimum width of 16 inches and should be embedded at
least 18 inches below finished grade. The foundation subgrade should be compacted with a vibratory
plate compactor or a jumping jack plate compactor to create a dense and unyielding subgrade.
Footings constructed to these requirements may be designed for an allowable soil bearing pressure of
1500 psf.
6.11 Construction Monitoring
Surface ground movement points should be installed at the top or the slope to monitor surface
settlement and horizontal ground movements during the construction. We recommend installing a line
of monitoring points along the west side of the house. The monitoring points should consist of a row of
rebar driven 2 feet into the ground prior to construction. Building settlement points should also be
installed on the house and garage.
The settlement points should be read daily during the construction and to an accuracy of 0.01 ft. in the
horizontal and vertical direction. The horizontal and vertical benchmark should be set off the property
on stable ground. All data should be provided to the geotechnical engineer on a daily basis.
The vibrating wire piezometer located in boring B-1 should be monitored before the start of
construction and during periods of rainfall during construction. The monitoring frequency will be
established by the geotechnical engineer based on each data set. The Contractor must protect the
vibrating wire piezometer from damage until the soldier pile wall is completed.
i PERRONE CONSULTING, INC., P.S.
Jacqueline Doman & Bruce Johnson
May 27, 2011
Page 9 of 9
7 ADDITIONAL GEOTECHNICAL SERVICES
We recommend that you retain Perrone Consulting, Inc. to review those portions of the plans and
specifications that pertain to foundations and earthwork to determine whether they are consistent with
the recommendations in this report.
During construction Perrone Consulting Inc. should monitor the work and provide consultation to
confirm that the conditions encountered are consistent with those indicated by our explorations and to
modify the design as necessary. Such activities would include: (1) observation of soldier pile wail
construction; (2) observation of interceptor trench drain construction; (3) observation of fill placement
and compaction; (4) evaluation of settlement monitoring data; and other geotechnical related
earthwork activities.
8 LIMITATIONS
This report was prepared for the exclusive use of the Owner for specific application to the design of
the project at this site as it relates to the geotechnical aspects discussed herein. The data and report
should be provided to prospective contractors for their information, but our report, conclusions and
interpretations should not be construed as a warranty of subsurface conditions included in this report.
Within the limitations of scope, schedule and budget, the analyses, conclusions, and
recommendations presented in this report were prepared in accordance with generally accepted
professional geotechnical engineering principles and practice in this area at the time this report was
prepared. We make no other warranty, either express or implied. These conclusions and
recommendations were based on our understanding of the project as described in this report and the
site conditions as observed at the time of our explorations.
If there is a substantial lapse of time between the submission of this report and the start of
construction at the site, or if conditions have changed due to natural causes or construction operations
at or adjacent to the site, or appear to be different from those described in our report, we recommend
that we review our report to determine the applicability of the conclusions and recommendations
considering the changed conditions and time lapse.
Additional guidance about this geotechnical report can be found in Appendix C of this report,
"Import nt Information about Your Geotechnical Engineering Report."
9 REFERENCES
American Society for Testing and Materials ASTM, (2005). "2005 Annual Book of Standards, Volume
04.08, Soil and Rock (1)."
Booth, D.B., Waldron, H.M., and Troost, K.G., 2004. "Geologic Map of the Poverty Bay 7.5'
Quadrangle, King and Pierce Counties, Washington," USGS Scientific Investigations Map
2854.
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NOTES
1ation datum is NAVD88.
2. See Figures 3 and 4 for Sections B-B' and D-D'
3. Reference: LDC Inc. Drawing, "Doman Residence, Existing Topographic
Map", Drawing TO-01, 3/24111.
Approximate location of test boring
R Property line
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FIGURE 2
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PERRONE CONSULTING INC., P.S.
Project No. 11105
1. Elevation datum is NAVD88.
2. See Figures 8 and 9 for sections B-B' and D-D'
3. Reference: Drawing, "Doman Residence, Existing Topographic
Map", Drawing TO-01, 3124/11.
LEGEND
* Approximate location of test boring
FL Property line
Soldier pile retaining wall
1+03 Soldier pile wall stationing
- - - - - - - - Limits of regrading
x Finished spot elevation
_ _ — _ — — Groundwater interceptor trench drain
Tight discharge pipeline
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Scale in feet
FIGURE 6
Slope Repair Plan
1445 SW 296th St. Landslide Repair
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Elevation "A" — —
Fill and
Colluvium
H (lagged wall)
40 psf
1ft
Elevation "B"
80 psf 8H
2.5 Elevation "C" Surcharge Seismic
1 �f
� �
Dense glacial deposits 110 psf 10 psf
1ft
1ft
Passive Pressure Active Pressure
Elevations (ft) Wall Height
Wall Station „ . °B" "C" "H" ft
0+00 120 115 115 5
0+08 120 114 108 6
0+46 120 110 110 10
0+70 124 112 110 12
1+01 128 116 115 12
1+31 128 120 120 8
N2=
1. Active pressures act over pile spacing above Elevation "B" and on 1 pile diameter below Elevation " B."
2. Passive pressures act over 3 pile diameters or pile spacing, whichever is least.
3. Lateral surcharge pressures due to heavy equipment loads must be added to active pressures given here
(See Figure 10).
4. Dimensions in feet, pressure in psf.
5. Q Design groundwater level
May 2011
° PERRONE CONSULTING, INC., P.S.
Project No.11105
FIGURE 9
Cantilevered Soldier Pile Wall
1445 SW 296th St. Landslide Repair
for Jacqueline Doman & Bruce Johnson
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Common backfill or topsoil
1 ft
Drain Gravel
Non -woven filter fabric
Perforated 4-inch
liameter PVC pipe
very dense
glacial deposit
Drain Gravel
U.S. Standard Percent Passing
Min 3 ft
Fill or
colluvium
1 ft min.
Non -Woven Drainage Geotextile
Sieve Size
by Dry Weight
Property
Recommended Value
3/8 inch
100
Minimum permeability
0.01 cm/sec
1/4 inch
30 - 50
Percent open area
Greater than 4%
No. 8
0-5
Porosity
Greater than 30%
NOTES:
1. Schematic only - not to scale
2. Drain pipe should be placed with perforations facing down
3. Refer to report text for more complete understanding
of this drawing.
FIGURE 11
Subsurface Groundwater Interceptor Trench Drain
2PERRONE CONSULTING, INC., P.S. 1445 SW 296th St. Landslide Repair
��Project No.11105 for Jacqueline Doman & Bruce Johnson
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Jacqueline Doman & Bruce Johnson
May 27, 2011
Page A-1
APPENDIX A
Geotechnical Explorations
PERRONE CONSULTING, INC., P.S.
Jacqueline Doman & Bruce Johnson
May 27, 2011
Page A-2
APPENDIX A — GEOTECHNICAL EXPLORATIONS
Borings B-1 through B-4 were drilled to depths ranging from 8 feet to 39 feet. The Key to Log of
Boring is shown in Figure A-1 and the boring logs are shown in Figures A-2 through A-5. Disturbed
samples were obtained using Standard Penetration Test (SPT) procedures at approximately 2%2 to 5-
foot intervals. A standard split spoon sampler was driven into the soil a distance of 18-inches with a
140-pound safety hammer free -falling from a height of 30 inches using a cathead and winch system.
Recorded blows for each six inches of penetration are shown on the boring logs. The number of
blows required to drive the sampler the last 12 inches is the Standard Penetration Test Resistance (N-
value). This resistance, or blow count, provides a qualitative measure of the relative density of
cohesionless soils and consistency of cohesive soils. Representative portions of the samples were
placed in plastic bags and transported to the laboratory for classification and testing.
Upon completion of each boring the borehole was backfilled. Borings B-2 and B-4 were backfilled with
bentonite chips. A vibrating wire piezometer was installed in boring B-1 and the borehole was
backfilled with grout. The VWP installation details are shown in Figure A-2. A groundwater
observation well was installed in boring B-3. The well installation and backfill details are shown on the
boring log, Figure A-4.
(5) PERRONE CONSULTING, INC., P.S.
EO
PERRONE CONSULTING, INC.
11220 Fieldstone Lane NE
Bainbridge Island, WA 98110
Telephone: (206) 778-8074
Project: 1445 SW 296th Street
Federal Way, Washington
UNIFIED SOIL CLASSIFICATION SYSTEM AND SYMBOL CHART
MAJOR DIVISIONS
ISYMBOLS
DESCRIPTIONS
GRAVEL CLEAN
i
GW
'wellyraded gravels, gravel -sand
AND GRAVELS
r��
mixtures, littleornofines
GRAVELLY LITTLE OR NO
�/'Poody
graded gravels,
COARSE SOILS FINES
��
GP
'gravel -sand mixtures, little
GRAINED
or no fines
�l
MORETHAN GJEG
50%OFGM
Silty gravels, gravel-sand-siltSOILS
COARSE WSFRACTION
mixtures
APERETAINED ON F
GC
Clayey grvels, gravel-sandclay
NO4SIEVE
mixtures
SWwell-graded
sands, gravelly
SAND
MORETHAN AND
sands, little or no fines
50%OFSANDYMATERIAL LIO
Poorly graded sands, gravelly
COARSER SOILS
SP
sands, little or no fines
THAN NO 200
SM
Silty sands, sand -silt mixtures
SIEVE SIZE MORETHAN
50%OF SANDS
COARSE WITH FINES...•'
FRACTION APPRECIABLE
t'
..
SC
1,Clayey sands, sand -clay mixtures
PASSING N0.4 AMOUNT OF
SEVE FINES
ML
Inorganic sills, very fin' sands.
rada four. rslttyld fine sands
orclayeysllaofsitplasrdty
FINE
SILTS
Inorganic days ol low to medium
LIQUID LIMIT
GRAINED
AND
LESS THAN50
CL
plastid . gravelly clam sandy
SOILS
CLAYS
ciam silty clays, roan days
_
—
OL
Organic silts and organic silty
clays of low plasticity
E THAN
MORE
Inorganic silts, micaceous or
diatomaceous fine sandy or silty
MATERIAL
SILTS
soils, elastic silt
UCH
Inorganic clays of high plasticity,
FINER THANLIQUID
AND
LIMIT
GREATERSI
NO.
THAN50fat
clays
SIEVE SIZE
CLAYS
--
OH
•Organic days of medium to high
;plasticity, organic silts
HIGHLY ORGANIC SOILS
—�'
PT
Peat, humus, swamp soils with
Ihigh organic content
NOTE: DUAL SYMBOLS USED FOR BORDERLINE
CLASSIFICATIONS
Blow Count 1 Density and Consistency Relationship
Coarse -Grained Soils
Fine -Grained Soils
N. SPT
N. SPT
Relative Density
Blows / Foot
Relative Consistency
Blows / Foot
Very loose
0-4
Very soft
<2
Loose
5 - 10
Soft
2-4
Medium dense
11 - 30
Medium stiff
5-8
Dense
31 - 50
Stiff
9 - 15
Very dense
>50
Very Stiff
16 - 30
Hard
>30
a
x Minor Descriptors Moisture Content
a
a
o Trace clay, silt, sand, gravel <5% Dry Absence of moisture, dusty
w Few clay, silt, sand, gravel 5 - 10% Moist Damp but no visible water
> Little clay, silt, sand, gravel 15 - 25% Wet Visible free water, from
Some clay, silt, sand, gravel 30 - 45% below the water table
of
Key to Log of Boring
Sheet 1 of 1
Abbreviations
AL Atterberg Limits
C Consolidation
DS Direct Shear
HA Hydrometer Analysis
LL Liquid Limit
LV Laboratory Vane Shear
N Number of hammer blows for last 12 inches driven
OVA Organic Vapor Analyzer
Pc Constant Head Permeability
Pf Falling Head Permeability
PI Plasticity Index
PP Pocket Penetrometer
SA Sieve Analysis
SG Specific Gravity
TV Torvane Shear
TX Triaxial Shear
Samoler Symbols
2-inch-O.D. Split Spoon Sampler Driven with
140-lb Hammer and 30-Inch Drop (SPT)
3-inch-O.D. Split Spoon Sampler with Brass Rings
Driven with 140-lb Hammer ar:d 30-inch Drop
2-inch-O.D. Split Spoon Sampler Driven with
140-lb Hammer and 18-inch Drop
® Grab Sample 3-inch-O.D. Shelby
Tube Sampler
Piezometer 5Vmbols
p R� Pipe in cement grout
�® Pipe in bentonite-cement
® Pipe in bentonite seal
HPipe in filter pack
FM
Slotted pipe in filter pack
Vibrating wire piezometer
Groundwater Level Symbols
1 Water level at time of drilling (ATD)
Q Water level measured in piezometer
General Notes
1. Descriptions and stratum lines are interpretive; field
descriptions may have been modified to reflect lab test
results. Descriptions on these logs apply only at the specific
boring locations and at the time the borings were advanced;
they are not warranted to be representative of subsurface
conditions at other locations or times.
2. Sail descriptions are recorded in the following order. SOIL
CLASSIFICATION (USCS Symbol), relative density or
consistency, color, moisture, plasticity or gradation,
angularity, minor consllluenis. additional comments
(organics, odor, etc.) [GEOLOGIC UNIT].
FIGURE A-1
PERRONE CONSULTING, INC.
11220 Fieldstone Lane NE
Bainbridge Island, WA 98110
Telephone: (206) 778-8074
Project: 1445 SW 296th Street
Federal Way, Washington
Borehole Location: Top of slope at north end of house
Drilling Contractor: Geologic Drilling & Exploration, Inc.
Drilling Method: Hollow -Stem Auger
Drill Rig Type: Acker Soil Mechanic
SAMPLES
cm
O ' J
Log of Boring B-1
Sheet 1 of 1
Date(s) Drilled: March 7, 2011
Logged By: V.J. Perrone
Total Depth of Borehole: 28.0 feet
Surface Elevation / Datum: 114 feet / NAVD88
c S Z9
U
m a 4) m 2 MATERIAL DESCRIPTION o R m -= -'� REMARKS
��
E 3 `� 8 m c" .0 C m
11Jm Gw ITZ mco? U' � ]a�
SANDY SILT (MQ. very IDose, tan, wet, fine-grained
sand, few organics [FILL]
Concrete rubble to
depth of 1.5 ft.
1
110
15
2
2-1-1
(2)
2-1-3
(4)
67
67
01
----- ---------- -----
CLAYEY SAND (SC), veryloose, tan, moist,- Fine- to
medium -grained sand, rew coarse -grained sand, low
plasticity day, few organics [FILL]
38
35
Groundwater ATD at
SILTY SAND (SM), medium dense, tan and mottled
rust, wet, Fine-grained sand [COLLUVIUM]
I
3f7H
depth of 7.5 ft.
3
3-4-9
100
25
105
(13)
10
— ,� Becomes brownish gray, moist
4
7-13-15
100
.
f
26
(28)
Gravelly
Drills gravelly.
SANDY SILT (ML). very dense, tan and mottled rust,
moist, 8W sand: 1-Inch layer of silty Fine sand
5
18-25-33
100
in sample I ACIAL DEPOSIT]
22
PP>4.5 tsf
100
(58)
1;5
i
SILTY SAND (SM), dense, ion and mottled rust, wet,— —
fine-grained sand, trace medium- to coarse -grained
DEPOSIT]
24
6
11-17-26
100
.
sand. trace One organics (GLACIAL
(43)
f-- Becomes very dense, gray
7
17-28-32
100
25
(60)
2
----------------------
SILT (ML), very dense, gray, moist, massive
[GLACIAL DEPOSIT]
8 17-32-50 1 100 I I 271 I PP>4.5 tsf
(S2) [NA
Drills like gravel at
Gravelly12 27 ft.
Bottom of Boring = 28.0 feet below ground surface. Auger refusal.
Free groundwater at 7.5 feet at time of drilling.
Geokon VPW Serial #1038043 installed at 18 feet.
FIGURE A-2
PERRONE CONSULTING, INC. Log of Boring B-2
11220 Fieldstone Lane NE
Bainbridge Island, WA 98110
Telephone: (206) 778-8074 Sheet 1 of 2
Project: 1445 SW 296th Street
Federal Way, Washington
Borehole Location: Top of slope at south end of house Date(s) Drilled: March 7, 2011
Drilling Contractor: Geologic Drilling & Exploration, Inc. Logged By: V.J. Perrone
Drilling Method: Hollow -Stern Auger Total Depth of Borehole: 39.0 feet
Drill Rig Type: Acker Soil Mechanic Surface Elevation / Datum: 124 feet / NAVD88
SAMPLES
of
J
> :15a
m N
z
s
MATERIAL DESCRIPTION
.. mNLe-E>a
o c -,
co cc ?
�
f�
SILTY SAND (SM), loose, brown, wet, Fine- to
medium rained sand, with organics [TOPSOIL]
SILTY SAND WITH ORGANICS (SM), very loose, tan,
i•
moist, fine- to coarse -grained sand, some debris [FILL]
1 2-3-3 50 1 16
120
(6)
+
T
SILTY SAND WITH GRAVEL (SM), very loose to loose,
5
orange-brown and mottled rust, moist, fine- to
coarse -grained sand [FILL]
2
2-2-2
78
(4)
3
2-5-3
44
-115
(8)
10
i— Grades wet
4
2-1-2
50
i
(3)
.t
SANDY SILT (MIL), Iocse, ggray, wet, Hne- to coarse -grained
sand, scattered organics [COLLUV[UM]
5
1-2-2
56
110
(4)
LEAN CLAY WITH SAND (CL), medlum stiff, tan and
15
mottled rust, moist, low plasticity clay, fine- to
coarse -grained sand; some slickensides and prismatic
6
2-4-8
100
fractures at top or sample [COLLUVLUM]
AL
(12)
i '•
SILTY SAND WITH GRAVEL (SM), very dense, tan and
y :
mottled rust, wet. Fine- to coarse -grained sand, subrounded
0
7
21`333-43
83
Irk }
gravel [GLACIAL DEPOSIT]
105
i— Increasing gravel content
20{
#
a
8
10-20-50/5
(70/11)
100
0
SANDY SILT (ML), very dense. [an and slightly mottled rust,
moist, fine- to few layers
9
9
15-25-40
100
ooars"ra€ned sand, gravel, thin
of silty send and low plasticity clay (GLACIAL DEPOSIT]
0
100
(65)
i
LL
25
f-- Grades to gray, wet, fine-grained sand with trace
10 12-31-50/5 70 medium- to coarse -grained sand and subangular gravel,
(81 /11) 1
massive
15
21
22
30
40
15
REMARKS
Pieces of asphalt in
samDlar shoe.
PP=0.5 tsf to 0.75 tsf
LL=47,P1=23
Drills like some gravel
at 17 ft.
Drills gravelly at 19 ft.
Very hard and slow drilling.
25 PP=4.5 tsf to >4.5 tsf I
I
22
FIGURE A-3
Project: 1445 SW 296th Street Log of Boring B-2
Federal Way, Washington
Sheet 2 of 2
- —
SAMPLES -
- — -
C
r
0
MATERIAL DESCRIPTION
e
.�
REMARKS
a
o
u1w ❑m
a
o s;
4)
m
m
Oq
2°s
H Z
aD co Z
0
_j
2010
30-
1 r I
SANDY SILT (ML). very dense, ray, we[, fine-grained sand,
lrara L A IAI ❑EPQSi (cantinued
gravely
SILTY SAND (SM), dense to very dense. gray, wel,
fine-grained sand, massive [GLACIAL DEPOSIT]
1
11
15-23-27
100
- : -:
28
(50)
35
r
f-- Becomes very dense, moist, layer of sandy silt in sample
12
16-31-5015
100
27
85
81.111
�
_ —
Bottom of Boring = 39.0 feet below ground surface.
Auger refusal.
40
- No free groundwater observed at time of drilling.
Boring backfilled with bentonite chips.
$0
75
50
70
55
i
65
60
i
i
60
i
65
FIGURE A-3
PERRONE CONSULTING, INC. (Sheet 2 of 2)
PERRONE CONSULTING, INC.
11220 Fieldstone Lane NE
Bainbridge Island, WA 98110
Telephone: (206) 778-8074
Project: 1445 SW 296th Street
Federal Way, Washington
Log of Boring B-3
Sheet 1 of 1
Borehole Location: Mid -slope at south end of house Date(s) Drilled: March 8, 2011
Drilling Contractor: Geologic Drilling & Exploration, Inc. Logged By: V.J. Perrone
Drilling Method: Hollow -Stem Auger Total Depth of Borehole: 16.3 feet
Drill Rig Type: Acker Soil Mechanic Surface Elevation / Datum: 103 feet / NAVD88
SAMPLES
o °3 w
£ m a f0 MATERIAL DESCRIPTION iEm m H o�
REMARKS
> a« '�LmmN a) a 7
aoTm UNWo Zm
I— Z Ccd: 20 03:
SILTY SAND WITH ORGANICS (SM), very Iaasa.
brown, wet, fined arse cograined sand [TOPSOIL]_
SANDY SILT (ML), very loose, tan and mottled rust,
L II moist, clayey, fine-grained sand, scattered organics
[COLLUVIUM]
90
75
1 1-1-2 100
(3)
2 3-5-7 100
(12)
3 4-4-7 100
(11)
4 4-9-24 100
(33)
5 19-27-5015 100
(77/11)
6 20-40-50/3 100
LEAN CLAY (CL), stiff, brownish gray, moist, few
fine-grained sand [COLLUVIUM]
SILTY SAND WITH GRAVEL (SM), very dense, _
brownish gray, moisl, fine- to coarse rained
sand, subangular gravel [GLACIAL DEPOSIT] 3/8/11
Bottom of Boring = 16.3 feet below ground surface.
Free groundwater at 11.8 feet at time of drilling.
Observation well installed; 0.0204nch slotted screen
at 5-12 feet in sanded interval 3-12 feet, bentonite chips
above and below.
28
PP=1.0 tsf
AL
24
LL=33, PI=10
30
PP=1.25 tsf
15
Drills gravelly.
15
18
Auqer refusal.
FIGURE A-4
PERRONE CONSULTING, INC.
11220 Fieldstone Lane NE
Bainbridge Island, WA 98110
Telephone: (206) 778-8074
Project: 1445 SW 296th Street
Federal Way, Washington
Borehole Location: Mid -slope at north end of house
Drilling Contractor: Geologic Drilling & Exploration, Inc.
Drilling Method: Hollow -Stem Auger
Drill Rig Type: Acker Soil Mechanic
SAMPLES
Log of Boring B-4
Sheet 1 of 1
Date(s) Drilled: March 8, 2011
Logged By: V.J. Perrone
Total Depth of Borehole: 8.0 feet
Surface Elevation / Datum: 89 feet / NAVD88
CF
F--Em
CL
?
m
>
—J
s
a
MATERIAL DESCRIPTION
of
m
10t�f
w
07
Q
O S^
m
0
co
85
80
1
75
1
70
60
• SILTY SAND WITH GRAVEL (SM), very loose, brown, wet,
flee- to coorse{Jrained sand, scattered organics
(COLLUVIUMI
r
i
1 1-1-2 33
(3) +
SILTY SAND WITH GRAVEL (SM), very dense, brownish
+' ray, moist, fine- to coars"rained sand, subangular gravel
F— [GLACIAL DEPOSIT]
2 12-24-32 100 `
(56) I
� I
3 30-50/5 100
Bottom of Boring = 8.0 feet below ground surface.
No free groundwater observed at time of drilling.
Boring backfilled with bentonite chips.
REMARKS
24
17
11
Auger refusal.
FIGURE A-5 J
Jacqueline Doman & Bruce Johnson
May 27, 2011
Page B-1
APPENDIX B
Laboratory Testing
(3)PERRONE CONSULTING, INC., P.S.
Jacqueline Doman & Bruce Johnson
May 27, 2011
Page B-2
APPENDIX B - LABORATORY TESTING
Laboratory testing consisted of Visual -Manual soil classification (ASTM D 2488) of all soil samples,
moisture contents (ASTM D 2216), and Atterberg limits (ASTM D 4318) on selected samples. The
moisture contents are shown on the boring logs. The Atterberg limit test results are shown on the
boring logs and in Figure B-1.
PERRONE CONSULTING, INC., P.S.
Jacqueline Doman & Bruce Johnson
May 27, 2011
Page C-1
APPENDIX C
Important Information about Your Ceotechnical
Engineering Report
PERRONE CONSULTING, INC., P.S.
r — Geolechnical Engineering Report
-
Geotechnical Services Are Performed for
Specific Purposes, Persons, and Projects
Geotechnical engineers structure their services to meet the specific needs of
their clients. A geotechnical engineering study conducted for a civil engi-
neer may not fulfill the needs of a construction contractor or even another
civil engineer. Because each geotechnical engineering study is unique, each
geotechnical engineering report is unique, prepared solelyfor the client. No
one except you should rely on your geotechnical engineering report without
first conferring with the geotechnical engineer who prepared it. And no one
— not even you — should apply the report for any purpose or project
except the one originally contemplated.
Read the full Report
Serious problems have occurred because those relying on a geotechnical
engineering report did not read it all. Do not rely on an executive summary.
Do not read selected elements only.
A Geotechnical Engineering Report Is Based on
A Unique Set of Project -Specific Factors
Geotechnical engineers consider a number of unique, project -specific fac-
tors when establishing the scope of a study. Typical factors include: the
client's goals, objectives, and risk management preferences; the general
nature of the structure involved, its size, and configuration; the location of
the structure on the site; and other planned or existing site improvements,
such as access roads, parking lots, and underground utilities. Unless the
geotechnical engineer who conducted the study specifically indicates oth-
erwise, do not rely on a geotechnical engineering report that was:
■ not prepared for you,
not prepared for your project,
not prepared for the specific site explored, or
completed before important project changes were made.
Typical changes that can erode the reliability of an existing geotechnical
engineering report include those that affect:
• the function of the proposed structure, as when it's changed from a
parking garage to an office building, or from a light industrial plant
to a refrigerated warehouse,
• elevation, configuration, location, orientation, or weight of the
proposed structure,
composition of the design team,
project ownership.
As a general rule, always inform your geotechnical engineer of project
changes —even minor ones —and request an assessment of their impact.
Geotechnical engineers cannot accept responsibility or liability for problems
that occur because their reports do not consider developments of which
they were not informed.
Subsurface Conditions Can Change
A geotechnical engineering report is based on conditions that existed at
the time the study was performed. Do not rely on a geotechnical engineer-
ing report whose adequacy may have been affected by: the passage of
time; by man-made events, such as construction on or adjacent to the site;
or by natural events, such as floods, earthquakes, or groundwater fluctua-
tions. Always contact the geotechnical engineer before applying the report
to determine if it is still reliable. A minor amount of additional testing or
analysis could prevent major problems.
Most Geotechnical Findings Are Professional
Opinions
Site exploration identifies subsurface conditions only at those points where
subsurface tests are conducted or samples are taken. Geotechnical engi-
neers review field and laboratory data and then apply their professional
judgment to render an opinion about subsurface conditions throughout the
site. Actual subsurface conditions may differ —sometimes significantly —
from those indicated in your report. Retaining the geotechnical engineer
who developed your report to provide construction observation is the
most effective method of managing the risks associated with unanticipated
conditions.
A Report's Recommendations Are Not Final
Do not overrely on the construction recommendations included in your
report. Those recommendations are not final, because geotechnical engi-
neers develop them principally from judgment and opinion. Geotechnical
engineers can finalize their recommendations only by observing actual
subsurface conditions revealed during construction. The geolechnical
engineer who developed your report cannot assume responsibility or
liability for the report's recommendations if that engineer does not perform
construction observation.
A Geotechnical Engineering Report Is Subject to
Misinterpretation
Other design team members' misinterpretation of geotechnical engineering
reports has resulted in costly problems. Lower that risk by having your geo-
technical engineer confer with appropriate members of the design team after
submitting the report. Also retain your geotechnical engineer to review perti-
nent elements of the design team's plans and specifications. Contractors can
also misinterpret a geotechnical engineering report. Reduce that risk by
having your geotechnical engineer participate in prebid and preconstruction
conferences, and by providing construction observation.
Do Not Redraw the Engineer's Logs
Geotechnical engineers prepare final boring and testing logs based upon
their interpretation of field logs and laboratory data. To prevent errors or
omissions, the logs included in a geotechnical engineering report should
never be redrawn for inclusion in architectural or other design drawings.
Only photographic or electronic reproduction is acceptable, but recognize
that separating logs from the report can elevate risk.
Give Camractors a Complete Report and
Guidance
Some owners and design professionals mistakenly believe they can make
contractors liable for unanticipated subsurface conditions by limiting what
they provide for bid preparation. To help prevent costly problems, give con-
tractors the complete geotechnical engineering report, but preface it with a
clearly written letter of transmittal. In that letter, advise contractors that the
report was not prepared for purposes of bid development and that the
report's accuracy is limited; encourage them to confer with the geotechnical
engineer who prepared the report (a modest fee may be required) and/or to
conduct additional study to obtain the specific types of information they
need or prefer. A prebid conference can also be valuable. Be sure contrac-
tors have sufficient time to perform additional study. Only then might you
be in a position to give contractors the best information available to you,
while requiring them to at least share some of the financial responsibilities
stemming from unanticipated conditions.
Read Responsibility Provisions Closely
Some clients, design professionals, and contractors do not recognize that
geotechnical engineering is far less exact than other engineering disci-
plines. This lack of understanding has created unrealistic expectations that
have led to disappointments, claims, and disputes. To help reduce the risk
of such outcomes, geotechnical engineers commonly include a variety of
explanatory provisions in their reports. Sometimes labeled "limitations'
many of these provisions indicate where geotechnical engineers' responsi-
bilities begin and end, to help others recognize their own responsibilities
and risks. Read these provisions closely. Ask questions. Your geotechnical
engineer should respond fully and frankly.
Geoenvironmental Concerns Are Not Covered
The equipment, techniques, and personnel used to perform a geoenviron-
mental study differ significantly from those used to perform a geolechnical
study. For that reason, a geotechnical engineering report does not usually
relate any geoenvironmental findings, conclusions, or recommendations;
e.g., about the likelihood of encountering underground storage tanks or
regulated contaminants. Unanticipated environmental problems have led
to numerous project failures. If you have not yet obtained your own geoen-
vironmental information, ask your geotechnical consultant for risk man-
agement guidance. Do not rely on an environmental report prepared for
someone else.
Obtain Professional Assistance To Deal with Mold
Diverse strategies can be applied during building design, construction,
operation, and maintenance to prevent significant amounts of mold from
growing on indoor surfaces. To be effective, all such strategies should be
devised for the express purpose of mold prevention, integrated into a com-
prehensive plan, and executed with diligent oversight by a professional
mold prevention consultant. Because just a small amount of water or
moisture can lead to the development of severe mold infestations, a num-
ber of mold prevention strategies focus on keeping building surfaces dry.
While groundwater, water infiltration, and similar issues may have been
addressed as part of the geotechnical engineering study whose findings
are conveyed in this report, the geotechnical engineer in charge of this
project is not a mold prevention consultant; none of the services per-
formed in connection with the geotechnical engineer's study
were designed or conducted for the purpose of mold preven-
tion. Proper implementation of the recommendations conveyed
-in this report will not of itself he sufficient to prevent mold from
growing in or on the structure involved.
Rely, on Your ASFE-Member Geotechncial
Engineer for Additional Assistance
Membership in ASFE/The Best People on Earth exposes geotechnical
engineers to a wide array of risk management techniques that can be of
genuine benefit for everyone involved with a construction project. Confer
with you ASFE-member geotechnical engineer for more information.
ASFE
THE BEST PEOPLE BN EARTtl
8811 Colesville Road/Suite G106, Silver Spring, MD 20910
Telephone:301/565-2733 Facsimile:301/589-2017
e-mail: info@asfe.org www.aste.org
Copyright 2004 by ASFE, Inc. Duplication, reproduction, or copying of this document in whole or in part, by any means whatsoever, is strictly prohibited, except with ASFEs
specific written permission. Excerpting, quoting, or otherwise extracting wording from this document is permitted only with the express written permission of ASFE, and only for
purposes of scholarly research or book review. Only members of ASFE may use this document as a complement to or as an element of a geotechnical engineering report. Any other
firm, individual, or other entity that so uses this document wilhoul being an ASFE member could be commiling negligent or intentional (fraudulent) misrepresentation.
1IGER06075.0MRP
SW 1/4 OF SEC 6, TWN 21 N, RGE 4 E, W,M., CITY OF FEDERAL WAY, WASHINGTON
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EXISTING SYMBOLS
ABBREVIATIONS
SYMBOL
DESCRIPTION
CB
CATCH BASIN
0
EXISTING REBAR W/CAP, AS NOTED
rl
CENTERLINE
®
MONITOR WELL/TEST HOLE
CMP
CORRUGATED METAL PIPE
❑
CATCH BASIN
CP
CONCRETE PIPE
-0-
UTILITY/POWER POLE
EL
ELEVATION
11T'
TELE. PEDESTAL
EXIST.
EXISTING
®
WATER METER
FL
FLOWLINE
X PK
EXISTING PK NAIL AND FLASHER
IE
INVERT ELEVATION
WATER VALVE
LCPE
LINED CORRUGATED POLYETHYLENE PIPE
SIGN
IT
PROPERTY LINE
CONIFEROUS TREE
PP
POWER POLE
PROPOSED STORM SYMBOLS
SYMBOL
DESCRIPTION
C
SD CAP
®
TYPE 1 CATCH BASIN, GRATED LID
TYPE 1 CATCH BASIN, SOLID LID
®
TYPE 2 CATCH BASIN, GRATED LID
0
TYPE 2 CATCH BASIN, SOLID LID
®
BEEHIVE MANHOLE COVER
®
SQUARE YARD DRAIN
®
ROUND YARD DRAIN
0
STORM CLEAN OUT
®
STORM PIPE
PVC
POLYVINYL CHLORIDE PIPE
R/W
RIGHT-OF-WAY
STA
STATION
SD
STORM DRAIN
SS
SANITARY SEWER
SSMH
SANITARY SEWER MANHOLE
SWIPE
SOLID WALL POLYETHYLENE PIPE
TYP
TYPICAL
TBR
TO BE REMOVED
1. ALL CONSTRUCTION SHALL BE IN ACCORDANCE WITH THE FEDERAL WAY REVISED CODE (FWRC),
APPLICABLE ORDINANCES, AND THE CITY COUNCIL CONDITIONS OF PROJECT APPROVAL. THESE
DOCUMENTS ARE SUPPLEMENTED BY THE STANDARD SPECIFICATIONS FOR ROAD, BRIDGE, AND
MUNICIPAL CONSTRUCTION (WSDOT/APWA), THE KING COUNTY ROAD STANDARDS (KCRS), AND THE
KING COUNTY SURFACE WATER DESIGN MANUAL (KCSWDM). IT SHALL BE THE SOLE
RESPONSIBILITY OF THE APPLICANT AND THE PROFESSIONAL ENGINEER TO CORRECT ANY ERROR,
OMISSION, OR VARIATION FROM THE ABOVE REQUIREMENTS FOUND IN THESE PLANS. ALL
CORRECTIONS SHALL BE AT NO ADDITIONAL COST OR LIABILITY TO THE CITY OF FEDERAL WAY.
2. THE DESIGN ELEMENTS WITHIN THESE PLANS HAVE BEEN REVIEWED ACCORDING TO THE FEDERAL
WAY ENGINEERING REVIEW CHECKLIST. SOME ELEMENTS MAY HAVE BEEN OVERLOOKED OR MISSED
BY THE CITY ENGINEERING PLAN REVIEWER. ANY VARIANCE FROM ADOPTED STANDARDS IS NOT
ALLOWED UNLESS SPECIFICALLY APPROVED BY THE CITY OF FEDERAL WAY, PRIOR TO
CONSTRUCTION.
3. APPROVAL OF THIS ROAD, GRADING, AND DRAINAGE PLAN DOES NOT CONSTITUTE AN APPROVAL OF
ANY OTHER CONSTRUCTION (I.E. DOMESTIC WATER CONVEYANCE, SEWER CONVEYANCE, GAS,
ELECTRICITY, ETC.)
4. BEFORE ANY CONSTRUCTION OR DEVELOPMENT ACTIVITY, A PRECONSTRUCTION MEETING MUST BE
HELD BETWEEN THE CITY OF FEDERAL WAY, THE APPLICANT, AND THE APPLICANT'S CONSTRUCTION
REPRESENTATIVE.
5. A SIGNED COPY OF THESE APPROVED PLANS MUST BE ON THE JOB SITE WHENEVER
CONSTRUCTION IS IN PROGRESS.
6. CONSTRUCTION NOISE AND ACTIVITY (ON PRIVATE PROPERTY) SHALL BE LIMITED AS PER FWIAC
(SECTION 19.105.040); NORMALLY THIS IS 7:00 A.M. TO 8:00 P.M., MONDAY THROUGH FRIDAY,
AND 9:00 A.M. TO 8:00 P.M. ON SATURDAYS.
7. CONSTRUCTION ACTIVITY WITHIN CITY RIGHTS -OF -WAY SHALL BE LIMITED TO THE HOURS OF 8:30
AM TO 3:00 PM.
8. IT SHALL BE THE APPLICANT'S/CONTRACTOR'S RESPONSIBILITY TO OBTAIN ALL CONSTRUCTION
EASEMENTS NECESSARY BEFORE INITIATING OFF -SITE WORK WITHIN THE ROAD RIGHT-OF-WAY.
9. FRANCHISED UTILITIES OF OTHER INSTALLATIONS THAT ARE NOT SHOWN ON THESE APPROVED
PLANS SHALL NOT BE CONSTRUCTED UNLESS AN APPROVED SET OF PLANS THAT MEET ALL CITY
REQUIREMENTS AND THE REQUIREMENTS OF KCRS CHAPTER 8 ARE SUBMITTED TO THE CITY OF
FEDERAL WAY AT LEAST THREE DAYS PRIOR TO CONSTRUCTION.
10. VERTICAL DATUM SHALL BE KCAS OR NGVD-29.
11. GROUNDWATER SYSTEM CONSTRUCTION SHALL BE WITHIN A RIGHT-OF-WAY OR APPROPRIATE
DRAINAGE EASEMENTS, BUT NOT UNDERNEATH THE ROADWAY SECTION. ALL GROUNDWATER
SYSTEMS MUST BE CONSTRUCTED IN ACCORDANCE WITH THE WSDOT/APWA STANDARD
SPECIFICATIONS.
12. ALL UTILITY TRENCHES IN THE RIGHT-OF-WAY SHALL BE BACKFILLED r CRUSHED ROCK AND
COMPACTED TO 95% DENSITY. WHEN TRENCH WIDTH IS 18 INCHES OR LESS, AND IS WITHIN THE
TRAVELED WAY, TRENCH WILL BE BACKFILLED WITH CONTROL DENSITY FILL (SELF -COMPACTED
FLOWABLE FILL) AS DEFINED BY WASHINGTON AGGREGATES AND CONCRETE ASSOCIATION. THE
AGGREGATE WILL BE 3/8-INCH MINUS.
13. ALL ROADWAY SUBGRADE SHALL BE BACKFILLED AND COMPACTED TO 95% DENSITY IN
ACCORDANCE WITH WSDOT 2-06.3.
14.OPEN CUTTING OF EXISTING ROADWAYS IS NOT ALLOWED UNLESS SPECIFICALLY APPROVED BY THE
PUBLIC WORKS DIRECTOR AND NOTED ON THESE APPROVED PLANS, ANY OPEN CUT SHALL BE
RESTORED IN ACCORDANCE WITH KCRS 8.03(B) 3.
15. THE CONTRACTOR SHALL BE RESPONSIBLE FOR PROVIDING ADEQUATE SAFEGUARDS, SAFETY
DEVICES, PROTECTIVE EQUIPMENT, FLAGGERS, AND ANY OTHER NEEDED ACTIONS TO PROTECT LIFE,
HEALTH, AND SAFETY OF THE PUBLIC, AND TO PROTECT PROPERTY IN CONNECTION WITH THE
PERFORMANCE OF WORK COVERED BY THE CONTRACTOR. ANY WORK WITHIN THE TRAVELED
RIGHT-OF-WAY THAT MAY INTERRUPT NORMAL TRAFFIC FLOW SHALL REQUIRE AT LEAST ONE
FLAGGER FOR EACH LANE OF TRAFFIC AFFECTED. ALL SECTIONS OF THE WSDOT STANDARD
SPECIFICATIONS 1-07.23 - TRAFFIC CONTROL, SHALL APPLY.
16. CONTRACTOR SHALL PROVIDE AND INSTALL ALL REGULATORY AND WARNING SIGNS PER THE LATEST
EDITION OF MANUAL ON UNIFORM TRAFFIC CONTROL DEVICES (MUTCD).
17. ALL UTILITIES SHALL BE ADJUSTED TO FINAL GRADE AFTER PAVING ASPHALT WEARING COURSE.
18. ROCKERIES ARE CONSIDERED TO BE A METHOD OF BANK STABILIZATION AND EROSION ONLY.
ROCKERIES SHALL NOT BE CONSTRUCTED TO SERVE AS RETAINING WALLS. ALL ROCKERIES SHALL
BE CONSTRUCTED IN ACCORDANCE WITH CFW DRAWING NUMBERS 3-22, 3-23. ROCKERIES MAY
NOT EXCEED SIX FEET IN HEIGHT FOR CUT SECTIONS OR FOUR FEET IN HEIGHT FOR FILL
SECTIONS UNLESS DESIGNED BY A GEOTECHNICAL OR STRUCTURAL ENGINEER LICENSED IN THE
STATE OF WASHINGTON.
I 4 4#5 SW 296TH ST LANDSLIDE REPAIR
OWNER/APPLICANT.•
GEOTECHNICAL ENGINEER.
STRUCTURAL ENGINEER.•
JAQUEL/NE DOMAN AND BRUCE JOHNSON
PERRONE CONSULTING INC., P.S.
BERGERABAM
1445 SW 296TH ST.
11220 FIELDSTONE LANE NE
33301 97H AVE S, SUITE 300
FEDERAL WAY, WA 98023
BAINBRIDGE ISLAND, WA 98110
FEDERAL WAY, WA 98003
CONTACT: VINCENT PERRONE
CONTACT SUE JOHNSON, P.E.
CIVIL ENGINEER
PHONE- (206) 778-8074
PHONE- (206) 431-2331
LDC, INC.
EMAIL: VJPERRONE®PERRONECONSUL TING COY
EMAIL: SUE. JOHNSON@ABAM. COM
14201 NE 200TH ST //100
WOODINV/LLE, WASHINGTON 98072
SURVEYOR.•
CONTACT: MARK VILLWOCK, P.E.
LDC, INC.
PHONE- (425) 806-1869
14201 NE 200TH ST //100
FAX: (425) 482-2893
WOODINVILLE, WASHINGTON 98072
EMAIL: MVILLWOCK®LDCCORP.COY
CONTACT- LAWRE'NCE KNAPP, PLS
PHONE. (425) 8D6-1869
CITYS PUBLIC #WKS DEPARTMENT
FAX: (425) 482-2893
PRECONSTRUCTION/INSPECTION NOTIFICATION
EMAIL: LKNAPPOLDCCORP. COY
PHONE • (253) 835-2700
CONSTRUCTION PLANS
SCALE: 1" = 30'
Ong
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/- -1 L, T`-s -, �1-1 '' ' J r f _ SW 296TH STREET
POSITION OF WEST QUARTER % / / )i
CORNER, SECTION 6 / / / / / / / / / // % /, / / 1 / I / / jj; // f� i �. RIGHT-OF-WAY
NOT FOUND THIS SURVEY / / / �...
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! S88'44'08" E 150.23
TABLE OF CONTENTS
1 COVER SHEET
2 EXISTING TOPOGRAPHIC MAP
3 SMALL SITE ESC PLAN
4-5 ESC NOTES AND DETAILS
6 GRADING AND STORM DRAINAGE PLAN
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-
LEGAL DESCRIPTION:
THE SOUTH 2O0.00 FEET OF THE NORTH 240.00 FEET OF THE WEST 150.00 FEET OF GOVERNMENT
LOT 5, SECTION 6, TOWNSHIP 21 NORTH, RANGE 4 EAST W.M., IN KING COUNTY, WASHINGTON.
ALSO KNOW AS PARCEL A CITY OF FEDERAL WAY BOUNDARY LINE ADJUSTMENT NO. BLA 96-0009.
BASIS OF POSITION.•
FOUND PK NAIL AND FLASHER AT NORTHEAST CORNER OF PARCEL.
BASIS OF BEARING:
HELD BEARING BETWEEN FOUND BASIS OF POSITION AND FOUND REBAR AND CAP AT SOUTHEAST
CORNER OF PARCEL.
HORIZONTAL DATUM.•
HELD BEARING PER WASHINGTON STATE PLANE COORDINATE SYSTEM, NORTH ZONE, ALONG THE
EAST LINE OF PARCEL TO BE N O1'4823" E. BEARING DERIVED FROM GPS OBSERVATION.
VERTICAL DATUM
NAI988 PER GPS OBSERVATION USING WASHINGTON STATE REFERENCE NETWORK.
NG NAVE 88 -3.50'
BENCHMARK: BENCHMARK
PK AT = ASIS OF POSITION
ELFV=1,28.16'
SURVEYREFERENCE.-
RECORD OF SURVEY FILED UNDER AUDITOR'S FILE NUMBER 9706109006, RECORDS OF KING
COUNTY WASHINGTON 611011997.
SURVEY NOTES:
1. FIELDWORK DONE MARCH 9, 2011.
2. THIS SURVEY IS A TOPOGRAPHIC SURVEY ONLY, NOT A BOUNDARY SURVEY. BOUNDARY
INFORMA77ON SHOWN HEREON IS INTENDED FOR ORIENTATION PURPOSES ONLY. EXISTING
CORNERS WERE FOUND AT EACH OF THE FOUR BOUNDARY CORNERS EXCEPT THE
NORTHWEST CORNER WHERE EVIDENCE OF LANDSLIDE ACTIVITY WAS OBSERVED.
PROJECT INFORMATION
SITE ADDRESS: 1445 SW 296TH ST LOT AREA (SF): 29,998 SF
FEDERAL WAY, WA 98023 LOT AREA (AC): 0.69 AC
TAX PARCEL.• 0629049044
PROPOSED DISTURBED AREA: 6,292 SF
IMPERVIOUS AREA: 0 SF
r,.
Call 2 Business Days Before You Dig
1-800-424-5555
Utilities Underground Location Center
OD,MT,ND,C*i WA)
RECEIVED
AUG log 201�
CITE OF FEDERAL WAy
CDS
PERMIT N0. XX-XXXXXX-XX
IAPPROVED
DATE
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DRAWING NAME: 111(
DESIGNER:
DRAFTING BY:
DATE:
SCALE:
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FASTING SYMBOLS
SYMBOL
DESCRIPTION
0
EXISTING REBAR W/CAP, AS NOTED
®
MONITOR WELL/TEST HOLE
❑
CATCH BASIN
-0-
UTILITY/POWER POLE
OTP
TELE. PEDESTAL
®
WATER METER
X PK
EXISTING PK NAIL AND FLASHER
WATER VALVE
SIGN
CONIFEROUS TREE
ABBREVIATIONS
CB CATCH BASIN
(Z CENTERLINE
CMP CORRUGATED METAL PIPE
CID CONCRETE PIPE
EL ELEVATION
EXIST. EXISTING
E FLOWLINE
IE INVERT ELEVATION
LCPE LINED CORRUGATED POLYETHYLENE PIPE
R PROPERTY LINE
PP POWER POLE
PVC POLYVINYL CHLORIDE PIPE
R/W RIGHT-OF-WAY
STA STATION
SD STORM DRAIN
SS SANITARY SEWER
SSMH SANITARY SEWER MANHOLE
SWPE SOLID WALL POLYETHYLENE PIPE
TYP TYPICAL
TBR TO BE REMOVED
E
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SURVEY INFORMATION
LEGAL DESCRIPTION:
THE SOUTH 200.00 FEET OF THE NORTH 240.00 FEET OF THE WEST 150.00 FEET OF GOVERNMENT
LOT 5, SECTION 6, TOWNSHIP 21 NORTH, RANGE 4 EAST W.M., IN KING COUNTY, WASHINGTON.
ALSO KNOW AS PARCEL A CITY OF FEDERAL WAY BOUNDARY LINE ADJUSTMENT NO. BLA 96-0009.
BASIS OF POSITION:
FOUND PK NAIL AND FLASHER AT NORTHEAST CORNER OF PARCEL.
BASIS OF BEARING:
HELD BEARING BETWEEN FOUND BASIS OF POSITION AND FOUND REBAR AND CAP AT SOUTHEAST
CORNER OF PARCEL.
HORIZONTAL DATUM.
HELD BEARING PER WASHINGTON STATE PLANE COORDINATE SYSTEM, NORTH ZONE, ALONG THE
EAST LINE OF PARCEL TO BE N 01'4823" E. BEARING DERIVED FROM GPS OBSERVATION.
VERTICAL DATUM.'
NAVD 1988 PER GPS OBSERVATION USING WASHINGTON STATE REFERENCE NETWORK
NGVD 29 = NAVD 88 -3.50'
BENCHMAR/G N
PK AT BASIS OF POS177ON
ELEV=128.16'
SURVEYREFERENCE.-
RECORD OF SURVEY FILED UNDER AUDITOR'S F'LE NUMBER 9706109006, RECORDS OF KING
COUNTY WASHINGTON 611011997.
SURVEYNOTES:
1. FIELDWORK DONE MARCH 9, 2011.
2. THIS SURVEY IS A TOPOGRAPHIC SURVEY ONLY, NOT A BOUNDARY SURVEY. BOUNDARY
INFORMATION SHOWN HEREON IS INTENDED FOR ORIENTATION PURPOSES ONLY. EXISTING
CORNERS WERE FOUND AT EACH OF THE FOUR BOUNDARY CORNERS EXCEPT THE
NORTHWEST CORNER WHERE EVIDENCE OF LANDSLIDE ACTIVITY WAS OBSERVED.
PROJECT INFORMATION
SITE ADDRESS: 1445 SW 296TH ST LOT AREA (SF): 29,998 SF
FEDERAL WAY, WA 98023 LOT AREA (AC): 0.69 AC
TAX PARCEL• 0629049044
PROPOSED DISTURBED AREA: 6,292 SF
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VERTICAL DATUM:
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NGVD 29 = NAIAD 88 -3.50'
BENCHMARK %
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ELEV=128.16'
LEGEND
CLEARING AREA
CLEARING LIMITS
SILT FENCE (DETAIL ON ER-03)
CONSTRUCTION SEQUENCE
1. PRIOR TO SITE CLEARING AND GRADING, A PRECONSTRUCTION MEETING SHALL BE
HELD WITH THE CONTRACTOR, CITY INSPECTOR AND APPLICANT. THE FINDINGS FROM
THIS MEETING SHALL BE STRICTLY FOLLOWED BY THE CONTRACTOR. IF ANY CHANGES
TO THE GRADING PLAN ARE REQUIRED, PLEASE CONTACT THE ENGINEER IMMEDIATELY.
2. POST A SIGN WITH THE NAME AND PHONE NUMBER OF THE ESC SUPERVISOR.
3. FLAG OR FENCE CLEARING LIMITS.
4. INSTALL SILT FENCE AND TRIANGULAR DIKE.
5. GEOTECHNICAL ENGINEER OBTAINS GROUNDWATER MEASUREMENTS USING THE
EXISTING VIBRATING WIRE PIEZOMETER AT BORING B-1.
6. CONTRACTOR CONFIRMS UTILITY LOCATIONS IN THE FIELD.
7. CONTRACTOR INSTALLS SETTLEMENT MONITORING POINTS ONT THE HOUSE
FOUNDATIONS, SEWAGE LIFT STATION, AND CONCRETE RETAINING WALL.
8. STRIP THE SITE VEGETATION AND PROVIDE ACCESS FOR CONSTRUCTION EQUIPMENT
TO THE PROPOSED CANTILEVERED SOLDIER PILE WALL.
9. INSTALL SOLDIER PILE WALL.
10. REGRADE SLOPES TO FINISH CONTOURS.
11. INSTALL GROUNDWATER INTERCEPTOR TRENCH DRAINS.
12. APPLY SLOPE EROSION PROTECTION AND RE -VEGETATE THE SLOPE.
13. RECONSTRUCT ROCKERY WALLS AND RESTORE LAWN AREA.
14. MAINTAIN EROSION CONTROL MEASURES IN ACCORDANCE WITH THE 2009 KCSWDM
AND MANUFACTURER'S RECOMMENDATIONS.
15. RELOCATE SURFACE WATER CONTROLS OR EROSION CONTROL MEASURES, OR INSTALL
NEW MEASURES SO THAT AS SITE CONDITIONS CHANGE, THE EROSION AND
SEDIMENTATION CONTROL IS ALWAYS IN ACCORDANCE WITH THE KCSWDM.
16. COVER ALL AREAS WITH MULCH, NETS AND BLANKETS, PLASTIC COVERING, SEEDING,
OR EQUIVALENT WITHIN TIME FRAMES AS SPECIFIED IN TESC NOTES.
17. STABILIZE ALL AREAS WITHIN SEVEN DAYS OF REACHING FINAL GRADE.
18. PRIOR TO FINAL CONSTRUCTION APPROVAL, THE PROJECT SITE SHALL: BE STABILIZED
TO PREVENT SEDIMENT -LADEN WATER FROM LEAVING THE PROJECT SITE AFTER
PROJECT COMPLETION. ALL DISTURBED AREAS OF THE PROJECT SITE SHALL BE
VEGETATED OR OTHERWISE PERMANENTLY STABILIZED. AT A MINIMUM, DISTURBED
AREAS MUST BE SEEDED AND MULCHED TO ENSURE THAT SUFFICIENT COVER WILL
DEVELOP SHORTLY AFTER FINAL APPROVAL. MULCH WITHOUT SEEDING IS ADEQUATE
FOR SMALL AREAS TO BE LANDSCAPED BEFORE OCTOBER 1.
19. ALL TEMPORARY ESC MEASURES SHALL BE REMOVED WITHIN 30 DAYS AFTER FINAL
SITE STABILIZATION IS ACHIEVED OR AFTER THE TEMPORARY MEASURES ARE NO
LONGER NEEDED. TRAPPED SEDIMENT SHALL BE REMOVED OR STABILIZED ONSITE.
DISTURBED SOIL AREAS RESULTING FROM REMOVAL OF MEASURES OR VEGETATION
SHALL BE PERMANENTLY STABILIZED WITH SEEDING OR SODDING.
DURING THE WORK, THE CONTRACTOR SHOULD PROVIDE THE GEOTECHNICAL ENGINEER
WITH DAILY RESULTS OF THE GROUND MOVEMENT MONITORING PROGRAM. SEE DRAWING
S-1 FOR CONSTRUCTION MONITORING.
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NAME: 11 105P-ER01
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ESC NOTES
1. APPROVAL OF THIS EROSION/SEDIMENTATION CONTROL (ESC) PLAN DOES NOT CONSTITUTE AN APPROVAL
OF PERMANENT ROAD OR DRAINAGE DESIGN (I.E. SIZE AND LOCATION OF ROADS, PIPES, RESTRICTORS,
CHANNELS, RETENTION FACILITIES, UTILITIES, ETC.).
2. THE IMPLEMENTATION OF THESE ESC PLANS AND THE CONSTRUCTION, MAINTENANCE, REPLACEMENT, AND
UPGRADING OF THESE ESC FACILITIES IS THE RESPONSIBILITY OF THE APPLICANT/CONTRACTOR UNTIL ALL
CONSTRUCTION IS APPROVED.
3. THE BOUNDARIES OF THE CLEARING LIMITS SHOWN ON THIS PLAN SHALL BE CLEARLY FLAGGED IN THE
FIELD PRIOR TO CONSTRUCTION. DURING THE CONSTRUCTION PERIOD, NO DISTURBANCE BEYOND THE
FLAGGED CLEARING LIMITS SHALL BE PERMITTED. THE FLAGGING SHALL BE MAINTAINED BY THE
APPLICANT/CONTRACTOR FOR THE DURATION OF CONSTRUCTION.
4. STABILIZED CONSTRUCTION ENTRANCES AND WASH PADS SHALL BE INSTALLED AT THE BEGINNING OF
CONSTRUCTION AND MAINTAINED FOR THE DURATION OF THE PROJECT. ADDITIONAL MEASURES MAY BE
REQUIRED TO ENSURE THAT ALL PAVED AREAS ARE KEPT CLEAN AND TRACKING IN THE ROADWAY DOES
NOT OCCUR FOR THE DURATION OF THE PROJECT. IF SEDIMENT IS TRACKED OFFSITE, PUBLIC ROADS
SHALL BE CLEANED THOROUGHLY AT THE END OF EACH DAY, OR MORE FREQUENTLY DURING WET
WEATHER, IF NECESSARY TO PREVENT SEDIMENT FROM ENTERING WATERS OF THE STATE. SEDIMENT SHALL
BE REMOVED FROM ROADS BY SHOVELING OR PICKUP SWEEPING AND SHALL BE TRANSPORTED TO A
CONTROLLED SEDIMENT DISPOSAL AREA. STREET WASHING WILL BE ALLOWED ONLY AFTER SEDIMENT IS
REMOVED IN THIS MANNER. STREET WASH WASTEWATER SHALL BE CONTROLLED BY PUMPING BACK ONSITE,
OR OTHERWISE BE PREVENTED FROM DISCHARGING INTO DRAINAGE SYSTEMS TRIBUTARY TO SURFACE
WATERS.
5. THE ESC FACILITIES SHOWN ON THIS PLAN MUST BE CONSTRUCTED PRIOR TO OR IN CONJUNCTION WITH
ALL CLEARING AND GRADING ACTIVITIES, AND IN SUCH A MANNER AS TO ENSURE THAT SEDIMENT LADEN
WATER DOES NOT ENTER THE DRAINAGE SYSTEM, ADJACENT PROPERTIES, OR VIOLATE APPLICABLE WATER
STANDARDS.
6. THE ESC FACILITIES SHOWN ON THIS PLAN ARE THE MINIMUM REQUIREMENTS FOR ANTICIPATED SITE
CONDITIONS. DURING THE CONSTRUCTION PERIOD, THESE ESC FACILITIES SHALL BE UPGRADED AND/OR
REVISED AS NEEDED FOR UNEXPECTED STORM EVENTS, AND MODIFIED TO ACCOUNT FOR CHANGING SITE
CONDITIONS (E.G. ADDITIONAL COVER MEASURES, RELOCATION OF DITCHES AND SILT FENCES, PERIMETER
PROTECTION, ETC.).
7. THE ESC FACILITIES SHALL BE INSPECTED DAILY BY THE APPLICANT/CONTRACTOR AND MAINTAINED AS
NECESSARY TO ENSURE THEIR CONTINUED PROPER FUNCTIONING.
8. ANY AREAS OF EXPOSED SOILS, INCLUDING ROADWAY EMBANKMENTS, THAT WILL NOT BE DISTURBED FOR
SEVEN (7) DAYS DURING THE DRY SEASON OR TWO (2) DAYS DURING THE WET SEASON, SHALL BE
IMMEDIATELY STABILIZED WITH THE APPROVED ESC METHODS (I.E. SEEDING, MULCHING, NETTING, EROSION
BLANKETS, ETC.).
9. ANY AREA NEEDING ESC MEASURES, NOT REQUIRING IMMEDIATE ATTENTION, SHALL BE ADDRESSED WITHIN
SEVEN (7) DAYS.
10. THE ESC FACILITIES ON INACTIVE SITES SHALL BE INSPECTED AND MAINTAINED A MINIMUM OF ONCE A
MONTH OR WITHIN 24 HOURS FOLLOWING A STORM EVENT.
11. AT NO TIME SHALL MORE THAN ONE (1) FOOT OF SEDIMENT BE ALLOWED TO ACCUMULATE WITHIN A
CATCH BASIN. ALL CATCH BASINS AND CONVEYANCE LINES SHALL BE CLEANED PRIOR TO PAVING. THE
CLEANING OPERATION SHALL NOT FLUSH SEDIMENT -LADEN WATER INTO THE DOWNSTREAM SYSTEM.
12, ANY PERMANENT RETENTION/DETENTION FACILITY USED AS A TEMPORARY SETTLING BASIN SHALL BE
MODIFIED WITH THE NECESSARY EROSION CONTROL MEASURES AND SHALL PROVIDE ADEQUATE STORAGE
CAPACITY. IF THE PERMANENT FACILITY IS TO FUNCTION ULTIMATELY AS AN INFILTRATION SYSTEM, THE
FACILITY SHALL NOT BE USED AS A TEMPORARY SETTLING BASIN. NO UNDERGROUND DETENTION TANKS
OR VAULTS SHALL BE USED AS A TEMPORARY SETTLING BASIN.
13. COVER MEASURES SHALL BE APPLIED IN ACCORDANCE WITH THE FOLLOWING REQUIREMENTS:
A) COVER MEASURES MUST BE INSTALLED IF AN AREA IS TO REMAIN UNWORKED FOR MORE THAN
SEVEN DAYS DURING THE DRY SEASON (MAY 1 TO SEPTEMBER 30) OR FOR MORE THAN TWO
CONSECUTIVE WORKING DAYS DURING THE WET SEASON (OCTOBER 1 TO APRIL 30). THESE TIME
LIMITS MAY BE RELAXED IF AN AREA POSES A LOW RISK OF EROSION DUE TO SOIL TYPE, SLOPE
GRADIENT, ANTICIPATED WEATHER CONDITIONS, OR OTHER FACTORS. CONVERSELY, THE CITY MAY
REDUCE THESE TIME LIMITS IF SITE CONDITIONS WARRANT GREATER PROTECTION (E.G., ADJACENT TO
SIGNIFICANT AQUATIC RESOURCES OR HIGHLY EROSIVE SOILS) OR IF SIGNIFICANT PRECIPITATION IS
EXPECTED.
B) ANY AREA TO REMAIN UNWORKED FOR MORE THAN 30 DAYS SHALL BE SEEDED OR SODDED UNLESS
THE CITY DETERMINES THAT WINTER WEATHER MAKES VEGETATION ESTABLISHMENT INFEASIBLE.
DURING THE WET SEASON, EXPOSED GROUND SLOPES AND STOCKPILE SLOPES WITH AN INCLINE OF
3 HORIZONTAL TO 1 VERTICAL (311:1V) OR STEEPER AND WITH MORE THAN TEN FEET OF VERTICAL
RELIEF SHALL BE COVERED IF THEY ARE TO REMAIN UNWORKED FOR MORE THAN 12 HOURS. ALSO
DURING THE WET SEASON, THE MATERIAL NECESSARY TO COVER ALL DISTURBED AREAS MUST BE
STOCKPILED ON SITE. THE INTENT OF THESE COVER REQUIREMENTS IS TO HAVE AS MUCH AREA AS
POSSIBLE COVERED DURING ANY PERIOD OF PRECIPITATION.
14. MANAGEMENT PRACTICES PROVIDING SIGNIFICANT TREE PROTECTION (PER FWRC) SHALL BE PROVIDED ON
THE ESC PLANS.
15. WET SEASON SPECIAL PROVISIONS, AS DESCRIBED IN SECTION D.5.2 OF APPENDIX D, KCSWDM ARE IN
EFFECT OCTOBER 1 THROUGH APRIL 30. PRIOR TO THE BEGINNING OF THE WET SEASON, ALL DISTURBED
AREAS SHALL BE REVIEWED TO IDENTIFY WHICH ONES CAN BE SEEDED IN PREPARATION FOR WINTER
RAINS. DISTURBED AREAS SHALL BE SEEDED WITHIN ONE WEEK OF THE BEGINNING OF THE WET SEASON.
DE -WATERING CONTROL NOTES
1. HIGHLY TURBID OR CONTAMINATED DEWATERING WATER SHALL BE HANDLED SEPARATELY FROM STORMWATER.
2. ALL TURBID DE -WATERING WATER SHALL BE DISPOSED OF USING ONE OF THE FOLLOWING OPTIONS:
A) INFILTRATION,
B) TRANSPORT OFFSITE IN A VEHICLE, SUCH AS A VACUUM FLUSH TRUCK, FOR LEGAL DISPOSAL IN A
MANNER THAT DOES NOT POLLUTE STATE WATERS,
C) ECOLOGY -APPROVED ON -SITE CHEMICAL TREATMENT OR OTHER SUITABLE TREATMENT TECHNOLOGIES,
D SANITARY SEWER DISCHARGE WITH LOCAL SEWER DISTRICT APPROVAL, IF THERE IS NO OTHER OPTION,
E) USE OF A SEDIMENTATION BAG WITH OUTFALL TO A DITCH OR SWALE FOR SMALL VOLUMES OF
LOCALIZED DE -WATERING, OR
F) FOUNDATION, VAULT, AND TRENCH DE -WATERING WATER, WHICH HAVE SIMILAR CHARACTERISTICS TO
STORMWATER RUNOFF AT THE SITE, SHALL BE DISPERSED TO NATIVE VEGETATION.
3. CLEAN, NON -TURBID DEWATERING WATER, SUCH AS WELL -POINT GROUND WATER, MAY BE DISCHARGED VIA
STABLE CONVEYANCE TO SYSTEMS TRIBUTARY TO SURFACE WATERS, PROVIDED THE DEWATERING FLOW
DOES NOT CAUSE EROSION OR FLOODING OF RECEIVING WATERS.
POLLUTANT CONTROL NOTES
1. ALL POLLUTANTS, INCLUDING WASTE MATERIALS AND DEMOLITION DEBRIS, THAT OCCUR ON -SITE SHALL BE
HANDLED AND DISPOSED OF IN A MANNER THAT DOES NOT CAUSE CONTAMINATION OF STORMWATER.
WOODY DEBRIS MAY BE CHOPPED AND SPREAD ON SITE.
2. COVER, CONTAINMENT AND PROTECTION FROM VANDALISM SHALL BE PROVIDED FOR ALL CHEMICALS, LIQUID
PRODUCTS, PETROLEUM PRODUCTS, AND NON -INERT WASTES PRESENT ON THE SITE (SEE CHAPTER
173-304 WAC FOR THE DEFINITION OF INERT WASTE). ON -SITE FUELING TANKS SHALL INCLUDE
SECONDARY CONTAINMENT.
3. ALL MAINTENANCE OF HEAVY EQUIPMENT AND VEHICLES SHALL BE DONE OFFSITE.
4. ACTIVITIES WHICH MAY RESULT IN DISCHARGE OR SPILLAGE OF POLLUTANTS TO THE GROUND OR INTO
STORMWATER RUNOFF MUST BE CONDUCTED USING SPILL PREVENTION MEASURES, SUCH AS DRIP PANS.
CONTAMINATED SURFACES SHALL BE CLEANED IMMEDIATELY FOLLOWING ANY DISCHARGE OR SPILL INCIDENT.
EMERGENCY REPAIRS MAY BE PERFORMED ON -SITE USING TEMPORARY PLASTIC PLACED BENEATH AND, IF
RAINING, OVER THE VEHICLE.
5. WHEEL WASH OR TIRE BATH WASTEWATER SHALL BE DISCHARGED TO A SEPARATE ON -SITE TREATMENT
SYSTEM OR TO THE SANITARY SEWER.
6. APPLICATION OF AGRICULTURAL CHEMICALS, INCLUDING FERTILIZERS AND PESTICIDES, SHALL BE
CONDUCTED IN A MANNER AND AT APPLICATION RATES THAT WILL NOT RESULT IN LOSS OF CHEMICAL TO
STORMWATER RUNOFF. MANUFACTURERS' RECOMMENDATIONS FOR APPLICATION RATES AND PROCEDURES
SHALL BE FOLLOWED.
7. MEASURES SHALL BE USED TO PREVENT OR TREAT CONTAMINATION OF STORMWATER RUNOFF BY PH
MODIFYING SOURCES. THESE SOURCES INCLUDE, BUT ARE NOT LIMITED TO, BULK CEMENT, CEMENT KILN
DUST, FLY ASH, NEW CONCRETE WASHING AND CURING WATERS, WASTE STREAMS GENERATED FROM
CONCRETE GRINDING AND SAWING, EXPOSED AGGREGATE PROCESSES, AND CONCRETE PUMPING AND MIXER
WASHOUT WATERS. STORMWATER DISCHARGES SHALL NOT CAUSE OR CONTRIBUTE TO A VIOLATION OF THE
WATER QUALITY STANDARD FOR PH IN THE RECEIVING WATER.
SW 1/4 OF SEC 6, TWN 21 N, RGE 4 E, W.M., CITY OF FEDERAL WAY, WASHINGTON
SECTION C.3 E-ROSION AND SEDIMENT CONTROL (ESC) MEASURES
C.3.2 MULCHING
1 /9/2009
Purpose
The purpose of mulching soils is to provide immediate temporary protection from erosion. Mulch also
enhances plant establishment by conserving moisture, holding fertilizer, seed, and topsoil in place, and
moderating soil temperatures. There is an enormous variety of mulches that may be used. Only the most
common types are discussed in this section.
Conditions of Use
As a temporary cover measure, mulch should be used:
1. On disturbed areas that require cover measures for less than 30 days
2. As a cover for seed during the wet season and during the hot summer months
3. During the wet season on slopes steeper than 3H:1 V with more than 10 feet of vertical relief.
Design and Installation Specifications
For mulch materials, application rates, and specifications, see Table C.3.2.A. Note: Thicknesses may, be
inereased,for disturbed areas in or near- critical areas or other areas highly susceptible to erosion
Maintenance Standards
1. The thickness of the mulch cover must be maintained.
2. Any areas that experience erosion shall be re -mulched andior protected with a net or blanket. If the
erosion problem is drainage related, then the drainage problem shall be assessed and alternate
drainage such as interceptor swales may be needed to fix the problem and the eroded area re -mulched.
2009 Su face Water Design Manual -Appendix C
C-86
FIGURE C.3.3.A IWATERNVAY INSTALLATION
DO NOT STRETCH SUWSTSMAT UNGS TIGHT -
ALLOW THE ROLLS TO MOLD TO ANY IAREODUWn11128
SLOPE SURFACE SHALL 8E SLIOOTH SORE
PLACEMENT FOR PROPER SM CONTACT
ANCHOR, STAPLE, AND ]INSTALL CHECK
SLOTS AS PER !MANUFACTURERS
RECOMMENDATIONS
AVOID JOINING MATERIAL IN THE
CENTER OF THE DITCH
LINIE, FERTILIZE AND SEED
BEFORE INSTALLATION
MIN. S• OVERLAP
FIGURE C.3.3.B SLOPE INSTALLATION
SLOPE SURFACE SHALL BE SMOOTH BEFORE
PLACEMENT FOR PROPER SOIL CONTACT
STAPLING PATTERN AS PER
MANUFACTURER'S RECOMMENDATIONS
MIN. 2"LAP OVER
_
C.3.3 NETS AND BLANKETS
IF THERE IS A BERM AT THE
TOP OF SLOPE, ANCHOR
UPSLOPE OF THE BERM
ANCHOR IN 6"x6" MIN. TRENCH
I I- AND STAPLE AT 12" INTERVALS
MIN. 5" OVERLAP
STAPLE OVERLAPS
MAX, 6' SPACING
BRING MATERIAL DOWN TO A LEVEL AREA, TURN
THE END UNDER 4" AN D STAPLE AT 12" INTERVALS
DO NOT STRETCH BLANKETSIMATTINGSTIGHT-
ALLOW THE ROLLS TO MOLD TO ANY IRREGULARITIES
FOR SLOPES LESS THAN 3H:1V, ROLLS LIME, FERTILIZE AND SEED BEFORE INSTALLATION.
MAY BE PLACED IN HORIZONTAL STRIPS PLANTING OF SHRUBS, TREES, ETC. SHOULD OCCUR
AFTER INSTALLATION.
2009 Surface, Water Design Manual -Appendix C
C-99
C.3.2 N4ULCHING
TABLE C.3.2.A NIULCH STANDARDS AND GUIDELINES
Mulch
Quality Standards
Application
Remarks
Material
Rates
Straw
Air-dried; free from
2"-3" thick; 2-3
Cost-effective protection when applied with adequate
undesirable seed and
bales per 1000 sf
thickness. Hand -application generally requires greater
coarse material
or 2-3 tons per acre
thickness than blown straw. Straw should be crimped to
avoid wind blow. The thickness of straw may be reduced
by half when used in conjunction with seeding.
Wood Fiber
No growth inhibiting
Approx. 25-30 Ibs
Shall be applied with hydromulcher. Shall not be used
Cellulose
factors
per 1000 sf or
without seed and tackifier unless the application rate is at
1000-1500 Ibs per
least doubled. Some wood fiber with very long fibers can
acre
be effective at lower application rates and without seed
or tackifier.
Compost
No visible water or dust
2" thick min.;
More effective control can be obtained by increasing
during handling. Must
approx. 100 tons
thickness to 3". Excellent mulch for protecting final
be purchased from
per acre (approx.
grades until landscaping because it can be directly
supplier with Solid
800lbs per cubic
seeded or tilled into soil as an amendment Sources for
Waste Handling Permit,
yard)
compost are available from the King County Commission
for Marketing Recyclable Materials at (206) 296-4439.
Hydraulic
This mulch category
Apply at rates from
The BFM shall not be applied immediately before, during
Matrices
includes hydraulic
3,000 Ibs per acre
or immediately after rainfall so that the matrix will have
(Bonded Fiber
slurries composed of
to 4,000 Ibs per
an opportunity to dry for 24 hours after installation.
Matrix)
wood fiber: paper fiber
acre and based on
Application rates beyond 2,500 pounds may interfere wth
or a combination of the
manufacturers
germination and are not usually recommended for turf
two held together by a
recommendations
establishment. BFM is generally a matrix where all fiber
binding system. The
and binders are in one bag, rather than having to mix
BFM shall be a mixture
components from various manufacturers to create a
of long wood fibers and
matrix. BFMs can be installed via helicopter in remote
various bonding agents.
areas. They are approximately $1,000 per acre cheaper
to install.
Chipped Site
Average size shall be
2" minimum
This is a cost-effective way to dispose of debris from
Vegetation
several inches.
thickness
clearing and grubbing, and it eliminates the problems
associated with burning. Generally, it should not be used
on slopes above approx. 10% because of its tendency to
be transported by runoff. It is not recommended within
200 feet of surface waters. If seeding is expected shortly
after mulch, the decomposition of the chipped vegetation
may tie up nutrients important to grass establishment.
2009 Surface Water Design Manual -Appendix C
C-97
SECTION(.3 EROSION AND SEDIMENT CONTROL (ESC) %IEASURI:S
C.3.4 PLASTIC COVERLNG
1/9/2009
1,19,12009
Purpose
Plastic covering provides immediate, short-term erosion protection to slopes and disturbed areas.
Conditions of Use
1. Plastic covering may be used on disturbed areas that require cover measures for less than 30 days.
2. Plastic is particularly useful for protecting cut and :till slopes and stockpiles. Note: The relatively
rapid breakdown of most polyethylene sheeting mrtkes it unsuitable for long -teem applications.
3. Clear plastic sheeting may be used over newly -seeded areas to create a greenhouse effect and
encourage grass growth. Clear plastic should not be used for this purpose during the summer months
because the resulting high temperatures can kill the grass.
4. Due to rapid runoff caused by plastic sheeting, this method shall not be used upslope of areas that
might be adversely impacted by concentrated runoff. Such areas include steep and/or unstable slopes.
Note: There have been marry problems with plastic, usually attributable to poor installation and
maintenance- However, the material itselfcan cause problems, even when correctly installed and
maintained because it generates high -velocity runof'and breaks down quickly due to ultraviolet
radiation In addition, if the plastic is not completely removed, it car? clog drainage system inlets and
outlets. It is highly recommended that alternatives to plastic sheeting be used whenever possible and that
its use be limited
Design and Installation Specifications
1. See Figure C.3.4.A for details.
2. Plastic sheeting shall have a minimum thickness of 0.06 millimeters.
3. If erosion at the toe of a slope is likely, a gravel berm, riprap, or other suitable protection shall be
installed at the toe of the slope in order to reduce the velocity of runoff.
FIGUREC.3.4.A PLASTIC COVERING
1 a MAX
TRE.% SANDBAGS, OR EOUNALWr
FK*ff
PLAITTIC
_ -�--- ��� MAYS USEOTOM HEFT MUST
:.._
SEAMS BETriEEN SHEETS MUST
OVERLAP A MNIMUM OF 12-AND
BE WEIGHTED OR TAPED
TOEl13HEET QSU
MMlIIY4'RTT16C1
F5WkVE E`ERG^' DI75PATI :N 1
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AT TOE [i1 AST .... _ - _ .. .
C-90
2009 Surface Water Design Manual - Appendix C
SECTION C.3 EROSION AND SEDIMENT CONTROL (ESC) MEASURES
C.3.3 NETS AND BLANKETS
Purpose
Erosion control nets and blankets are intended to prevent erosion and hold seed and mulch in place on
steep slopes and in channels so that vegetation can become well established. In addition, some nets and
blankets can be used to permanently reinforce turf to protect drainage ways during high flows. bets are
strands of material woven into an open, but high -tensile strength net (for example, jute matting). Blankets
are strands of material that are not tightly woven, but instead form a laver of interlocking fibers, typically
held together by a biodegradable or photodegradable netting (for example, excelsior or straw blankets).
They generally have lower tensile strength than nets, but cover the ground more completely. Coir
(coconut fiber) fabric comes as both nets and blankets.
Conditions of Use
Erosion control nets and blankets should be used
1. For permanent stabilization of slopes 2H:1 V or greater and with more than 10 feet of vertical relief
2. In conjunction with seed for final stabilization of a slope, not for temporary cover. However, they
may be used for temporary applications as long as the product is not damaged by repeated handling.
In fact, this method of slope protection is superior to plastic sheeting, which generates high -velocity
runoff
3. For drainage ditches and swales (highly recommended). The application of appropriate netting or
blanket to drainage ditches and swales can protect bare soil from channelized runoff while vegetation
is established. Nets and blankets also can capture a great deal of sediment due to their open, porous
structure. Synthetic nets and blankets may be used to permanently stabilize channels and may provide
a cost-effective, environmentally preferable alternative to riprap.
Design and Installation Specifications
I. See Figure C.3.3.A and Figure C.3.3.B for typical orientation and installation of nettings and blankets.
Note: Installation is critical to the effectiveness of these products. If good ground contact is not
achieved, runoff can concentrate under the product, resulting in significant erosion.
2. Jute matting must be used in conjunction with mulch. Excelsior, woven straw 'blankets, and coir
(coconut fiber) blankets may be installed without mulch. There are many other types of erosion
control nets and blankets on the market that may be appropriate in certain circumstances. Other
types of products will have to be evaluated individually. In general, most nets (e.g., jute matting)
require mulch in order to prevent erosion because they have a fairly open structure. Blankets
typically do not require mulch because they usually provide complete protection of the surface.
3. Purely synthetic blankets are allowed but shall only be used for long-term stabilization of waterways.
The organic blankets authorized above are better for slope protection and short-term waterway
protection because they retain moisture and provide organic matter to the soil, substantially improving
the speed and success of re -vegetation.
Maintenance Standards
I . Good contact with the ground must be maintained, and there must not be erosion beneath the net or
blanket.
2. Any areas of the net or blanket that are damaged or not in close contact with the ground shall be
repaired and stapled.
3. If erosion occurs due to poorly controlled drainage, the problem shall be fixed and the eroded area
protected.
1/9/2009 2009 Surface Water Design Manual -Appendix C
C-88
C.3.5 MARK CLEARING LIMITS VMINIMIZE CLEARING
Maintenance Standards for Plastic Covering
1. Tom sheets must be replaced and open seams repaired.
2. If the plastic begins to deteriorate due to ultraviolet radiation, it must be completely removed and
replaced.
C.3.'5 MARK CLEARING LIMITS/MINIMIZE CLEARING
Purpose
Minimizing clearing is the most effective method of erosion control. Undisturbed vegetation intercepts
and slows rainwater. Plant roots hold soil in place, and dead vegetation on the ground acts as a mulch.
Applications
Clearing limits shall be marked and clearing minimized on any site where significant areas of undisturbed
vegetation will be retained.
Design Specifications
1. Minimizing clearing should be incorporated into the site design. Clearing limits must be marked on
the small site ESC plan.
2. On the ground, clearing limits must be clearly marked with brightly colored tape or plastic or metal
safety- fencing. If tape is used, it should be supported by vegetation or stakes, and should be about 3
to 6 feet high and highly visible. Equipment operators should be informed of areas of vegetation that
are to be left undisturbed.
3. The duff layer, native top soil, and natural vegetation shall be retained in an undisturbed state to the
maximum extent practicable. If it is not practicable to retain the duff layer in place, it should be
stockpiled on -site, covered to prevent erosion, and replaced immediately upon completion of the
ground disturbing activities.
Maintenance
Fencing shall be inspected regularly and repaired or replaced as needed.
2009 Surface Water Design Manual -Appendix C
I �
Call 2 Business Days Before You Dig
1-800-424-5555
Utilities Underground Location Center
(ID,MT,ND,OR,WA)
C-91
1/912009
PERMIT N0. XX-XXXXXX-XX
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JOB NUMBER: 11-105
DRAWING
NAME: 11105P-ER02
DESIGNER: GRB
DRAFTING
BY: BPC
DATE:
6-28-11
SCALE:
AS NOTED
JURISDICTION: FEDERAL WAY
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SW 1/4 OF SEC 6, TWN 2' N, RGE 4 E, W.M., CITY OF FEDERAL WAY, WASHINGTON
SECTION C.3 EROSION AND SEDIMENT CONTROL (ESC) MEASURES
C.3.6 SILT FENCE
Purpose
Use of a silt fence reduces the transport of coarse sediment from a construction site by providing a
temporary physical barrier to sediment and reducing the runoff velocities of overland flow.
Conditions of Use
Silt fence may be used downslope of all disturbed areas. Silt fence is not intended to treat concentrated
flows, nor is it intended to treat substantial amounts of overland flow.
Design and Installation Specifications
1. See Figure C.3.6.A and Figure C.3.6.13 for details.
2. The geotextile used must meet the standards listed below. A copy of the manufacturer's fabric
specifications must be available onsite.
AOS {ASTM D4751 } 30-100 sieve size (0.60-0
3. Standard strength fabric requires wire backing to increase the strength of the fence. Wire backing or
closer post spacing may be required for extra strength fabric if field performance warrants a stronger
fence.
4. Where the fence is installed, the slope shall be no steeper than 2H:1V.
5. If a typical silt fence (per Figure C.3.6-A) is used, the standard 4 x 4 trench may not be reduced as
long as the bottom 8 inches of the silt fence is well buried and secured in a trench that stabilizes the
fence and does not allow water to bypass or undermine the silt fence.
6. Silt fences shall be located so as to avoid interfering with the movement of juvenile salmonids
attempting to enter off -channel areas or drainages.
Maintenance Standards
1. Any damage shall be repaired immediately.
2. If concentrated flows are evident uphill of the fence, they must be intercepted and conveyed to a
sediment trap or pond.
3. It is important to check the uphill side of the fence for signs of the fence clogging and acting as a
barrier to flow and then causing channelization of flows parallel to the fence. If this occurs, replace
the fence or remove the trapped sediment.
4. Sediment must be removed when the sediment is 6 inches high.
5. If the filter fabric (geotextile) has deteriorated due to ultraviolet breakdown, it shail be replaced.
1/9/2009 2009 Surface Water Design Manual - Appendix C
C-92
.15 min) for slit film
50-100 sieve size (0.30-0.15 min) for other fabrics
Water Permittivity (ASTM D4491)
0.02 sec-1 minimum
Grab Tensile Strength (ASTM D4632)
180 Ibs, min. for extra strength fabric
100 Ibs, min. for standard strength fabric
Grab Tensile Elongation (ASTM D4632)
30% max.
Ultraviolet Resistance (ASTM D4355)
70% min.
C.3.10 SEEDING
C.3.10 SEEDING
Purpose
Seeding is intended to reduce erosion by stabilizing exposed soils. A cell -established vegetative cover is
one of the most effective methods of reducing erosion.
Conditions of Use
1. Seeding shall be used throughout the project on disturbed areas that have reached final grade or that
will remain unworked for more than 30 days.
2. At the County's discretion, seeding without mulch during the dry season is allowed even though it
will take more than seven days to develop an effective cover. Mulch is. however, recommended at all
times because it protects seeds from heat, moisture loss, and transport due to runoff.
3. At final site stabilization, all disturbed areas not otherwise vegetated or stabilized shall be seeded and
mulched.
Design and Installation Specifications
1. The best time to seed is April 1 through June 30, and September 1 through October 15. Areas may be
seeded between July 1 and August 31, but irrigation may be required in order to grow adequate cover.
Areas may also be seeded during the winter months, but it may take several months to develop a
dense groundcover due to cold temperatures. The application and maintenance of mulch is critical for
winter seeding.
2. To prevent seed from being washed away, confirm that all required surface water control measures
have been installed.
3. The seedbed should be firm but not compacted because soils that are well compacted will not
vegetate as quickly or thoroughly.
4. In general, 10-20-20 N-P-K (nitrogen -phosphorus -potassium) fertilizer may be used at a rate of 90
pounds per acre. Slow -release fertilizers are preferred because they are more efficient and have fewer
environmental impacts. It is recommended that areas being seeded for final landscaping conduct soil
tests to determine the exact type and quantity of fertilizer needed. This will prevent the over -
application of fertilizer. Disturbed areas within 200 feet of water bodies and wetlands must use slow -
release low -phosphorus fertilizer (typical proportions 3-1-2 N-P-K).
5. The following requirements apply to mulching:
a) Mulch is always required for seeding slopes greater than 3H:1 V (see Section D.4.2.1).
b) If seeding during the wet season, mulch is required.
c) The use of mulch may be required during the dry season at the County's discretion is grass growth
is expected to be slow, the soils are highly erodible due to soil type or gradient, there is a water
body close to the disturbed area, or significant precipitation is anticipated before the grass will
provide effective cover.
d) Mulch may be applied on top of the seed or simultaneously by hydroseeding.
6. Hydroseeding is allowed as long as tackifier is included. Hydroseeding with wood fiber mulch is
adequate during the dry season. During the wet season, the application rate shall be doubled because
the mulch and tackifier used in hydroseeding break down fairly rapidly. It may be necessary in some
applications to include straw with the wood fiber, but this can be detrimental to germination.
7. Areas to be permanently landscaped shall use soil amendments. Good quality topsoil shall be tilled
into the top six inches to reduce the need for fertilizer and improve the overall soil quality. Most
native soils will require the addition of four inches of well -rotted compost to be tilled into the soil to
2009 Surface Water Design Manual -Appendix C 1/9/2009
C-101
C.3.6 SILT FENCE.
FIGURE C.3.6.A SILT FENCE
_771
JOINTS IN FILTER FABRIC SHALL BE SPLICED
AT POSTS. USE STAPLES, WIRE RINGS, OR
EQUIVALENT TO ATTACH FABRIC TO POSTS.
2'W' BY 14 Ga. WIRE OR
EQUIVALENT. IF STANDARD
STRENGTH FABRIC USED
FILTER FABRIC
II I
II I N
II
-.---- -- _ ITS\ N
J VMAX. '4 I MINIMUM4WTRENCH E
BACKFILL TRENCH WITH
NATIVE SOIL OR 31,V-1.5'
POST SPACING MAY BE INCREASED WASHED GRAVEL
TO V IF WIRE BACKING IS USED
2'x4' WOOD POSTS, STEEL FENCE
NOTE FILTER FABRIC FENCES SHALL BE POSTS, REBAR, OR EQUIVALENT
INSTALLED ALONG CONTOUR WHENEVER POSSIBLE
FIGURE C.3.6.13 SILT FENCE INSTALLATION AND MAINTENANCE
Digireech
Reinforce
Toe in -fabric
hionkor
Maintain and c1mi
2009 Surface Water Design Manual -Appendix C 1l9;2009
C-93
SECTION C.3 EROSION AND SEDIMENT CONTROL (ESC) MEASURES
provide a good quality topsoil. Compost us%tid should meet Ecology publication 98-38 specifications
for Grade A quality compost
8. the seed mixes listed below include recommended mixes for both temporary and permanent seeding.
these mixes, with the exception of the wetland mix, shall be applied at a rate of 120 pounds per acre.
This rate may be reduced if soil amendments or slow -release fertilizers are used. Local suppliers
should be consulted for their recommendations because the appropriate mix depends on a variety of
factors, including exposure, soil type, slope, and expected foot traffic. Alternative seed mixes
approved by the County may be used.
TABLE C.3.I0
Maintenance Standards for Seeding
1. Any seeded areas that fail to establish at least 80 percent cover within one month shall be reseeded. If
reseeding is ineffective, an alternate method, such as sodding or nets/blankets, shall be used. If winter
weather prevents adequate grass growth, this time limit may be relaxed at the discretion of the County
when critical areas would otherwise be protected.
2. After adequate cover is achieved, any areas that experience erosion shall be re -seeded and protected
by mulch. If the erosion problem is drainage related, the problem shall be fixed and the eroded area
re -seeded and protected by mulch.
3. Seeded areas shall be supplied with adequate, moisture, but not watered to the extent that it causes
runoff
1/9/2009 2009 Surface Water Design Manual - Appendix C
C-102
ry
.A TEMPORARY EROSION CONTROL SEED lIIX
FIGURE C.3.6.13 SILT FENCE INSTALLATION AND MAINTENANCE
Digireech
Reinforce
Toe in -fabric
hionkor
Maintain and c1mi
2009 Surface Water Design Manual -Appendix C 1l9;2009
C-93
SECTION C.3 EROSION AND SEDIMENT CONTROL (ESC) MEASURES
provide a good quality topsoil. Compost us%tid should meet Ecology publication 98-38 specifications
for Grade A quality compost
8. the seed mixes listed below include recommended mixes for both temporary and permanent seeding.
these mixes, with the exception of the wetland mix, shall be applied at a rate of 120 pounds per acre.
This rate may be reduced if soil amendments or slow -release fertilizers are used. Local suppliers
should be consulted for their recommendations because the appropriate mix depends on a variety of
factors, including exposure, soil type, slope, and expected foot traffic. Alternative seed mixes
approved by the County may be used.
TABLE C.3.I0
Maintenance Standards for Seeding
1. Any seeded areas that fail to establish at least 80 percent cover within one month shall be reseeded. If
reseeding is ineffective, an alternate method, such as sodding or nets/blankets, shall be used. If winter
weather prevents adequate grass growth, this time limit may be relaxed at the discretion of the County
when critical areas would otherwise be protected.
2. After adequate cover is achieved, any areas that experience erosion shall be re -seeded and protected
by mulch. If the erosion problem is drainage related, the problem shall be fixed and the eroded area
re -seeded and protected by mulch.
3. Seeded areas shall be supplied with adequate, moisture, but not watered to the extent that it causes
runoff
1/9/2009 2009 Surface Water Design Manual - Appendix C
C-102
ry
.A TEMPORARY EROSION CONTROL SEED lIIX
%Weight
%Purity
%Germination
Chewings or red fescue (Festuca rubra var.
commutata or Festuca rubra)
40
98
90
Annual or perennial rye (Lolium multiflortrm or Lolium
perenne)
40
98
90
TABLE C3.10.B LANDSCAPING SEED MIX
°le, Weight
%Purity
%Germination
Perennial
I J''
Call 2 Business Days Before You Dig
1-800-424-5555
Utilities Underground Location Center
(ID,MT,ND,OR,WA
PERMIT N0. XX-XXXXXX-XX
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SURVEY INFORMA TION
VERTICAL DATUM:
NAVD 1988 PER GPS OBSERVATION USING WASHINGTON STATE REFERENCE NETWORK.
NGVD 29 = NAVD 88 -3.50'
BENCHMARK \K BENCHMARK
PK AT BASIS OF POSITION
ELEV=128.16'
GR4DING QUANTITIES
CUT. 1,390 CY
FILL- 9 CY
DRAINAGE NOTES
1. PROOF OF LIABILITY INSURANCE SHALL BE SUBMITTED TO THE CITY PRIOR TO, OR AT,
THE PRECONSTRUCTION MEETING.
2. ALL PIPE AND APPURTENANCES SHALL BE LAID ON A PROPERLY PREPARED
FOUNDATION IN ACCORDANCE WITH WSDOT SPECIFICATIONS. THIS SHALL INCLUDE
LEVELING AND COMPACTING THE TRENCH BOTTOM, THE TOP OF FOUNDATION MATERIAL,
AND REQUIRED PIPE BEDDING, TO A UNIFORM GRADE SO THAT THE ENTIRE PIPE IS
SUPPORTED BY A UNIFORMLY DENSE UNYIELDING BASE.
3. ALL PIPE IN THE ROW THAT IS IN EXCESS OF 18" IN DIAMETER MUST BE PLAIN OR
REINFORCED CONCRETE. ADDITIONALLY, IF MORE THAN 100' OF NON -CONCRETE PIPE
IS INSTALLED, THE PIPE MUST BE VIDEOED TO VERIFY THE INTEGRITY OF THE
COMPLETED SYSTEM. THE CONTRACTOR SHALL PROVIDE A COPY OF THE VIDEO TO
THE CITY.
4. STORM PIPE WITHIN THE PUBLIC RIGHT OF WAY SHALL HAVE A MINIMUM DIAMETER OF
12" (8" DIAMETER DUCTILE IRON PIPE MAY BE PERMITTED ON CROSS STREET
LATERALS LESS THAN 66 FEET LONG, ONLY TO AVOID UTILITY CONFLICT OR MEET
SHALLOW GRADIENT AS APPROVED BY THE PUBLIC WORKS DEPARTMENT).
5. STEEL PIPE SHALL BE GALVANIZED AND HAVE ASPHALT TREATMENT #1 OR BETTER
INSIDE AND OUTSIDE.
6. ALL DRAINAGE STRUCTURES, SUCH AS CATCH BASINS AND MANHOLES, NOT LOCATED
WITHIN A TRAVELED ROADWAY OR SIDEWALK SHALL HAVE SOLID LOCKING LIDS. ALL
DRAINAGE STRUCTURES ASSOCIATED WITH A PERMANENT RETENTION/DETENTION
FACILITY SHALL HAVE SOLID LOCKING LIDS.
7. ALL DRIVEWAY CULVERTS LOCATED WITHIN THE RIGHT-OF-WAY SHALL BE OF
SUFFICIENT LENGTH TO PROVIDE A MINIMUM 3:1 SLOPE FROM THE EDGE OF THE
DRIVEWAY TO THE BOTTOM OF THE DITCH. CULVERTS SHALL HAVE BEVELED END
SECTIONS TO MATCH THE SIDE SLOPES.
8. ROCK FOR EROSION PROTECTION OF DITCHES, CHANNELS AND SWALES, WHERE
REQUIRED, MUST BE OF SOUND QUARRY ROCK, PLACED TO A DEPTH OF ONE FOOT
AND MUST MEET THE FOLLOWING SPECIFICATIONS: 4"-8" ROCK/40%-70% PASSING;
274" ROCK/30%-40% PASSING; AND -2" ROCK/10%-20% PASSING. INSTALLATION
SHALL BE IN ACCORDANCE WITH KCRS, OR AS AMENDED BY THE APPROVED PLANS.
RECYCLED ASPHALT OR CONCRETE RUBBLE SHALL NOT BE USED.
9. LOTS NOT APPROVED FOR INFILTRATION SHALL BE PROVIDED WITH DRAINAGE OUTLETS
(STUB -OUTS). STUB -OUTS SHALL CONFORM TO THE FOLLOWING:
A. EACH OUTLET SHALL BE SUITABLY LOCATED AT THE LOWEST ELEVATION ON THE LOT,
SO AS TO SERVICE ALL FUTURE ROOF DOWNSPOUTS AND FOOTING DRAINS,
DRIVEWAYS, YARD DRAINS, AND ANY OTHER SURFACE OR SUB -SURFACE DRAINS
NECESSARY TO RENDER THE LOTS SUITABLE FOR THEIR INTENDED USE. EACH
OUTLET SHALL HAVE FREE -FLOWING, POSITIVE DRAINAGE TO AN APPROVED
STORMWATER CONVEYANCE SYSTEM OR TO AN APPROVED OUTFALL LOCATION.
B. OUTLETS ON EACH LOT SHALL BE LOCATED WITH A FIVE-FOOT HIGH, 2 X 4 STAKE
MARKED "STORM". THE STUB -OUT SHALL EXTEND ABOVE SURFACE LEVEL, BE
VISIBLE AND BE SECURED TO THE STAKE.
C. PIPE MATERIAL SHALL CONFORM TO UNDERDRAIN SPECIFICATIONS DESCRIBED IN THE
KCRS AND, IF NON-METALLIC, THE PIPE SHALL CONTAIN WIRE OR OTHER
ACCEPTABLE DETECTION.
D. DRAINAGE EASEMENTS ARE REQUIRED FOR DRAINAGE SYSTEMS DESIGNED TO CONVEY
FLOWS THROUGH INDIVIDUAL LOTS.
E. THE APPLICANT/CONTRACTOR IS RESPONSIBLE FOR COORDINATING THE LOCATIONS OF
ALL STUB -OUT CONVEYANCE LINES WITH RESPECT TO THE UTILITIES (I.E. POWER,
GAS, TELEPHONE, TELEVISION).
F. ALL INDIVIDUAL STUB -OUTS SHALL BE PRIVATELY OWNED AND MAINTAINED BY THE
LOT HOMEOWNER.
Smooth Coupling Band
for Smooth Pipe
material to be,
ASTM A 36114"
plate galvanized
after fabrication
per ASTM A 123
'all holes
s ois to be
1 I9w x 1t4"
Plate Detail
or
coupling band collar (2" pipe)
1"
114" 14
plate (see detail)
material to be ASTM
A 36 galvanized after
1 I&' x & stakes JQ fabrication per ASTM
flatten to point each side of culvert A 153
Anchor Assembly -
Corrugated Metal Pipe
THIS ANCHOR ASSEMBLY TO BE USED
WITH HDPE LINE PER RD-01.
tars-e�r;�rrr=�
0
MOTES:
1. The smooth coupling bard shall be used in
combination With conCneOe pipe.
2. Concrete pipe without bet and spigot shell
not be instated on grades in excess of 20°/6.
3. The first anchor shall be installed on the first
section of the lower end of the pipe and
remaining anchors evenly spaced throughout
the Installation.
4. if the pipe being installed has a manhole or
catch basin on the lower end of the pipe, the
first pipe anchor may be eliminated.
5. When CMP is used, the anchors may be
attached to the coupling bands used to pin
the pipe as long as the specified spacing is
not exceeded.
6. All pipe anchors shall be securely instated
before badcfffirg around the pipe.
PIPE SLOPE ANCHOR DETAIL
NOT TO SCALE
NW 1/4, SW 1/4, SEC 6, TWN 21 N, RGE 4 E, W.M., CITY OF FEDERAL WAY, KING COUNTY, WASH/NGTON
OUTFALL LOCATION AT SAME
LOCATION AS CITY PIPE OUTFALL
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JOB NUMBER: 11-105
DRAWING
NAME:11105P-SDO1
DESIGNER: GRB
DRAFTING
BY: BPC
DATE:
6-28-11
SCALE:
1" =20'
JURISDICTION: FEDERAL WAY
SD=01
SHEET
6 OF 6