22-105973-Geotech Report Update-01-12-23
Proposed Creekwood Development Page | i
December 30, 2022
Revision History
Version Description/Comment Date Notes, As
Required
001 Updated Geotechnical Engineering Report April 28, 2017
002
Geotechnical Engineering Report Addendum:
Revised Ravine Crossing and Comment
Response Letter
October 23, 2020
003 Updated Geotechnical Engineering Report December 20, 2022
Proposed Creekwood Development Page | ii
December 30, 2022
Table of Contents
1 INTRODUCTION AND PROJECT DESCRIPTION ......................................................................................... 1
2 SUBSURFACE EXPLORATIONS .................................................................................................................. 2
2.1 Vertical Datum .............................................................................................................................. 2
2.2 Exploration Program Summary ..................................................................................................... 2
3 LABORATORY TESTING ............................................................................................................................ 4
4 SURFACE AND SUBSURFACE CONDITIONS .............................................................................................. 5
4.1 Surface Conditions ........................................................................................................................ 5
4.2 Site Soils ........................................................................................................................................ 7
4.3 Site Geology .................................................................................................................................. 7
4.4 DNR Landslide Inventory ............................................................................................................... 8
4.5 Subsurface Conditions .................................................................................................................. 9
4.6 Groundwater ............................................................................................................................... 10
4.7 Aerial Photo Review .................................................................................................................... 11
5 GEOLOGIC HAZARDS ............................................................................................................................. 11
5.1 Seismic Hazards ........................................................................................................................... 11
5.2 Erosion Hazard Areas .................................................................................................................. 12
5.3 Landslide Hazard Areas ............................................................................................................... 12
5.4 Slope Stability .............................................................................................................................. 14
5.5 Buffers and Setbacks ................................................................................................................... 15
6 ENGINEERING CONCLUSIONS AND RECOMMENDATIONS ................................................................... 16
6.1 Seismic Design Recommendations ............................................................................................. 16
Seismic Site Class ........................................................................................................ 17
Design Parameters ..................................................................................................... 17
Peak Ground Acceleration ......................................................................................... 17
Earthquake Induced Geologic Hazards ................................................................... 18
6.2 Shallow Foundation design .................................................................................................... 18
Spread Footing Design ............................................................................................... 19
6.3 Floor Slab Support ....................................................................................................................... 21
6.4 Subgrade/Basement Walls .......................................................................................................... 21
Design Values .............................................................................................................. 21
Wall Drainage .............................................................................................................. 22
6.5 Temporary Excavations ............................................................................................................... 23
6.6 Permanent Cut and Fill Slopes .................................................................................................... 24
6.7 Site Drainage ............................................................................................................................... 24
7 EARTHWORK RECOMMENDATIONS ...................................................................................................... 25
7.1 Site Preparation and Grading ...................................................................................................... 25
7.2 Fill Material, Placement, and Compaction .................................................................................. 25
Structural Fill ............................................................................................................... 25
Materials ...................................................................................................................... 26
Placement and Compaction ...................................................................................... 26
Suitability of Excavated Material for Use as Fill ...................................................... 26
7.3 Wet Weather and Wet Condition Considerations ...................................................................... 27
7.4 Review of Plans and Specifications ............................................................................................. 28
7.5 Construction Observations ......................................................................................................... 28
Proposed Creekwood Development Page | iii
December 30, 2022
8 LIMITATIONS ......................................................................................................................................... 29
9 REFERENCES .......................................................................................................................................... 30
Figures
Figure 1 – Site Location Map
Figure 2 – Site and Exploration Plan
Figure 3 – Site Vicinity Map
Figure 4 – NRCS Soils Map
Figure 5 – Geologic Map
Figure 6 – DNR Landslide Inventory
Figure 7 – Liquefaction Susceptibility Map
Figure 8 – Fault Hazards Map
Figure 9 – Typical Drainage and Backfilling
Figure 10 – 2018 IBC Appendix J Detail
Appendices
Appendix A – Subsurface Explorations
Appendix B – Laboratory Test Results
Appendix C – Slope Stability Analysis
Proposed Creekwood Page |1
December 30, 2022
1 INTRODUCTION AND PROJECT DESCRIPTION
This Updated Geotechnical Engineering Report presents the results of our geotechnical engineering
studies for the proposed Creekwood residential plat to be constructed in Federal Way,
Washington. The location of the project is shown on the attached Site Location Map, Figure 1.
The project site is located between 21st Avenue SW and SW Dash Point Road. Our services
included excavating a total of thirteen test pits, excavating three hand augers, drilling ten borings
to depths of 4½ to 51½ feet below existing grades, performing laboratory testing on select
samples, completing detailed slope stability analyses for the proposed grading plan, addressing
the City of Federal Way (the City) Critical Areas Ordinance Title 18, and providing geotechnical
recommendations for the design and construction of the proposed residential plat.
Our understanding of the updated project scope is based on our correspondence with you and
your project civil engineer (Barghausen Consulting Engineers). We have reviewed our previously
prepared Updated Geotechnical Engineering Report dated April 28, 2017 and all
addendum/comment response letters to the City and their third party reviewer GeoDesign Inc
(now NV5), our understanding of the Federal Way current Development Codes, and our
experience in the area.
The proposed Creekwood development includes twenty new residential lots with associated
roads, stormwater tracts, utilities, and open space areas. The lots will be accessed off a new road
that extends west from 21st Avenue SW. A secondary connection will be made to the current
southern terminus of 22nd Avenue SW. The new road will generally be at grade, but some minor
cuts will be required along the north side of the road in front of Lots 16 through 20. The originally
proposed soldier pile wall where the new road crosses the ravine in the north-central portion of
the site will be replaced with a constructed an earth fill embankment supported by cast-in-place
retaining walls will be used. Also, the proposed lined stormwater detention pond with tiered
retaining walls will be replaced with an underground detention vault. No grading or development
will occur on the steep slope area at the back side of Lots 2 through 20. We anticipate the
proposed residences will consist of conventional one or two-story wood-framed structures
supported on shallow foundations and associated driveways. Some of the residences will have
daylight basements in order to accommodate the proposed grading plan. The project site and
the proposed development are shown on the attached Site and Exploration Plan and Site Vicinity
Map, Figures 2 and 3, respectively.
Proposed Creekwood Page |2
December 30, 2022
We received signed authorization to proceed with this updated report and our scope of services
from Barry Margolese at Amalani LLC and Tom Barghausen, Barghausen Consulting Engineers
(Barghausen) on November 10, 2022. This report is based on the current proposed civil design
plans provided by Barghausen dated November 28, 2022.
2 SUBSURFACE EXPLORATIONS
2.1 Vertical Datum
The elevations referred to in this report are based on the survey completed by Barghausen, Inc
using the NGVD29 datum. Our assumptions and understanding of the proposed grading of the
project are based on our conversations and email correspondence with Tom Barghausen, Teague
Aalvik of Barghausen Consulting Engineers (Barghausen) and other members of the design team,
as well as the Grading and Utility Plan provided to us on December 6, 2022.
2.2 Exploration Program Summary
GeoResources, LLC (GeoResources) evaluated subsurface conditions across the project site by
excavating a series of test pits, hollow-stem auger borings, and hand augers. Table 1, below,
summarizes the approximate functional locations, surface elevations, and termination depths of
our explorations.
The test pits, designated TP-1 through TP-13 and boring B-1 were excavated and drilled on
January 3, 2014. We returned to the site on January 14, 2014 and completed borings B-2 through
B-4. In order to address third-party review comments, we drilled borings B-5 through B-9
between August 10, 2015 and August 14, 2015. Three hand auger explorations were excavated
on August 24, 2015. The specific number, locations, and depths of our explorations were selected
based on the configuration of the proposed development and were adjusted in the field based
on site access limitations. The approximate locations of the subsurface explorations are shown
on the Site and Exploration Plan, Figure 2. Descriptions of the exploration program and
exploration logs are presented in Appendix A.
Proposed Creekwood Page |3
December 30, 2022
TABLE 1
APPROXIMATE LOCATIONS, ELEVATIONS, AND DEPTHS OF EXPLORATIONS
Test Pit/ Boring
Number Functional Location
Surface
Elevation1
(feet)
Termination
Depth
(feet)
Termination
Elevation1
(feet)
TP-1 NE corner of site 276 11.0 265.0
TP-2 Above top of slope, proposed lot 23 277 9.0 268.0
TP-3 Along existing trail, on proposed roadway 274 11.0 270.0
TP-4 Top of Slope 130’ SW of TP-3 245 10.0 235.0
TP-5 East knob, proposed stormwater tract 250 8.0 242.0
TP-6 West knob, proposed stormwater tract 250 8.0 242.0
TP-7 West knob, SW of TP-6 246 8.0 238.0
TP-8 West of TP-7 251 8.0 243.0
TP-9 Center of west portion of site 256 9.0 247.0
TP-10 West knob, near north slope 259 10.0 249.0
TP-11 North-center of west knob, East of TP-9 256 8.0 248.0
TP-12 West knob 250 5.0 245.0
TP-13 West knob, near 22nd Av SW 238 7.0 231.0
B-1 Center of north property line 234 11.5 222.5
B-2 275’ SW of B-1, 115’ NE of slope 244 41.5 202.5
B-3 305’ S by 175 W of NE property corner 246 31.0 215
B-4 90’ N of B-3 249 51.5 197.5
B-5 160’ SW of B-1 248 50.8 197.2
B-6 Top of Slope, 200’ S of B-5 250 51.5 198.5
B-7 E of Slope, 65’ S of N property line 240 51.5 188.5
B-8 Top of slope, 215’ SE of B-7 270 51.5 218.5
B-9 Bottom of Slope, 250’ SE of B-6 196 16.5 179.5
B-10 Bottom of Slope, 315’ W of B-9 202 14.0 188.0
HA-1 On slope, 135’ S of TP-5 210 7.5 202.5
HA-2 300’ S of N property line, E of stream 195 5.5 189.5
HA-3 Bottom of Slope, 275’ W of B-6 210 4.5 203.5
1 Elevation datum: Grading and Utility Plan prepared by Barghausen using the City of Federal Way NGVD29 datum.
The explorations completed as part of this evaluation indicate the subsurface conditions at
specific locations only, as actual conditions can vary across the site. Furthermore, the nature and
extent of such variation would not become evident until additional explorations are performed
or until construction activities have begun. Based on our experience in the area and extent of
prior explorations in the area, it is our opinion that the soils encountered in the explorations are
generally representative of the soils at the site.
Proposed Creekwood Page |4
December 30, 2022
Test Pits
The test pits were excavated by a medium sized track-mounted excavator operated by a licensed
earthwork contractor working under subcontract to GeoResources. Our field representative
logged the subsurface conditions encountered in each test pit and obtained representative soil
samples. The soil densities presented on the test pit logs were based on the difficulty of
excavation and our experience. The test pits were backfilled with excavated soil and tamped in
place, but not otherwise compacted.
Borings
During drilling, soil samples were obtained at 2½ and 5 foot depth intervals in accordance with
Standard Penetration Test (SPT) as per the test method outlined by ASTM D1586. The SPT method
consists of driving a standard 2 inch-outer-diameter split-spoon sampler 18 inches into the soil
with a 140 pound hammer. The number of blows required to drive the sampler through each 6
inch interval is counted, and the total number of blows struck during the final 12 inches is
recorded as the Standard Penetration Resistance, or “SPT blow count”. If a total of 50 blows are
recorded within any 6-inch interval (refusal), the driving is stopped, and the blow counts are
recorded as 50 blows for the actual distance the sampler was driven. The resulting Standard
Penetration Resistance values indicate the relative density of granular soils and the relative
consistency of cohesive soils. Each boring was then abandoned by the driller in accordance with
state law.
Hand Augers
A field representative from our office continuously excavated our hand auger test holes,
maintained logs of the subsurface conditions encountered, obtained representative soil samples,
and observed pertinent site features. Soil densities presented on the hand auger logs were
estimated based on the difficulty of excavation and our experience. Each hand auger was then
backfilled with the excavated soil.
3 LABORATORY TESTING
Geotechnical laboratory tests were performed on select samples retrieved from our explorations
to estimate the index engineering properties of the soils encountered. Laboratory testing
included visual soil classification per ASTM D2487 and ASTM D2488, moisture content
determinations per ASTM D2216, and grain size analyses per ASTM D6913 standard procedures.
The results of the laboratory tests are summarized below in Table 2 and graphical outputs are
included in Appendix B.
Proposed Creekwood Page |5
December 30, 2022
TABLE 2:
LABORATORY TEST RESULTS FOR ON-SITE SOILS
Exploration Number
Moisture
Content
(percent)
Gravel
Content
(percent)
Sand
Content
(percent)
Silt/Clay
Content
(percent)
D10 Ratio
(mm)
TP-1, D: 8’ 7.3 25.0 69.0 6.0 0.1569
TP-3, D: 3’ 10.4 25.0 68.0 7.0 0.1275
TP-4, D: 6-10’ 7.1 16.0 76.0 8.0 0.1278
TP-5, D: 1.5-3.5’ 11.4 2.0 78.0 20.0 <0.075
TP-7, D: 2-6’ 12.1 18.0 68.0 14.0 <0.075
B-5, S-5, D: 15’ 8.3 1.7 87.3 11.0 <0.075
B-5, S-7, D: 25’ 5.9 0.1 89.3 10.6 <0.075
B-5, S-9, D: 35’ 18.0 0.5 91.4 8.1 0.0951
B-5, S-10, D: 40’ 14.7 17.6 73.0 9.4 0.0844
B-6, S-2, D: 5’ 4.3 0.3 89.2 10.5 <0.075
B-8, S-1, D: 5’ 5.7 4.5 81.3 14.2 <0.075
B-9, S-2, D: 5’ 19.4 16.5 72.1 11.4 <0.075
B-9, S-5, D: 12.5’ 18.9 2.9 92.5 4.6 0.2092
4 SURFACE AND SUBSURFACE CONDITIONS
4.1 Surface Conditions
As stated, the subject parcel is located west of 21st Avenue SW and south of the end of 22nd
Avenue SW in the Dash Point area of Federal Way, Washington. The parcel is rectangular in
shape, measuring approximately 655 feet (north to south) by 1,322 feet (east to west) and
encompassing approximately 20 acres. The site is currently vacant. The site is bounded by
existing single family development and the south terminus of 22nd Avenue SW on the north, 21st
Avenue SW and existing commercial development on the east, and by wooded slopes and trails
on the south and west.
Located along the western margin of the Federal Way glacial upland area, the site generally
slopes down from the north to south to the Dakota Creek drainage, while the western side of the
site slopes down to the west. In the northwest portion of the site there are slopes inclined down
to the north at about 30 to 50 percent. The west central and northeast portions of the site vary
in steepness, mostly sloping down to the south and southeast at inclinations of 20 to 50 percent,
with areas of the proposed buildings sites flatter than 20 percent. Near the south end of 22nd
Avenue SW is the head of an unnamed stream, which flows to the south. The side slopes of this
Proposed Creekwood Page |6
December 30, 2022
unnamed stream are inclined at approximately 35 to 55 percent. This unnamed stream flows
into the west flowing Dakota Creek in the south-central portion of the site.
The north side wall of Dakota Creek slopes down to the south at 20 to 50 percent. The existing
site conditions are shown on the Site Vicinity Map, Figure 3. The total topographic relief across
the site is on the order of 150 feet.
No surface water or seepage was observed on the flatter upland portion of the site or on the
steep slope areas along the north property line. There are mapped wetlands on the sloping,
southern portions of the site. Soundview Consultants has performed a Wetland and Fish and
Wildlife Habitat Assessment and Buffer Enhancement Plan dated December 2022. These
wetlands are generally located in the central and eastern portions of the site (below proposed
lots 17 through 20). There were no observed seeps or other delineated wetland areas on the
slopes below lots 3 through 16. Dakota Creek flows from east to west along the southern portion
of the site. A walking /utility access path is located along the north side of Dakota Creek and
along the ravine that bisects the site from the stream up to the south terminus of 22nd Avenue
SW.
Erosion was observed at the northern terminus of the ravine that begins south of the end of 22nd
Avenue SW. This erosion appears related to uncontrolled discharging of stormwater runoff from
the adjacent plat, significant yard waste dumping into the ravine, and the past installation of the
stormwater bypass line that extends south along the west side of the ravine. The old culvert
discharged above the ravine and based on information obtained from the City, caused the
erosion that created the ravine. Erosion was observed on the east side of the ravine in the form
of exposed soils. Uncontrolled yard waste along the north side of the property has inhibited
vegetation growth. Erosion was observed along the margins of the ravine headwalls and a
landslide deposit is mapped in the eastern portion of the site.
Since our original report was prepared, we understand that a landslide occurred about 700 feet
north of the site on the slope that extends down from the top of the glacial upland area to SW
Dash Point Road (SR 509). The landslide occurred on March 16, 2017. The City hired Landau
Associates to do an initial review of the slide. In their July 6, 2017 Technical Memorandum to the
City, they concluded that the rise of the “true” groundwater table within the deeper advanced
outwash caused the shallow colluvium to fail, along with surface water from the ditch along SW
308th Street and above the failure. The topography, surface water runoff, and soil conditions
differ in this area from the main Creekwood Plat property, and the area of the slide should have
no impact on the proposed project.
Proposed Creekwood Page |7
December 30, 2022
4.2 Site Soils
The USDA Natural Resource Conservation Service (NRCS) Web Soil Survey maps the soils in the
area of the site as Alderwood gravelly sandy loam (AgB and AgD) and Alderwood & Kitsap soil
(AkF). An excerpt of the NRCS map for the site vicinity is attached as Figure 4.
• Alderwood gravelly sandy loam (AgB and AgD): The Alderwood soils are derived from glacial
till that form on slopes of 0 to 6 percent (AgB) or 15 to 30 percent (AgD) slopes and are
listed as having “slight” (AgB) or “moderate” (AgD) erosion hazards, respectively. These
soils are included in hydrologic group B/C.
• Alderwood & Kitsap soil (AkF): The Kitsap soils are described as being derived from
undifferentiated glacial till and/or lacustrine deposits. The Alderwood-Kitsap soils form
on very steep slopes and have a “very severe” erosion hazard when exposed. These soils
are included in hydrologic group C/D.
4.3 Site Geology
Since our original report was completed, the originally referenced Geologic Map of the Poverty Bay
7.5-minute Quadrangle, Washington (Booth, D.B., Waldron, H.H., and Troost, K.G., 2003) was
updated. The newer Lidar-revised geologic map of the Poverty Bay 7.5’ quadrangle, King and Pierce
Counties, Washington by Tabor, Booth, and Troost (2014) indicates the upper, flatter portions of
the site are underlain by ice contact deposits (Qvi), that are similar to the originally referenced
recessional outwash deposits but are less well sorted and have a higher silt content. The ice
contact soils may also locally contain larger intact clasts of the underlying glacial till. The site
area is also underlain glacial till (Qvt) and advance outwash (Qva). The new map shows a landslide
deposit (Qls) in the eastern portion of the site and alluvium (Qva) along the flowing creek on the
south side of the site. These glacial soils were deposited during the Vashon Stade of the Fraser
Glaciation, approximately 12,000 to 15,000 years ago. An excerpt of the above referenced map is
included as Figure 5.
• Alluvium (Qa): Alluvial soils generally consist of normally consolidated, stratified deposits
of sand, silt, clay, and occasional peat that were deposited along Dakota Creek flowing
from east to west across the south side of the site. The existing topography, as well as
the surficial and shallow soils in the area, are the result of fluvial action, including down-
cutting by the river, channel meandering and migration, and flood deposits.
• Landslide deposits (Qls): Landslide deposit consists of jumbled mixtures of gravel, sand, silt
and clay that are typically in a loose condition. The landslides deposits are associated with
mass wasting events along the coastal bluffs along the Puget Sound, particularly where
coarse deposits overly finer grain deposits. Some of the large areas of landslide debris
are associated with prehistoric mass wasting events associated with the retreat of the
prehistoric continental ice mass, while other areas are more recent.
Proposed Creekwood Page |8
December 30, 2022
• Ice contact deposits (Qvi): The ice contact deposits typically consist of a poorly sorted, lightly
stratified mixture of silt, sand and gravel that may locally contain intact pieces of glacial
till. The ice contact soils were deposited by along the margins of the ice mass. The ice-
contact deposits may or may not have been overridden by continental ice mass and are
typically considered normally consolidated and off moderate strength characteristics. This
soil unit is generally observed to be in a normally consolidated condition and exhibits
moderate strength and moderate compressibility characteristics where undisturbed.
Stormwater infiltration potential in recessional outwash soils is generally favorable.
• Glacial till (Qvt): The glacial till consists of a heterogeneous mixture of clay, silt, sand and
gravel that was deposited at the base of the continental ice mass and is typically
encountered in a very dense condition. Because the glacial till was overridden by the ice
mass, it is considered over consolidated and is found in a very dense condition and
exhibits high strength and low compressibility characteristics where undisturbed.
Because of the compact and silty nature of glacial till, the potential for stormwater
infiltration is low.
• Advance outwash (Qva): The advance outwash typically consists of a poorly sorted, lightly
stratified mixture of sand and gravel that may locally contain silt and clay. The advance
outwash was deposited by meltwaters emanating from the advancing ice mass. Because
these soils were subsequently overridden by the continental ice mass, they are
considered over-consolidated, and exhibit high strength and low compressibility
characteristics where undisturbed. Stormwater infiltration potential in advance outwash
soils is generally favorable.
4.4 WGS Landslide Mapping
We reviewed the Washington Geological Survey (WGS) protocol landslide mapping for the site
and surrounding area, which maps landslide landforms using lidar based on the criteria provided
in the Protocol for Landslide Mapping from LiDAR Data in Washington State (Slaughter, et al, 2017).
This data was not available at the time our original report was prepared. The WGS protocol
landslide mapping has identified two landslides within the areas identified as natural hazards
areas in both this report and our original report. The western of the two slides, generally aligns
with the City of Federal Way sewer and storm drain easements that extend south from the
terminus of 22nd Avenue SW. This slide is identified as a non-field verified prehistoric (more than
150 years old) earth or debris flow with an estimated head scarp height of 28 feet and estimate
failure depth of 24 feet. The larger eastern landslide is identified as a non-field verified pre-
historic earth or debris flow with a 47-foot tall head scarp and 43-foot failure depth. An excerpt
of the WGS protocol landslide mapping that includes the nearest landslide features to the site is
attached as Figure 6.
Proposed Creekwood Page |9
December 30, 2022
4.5 Subsurface Conditions
At the locations of our explorations, we encountered slightly variable subsurface conditions that
generally confirmed the mapped stratigraphy. The subsurface conditions encountered in each
exploration are included below in Table 3 and descriptions of the various soil types encountered
across the site are summarized in the following sections.
TABLE 3
APPROXIMATE THICKNESSES, DEPTHS, AND ELEVATIONS OF SOIL LAYERS
Test Pit /
Boring
Number
Thickness of
Forest Duff /
Topsoil
(feet)
Thickness of
Alluvium
(feet)
Thickness of
Weathered Till
/ Outwash
(feet)
Depth to Dense
Glacial Till /
Outwash
(feet)
Elevation1 of
Dense Glacial
Till / Outwash
(feet)
TP-1 NE NE NE 2.0 261.5
TP-2 1.0 NE 3.0 4.0 262.3
TP-3 1.5 NE 2.5 4.0 263.5
TP-4 2.0 NE 2.5 3.5 229.5
TP-5 1.5 NE 2.0 3.5 236.2
TP-6 1.0 NE 2.0 3.0 236.5
TP-7 1.0 NE 5.0 5.7 229.3
TP-8 1.0 NE 4.0 5.0 N/E
TP-9 0.5 NE 4.5 5.0 N/E
TP-10 1.0 NE 4.0 5.0 N/E
TP-11 1.0 NE 3.0 4.0 N/E
TP-12 1.0 NE 2.5 3.5 240.8
TP-13 1.0 NE 2.0 3.0 228.5
B-1 1.5 10.0 + NE N/E N/E
B-2 2.5 12.5 7.5 20.0 214.0
B-3 1.0 4.0 2.0 7.0 237.0
B-4 2.5 2.5 5.0 10.0 239.0
B-5 0.5 9.5 N/E 10.0 230.0
B-6 0.5 9.5 N/E 10.0 240.0
B-7 1.0 14.0 N/E 15.0 221.0
B-8 0.5 14.5 25.0 * 40.0 222.0
B-9 0.5 16 + N/E N/E N/E
B-10 1.5 12.5 + N/E N/E N/E
HA-1 1.0 6.5 N/E N/E N/E
HA-2 0.5 5.0 N/E N/E N/E
HA-3 1.0 3.5 N/E N/E N/E
1 Elevation datum: Grading and Utility Plan prepared by Barghausen using the City of Federal Way NGVD29 datum.
Notes: + Encountered to the full depth explored, * Recessional outwash
Proposed Creekwood Page |10
December 30, 2022
• Surficial Materials: The site is typically covered by 6 to 12 inches of forest duff and topsoil,
with localized areas as thick as 18 to 30 inches. We anticipate that deeper areas of topsoil
and forest duff will be encountered in areas of larger trees and in localized depressions
across the site.
• Alluvium: In the lower portion of the site, near the wetland area and Dakota Creek, several
of our explorations encountered a medium stiff to stiff silt with some sand. The silt had
elevated moisture contents. Laboratory tests indicate that the silt is non-plastic. We
interpret these cohesive soils to be alluvium. The silt was typically underlain by loose to
medium dense sand with minor amounts of silt and variable amounts of gravel that we
also interpret to be alluvium.
• Recessional/Ice Contact Deposits: Below the surficial forest duff, our test pits typically
encountered loose to medium dense silty fine to medium sand with varying amounts of
gravel and minor amounts of roots. We interpret these shallow soils to be a shallow soil
horizon between the topsoil and the deeper glacial till.
• Glacial Till: The weathered and un-weathered glacial till soils encountered in upper
portions of many of our borings appear marginally suitable for reuse as structural fill at
their present moisture contents. However, these soils will be difficult or impossible to
reuse during wet weather, due to their moderately high fines contents, and may become
suitable for reuse during a period of dry weather if they can be aerated to reduce their
moisture content.
• Advance Outwash: The gravelly sands and sandy gravels underlying parts of the site will
provide a favorable source of fill soils that can be used in a broad range of weather
conditions, although aeration or sprinkling might be needed to achieve optimum
moisture content during especially wet or dry (more than 3 percent from optimum
moisture) conditions, respectively. Any boulders or large cobbles present in these soils
would need to be removed from the matrix for certain fill applications.
4.6 Groundwater
No groundwater seepage was observed in the test pits at the time of excavation, but three of our
deeper borings encountered groundwater seepage. Several of our test pits encountered
mottling at shallow depths which can be indicative of a perched groundwater table. As discussed
above in “Surface Conditions” of this report, there are several mid-slope seeps and wetland areas
in the central and eastern portions of the site. These areas have been identified by the project
wetland consultant, Soundview Consultants and described in detail in their Wetland Delineation
and Habitat Assessment. The depth of water in boring B-2 generally correlates to the
seeps/wetland areas of the south and east. However, the depth to perched groundwater in
boring B-4 and lack of wetlands/seeps on the slope below boring B-4 indicates that the perched
Proposed Creekwood Page |11
December 30, 2022
water table daylights at about the stream elevation further to the south. This water level, where
encountered, is depicted on the slope stability cross sections attached in Appendix C.
We interpret the observed mottling and mid-slope seeps/wetlands to be indicative of a perched
groundwater table. Perched groundwater develops when the vertical infiltration rate of
precipitation through a more permeable soil is slowed at depth by a deeper, less permeable soil
type. We expect that perched groundwater may develop seasonally atop the deeper and denser
glacial till or silt interbeds. The deeper groundwater seepage encountered in our borings
generally corresponded to the elevations of the mapped wetlands on the sloping portion of the
site. We anticipate fluctuations in the local groundwater levels likely will occur in response to
precipitation patterns, off site construction activities, and site utilization. After the site is
developed, the amount of seasonal perched groundwater should decrease over time.
We expect the water to be shallower in the wetter, winter months and deeper during the drier
winter months. Changes in local groundwater levels will also occur in response to off-site
construction activities and site utilization.
4.7 Aerial Photo Review
On April 28, 2015, a geologist from our office reviewed historic aerial photos at the Washington
State Department of Natural Resources’ air photo archives. We reviewed aerial photos collected
pre and post development of the Lakota Ridge plat. Aerial photographs reviewed dated from
1976 to 1995. Most of these photographs were from high elevations and had stereo-pairs, which
provided a three dimension view the site vicinity. The images supported the timeline described
above, with the scour channel below the Lakota Ridge plat visible in the 1978 photograph, and
the City of Federal Way stormwater bypass visible in the 1989 photograph.
5 GEOLOGIC HAZARDS
5.1 Seismic Hazards
Earthquake-induced geologic hazards per City of Federal Way Revised Code (2016 FWRC), Chapter
19.05.070.G(3) may include liquefaction, lateral spreading, slope instability, and ground surface
fault rupture. In our opinion, the potential for liquefaction and lateral spreading is not significant
because of the dense nature of the on-site soils and the groundwater depth. Additionally, the
Liquefaction Susceptibility Map of King County (Figure 7) indicates the site is an are mapped as
having a “very low” susceptibility to liquefaction. As previously described, the ground surface in
the site area generally slopes down to the south from the existing terminus of 22nd Avenue SW.
Proposed Creekwood Page |12
December 30, 2022
Based on our review, subsurface explorations and slope stability modeling, it is our opinion the
potential for earthquake-induced slope instability is low. In addition, the site is located near the
Tacoma fault zone, as show on Figure 8, but no evidence of ground fault rupture was observed
in the subsurface explorations. Therefore, in our opinion the potential for ground surface fault
rupture is low.
5.2 Erosion Hazard Areas
The FWRC, Chapter 19.05.070.G(1) defines erosion hazard areas as “those areas identified by the
U.S. Department of Agriculture’s (USDA) Natural Resource Conservation Service (NRCS) as having
a moderate to severe or severe to very severe rill and inter-rill erosion hazard due to natural
agents such as wind, rain, splash, frost action or stream flow; those areas containing the following
group of soils when they occur on slopes of 15 percent or greater: Alderwood-Kitsap (“AkF”),
Alderwood gravelly sandy loam (“AgD”), Kitsap silt loam (“KpD”), Everett (“EvD”), and Indianola
(“InD”); and those areas impacted by shore land and/or stream bank erosion”
The USDA NRCS web soil survey (Figure 4) maps the soils on the flatter upland area as the
Alderwood soils, the Alderwood soils typically have “slight” or “moderate” erosion hazards,
depending on slope inclination. The soils along the more steeply sloping southwestern and
western margin of the site are mapped as the Alderwood-Kitsap formation which have a “severe”
erosion hazard. Based on the mapping, the more steeply sloping portions of the site meet the
technical definition of an Erosion Hazard area per the City code.
5.3 Landslide Hazard Areas
The FWRC, Chapter 19.05.070.G(2) defines landslide hazard areas as “those areas potentially
subject to episodic downslope movement of a mass of soil or rock including but not limited to
the following areas”:
a. Any area with a combination of:
i. Slopes greater than 15 percent;
ii. Permeable sediment overlying a relatively impermeable sediment or bedrock;
iii. Springs or groundwater seeps.
b. Any area which has shown movement during the Holocene epoch, from 10,000 years
ago to the present, or which is underlain by mass wastage debris of that epoch.
c. Any area potentially unstable as a result of rapid stream incision, stream bank erosion
or undercutting by wave action.
d. Any area located in a ravine or on an active alluvial fan, presently or potentially subject
to inundation by debris flows or flooding.
Proposed Creekwood Page |13
December 30, 2022
e. Those areas mapped as Class U (unstable), UOS (unstable old slides), and URS (unstable
recent slides) by the Department of Ecology’s Coastal Zone Atlas.
f. Areas designated as quaternary slumps, earthflows, mudflows, lahars, or landslides on
maps published by the U.S. Geological Survey or Washington State Department of
Natural Resources.
g. Slopes having gradients greater than 80 percent subject to rockfall during seismic
shaking
h. Any area with a slope of 40 percent or steeper and with a vertical relief of 10 or more
feet except areas composed of consolidated rock. A slope is delineated by establishing
its toe and top and is measured by averaging the inclination over at least 10 feet of
vertical relief.
The slopes on the south side of the parcel are steeper than 15 percent and have several mid-
slope wetlands/seepage zones. The seeps did not extend the full length of the slope, but were
generally isolated to the eastern portion of the parcel consistent with the wetland mapping
performed by Soundview Consultants. No landslide deposits were mapped on the original 2003
Poverty Bay Quadrangle, but the 2014 update identified two landslides as described above in
section 4. 4 of this report. Neither slide shown on the WGS landslide mapping (Figure 6) has been
field verified. Based on our field reconnaissance, review of aerial photographs, and subsurface
explorations, the smaller, western landslide generally aligns with the City utilities that were
installed in 1989 that predates the Lidar mapping. The eastern landslide appears consistent with
topographic features observed onsite. The proximity of both features to the proposed
development has been evaluated by our slope stability analyses in section 5.4 of this report. An
area of landslide debris/mass wasting deposit is noted on the 2003 geologic map, but this area
is located north and west of the site and west of Dash Point Road.
The stream that flows from east to west (Dakota Creek) is located in a shallow, incised stream
channel. More deeply incised stream bank erosion was noted along the ravine that extends
south from 22nd Avenue SW, which appears directly related to uncontrolled discharging from
the municipal storm drainage system. No areas of alluvial fans were noted or observed on or
within the vicinity of the subject site. The Alderwood-Kitsap soils mapped on the more steeply
sloping southern portion of the site are listed as having a “severe” limitation for building because
of slopes by the USDA Soil Conservation Service. The Coastal Atlas does not extend to the subject
site. We would anticipate that the flatter, upland portion of the site would be mapped as stable
while the more steeply sloping southern and western portions of the site and offsite areas would
be mapped as “intermediate” or “unstable” because of the height and inclination of the slopes.
Additionally, several slopes below the proposed lots are steeper than 40 percent with more than
10 feet of relief.
Proposed Creekwood Page |14
December 30, 2022
Based on our observations and literature review, the more steeply sloping eastern portion of the
site meets the technical definition (15 percent slopes with seeps and 40 percent slopes with more
than 10 feet of relief) of a Landslide Hazard Area. The top of slope is depicted on the Site and
Exploration Plan, Figure 2.
5.4 Slope Stability
We originally analyzed the global and internal slope stability of both the existing and proposed
slope geometries using cross sections A-A’, B-B’, C-C’, D-D’, E-E’. To address previous third party
review comments, we included four additional profiles, F-F’, G-G’, ND-ND’, and SP-SP’, in our slope
stability analysis. The locations of all profiles are shown on Figure 2. At each location, a
piezometric (groundwater) table was used based on the depth to water in our borings and
locations of mid-slope seeps and springs, as wells as the stream channel on the south side of the
site. The cross section for each of these locations, as well as stability results using both static and
dynamic conditions are included in Appendix C.
We used the computer program SLIDE2 version 9.026, from RocScience 2022, to perform the
slope stability analyses. The computer program SLIDE uses a number of methods to estimate
the factor of safety (FS) of the stability of a slope by analyzing the shear and normal forces acting
on a series of vertical “slices” that comprise a failure surface. Each vertical slice is treated as a
rigid body; therefore, the forces and/or moments acting on each slice are assumed to satisfy
static equilibrium (i.e., a limit equilibrium analysis). The FS is defined as the ratio of the forces
available to resist movement to the forces of the driving mass. An FS of 1.0 means that the driving
and resisting forces are equal; an FS less than 1.0 indicates that the driving forces are greater
than the resisting forces (indicating failure). We used the Generalized Limit Equilibrium method
using the Morgenstern-Price analysis, which satisfies both moment and force equilibrium, to
search for the location of the most critical failure surfaces and their corresponding FS. The most
critical surfaces are those with the lowest FS for a given loading condition, and are therefore the
most likely to move.
Since our original report and addendum were completed, the City adopted the 2018 International
Building Code which results in a significant increase of the seismic acceleration used in the
stability analysis. The proposed ground surface elevations were modified according on the
various cross sections from our previous work to reflect the current grading plan. Some of the
soil index properties referenced above are slightly higher than in our previous report, but they
still fall within parameters of both the Geotechnical Properties of Geologic Materials by Koloski,
Schwarz, and Tubbs as presented in the Engineering Geology In Washington, Volume 1
(Washington Division of Geology and Earth Resources Bulletin 78) and the Washington State
Proposed Creekwood Page |15
December 30, 2022
Department of Transportation (WSDOT) Geotechnical Design Manual (GDM). Details of the slope
stability analyses are included in Appendix C. Table 4, below, summarizes the results of our slope
stability analyses.
TABLE 4
SLOPE STABILTY ANALYSIS RESULTS
Cross Section Line Existing Static Existing Seismic Proposed Static Proposed Seismic
A-A’ 1.3 0.6 2.3 1.2
B-B’ 2.9 1.2 2.8 1.2
C-C’ 2 1.3 4.5 2.1
D-D’ 2.2 1.4 2.2 1.3
E-E’ 1.2 0.7 1.2/3.5 0.7/1.5
F-F’ 1.4 0.7 1.4/2 0.7/1.2
G-G’ 2.6 1.4 2.6 1.4
SP-SP’ 2.2 1.3 2.6 1.3
ND-ND’ 2.2 1.3 2.2 1.3
5.5 Buffers and Setbacks
The FWRC 19.145.230 – “Landslide hazard areas protection measures” requires a standard 50-foot
setback from geologically hazardous areas. The code (FWRC 19.145.230 (4) allows for reduction
of the buffers and setbacks, and even for improvements within the landslide hazard area, when
a qualified professional demonstrates that the improvements will not lead to or create any
increased slide hazard or be at risk of damage by the landslide hazard.
The proposed lot layout was originally created using a reduced buffer/setback of 25-feet. Lots
that are located above the delineated landslide hazard areas provide building pad areas with
factors of safety greater 1.5 and 1.1 for the static and seismic conditions, respectively, while
maintaining the required 25-foot setback from the determined geologically hazardous areas. As
shown on the current Site and Exploration Plan, Figure 2, the building envelope for each lot is
setback 25 feet from the top of slope/landslide hazard area line. The proposed lot layout satisfies
this requirement and provides lots that have sufficient building area while maintaining the
required 25-foot setback from the determined geologically hazardous areas.
Some grading and filling may be required along the western side of lots 6-11, but all grading will
occur outside of the landslide hazard area. Any such grading on these lots should conform to
Proposed Creekwood Page |16
December 30, 2022
the recommendation outlined in Appendix J of the International Building Code for grading on
slopes steeper than 5H:1V (Horizontal:Vertical) as discussed below in the “Permanent Cut and
Fill Slopes” section of this report.
As shown in the slope stability modeling (section A-A’), there is no adverse impact to the slopes
or proposed development from the modification to the setback areas required on lots in this
area. Buffer modifications will be required where Road B crosses the ravine and connects to Road
A (extension of 22nd Avenue SW). In this location, the roadway is required for fire and EVA access,
as well as for traffic connectivity. The road will cross the incised ravine. The ravine is not a natural
occurring feature but was created by uncontrolled discharge from the municipal storm system
and yard waste dumping. The proposed structural fill soil embankment supported by cast-in-
place retaining walls will minimize intrusion in the wetland/stream buffer downslope of the
roadway. Dense soils were observed on the eastern wall of the ravine, while the soils
encountered in the boring on the west side of the ravine were generally in a medium dense
condition.
The proposed modifications will result in an increase of the overall stability of this portion of the
site. It is our opinion that this report and accompanying plans prepared by Barghausen, satisfy
the requirements of FWRC 19.145.230 for allowing a development activity or land surface
modification within the required 25-foot buffer/setback from a geologic hazard. Furthermore,
the reduced buffer was accepted by the City’s third-party reviewer.
6 ENGINEERING CONCLUSIONS AND RECOMMENDATIO NS
Based on our current understanding of the proposed project and on the results of our
geotechnical analyses, we have developed geotechnical recommendations for design and
construction of the proposed Creekwood Plat Project. The following sections provide
recommendations for seismic design considerations, foundation design, permanent building
walls, floor slabs, drainage, pavements, and other pertinent geotechnical design and construction
issues.
6.1 Seismic Design Recommendations
The site is located in the Puget Sound region of western Washington, which is seismically active.
Seismicity in this region is attributed primarily to the interaction between the Pacific, Juan de Fuca
and North American plates. The Juan de Fuca plate is subducting beneath the North American
plate at the Cascadia Subduction Zone (CSZ). This produces both intercrustal (between plates)
Proposed Creekwood Page |17
December 30, 2022
and intracrustal (within a plate) earthquakes. In the following sections we discuss the design
criteria and potential hazards associated with the regional seismicity.
Seismic Site Class
Based on our observations and the subsurface units mapped at the site, we interpret the
structural site conditions to correspond to a seismic Site Class “C” in accordance with the 2018
IBC documents and American Society of Civil Engineers (ASCE) standard 7-16 Chapter 20 Table
20.3-1. This is based on the reviewed and anticipated range of SPT (Standard Penetration Test)
blow counts for the soil types in the site area. These conditions were assumed to be
representative for the subsurface conditions for the site.
Design Parameters
The U.S. Geological Survey (USGS) completed probabilistic seismic hazard analyses (PSHA) for the
entire country in November 1996, which were updated and republished in 2002 and 2008. We
used the ATC Hazard by Location website to estimate seismic design parameters at the site. Table
5, below, summarizes the recommended design parameters.
TABLE 5:
2018 IBC PARAMETERS FOR DESIGN OF SEISMIC STRUCTURES
Spectral Response Acceleration (SRA) and Site
Coefficients Short Period
Risk Category II/III
Mapped SRA Ss = 1.358g
Site Coefficients (Site Class C) Fa = 1.200
Maximum Considered Earthquake SRA SMS = 1.630g
Design SRA SDS = 1.087
Peak Ground Acceleration
The mapped peak ground acceleration (PGA) for this site is 0.574g. To account for site class, the
PGA is multiplied by a site amplification factor (FPGA) of 1.2. The resulting site modified peak
ground acceleration (PGAM) is 0.688g. In general, estimating seismic earth pressures (kh) by the
Mononobe-Okabe method or seismic inputs for slope stability analysis are taken as 50 percent
of the PGAM, or 0.34g.
Proposed Creekwood Page |18
December 30, 2022
Earthquake Induced Geologic Hazards
Earthquake-induced geologic hazards may include liquefaction, lateral spreading, slope
instability, and ground surface fault rupture. Liquefaction is a phenomenon where there is a
reduction or complete loss of soil strength due to an increase in pore water pressure in soils. The
increase in pore water pressure is induced by seismic vibrations. Liquefaction primarily affects
geologically recent deposits of loose, uniformly graded, fine-grained sands and granular silts that
are below the groundwater table. The site is mapped as having a “very low” liquefaction
susceptibility by the Liquefaction Susceptibility Map of King County, Washington (palmer et al,
2004); an excerpt of this map is included as Figure 7.
The soils encountered in our explorations primarily consist of medium dense to very dense sand
(advance outwash sand and glacial till), alluvium was observed near the creek beds. In our
opinion, the glacial soils are not prone to liquefaction induced settlements during a seismic event,
the alluvium may experience some liquefaction induced settlement, but due to the limited depth
of alluvium and distance to the proposed development, the settlement should be minimal.
Based on our slope stability analyses (see Appendix C), it is our opinion that the potential for
earthquake-induced slope instability on the site is low. According to the Department of Natural
Resources Geologic Hazards Map (Geologic Information Portal), the site is located within the
Tacoma Fault zone, with delineated faults being about 0.8 to 1.55 miles south and north of the
site, respectively. As mentioned previously a copy of the USGS Interactive Fault Map for the
general area is included as Figure 8. No evidence of ground fault rupture was observed in the
subsurface explorations or out site reconnaissance. Therefore, in our opinion, the proposed
structure should have no greater risk for ground fault rupture than other structures located in
the area.
6.2 Shallow Foundation design
Based on the encountered subsurface conditions at the locations explored and the preliminary
site layout, it is our opinion that the residences, vault, and retaining walls associated with the
Road “B” alignment be supported by shallow foundations. Some of the walls will need to be
supported on pin piles, discussed below is Section 6.3. Spread footings should be founded on
the medium dense to dense to very dense native glacial soils, or on structural fill that extends to
suitable native soils. Based on our understanding of the proposed locations of the single-family
residences it is our opinion that shallow foundations may be used to support the buildings;
however, considerations for setbacks from the steep slope should be taken. We have not been
Proposed Creekwood Page |19
December 30, 2022
provided with the design loads and have assumed that the residences will be lightly loaded, but
the vault and Road “B” retaining wall will impose higher loads.
Spread Footing Design
Footings should bear either on properly placed and compacted structural fill or suitable native
soils. Removal of unsuitable soils below the footings should extend beyond the foundation edges
1-foot horizontally for every 1-foot of vertical excavation. Loose, soft, or other unsuitable
material present at the base of the excavation should be removed prior to placement of
structural fill. The soil at the base of the excavations should be protected against disturbance
from weather, traffic, or other adverse conditions. The excavation should be backfilled with
suitable materials as described in the “Structural Fill” section of this report. If Control Density Fill
(CDF) is used as backfill, the horizontal extent of the excavation can be limited to 1H:2V on each
side of the footing.
We recommend a minimum width of 24 inches for isolated footings and at least 18 inches for
continuous wall footings. All footing elements should be embedded at least 18 inches below
grade for frost protection. For footing bearing surfaces prepared as described in this report we
recommend using an allowable soil bearing capacity of 2,500 psf (pounds per square foot) for
design of the residence but the vault and retaining walls can be designed for 3,500 provided they
are cast directly on the deeper, dense glacially consolidated soils. This value is for combined
dead and long-term live loads. The weight of the footing and any overlying backfill may be
neglected. The allowable bearing value may be increased by one-third for transient loads such
as those induced by seismic events or wind loads.
Lateral loads may be resisted by friction on the base of footings and floor slabs and as passive
pressure on the sides of footings. We recommend that an allowable coefficient of friction of 0.30
be used to calculate friction between the concrete and the underlying structural fill. Passive
pressure may be determined using an allowable equivalent fluid density of 300 pcf (pounds per
cubic foot). Factors of safety have been applied to these values.
We estimate that settlements of footings designed and constructed as recommended will be less
than 1 inch, for the anticipated load conditions, with differential settlements between
comparably loaded footings of ½ inch or less. Most of the settlements should occur essentially
as loads are being applied; however, disturbance of the foundation subgrade during construction
could result in larger settlements than estimated.
Proposed Creekwood Page |20
December 30, 2022
6.3 Pin Piles
Pin piles consist of small to midsize diameter Schedule-80 steel pipe that are driven into the
underlying soils to refusal. The pin pile diameters typically range from 2 to 8 inches. Individual
pipe segments typically range from about 5 to 21 feet in length and are successively joined with
external threaded couplings, internal slip couplings, or butt welds as pile driving progresses. The
large diameter piles use a pneumatic or hydraulic hammer mounted on the arm of a construction
vehicle. The pin piles have little to no lateral strength, unless battered. The pin piles must obtain
adequate embedment to provide support to the structure. We recommend a minimum
embedment of 15 feet below the ground surface at existing grades.
Regardless of diameter or installation method, we recommend that each pin pile be driven to
refusal during sustained driving. Refusal criteria should be based on load test data from the
contractor for the given pile diameter and hammer type. Because refusal depths are difficult to
predict and soil conditions could vary significantly across the site, we recommend a test pile be
installed. The contractor should be prepared for variable pile lengths. Also, it may be necessary
to modify pile layouts if obstructions are encountered during pile-driving.
When refusal criteria has been met, the pin piles can be cut to a predetermined height or
elevation. To provide a good bond between the piles and the existing foundation, a steel bracket
is typically installed on the foundation element, with an adjustable element to provide a pre-
loaded condition. A structural engineer should be responsible for designing the reinforced steel
and foundation elements. The minimum pile spacing (center to center) shall be determined by
the structural engineer.
TABLE 6:
PIN PILE CAPACITIES
Design Parameter 3 inch
diameter
4 inch
diameter
6 inch
diameter
Static Compressive Capacity 12,000 pounds 20,000 pounds 30,000 pounds
Transient Compressive Capacity 16,000 pounds 26,000 pounds 40,000 pounds
Notes:
Capacities are provided as allowable values.
Uplift capacity is not applicable if slip couplings are used.
For the proposed walls, we recommend that 3 to 6 inch pin piles be utilized. These pilings will
need to be installed by a larger, machine-mounted hammer. A properly installed pin pile driven
Proposed Creekwood Page |21
December 30, 2022
to refusal (defined by the required capacity, installation contractor, and/or accepted construction
practice) should provide the following allowable axial capacities.
In areas where the lengths of the pin piles are exposed and not directly incorporated into the
foundation grade beams, the area around the pin piles should be backfilled with a well-draining
material such as angular quarry spalls. Verification testing should be performed in accordance
with the ASTM Quick Test Method (ASTM D1143) on 5 percent of the installed piles, or a minimum
of 3, whichever is greater.
6.4 Floor Slab Support
We anticipate that the floors of the residences and vault will consist of a slab-on-grade floor. Slab-
on-grade floors should be supported on the still native soils or on structural fill prepared as
described above. Areas of old fill material should be evaluated during grading activity for
suitability of structural support. Areas of significant organic debris should be removed.
We recommend that floor slabs for the residences be directly underlain by a minimum 4 inch
thick pea gravel or washed 5/8 inch crushed rock and should contain less than 2 percent fines.
This layer should be placed in a single lift and compacted to an unyielding condition.
A synthetic vapor retarder is recommended to control moisture migration through the slabs for
the residences. This is of particular importance where moisture migration through the slab is an
issue, such as where adhesives are used to anchor carpet or tile to the slab. A subgrade modulus
of 200 pci (pounds per cubic inch) may be used for floor slab design. We estimate that settlement
of the floor slabs designed and constructed as recommended, will be 1/2 inch or less over a span
of 50 feet.
6.5 Subgrade/Basement Walls
The lateral pressures acting on retaining walls (such as basement or grade separation walls) will
depend upon the nature and density of the soil behind the wall as well as the presence or
absence of hydrostatic pressure. Below we provide recommended design values and drainage
recommendations for retaining walls.
Design Values
For walls backfilled with granular well-drained soil such as gravel backfill for walls or permeable
ballast, we provided the appropriate active and at-rest equivalent fluid pressures in Table 7
below. If walls taller than 6 feet are required, as seismic surcharge should be included where
Proposed Creekwood Page |22
December 30, 2022
required by the code. If walls will be constructed with a backslope and will be braced or otherwise
restrained against movement, we should be notified so that we can evaluate the anticipated
conditions and recommend an appropriate at-rest earth pressure.
TABLE 7:
RECOMMENDED LATERAL EARTH PRESSURES FOR DESIGN OF RETAINING WALLS
Lateral Earth Pressure Condition,
equivalent fluid density (PCF)
Backfill Material
Gravel Backfill for Walls
(WSDOT 9-03.12(2))
Permeable Ballast
(WSDOT 9-03.9(2))
At-rest, level backslope 55 45
Active, level backslope 35 27
Active, 3H:1V backslope 48 32
Active, 2H:1V backslope 55 36
Seismic Surcharge 16H 12H
Lateral loads may be resisted by friction on the base of footings and as passive pressure on the
sides of footings and the buried portion of the wall, as described in the “Foundation Support”
section of this report.
Wall Drainage
Adequate drainage behind retaining structures is imperative. Positive drainage which controls
the development of hydrostatic pressure can be accomplished by placing a zone of drainage
behind the walls. Granular drainage material should contain less than 2 percent fines and at
least 30 percent retained on the US No. 4 sieve.
A minimum 4 inch diameter perforated or slotted PVC pipe should be placed in the drainage zone
along the base and behind the wall to provide an outlet for accumulated water and direct
accumulated water to an appropriate discharge location. We recommend that a nonwoven
geotextile filter fabric be placed between the soil drainage material and the remaining wall
backfill to reduce silt migration into the drainage zone. The infiltration of silt into the drainage
zone can, with time, reduce the permeability of the granular material. The filter fabric should be
placed such that it fully separates the drainage material and the backfill, and should be extended
over the top of the drainage zone. Typical wall drainage and backfilling details are shown on
Figure 9.
Proposed Creekwood Page |23
December 30, 2022
A soil drainage zone should extend horizontally at least 18 inches from the back of the wall. The
drainage zone should also extend from the base of the wall to within 1 foot of the top of the wall.
The soil drainage zone should be compacted to approximately 90 percent of the maximum dry
density (MDD), as determined in accordance with ASTM D1557. Over-compaction should be
avoided as this can lead to excessive lateral pressures on the wall. A geocomposite drain mat
may also be used instead of free draining soils, provided it is installed in accordance with the
manufacturer’s instructions.
6.6 Temporary Excavations
All job site safety issues and precautions are the responsibility of the contractor providing
services/work. The following cut/fill slope guidelines are provided for planning purposes only.
Temporary cut slopes will likely be necessary during grading operations or utility installation. All
excavations at the site associated with confined spaces, such as utility trenches and retaining
walls, must be completed in accordance with local, state, or federal requirements including
Washington Administrative Code (WAC) and Washington Industrial Safety and Health
Administration (WISHA). Excavation, trenching, and shoring is covered under WAC 296-155 Part
N.
Based on WAC 296-155-66401, it is our opinion that the very dense glacial till would be classified
as Type A soils; the advance outwash would be classified as Type B soils; and the recessional
outwash/ice contact and alluvial soils would be classified as Type C soils.
According to WAC 296-155-66403, for temporary excavations of less than 20 feet in depth, the
side slopes in Type A soils should be sloped at a maximum inclination of ¾H:1V or flatter from
the toe to top of the slope; the side slopes in Type B soils should be sloped at a maximum
inclination of 1H:1V or flatter from the toe to top of the slope; and the side slopes in Type C soils
should be sloped at a maximum inclination of 1½H:1V or flatter from the toe to top of the
slope. All exposed slope faces should be covered with a durable reinforced plastic membrane
during construction to prevent slope raveling and rutting during periods of precipitation. These
guidelines assume that all surface loads are kept at a minimum distance of at least one half the
depth of the cut away from the top of the slope and that significant seepage is not present on
the slope face. Flatter cut slopes will be necessary where significant raveling or seepage occurs,
or if construction materials will be stockpiled along the slope crest.
Where it is not feasible to slope the site soils back at these inclinations, a retaining structure
should be considered. Retaining structures greater than 4 feet in height (bottom of footing to
Proposed Creekwood Page |24
December 30, 2022
top of structure) or that have slopes of greater than 15 percent above them, should be
engineered per Washington Administrative Code (WAC 51-16-080 item 5). This information is
provided solely for the benefit of the owner and other design consultants, and should not be
construed to imply that GeoResources assumes responsibility for job site safety. It is understood
that job site safety is the sole responsibility of the project contractor.
6.7 Permanent Cut and Fill Slopes
Where cut and fill slopes are required, we recommend a maximum slope of 2H:1V
(Horizontal:Vertical) for permanent cut and fill slopes. In areas where 2H:1V slopes are not
feasible, retaining structures should be considered. Retaining structures taller than 4 feet in
height (bottom of footing to top of structure) or have slopes of greater than 15 percent above
them, they should be designed by a qualified engineer and will require a separate building permit
from the City.
Fill slopes constructed on grades that are steeper than 5H:1V (20 percent) should be "keyed" into
the undisturbed native soils by cutting a series of horizontal benches and should be constructed
in accordance with Appendix J of the 2018 IBC, as shown on Figure 10. The benches should be
1½ times the width of the equipment used for grading and be a maximum of 3 feet in height.
Subsurface drainage may be required in areas where significant seepage is encountered during
grading. Collected drainage should be directed to an appropriate discharge point.
6.8 Site Drainage
All ground surfaces, pavements and sidewalks at the site should be sloped to direct surface water
away from the structures, slopes, and property lines. Surface water runoff should be controlled
by a system of curbs, berms, drainage swales, and or catch basins, and conveyed to an
appropriate discharge point.
We recommend that footing drains are installed for the residences in accordance with IBC
1805.4.2, and basement walls (if utilized) have a wall drain as describe above. The downsp outs
should not be connected to directly the footings drains until they are combined to tightline to the
discharge point. If the basement cut extends below the adjacent municipal stormwater system,
a sump and pump system may be required.
Proposed Creekwood Page |25
December 30, 2022
7 EARTHWORK RECOMMENDATIONS
7.1 Site Preparation and Grading
All structural areas on the site to be graded should be stripped of vegetation, organic surface
soils, and other deleterious materials including previously placed, undocumented fill, and any
construction debris. Organic topsoil is not suitable for use as structural fill but may be used for
limited depths in non-structural areas. We anticipate that stripping depths ranging from 6 to 30
inches should be expected to remove unsuitable soils.
Where placement of fill material is required, the stripped/exposed subgrade areas should be
compacted to a firm and unyielding surface prior to placement of any fill. Excavations for debris
removal should be backfilled with structural fill and compacted to the densities described in the
“Structural Fill” section of this report. The exposed subgrade soil should be proof-rolled with
heavy rubber-tired equipment during dry weather or probed with a ½-inch-diameter steel rod
during wet weather conditions prior to placement of structural fill.
Soft, loose, or otherwise unsuitable areas delineated during proof rolling or probing should be
recompacted, if practical, or over-excavated and replaced with structural fill. The depth and
extent of over-excavation should be evaluated by our field representative at the time of
construction. The areas of previously placed, undocumented fill material should be evaluated
during grading operations to determine if they need mitigation, recompaction or removal.
7.2 Fill Material, Placement, and Compaction
According to the provided site plans, there will be minimal amounts of cutting and filling required
to achieve design grades. Cuts and fills will typically be on the order of a couple feet. The thickest
fills will be isolated to the area of lots 9 through 13, and where Road B crosses the incised ravine.
Structural Fill
All material placed as fill for the proposed wall should be placed as structural fill. Material placed
as structural fill should be free of debris, organic matter, trash, and cobbles greater than 4-inches
in diameter. The moisture content of the fill material should be adjusted as necessary for proper
compaction.
Proposed Creekwood Page |26
December 30, 2022
Materials
The suitability of material for use as structural fill will depend on the gradation and moisture
content of the soil. As the amount of fines (material passing US No. 200 sieve) increases, soil
becomes increasingly sensitive to small changes in moisture content and adequate compaction
becomes more difficult to achieve. During wet weather, we recommend the use of well-graded
sand and gravel with less than 5 percent (by weight) passing the US No. 200 sieve based on that
fraction passing the ¾-inch sieve, such as Gravel Backfill for Walls (WSDOT 9-03.12(2)). If
prolonged dry weather prevails during the wall construction, higher fines content (up to 10 to
12 percent) may be acceptable.
Placement and Compaction
The appropriate lift thickness will depend on the structural fill characteristics and compaction
equipment used, but it is typically limited to 4 to 6 inches for hand operated equipment; thicker
lifts may be appropriate for larger equipment. For larger equipment such as a hoe-pac or drum
roller, we recommend a maximum loose-lift thickness of 12 inches. Structural fill should be
compacted to at least 95 percent of the MDD as determined by the Modified Proctor (ASTM
D1557), except for within 12 inches of the back of the wall, as described in the “Wall Drainage”
section of this report. Additionally, the moisture content should be maintained within 3 percent
of the optimum moisture content in accordance with ASTM D1557.
Suitability of Excavated Material for Use as Fill
Based on our visual classification and results of the grain size analysis performed (see
Appendix B), some of the on-site soil would not satisfy the structural fill gradation
recommendations for use during wet weather or in wet conditions. In general, the potential to
reuse the encountered site soils is described below.
• Surficial Organic Soils: The forest duff, topsoil, and organic-rich soils mantling most of the
site are not suitable for use as structural fill under any circumstances, due to their high
organic content. Consequently, these materials can be used only for non-structural
purposes, such as in landscaping areas.
• Ice-Contact Soils: The shallow silty sand encountered 1 to 3 feet below existing grades,
which we interpret to be recessional/ice contact soils, are comparable to sandy “pit run”
and may be used for use as structural fill during moderate wet weather months,
depending on their fines content.
Proposed Creekwood Page |27
December 30, 2022
• Glacial Till: The glacial till soils underlying most of the site appear suitable for reuse as
structural fill at their present moisture contents. However, these soils will be difficult or
impossible to reuse during wet weather, due to their relatively high silt contents.
• Advance Outwash: The gravelly sands and sandy gravels underlying parts of the site will
provide a favorable source of fill soils that can be used in a broad range of weather
conditions, although aeration or sprinkling might be needed to achieve an optimum
moisture content during especially wet or dry conditions, respectively. Any boulders or
large cobbles present in these soils would need to be removed from the matrix for certain
fill applications.
On-site soil could be used as fill in dry weather and dry conditions, but may require thinner lifts
and/or more effort to achieve the compaction requirements. On-site soil containing organics or
fill debris would be unsuitable for use as structural fill.
7.3 Wet Weather and Wet Condition Considerations
In the Puget Sound area, wet weather generally begins about mid-October and continues through
about May, although rainy periods could occur at any time of year. Therefore, it would be
advisable to schedule earthwork during the dry weather months of June through September.
Most of the soil at the site likely contains sufficient fines to produce an unstable mixture when
wet. Such soil is highly susceptible to changes in water content and tends to become unstable
and difficult or impossible to proof-roll and compact if the moisture content significantly exceeds
the optimum. In addition, during wet weather months, the groundwater levels could increase,
resulting in seepage into site excavations. Performing earthwork during dry weather would
reduce these problems and costs associated with rainwater, construction traffic, and handling of
wet soil. However, should wet weather/wet condition earthwork be unavoidable, the following
recommendations are provided:
• The ground surface in and surrounding the construction area should be sloped as much
as possible to promote runoff of precipitation away from work areas and to prevent
ponding of water.
• Work areas or slopes should be covered with plastic. The use of sloping, ditching, sumps,
dewatering, and other measures should be employed as necessary to permit proper
completion of the work.
• Earthwork should be accomplished in small sections to minimize exposure to wet
conditions. That is, each section should be small enough so that the removal of
unsuitable soils and placement and compaction of clean structural fill could be
accomplished on the same day. The size of construction equipment may have to be
Proposed Creekwood Page |28
December 30, 2022
limited to prevent soil disturbance. It may be necessary to excavate soils with a backhoe,
or equivalent, and locate them so that equipment does not pass over the excavated area.
Thus, subgrade disturbance caused by equipment traffic would be minimized.
• Fill material should consist of clean, well-graded, sand and gravel, of which not more than
5 percent fines by dry weight passes the No. 200 mesh sieve, based on wet-sieving (ASTM
D1140) the fraction passing the ¾-inch mesh sieve. The gravel content should range from
between 20 and 50 percent retained on a No. 4 mesh sieve. The fines should be non-
plastic.
• No soil should be left uncompacted and exposed to moisture. A smooth-drum vibratory
roller, or equivalent, should roll the surface to seal out as much water as possible.
• In-place soil or fill soil that becomes wet and unstable and/or too wet to suitably compact
should be removed and replaced with clean, granular soil (see gradation requirements
above).
• Excavation and placement of structural fill material should be observed on a full-time
basis by a geotechnical engineer (or representative) experienced in wet weather/wet
condition earthwork to determine that all work is being accomplished in accordance with
the project specifications and our recommendations.
• Grading and earthwork should not be accomplished during periods of heavy, continuous
rainfall.
The above are supplemental recommendations to the Temporary Sediment and Erosion Control
Plan and Stormwater Pollution and Prevention Plan (SWPPP) that will be required by the city.
7.4 Review of Plans and Specifications
We recommend that GeoResources be retained to review those portions of the plans and
specifications pertaining to the foundations, shoring, and earthwork prior to printing the
90 percent drawings to determine that they are in accordance with recommendations presented
in this report.
7.5 Construction Observations
We recommend that GeoResources continue to be retained to observe the geotechnical aspects
of construction, particularly the shoring (if necessary), foundations, retaining walls, temporary
dewatering, fill placement and compaction, and drainage activities. This observation would allow
us to continue to verify the subsurface conditions as they are exposed during construction and
to determine that work is accomplished in accordance with our recommendations. If conditions
Proposed Creekwood Page |29
December 30, 2022
encountered during construction differ from those anticipated, we can provide
recommendations for the conditions actually encountered.
8 LIMITATIONS
This report was prepared for the exclusive use of Amalani, Barghausen Consulting Engineers, and
the project design team for specific application to this project. This report should be provided to
prospective contractors for information of factual data only, and not as a warranty of subsurface
conditions, such as those interpreted from the exploration logs and discussions of subsurface
conditions included in this report.
The analyses, conclusions, and recommendations contained in this report are based on site
conditions as they presently exist. We assume that the exploratory test pits and soil borings
made for this project are representative of the subsurface conditions through the site; i.e., the
subsurface conditions everywhere are not significantly different from those disclosed by the
explorations. If conditions different from those described in this report are observed or appear
to be present during construction, we should be advised at once so that we can review these
conditions and reconsider our recommendations, where necessary. If there is a substantial lapse
of time between submission of our report and the start of work at the site, or if conditions have
changed because of natural forces or construction operations at or near the site, it is
recommended that this report be reviewed to determine the applicability of the conclusions and
recommendations.
Within the limitations of the 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.
Unanticipated soil conditions are commonly encountered and cannot be fully determined by
merely taking soil samples. Such unexpected conditions frequently require that additional
expenditures be made to attain a properly constructed project. Therefore, some contingency
fund is recommended to accommodate such potential extra costs.
The scope of our services did not include environmental assessment or evaluation regarding the
presence or absence of wetlands or hazardous or toxic materials in the soil, surface water,
groundwater, or air at the subject site other than those activities described in this report.
GeoResources, LLC.
Proposed Creekwood Page |30
December 30, 2022
9 REFERENCES
ASTM International (ASTM), 2007, Annual book of standards, Construction, v. 04.08, Soil and
Rock (I): D 420 – D 5779: West Conshohocken, Pa.
Booth, D.B., Waldron, H.H., and Troost, K.G., The Geologic Map of the Poverty Bay 7.5-minute
Quadrangle, Washington, 1:24,000, Miscellaneous Field Study - MF2854
Federal Way, Revised Code, A Codification of the General Ordinances of the City of Federal
Way, Washington (http://www.codepublishing.com/wa/federalway/)
International Building Code (IBC) 2018
Koloski, J., Schwarz, S., and Tubbs, D., Geotechnical Properties of Geologic Materials, in
Engineering Geology in Washington, Volume I, Washington Division of Geology and Earth
Resources, Bulletin 78. 1978
U.S. Geological Survey (USGS), 2008, National seismic hazard database
(http://earthquake.usgs.gov/hazmaps/).
Washington State Department of Natural Resources, Geologic Information Portal,
(http://www.dnr.wa.gov/programs-and-services/geology/publications-and-data/geologic-
information-portal).
Washington State Department of Transportation (WSDOT), 2019, Geotechnical Design Manual.
Olympia, Wash., Washington State Department of Transportation.
Washington State Department of Transportation (WSDOT), 2019, Standard specifications for
road, bridge, and municipal construction: Olympia, Wash., Washington State Department of
Transportation.
Proposed Creekwood Page |31
December 30, 2022
Appendix A – Subsurface Explorations
Proposed Creekwood Page | A
December 22, 2022
Appendix B – Laboratory Test Results
Proposed Creekwood Page | B
December 22, 2022
Appendix C – Slope Stability Analyses
Approximate Site Location
Figure created from King County iMap
(https://gismaps.kingcounty.gov/iMap/)
Not to Scale
Site Location Map
Proposed Creekwood Plat
xxx 21st Avenue SW
Federal Way, Washington
PN: 1221039037
Doc ID: Amalani.CreekWood.F_Rev05 December 2022 Figure 1
Scale:1" = 100'
Notes:
Site and Exploration Plan developed from Preliminary Grading and
tility Plan ̀by Barghausen Consulting Engineers, Inc. Dated 11/28/2022 Site and Exploration Plan
Proposed Creekwood Plat
Federal Way, Washington
PN: 1221039037
DocID: Amalani.Creekwood.F2.Rev05 December 2022 Figure 24809 Pacific Hwy. E. | Fife, Washington 98424 | 253.896.1011 | www.georesources.rocks
B-3
TP-10
B-4
TP-11
TP-12
TP-7
TP-8
TP-9
TP-6
TP-13
TP-4
TP-5
TP-2
TP-1
TP-3
B-6
B-2
B-5
B-9
B-10
B-8
B-7
B-1 E
E'
ND'
ND
D
D'
F'
F
A'
A
B B'
C C'
SP
SP'
G G'
TP-1 Approximate Test Pit Location
HA-1 Approximate Hand Auger Location
B-2 Approximate Boring Location
A-A' Cross Section Location
HA-1HA-2
HA-3
Approximate Site Location
Figure created from King County iMap
(https://gismaps.kingcounty.gov/iMap/)
Not to Scale
Site Vicinity Map
Proposed Creekwood Plat
xxx 21st Avenue SW
Federal Way, Washington
PN: 1221039037
Doc ID: Amalani.CreekWood.F_Rev05 December 2022 Figure 3
Approximate Site Location
Figure created from Web Soil Survey
(http://websoilsurvey.sc.egov.usda.gov/App/WebSoilSurvey.aspx)
Soil
Type Soil Name Parent Material Slopes Erosion Hazard Hydrologic
Soils Group
AgB Alderwood gravelly sandy
loam Glacial Till 0 to 6 Slight B/C
AgD 15 to 30 Moderate B/C
AkF Alderwood & Kitsap Undifferentiated glacial till
and/or lacustrine sediments
Very
steep Very Severe C/D
Not to Scale
NRCS Soils Map
Proposed Creekwood Plat
xxx 21st Avenue SW
Federal Way, Washington
PN: 1221039037
Doc ID: Amalani.CreekWood.F_Rev05 December 2022 Figure 4
Approximate Site Location
An excerpt from the Lidar-revised Geologic Map of the Poverty Bay 7.5' Quadrangle, King and Pierce Counties, Washington,
by Tabor, R.W., Booth, D.B., and Troost, K.G. (2014)
Symbol Geologic Unit
Qls Landslide Deposits (Holocene)
Qa Alluvium (Holocene)
Qvi Ice-contact deposits
Qvt Vashon Till
Qva Advance Outwash
Not to Scale
Geologic Map
Proposed Creekwood Plat
xxx 21st Avenue SW
Federal Way, Washington
PN: 1221039037
Doc ID: Amalani.CreekWood.F_Rev05 December 2022 Figure 5
Approximate Site Location
Map created from the Washington Geologic Information Portal (geologyportal.dnr.wa.gov)
Not to Scale
WGS Landslide Mapping
Proposed Creekwood Plat
xxx 21st Avenue SW
Federal Way, Washington
PN: 1221039037
Doc ID: Amalani.CreekWood.F_Rev05 December 2022 Figure 6
Approximate Site Location
Map created from the Liquefaction Susceptibility Map of King County, Washington by Stephen P. Palmer, Sammantha L.
Magsino, Eric L. Bilderback, James L. Poelstra, Derek S. Folger, and Rebecca A. Niggemann (September 2004)
Not to Scale
Liquefaction Susceptibility Map
Proposed Creekwood Plat
xxx 21st Avenue SW
Federal Way, Washington
PN: 1221039037
Doc ID: Amalani.CreekWood.F_Rev05 December 2022 Figure 7
Approximate Site Location
Map created from the Washington Geologic Information Portal (geologyportal.dnr.wa.gov)
Not to Scale
Fault Hazards Map
Proposed Creekwood Plat
xxx 21st Avenue SW
Federal Way, Washington
PN: 1221039037
Doc ID: Amalani.CreekWood.F_Rev05 December 2022 Figure 8
1.55 mi
0.80 mi
Typical Drainage and Backfill Detail
Proposed Creekwood Plat
xxx 21st Avenue SW
Federal Way, Washington
PN: 1221039037
DocID: Amalani.CreekWood.F_Rev05 December 2022 Figure 9
6.The subdrain should consist of 4” diameter (minimum),
slotted or perforated plastic pipe meeting the requirements
of AASHTO M 304; 1/8-inch maximum slot width; 3/16- to 3/8-
inch perforated pipe holes in the lower half of pipe, with
lower third segment unperforated for water flow; tight joints;
sloped at a minimum of 6”/100’ to drain; cleanouts to be
provided at regular intervals.
7.Surround subdrain pipe with 8 inches (minimum) of washed
pea gravel (2” below pipe” or 5/8” minus clean crushed gravel.
Washed pea gravel to be graded from 3/8-inch to No.8
standard sieve.
8.See text for floor slab subgrade preparation.
1.Washed pea gravel/crushed rock beneath floor slab could be
hydraulically connected to perimeter/subdrain pipe. Use of 1”
diameter weep holes as shown is one applicable method. Crushed
gravel should consist of 3/4” minus. Washed pea gravel should consist
of 3/8” to No. 8 standard sieve.
2.Wall backfill should meet WSDOT Gravel Backfill for walls Specification
9-03-12(2).
3.Drainage sand and gravel backfill within 18” of wall should be
compacted with hand-operated equipment. Heavy equipment should
not be used for backfill, as such equipment operated near the wall
could increase lateral earth pressures and possibly damage the wall.
The table below presents the drainage sand and gravel gradation.
4.All wall back fill should be placed in layers not exceeding 4” loose
thickness for light equipment and 8” for heavy equipment and should
be densely compacted. Beneath paved or sidewalk areas, compact to
at least 95% Modified Proctor maximum density (ASTM: 01557-70
Method C). In landscaping areas, compact to 90% minimum.
5.Drainage sand and gravel may be replaced with a geocomposite core
sheet drain placed against the wall and connected to the subdrain
pipe. The geocomposite core sheet should have a minimum
transmissivity of 3.0 gallons/minute/foot when tested under a gradient
of 1.0 according to ASTM 04716.
IBC Appendix J Detail
Proposed Creekwood Plat
xxx 21st Avenue SW
Federal Way, Washington
PN: 1221039037
Doc ID: Amalani.CreekWood.F_Rev05 December 2022 Figure 10
Appendix A
Subsurface Explorations
SOIL CLASSIFICATION SYSTEM
MAJOR DIVISIONS
GROUP
SYMBOL
GROUP NAME
COARSE
GRAINED
SOILS
More than 50%
Retained on
No. 200 Sieve
GRAVEL
More than 50%
Of Coarse Fraction
Retained on
No. 4 Sieve
CLEAN
GRAVEL
GW
WELL-GRADED GRAVEL, FINE TO COARSE GRAVEL
GP
POORLY-GRADED GRAVEL
GRAVEL
WITH FINES
GM
SILTY GRAVEL
GC
CLAYEY GRAVEL
SAND
More than 50%
Of Coarse Fraction
Passes
No. 4 Sieve
CLEAN SAND
SW
WELL-GRADED SAND, FINE TO COARSE SAND
SP
POORLY-GRADED SAND
SAND
WITH FINES
SM
SILTY SAND
SC
CLAYEY SAND
FINE
GRAINED
SOILS
More than 50%
Passes
No. 200 Sieve
SILT AND CLAY
Liquid Limit
Less than 50
INORGANIC
ML
SILT
CL
CLAY
ORGANIC
OL
ORGANIC SILT, ORGANIC CLAY
SILT AND CLAY
Liquid Limit
50 or more
INORGANIC
MH
SILT OF HIGH PLASTICITY, ELASTIC SILT
CH
CLAY OF HIGH PLASTICITY, FAT CLAY
ORGANIC
OH
ORGANIC CLAY, ORGANIC SILT
HIGHLY ORGANIC SOILS
PT
PEAT
NOTES: SOIL MOISTURE MODIFIERS:
1. Field classification is based on visual examination of soil Dry- Absence of moisture, dry to the touch
in general accordance with ASTM D2488-90.
Moist- Damp, but no visible water
2. Soil classification using laboratory tests is based on
ASTM D6913. Wet- Visible free water or saturated, usually soil is
obtained from below water table
3. Description of soil density or consistency are based on
interpretation of blow count data, visual appearance of
soils, and or test data.
Unified Soils Classification System
Proposed Creekwood Plat
xxx 21st Avenue SW
Federal Way, Washington
PN: 1221039037
Doc ID: Amalani.CreekWood.F_Rev05 December 2022 Figure A-1
5
10
15
20
25
30
Topsoil
Tan mottled silt with sand, small gravel
(medium stiff to stiff, moist to wet)
Tan silt gradation to sandy silt (medium stiff,
moist)
(stiff, moist)
Bottom of Boring
CompletedJanuary 13, 2014
1
2
3
4
2
4
5
4
5
5
12
3
3
3
3
6
TOTAL DEPTH:11.5ft DRILLING METHOD:Hollow Stem Auger LOGGED BY:RMP
TOP ELEVATION:DRILLING COMPANY:Boretec,Inc.HAMMER TYPE:Cathead
LATITUDE:DRILL RIG:HAMMER WEIGHT:140 lb
LONGITUDE:NOTES:
NOTES Creekwood Residential Plat
1. Refer to log key for definition of symbols, abbreviations and codes XXX 21st Ave SW/22nd Ave SW
2. USCS designation is based on visual manual classification Federal Way, WA
and selected lab testing
3. Groundwater level, if indicated, is for the date shown and may vary
4. N.E. = Not Encountered LOG OF BORING B-1
5. ATD = At the Time of Drilling
JOB: Amalani.Creekwood Sheet 1 of
GeoResources, LLC FIG.A-2DepthElevationSOIL DESCRIPTION DRILLING
NOTES
SampleSamplerSymbolTEST RESULTS
10 20 30 40 50
Penetration - (blows per foot)
% Fines (<0.075mm)
% Water Content
Plastic Limit Liquid Limit
BlowCountGroundWater1
0
5
10
15
20
25
30
Brown fine sandy silt (stiff, moist to wet)
as above with 3" thick brown sand lens
Brown silty SAND with gravel (dense, damp)
Brown SAND with trace gravel, silt (very
dense, moist) (Advance SAND?)
Brown coarse SAND with trace gravel (very
dense, moist)
on rock/
bouncing
sandy
cuttings
1
2
3
4
5
6
7
8
9
84
90*
100
7
9
11
7
7
10
11
15
17
10
10
11
23
41
43
16
40
50/5
2
50/6
50/3
100/5"
TOTAL DEPTH:41.5 DRILLING METHOD:Hollow Stem Auger LOGGED BY:DCB
TOP ELEVATION:DRILLING COMPANY:Boretec,Inc.HAMMER TYPE:CatHead
LATITUDE:DRILL RIG:HAMMER WEIGHT:140 lb
LONGITUDE:NOTES:
NOTES Creekwood Residential Plat
1. Refer to log key for definition of symbols, abbreviations and codes XXX 21st Ave SW/22nd Ave SW
2. USCS designation is based on visual manual classification Federal Way, WA
and selected lab testing
3. Groundwater level, if indicated, is for the date shown and may vary
4. N.E. = Not Encountered LOG OF BORING B-2
5. ATD = At the Time of Drilling
JOB: Amalani.Creekwood Sheet 1 of
GeoResources, LLC FIG.A-3DepthElevationSOIL DESCRIPTION DRILLING
NOTES
SampleSamplerSymbolTEST RESULTS
10 20 30 40 50
Penetration - (blows per foot)
% Fines (<0.075mm)
% Water Content
Plastic Limit Liquid Limit
BlowCountGroundWater2
35
40
45
50
55
60
65
Bottom of Boring
CompletedJanuary 14, 2014
rocky drilling
10
11
90*
50/5"
24
40
50/6
ATD
TOTAL DEPTH:41.5 DRILLING METHOD:Hollow Stem Auger LOGGED BY:DCB
TOP ELEVATION:DRILLING COMPANY:Boretec,Inc.HAMMER TYPE:CatHead
LATITUDE:DRILL RIG:HAMMER WEIGHT:140 lb
LONGITUDE:NOTES:
NOTES Creekwood Residential Plat
1. Refer to log key for definition of symbols, abbreviations and codes XXX 21st Ave SW/22nd Ave SW
2. USCS designation is based on visual manual classification Federal Way, WA
and selected lab testing
3. Groundwater level, if indicated, is for the date shown and may vary
4. N.E. = Not Encountered LOG OF BORING B-2
5. ATD = At the Time of Drilling
JOB: Amalani.Creekwood Sheet 2 of
GeoResources, LLC FIG.A-3DepthElevationSOIL DESCRIPTION DRILLING
NOTES
SampleSamplerSymbolTEST RESULTS
10 20 30 40 50
Penetration - (blows per foot)
% Fines (<0.075mm)
% Water Content
Plastic Limit Liquid Limit
BlowCountGroundWater2
0
5
10
15
20
25
30
Topsoil
Tan mottled silty SAND
Tan mottled silty SAND (loose, moist)
Gray brown silty SAND (medium dense, moist
to wet)
fine to medium SAND with silty sand lenses
(dense, moist)
as above with cobbles/gravel (very dense)
Tan SAND with gravel (very dense, moist)
Bottom of Boring
CompletedJanuary 14, 2014
heave
perched at 7'
1
2
3
4
5
6
7
8
93
90*
4
3
6
7
11
17
13
15
21
50/3"
2
24
43
50/6
13
18
25
27
40
50/5
29
50/6
ATD
TOTAL DEPTH:31 DRILLING METHOD:Hollow Stem Auger LOGGED BY:RMP
TOP ELEVATION:DRILLING COMPANY:Boretec,Inc.HAMMER TYPE:CatHead
LATITUDE:DRILL RIG:HAMMER WEIGHT:140 lb
LONGITUDE:NOTES:
NOTES Creekwood Residential Plat
1. Refer to log key for definition of symbols, abbreviations and codes XXX 21st Ave SW/22nd Ave SW
2. USCS designation is based on visual manual classification Federal Way, WA
and selected lab testing
3. Groundwater level, if indicated, is for the date shown and may vary
4. N.E. = Not Encountered LOG OF BORING B-3
5. ATD = At the Time of Drilling
JOB: Amalani.Creekwood Sheet 1 of
GeoResources, LLC FIG.A-4DepthElevationSOIL DESCRIPTION DRILLING
NOTES
SampleSamplerSymbolTEST RESULTS
10 20 30 40 50
Penetration - (blows per foot)
% Fines (<0.075mm)
% Water Content
Plastic Limit Liquid Limit
BlowCountGroundWater1
0
5
10
15
20
25
30
Tan mottled SILT & SAND with gravel
(medium dense, moist)
gravel (dense, moist) (Weathered Glacial Till?)
Gray silty SAND with gravel (very dense,
moist) (Glacial Till?)
Brown SAND with trace silt (dense to very
dense, moist) (Advance SAND)
increased
density
1
2
3
4
5
6
7
8
9
10
90*
66
88
64
9
12
13
10
15
23
9
12
21
29
40
50/4
35
50/4
15
22
28
22
29
37
28
40
48
15
22
42
50/6
ATD
TOTAL DEPTH:51.5 DRILLING METHOD:Hollow Stem Auger LOGGED BY:RMP/DCB
TOP ELEVATION:DRILLING COMPANY:Boretec,Inc.HAMMER TYPE:cathead
LATITUDE:DRILL RIG:HAMMER WEIGHT:140 lb
LONGITUDE:NOTES:
NOTES Creekwood Residential Plat
1. Refer to log key for definition of symbols, abbreviations and codes XXX 21st Ave SW/22nd Ave SW
2. USCS designation is based on visual manual classification Federal Way, WA
and selected lab testing
3. Groundwater level, if indicated, is for the date shown and may vary
4. N.E. = Not Encountered LOG OF BORING B-4
5. ATD = At the Time of Drilling
JOB: Amalani.Creekwood Sheet 1 of
GeoResources, LLC FIG.A-5DepthElevationSOIL DESCRIPTION DRILLING
NOTES
SampleSamplerSymbolTEST RESULTS
10 20 30 40 50
Penetration - (blows per foot)
% Fines (<0.075mm)
% Water Content
Plastic Limit Liquid Limit
BlowCountGroundWater2
35
40
45
50
55
60
65
as above with silt lense (damp)
(wet)
(saturated)
Bottom of Boring
CompletedJanuary 14, 2014
11
12
13
14
92*
47
50/5
44
50/5
25
50/6
22
42
50/5
TOTAL DEPTH:51.5 DRILLING METHOD:Hollow Stem Auger LOGGED BY:RMP/DCB
TOP ELEVATION:DRILLING COMPANY:Boretec,Inc.HAMMER TYPE:cathead
LATITUDE:DRILL RIG:HAMMER WEIGHT:140 lb
LONGITUDE:NOTES:
NOTES Creekwood Residential Plat
1. Refer to log key for definition of symbols, abbreviations and codes XXX 21st Ave SW/22nd Ave SW
2. USCS designation is based on visual manual classification Federal Way, WA
and selected lab testing
3. Groundwater level, if indicated, is for the date shown and may vary
4. N.E. = Not Encountered LOG OF BORING B-4
5. ATD = At the Time of Drilling
JOB: Amalani.Creekwood Sheet 2 of
GeoResources, LLC FIG.A-5DepthElevationSOIL DESCRIPTION DRILLING
NOTES
SampleSamplerSymbolTEST RESULTS
10 20 30 40 50
Penetration - (blows per foot)
% Fines (<0.075mm)
% Water Content
Plastic Limit Liquid Limit
BlowCountGroundWater2
0
5
10
15
20
25
30
245
240
235
230
225
220
Forest duff/ root mat
Tan to grey sandy SILT w/ gravel
(mottling)(med. dense dense, damp)
Grey to tan silty medium sand (dense, moist)
Grey medium SAND with silt (Very dense,
moist) (advance outwash?)
NM- 5.9%
Grey medium SAND with trace silt (very
dense, moist) (advance outwash?)
5
7
68
81
90
9
9
11
13
9
11
15
22
29
29
21
25
14
28
40
22
31
50/6
18
40
50/6
27
50/6
TOTAL DEPTH:50.8 DRILLING METHOD:Hollow Stem Auger LOGGED BY:KEB
TOP ELEVATION:248'DRILLING COMPANY:Boretec, Inc.HAMMER TYPE:Cathead
LATITUDE:DRILL RIG:EC95 HAMMER WEIGHT:140 lb
LONGITUDE:NOTES:West side of ravine in Tract A
NOTES Creekwood Residential Plat
1. Refer to log key for definition of symbols, abbreviations and codes XXX 21st Ave SW/22nd Ave SW
2. USCS designation is based on visual manual classification Federal Way, WA
and selected lab testing
3. Groundwater level, if indicated, is for the date shown and may vary
4. N.E. = Not Encountered LOG OF BORING B-5
5. ATD = At the Time of Drilling
JOB: Amalani.Creekwood Sheet 1 of
GeoResources, LLC FIG.A-6DepthElevationSOIL DESCRIPTION DRILLING
NOTES
SampleSamplerSymbolTEST RESULTS
10 20 30 40 50
Penetration - (blows per foot)
% Fines (<0.075mm)
% Water Content
Plastic Limit Liquid Limit
BlowCountGroundWater2
35
40
45
50
55
60
65
215
210
205
200
195
190
185
Grey medium SAND with trace silt (very
dense, wet) (advance outwash?)
Grey medium SAND with trace silt and occ
gravel(very dense, wet)(advance outwash?)
Tan to grey sandy SILT (very dense, moist)
Bottom of Boring
CompletedAugust 10, 2015
9
10
86
90
24
36
50/6
18
40
50/5
31
50/6
29
50/4
ATD
TOTAL DEPTH:50.8 DRILLING METHOD:Hollow Stem Auger LOGGED BY:KEB
TOP ELEVATION:248'DRILLING COMPANY:Boretec, Inc.HAMMER TYPE:Cathead
LATITUDE:DRILL RIG:EC95 HAMMER WEIGHT:140 lb
LONGITUDE:NOTES:West side of ravine in Tract A
NOTES Creekwood Residential Plat
1. Refer to log key for definition of symbols, abbreviations and codes XXX 21st Ave SW/22nd Ave SW
2. USCS designation is based on visual manual classification Federal Way, WA
and selected lab testing
3. Groundwater level, if indicated, is for the date shown and may vary
4. N.E. = Not Encountered LOG OF BORING B-5
5. ATD = At the Time of Drilling
JOB: Amalani.Creekwood Sheet 2 of
GeoResources, LLC FIG.A-6DepthElevationSOIL DESCRIPTION DRILLING
NOTES
SampleSamplerSymbolTEST RESULTS
10 20 30 40 50
Penetration - (blows per foot)
% Fines (<0.075mm)
% Water Content
Plastic Limit Liquid Limit
BlowCountGroundWater2
0
5
10
15
20
25
30
Forest Duff
Tan SAND w/ some silt (medium dense,
damp)
Tan SAND w/ some silt and occ gravel
(medium dense, moist)
Grey medium SAND w/ some silt and occ.
gravel (medium dense, moist)
Grey medium gravelly SAND w/ some silt
(Dense, moist)
Grey medium SAND w/ some silt (dense to
very dense, moist)
2
7
9
10
9
10
12
8
11
15
10
12
14
13
14
13
19
24
26
14
22
27
18
24
29
TOTAL DEPTH:51.5 DRILLING METHOD:Hollow Stem Auger LOGGED BY:KEB
TOP ELEVATION:DRILLING COMPANY:Boretec, Inc.HAMMER TYPE:Cathead
LATITUDE:DRILL RIG:EC95 HAMMER WEIGHT:140 lb
LONGITUDE:NOTES:West side of ravine, near proposed lot 19
NOTES Creekwood Residential Plat
1. Refer to log key for definition of symbols, abbreviations and codes XXX 21st Ave SW/22nd Ave SW
2. USCS designation is based on visual manual classification Federal Way, WA
and selected lab testing
3. Groundwater level, if indicated, is for the date shown and may vary
4. N.E. = Not Encountered LOG OF BORING B-6
5. ATD = At the Time of Drilling
JOB: Amalani.Creekwood Sheet 1 of
GeoResources, LLC FIG.A-7DepthElevationSOIL DESCRIPTION DRILLING
NOTES
SampleSamplerSymbolTEST RESULTS
10 20 30 40 50
Penetration - (blows per foot)
% Fines (<0.075mm)
% Water Content
Plastic Limit Liquid Limit
BlowCountGroundWater2
35
40
45
50
55
60
65
Grey medium SAND w some silt and occ fine
gravel (very dense, moist)
Grey silty medium SAND (very dense,
saturated)
Bottom of Boring
CompletedAugust 10, 2015
76
75
72
15
25
25
26
26
50/6
29
35
40
25
26
36
ATD
TOTAL DEPTH:51.5 DRILLING METHOD:Hollow Stem Auger LOGGED BY:KEB
TOP ELEVATION:DRILLING COMPANY:Boretec, Inc.HAMMER TYPE:Cathead
LATITUDE:DRILL RIG:EC95 HAMMER WEIGHT:140 lb
LONGITUDE:NOTES:West side of ravine, near proposed lot 19
NOTES Creekwood Residential Plat
1. Refer to log key for definition of symbols, abbreviations and codes XXX 21st Ave SW/22nd Ave SW
2. USCS designation is based on visual manual classification Federal Way, WA
and selected lab testing
3. Groundwater level, if indicated, is for the date shown and may vary
4. N.E. = Not Encountered LOG OF BORING B-6
5. ATD = At the Time of Drilling
JOB: Amalani.Creekwood Sheet 2 of
GeoResources, LLC FIG.A-7DepthElevationSOIL DESCRIPTION DRILLING
NOTES
SampleSamplerSymbolTEST RESULTS
10 20 30 40 50
Penetration - (blows per foot)
% Fines (<0.075mm)
% Water Content
Plastic Limit Liquid Limit
BlowCountGroundWater2
0
5
10
15
20
25
30
240
235
230
225
220
215
210
Topsoil/ forest duff
Tan/orange SAND with silt (mottling)(medium
dense, damp)
Tan to grey sandy SILT (med. dense/dense,
moist)
Brown silty SAND w/ gravel (very dense,
moist)
Grey medium SAND w/ trace silt (very dense,
moist)(advance outwash?)
Grey medium silty SAND (dense,
wet)(advance outwash?)
64
62
72
10
7
7
10
12
21
9
9
14
7
8
13
18
27
37
16
21
41
17
28
44
17
21
26
ATD
TOTAL DEPTH:51.5 ft DRILLING METHOD:Hollow Stem Auger LOGGED BY:KEB
TOP ELEVATION:240'DRILLING COMPANY:Boretec, Inc.HAMMER TYPE:Cathead
LATITUDE:DRILL RIG:EC95 HAMMER WEIGHT:140 lbs
LONGITUDE:NOTES:East side of ravine at top of slope nearest to 22nd Ave SW
NOTES Creekwood Residential Plat
1. Refer to log key for definition of symbols, abbreviations and codes XXX 21st Ave SW/22nd Ave SW
2. USCS designation is based on visual manual classification Federal Way, WA
and selected lab testing
3. Groundwater level, if indicated, is for the date shown and may vary
4. N.E. = Not Encountered LOG OF BORING B-7
5. ATD = At the Time of Drilling
JOB: Amalani.Creekwood Sheet 1 of
GeoResources, LLC FIG.A-8DepthElevationSOIL DESCRIPTION DRILLING
NOTES
SampleSamplerSymbolTEST RESULTS
10 20 30 40 50
Penetration - (blows per foot)
% Fines (<0.075mm)
% Water Content
Plastic Limit Liquid Limit
BlowCountGroundWater2
35
40
45
50
55
60
65
205
200
195
190
185
180
175
Grey medium SAND (very dense, wet)
(advance outwash?)
Grey medium SAND (very dense, saturated)
(advance outwash?)
Bottom of Boring
CompletedAugust 10, 2015
74
95
91
65
14
24
50/6
11
45
50/6
25
41
50/5
25
25
40
TOTAL DEPTH:51.5 ft DRILLING METHOD:Hollow Stem Auger LOGGED BY:KEB
TOP ELEVATION:240'DRILLING COMPANY:Boretec, Inc.HAMMER TYPE:Cathead
LATITUDE:DRILL RIG:EC95 HAMMER WEIGHT:140 lbs
LONGITUDE:NOTES:East side of ravine at top of slope nearest to 22nd Ave SW
NOTES Creekwood Residential Plat
1. Refer to log key for definition of symbols, abbreviations and codes XXX 21st Ave SW/22nd Ave SW
2. USCS designation is based on visual manual classification Federal Way, WA
and selected lab testing
3. Groundwater level, if indicated, is for the date shown and may vary
4. N.E. = Not Encountered LOG OF BORING B-7
5. ATD = At the Time of Drilling
JOB: Amalani.Creekwood Sheet 2 of
GeoResources, LLC FIG.A-8DepthElevationSOIL DESCRIPTION DRILLING
NOTES
SampleSamplerSymbolTEST RESULTS
10 20 30 40 50
Penetration - (blows per foot)
% Fines (<0.075mm)
% Water Content
Plastic Limit Liquid Limit
BlowCountGroundWater2
0
5
10
15
20
25
30
270
265
260
255
250
245
240
Topsoil/ forest duff
Tan medium SAND with some silt (medium
dense, damp)
Grey medium SAND with trace silt (medium
dense becomes dense, moist)
1 8
12
14
14
40
17
12
18
20
17
17
21
15
17
21
13
20
26
TOTAL DEPTH:51.5 DRILLING METHOD:Hollow Stem Auger LOGGED BY:KEB
TOP ELEVATION:270 ft DRILLING COMPANY:Boretec, Inc.HAMMER TYPE:Cathead
LATITUDE:DRILL RIG:EC95 HAMMER WEIGHT:140 lbs
LONGITUDE:NOTES:East of ravine SE of B-7 at top of slope
NOTES Creekwood Residential Plat
1. Refer to log key for definition of symbols, abbreviations and codes XXX 21st Ave SW/22nd Ave SW
2. USCS designation is based on visual manual classification Federal Way, WA
and selected lab testing
3. Groundwater level, if indicated, is for the date shown and may vary
4. N.E. = Not Encountered LOG OF BORING B-8
5. ATD = At the Time of Drilling
JOB: Amalani.Creekwood Sheet 1 of
GeoResources, LLC FIG.A-9DepthElevationSOIL DESCRIPTION DRILLING
NOTES
SampleSamplerSymbolTEST RESULTS
10 20 30 40 50
Penetration - (blows per foot)
% Fines (<0.075mm)
% Water Content
Plastic Limit Liquid Limit
BlowCountGroundWater2
35
40
45
50
55
60
65
235
230
225
220
215
210
205
Grey to tan silty SAND (very dense,
moist)(advance outwash?)
Grey medium SAND (very dense,
moist)(advance outwash?)
Bottom of Boring
CompletedAugust 10, 2015
61
89
66
16
24
37
14
23
28
22
42
47
19
25
41
TOTAL DEPTH:51.5 DRILLING METHOD:Hollow Stem Auger LOGGED BY:KEB
TOP ELEVATION:270 ft DRILLING COMPANY:Boretec, Inc.HAMMER TYPE:Cathead
LATITUDE:DRILL RIG:EC95 HAMMER WEIGHT:140 lbs
LONGITUDE:NOTES:East of ravine SE of B-7 at top of slope
NOTES Creekwood Residential Plat
1. Refer to log key for definition of symbols, abbreviations and codes XXX 21st Ave SW/22nd Ave SW
2. USCS designation is based on visual manual classification Federal Way, WA
and selected lab testing
3. Groundwater level, if indicated, is for the date shown and may vary
4. N.E. = Not Encountered LOG OF BORING B-8
5. ATD = At the Time of Drilling
JOB: Amalani.Creekwood Sheet 2 of
GeoResources, LLC FIG.A-9DepthElevationSOIL DESCRIPTION DRILLING
NOTES
SampleSamplerSymbolTEST RESULTS
10 20 30 40 50
Penetration - (blows per foot)
% Fines (<0.075mm)
% Water Content
Plastic Limit Liquid Limit
BlowCountGroundWater2
0
5
10
15
20
25
30
195
190
185
180
175
170
165
Gravelly topsoil/forest duffBrown SAND with gravel
Dark gray medium SAND (loose wet)
Brown to gray medium SAND with trace silt
(loose, saturated)
Light gray medium SAND (dense, wet)
Bottom of Boring
Completed8/14/2015
1
2
3
4
5
6
3
2
5
4
2
2
2
2
2
2
2
5
9
15
17
10
17
18
ATD
TOTAL DEPTH:16.5 DRILLING METHOD:HSA LOGGED BY:STM
TOP ELEVATION:196 DRILLING COMPANY:Boretec, Inc HAMMER TYPE:cathead
LATITUDE:DRILL RIG:EC-95 HAMMER WEIGHT:140 lbs
LONGITUDE:NOTES:
NOTES Creekwood Residential Plat
1. Refer to log key for definition of symbols, abbreviations and codes XXX 21st Ave SW/22nd Ave SW
2. USCS designation is based on visual manual classification Federal Way, WA
and selected lab testing
3. Groundwater level, if indicated, is for the date shown and may vary
4. N.E. = Not Encountered LOG OF BORING B-9
5. ATD = At the Time of Drilling
JOB: Amalani.Creekwood Sheet 1 of
GeoResources, LLC FIG.A-10DepthElevationSOIL DESCRIPTION DRILLING
NOTES
SampleSamplerSymbolTEST RESULTS
10 20 30 40 50
Penetration - (blows per foot)
% Fines (<0.075mm)
% Water Content
Plastic Limit Liquid Limit
BlowCountGroundWater1
0
5
10
15
20
25
30
200
195
190
185
180
175
170
Topsoil/Forest Duff (wet)
Dark brown SAND with some gravel, silt
(loose, wet)
Gray medium SAND with trace silt (loose,
saturated)
becomes dense
Bottom of Boring
Completed8/14/2015
1
2
3
4
5
6
6
3
1
1
0
2
2
2
3
7
5
10
14
19
ATD
TOTAL DEPTH:14 DRILLING METHOD:HSA LOGGED BY:STM
TOP ELEVATION:202 DRILLING COMPANY:Boretec, Inc HAMMER TYPE:cathead
LATITUDE:DRILL RIG:EC-95 HAMMER WEIGHT:140lbs
LONGITUDE:NOTES:
NOTES Creekwood Residential Plat
1. Refer to log key for definition of symbols, abbreviations and codes XXX 21st Ave SW/22nd Ave SW
2. USCS designation is based on visual manual classification Federal Way, WA
and selected lab testing
3. Groundwater level, if indicated, is for the date shown and may vary
4. N.E. = Not Encountered LOG OF BORING B-10
5. ATD = At the Time of Drilling
JOB: Amalani.Creekwood Sheet 1 of
GeoResources, LLC FIG.A-11DepthElevationSOIL DESCRIPTION DRILLING
NOTES
SampleSamplerSymbolTEST RESULTS
10 20 30 40 50
Penetration - (blows per foot)
% Fines (<0.075mm)
% Water Content
Plastic Limit Liquid Limit
BlowCountGroundWater1
Test Pit TP-1
Location: East knob, NE corner of site along east property line.
Approximate Elevation: 276 feet
Depth (feet) Soil Type Soil Description
0 - 2 SP Brown SAND with gravel, debris (medium dense, moist)
2 - 11 SP Brown gravelly SAND with some silt, slightly compact (medium dense to dense, moist)
(Outwash Deposits)
Terminated at 11 feet below ground surface.
No caving observed
No groundwater seepage or mottling observed.
Test Pit TP-2
Location: Above top of slope, proposed lot 23
Approximate Elevation: 277 feet
Depth (feet) Soil Type Soil Description
0 - 1 - Forest Duff/Topsoil with numerous roots
1 - 4 SP Brown gravelly SAND with some silt, scattered roots (medium dense, moist) (Weathered
Outwash Deposits)
4 - 9 SP Brown SAND with gravel, trace silt, slightly compact(medium dense to dense, moist)
(Outwash Deposits)
Terminated at 9 feet below ground surface.
No caving observed.
No groundwater seepage or mottling observed.
Test Pit TP-3
Location: Along existing trail, on proposed roadway
Approximate Elevation: 274 feet
Depth (feet) Soil Type Soil Description
0 - 1½ - Forest Duff/Topsoil with numerous roots
1½ - 4 SP Brown gravelly SAND with some silt, scattered roots (medium dense, moist) (Weathered
Outwash Deposits)
4 - 11 SP Brown medium grained SAND with gravel (medium dense, moist) (Outwash Deposits)
Terminated at 4 feet below ground surface.
No caving observed.
No groundwater seepage observed.
Logged by: R.M. Phillips Excavated on: January 3, 2014
GeoResources, LLC
5007 Pacific Highway East, Suite 16
Fife, Washington 98424
Phone: 253-896-1011
Fax: 253-896-2633
Test Pit Logs
Proposed Residential Plat
xxx 21st Way SW
Federal Way, Washington
Job: Amalani.CreekWood July 2016 Figure A-12
Test Pit TP-4
Location: East knob, proposed stormwater tract
Approximate Elevation: 245 feet
Depth (feet) Soil Type Soil Description
0 - 2 - Forest Duff/Topsoil with numerous roots
2 - 3½ SM Brown silty SAND with scattered roots (loose, moist) (Weathered Outwash Deposits)
3½ - 10 SP Brown gravelly fine to medium SAND with some silt, slightly compact (medium dense to
dense, moist) (Outwash Deposits)
Terminated at 10 feet below ground surface.
Minor sloughing observed in upper 3 feet.
No groundwater seepage or mottling observed.
Test Pit TP-5
Location: East knob, proposed stormwater tract
Approximate Elevation: 250 feet
Depth (feet) Soil Type Soil Description
0 - 1½ - Forest Duff/Topsoil with numerous roots
1½ - 3½ SM Brown silty fine to medium SAND with scattered roots (loose, moist) (Weathered
Outwash Deposits)
3½ - 8 SP Brown SAND with gravel (medium dense to dense, moist) (Outwash Deposits)
Terminated at 8 feet below ground surface.
Minor sloughing observed in upper 3 feet.
No groundwater seepage or mottling observed.
Test Pit TP-6
Location: West knob, proposed stormwater tract
Approximate Elevation: 250 feet
Depth (feet) Soil Type Soil Description
0 - 1 - Forest Duff/Topsoil with numerous roots
1 - 3 SM Brown silty fine to medium grained SAND with scattered roots (medium dense, moist)
(Weathered Outwash)
3 - 8 SP Brown fine to medium grained SAND with trace gravel, compact (dense, moist)
(Outwash Deposits)
Terminated at 8 feet below ground surface.
No caving observed.
No groundwater seepage observed.
Logged by: R.M. Phillips Excavated on: January 3, 2014
GeoResources, LLC
5007 Pacific Highway East, Suite 16
Fife, Washington 98424
Phone: 253-896-1011
Fax: 253-896-2633
Test Pit Logs
Proposed Residential Plat
xxx 21st Way SW
Federal Way, Washington
Job: Amalani.CreekWood July 2016 Figure A-13
Test Pit TP-7
Location: West knob, SW of TP-6
Approximate Elevation: 246 feet
Depth (feet) Soil Type Soil Description
0 - 1 - Forest Duff/Topsoil with numerous roots
1 - 6 SM Gray mottled gravelly SAND with some silt (medium dense, moist) (Weathered Outwash
Deposits)
6 - 8 ML Gray fine sandy SILT (stiff to very stiff, moist) (Glacial Lacustrine Sediments)
8 - 11 SP/GP Brown to gray SAND/GRAVEL with trace silt (dense, moist) (Outwash Deposits)
Terminated at 11 feet below ground surface.
No caving observed.
No groundwater seepage observed. Mottling observed between depths of 1 to 6 feet.
Test Pit TP-8
Location: W est of TP-7
Approximate Elevation: 251 feet
Depth (feet) Soil Type Soil Description
0 - 1 - Forest Duff/Topsoil with numerous roots
1 - 5 SM Gray mottled silty SAND with gravel, trace roots (medium dense, moist) (Weathered
Till/Lacustrine?)
5 - 8 SM Gray silty SAND with gravel, cobbles, compact (dense to very dense, moist) (Glacial Till)
Terminated at 8 feet below ground surface.
No caving observed.
No groundwater seepage observed. Mottling observed between depths of 1 to 5 feet.
Test Pit TP-9
Location: Center of west portion of site
Approximate Elevation: 256 feet
Depth (feet) Soil Type Soil Description
0 - ½ - Topsoil with numerous roots
½ - 5 SM Brown silty SAND with gravel, mottled (medium dense, m oist) (Weathered Recessional
Outwash)
5 - 9 SM Gray silty SAND with gravel (dense, moist) (Glacial Till)
Terminated at 9 feet below ground surface.
No caving observed.
No groundwater seepage observed. Mottling observed above depth of 5 feet.
Logged by: R.M. Phillips Excavated on: January 3, 2014
GeoResources, LLC
5007 Pacific Highway East, Suite 16
Fife, Washington 98424
Phone: 253-896-1011
Fax: 253-896-2633
Test Pit Logs
Proposed Residential Plat
xxx 21st Way SW
Federal Way, Washington
Job: Amalani.CreekWood July 2016 Figure A-14
Test Pit TP-10
Location: West knob, near north slope
Approximate Elevation: 259 feet
Depth (feet) Soil Type Soil Description
0 - 1 - Forest Duff/Topsoil with numerous roots
1 - 5 SM Brown silty SAND with gravel, mottled (medium dense, moist) (Weathered Recessional
Outwash)
5 - 10 SM Gray silty SAND with gravel, cobbles, compact but friable (medium dense to dense,
moist) (weak Glacial Till)
Terminated at 10 feet below ground surface.
No caving observed.
No groundwater seepage or mottling observed.
Test Pit TP-11
Location: North-center of west knob, East of TP-9
Approximate Elevation: 256 feet
Depth (feet) Soil Type Soil Description
0 - 1 - Forest Duff/Topsoil with numerous roots
1 - 4 SP Brown SAND with silt, mottling at basal contact (medium dense, moist) (Native
Weathered Outwash Deposits)
4 - 6 SP Brown SAND with gravel (medium dense to dense, moist) (Native Outwash Deposits)
6 - 8 GP Sandy GRAVEL with cobbles, compact (medium dense to dense, moist)
Terminated at 8 feet below ground surface.
No caving observed.
No groundwater seepage observed. Minor mottling observed at 4 feet below the ground
surface.
Test Pit TP-12
Location: West knob
Approximate Elevation: 250 feet
Depth (feet) Soil Type Soil Description
0 - 1 - Forest Duff/Topsoil with numerous roots
1 - 3 ½ SM Brown silty fine to medium grained SAND with scattered roots (medium dense, moist)
(Weathered Outwash)
3 ½ - 5 SM/ML Gray SILT/ SAND with gravel (medium dense to dense/stiff , moist) (weak Glacial
Till/Lacustrine?)
Terminated at 5 feet below ground surface.
No caving observed.
No groundwater seepage observed.
Logged by: R.M. Phillips Excavated on: January 3, 2014
GeoResources, LLC
5007 Pacific Highway East, Suite 16
Fife, Washington 98424
Phone: 253-896-1011
Fax: 253-896-2633
Test Pit Logs
Proposed Residential Plat
xxx 21st Way SW
Federal Way, Washington
Job: Amalani.CreekWood July 2016 Figure A-15
Test Pit TP-13
Location: W est knob, near 22nd Av SW
Approximate Elevation: 238 feet
Depth (feet) Soil Type Soil Description
0 - 1 - Forest Duff/Topsoil with numerous roots
1 - 3 SM Brown silty SAND with gravel, mottled (medium dense, moist) (Weathered Recessional
Outwash)
3 - 7 SM Gray silty SAND with gravel (dense, moist) (Glacial Till)
Terminated at 7 feet below ground surface.
No caving observed.
No groundwater seepage observed. Minor mottling observed above 3 feet depth.
Logged by: R.M. Phillips Excavated on: January 3, 2014
GeoResources, LLC
5007 Pacific Highway East, Suite 16
Fife, Washington 98424
Phone: 253-896-1011
Fax: 253-896-2633
Test Pit Logs
Proposed Residential Plat
xxx 21st Way SW
Federal Way, Washington
Job: Amalani.CreekWood July 2016 Figure A-16
Hand Auger HA-1
Location: Approximately ½ way up slope between proposed Lot 21 and Tract C
Approximate Elevation: 210 feet
Depth (feet) Soil Type Soil Description
0.0 - 1.0 - Forest Duff, Topsoil
1.0 - 3.5 - Light brown / tan fine SAND with some gravel (medium dense, dry)
3.5 - 5.0 - Brown SAND (medium dense, moist)
5.0 - 6.0 SP Brown SAND (medium dense to dense, moist to wet)
6.0 - 7.5 SP Tan SAND (medium dense to dense, moist)
Terminated at 7 feet below ground surface.
Caving observed from surface.
Groundwater seepage observed at 5.5 feet depth.
Hand Auger HA-2
Location: Approximately in the middle of “Road B” and Tract C near 6’ mulch trail
Approximate Elevation: 195 feet
Depth (feet) Soil Type Soil Description
0.0 - 0.5 - Black Topsoil, Forest Duff
0.5 - 3.5 SP Grey/ Brown SAND with some gravel (medium dense, moist)
3.5 - 5.0 SP Grey coarse SAND with some organics (medium dense, wet)
5.0 - 5.5 SP Tan SAND (medium dense to dense, moist)
Terminated at 5.5 feet below ground surface.
No caving observed.
Groundwater seepage observed at 3.5 to 5 feet depth.
Hand Auger HA-3
Location: 10’ upslope from the center of back edge of proposed Lot 19
Approximate Elevation: 210 feet
Depth (feet) Soil Type Soil Description
0.0 - 1.0 - Forest Duff, Topsoil
1.0 - 4.5 SP Tan SAND with silt, organics, and some gravel (dense, dry)
Terminated at 4.5 feet below ground surface.
Caving observed from surface.
No groundwater seepage observed.
Logged by: DRT Excavated on: August 24, 2015
GeoResources, LLC
5007 Pacific Highway East, Suite 16
Fife, Washington 98424
Phone: 253-896-1011
Fax: 253-896-2633
Hand Auger Logs
Proposed Residential Plat
xxx 21st Way SW
Federal Way, Washington
Job: Amalani.CreekWood July 2016 Figure A-17
Appendix B
Laboratory Test Results
These results are for the exclusive use of the client for whom they were obtained. They apply only to the samples tested and are not indicitive of apparently identical samples.Tested By: Checked By:
GeoResources, LLC
Fife, WA
(no specification provided)*
PL=LL=PI=
USCS (D 2487)=AASHTO (M 145)=
D90=D85=D60=
D50=D30=D15=
D10=Cu=Cc=
Remarks
Grey medium SAND with silt (Very dense, moist) (advance
outwash?)
NM-8.3%1.25
1
.75
.5
.375
#4
#10
#20
#40
#60
#100
#200
100.0
100.0
100.0
100.0
100.0
98.3
95.3
89.0
66.2
29.1
16.4
11.0
SP-SM
0.9194 0.6789 0.3878
0.3392 0.2541 0.1297
JPK
Amalani, LLC
Creekwood Residential Plat
Amalani.Creekwood
Material Description
Atterberg Limits (ASTM D 4318)
Classification
Coefficients
Date Received:Date Tested:
Tested By:
Checked By:
Title:
Date Sampled:Source of Sample: B-5 Depth: 15Sample Number: 5
Client:
Project:
Project No:Figure
TEST RESULTS
Opening Percent Spec.
*Pass?
Size Finer (Percent) (X=Fail)PERCENT FINER0
10
20
30
40
50
60
70
80
90
100
GRAIN SIZE - mm.
0.0010.010.1110100
% +3"Coarse
% Gravel
Fine Coarse Medium
% Sand
Fine Silt
% Fines
Clay
0.0 0.0 1.7 3.0 29.1 55.2 11.06 in.3 in.2 in.1½ in.1 in.¾ in.½ in.3/8 in.#4#10#20#30#40#60#100#140#200Particle Size Distribution Report
These results are for the exclusive use of the client for whom they were obtained. They apply only to the samples tested and are not indicitive of apparently identical samples.Tested By: Checked By:
GeoResources, LLC
Fife, WA
(no specification provided)*
PL=LL=PI=
USCS (D 2487)=AASHTO (M 145)=
D90=D85=D60=
D50=D30=D15=
D10=Cu=Cc=
Remarks
Poorly graded san
NM- 5.9%
1.25
1
.75
.5
.375
#4
#10
#20
#40
#60
#100
#200
100.0
100.0
100.0
100.0
100.0
99.9
99.4
95.2
77.2
32.5
16.5
10.6
0.5608 0.4880 0.3452
0.3098 0.2400 0.1307
JPK
8/10/15
Amalani, LLC
Creekwood Residential Plat
Amalani.Creekwood
Material Description
Atterberg Limits (ASTM D 4318)
Classification
Coefficients
Date Received:Date Tested:
Tested By:
Checked By:
Title:
Date Sampled:Source of Sample: B-5 Depth: 25Sample Number: 7
Client:
Project:
Project No:Figure
TEST RESULTS
Opening Percent Spec.
*Pass?
Size Finer (Percent) (X=Fail)PERCENT FINER0
10
20
30
40
50
60
70
80
90
100
GRAIN SIZE - mm.
0.0010.010.1110100
% +3"Coarse
% Gravel
Fine Coarse Medium
% Sand
Fine Silt
% Fines
Clay
0.0 0.0 0.1 0.5 22.2 66.6 10.66 in.3 in.2 in.1½ in.1 in.¾ in.½ in.3/8 in.#4#10#20#30#40#60#100#140#200Particle Size Distribution Report
These results are for the exclusive use of the client for whom they were obtained. They apply only to the samples tested and are not indicitive of apparently identical samples.Tested By: Checked By:
GeoResources, LLC
Fife, WA
(no specification provided)*
PL=LL=PI=
USCS (D 2487)=AASHTO (M 145)=
D90=D85=D60=
D50=D30=D15=
D10=Cu=Cc=
Remarks
Grey medium SAND with trace silt (very dense, wet) (advance
outwash?)
1.25
1
.75
.5
.375
#4
#10
#20
#40
#60
#100
#200
100.0
100.0
100.0
100.0
99.5
99.5
98.9
97.4
79.4
26.6
12.9
8.1
SP-SM
0.5936 0.4997 0.3489
0.3189 0.2612 0.1894
0.0951 3.67 2.06
NM-18%
JPK
Amalani, LLC
Creekwood Residential Plat
Amalani.Creekwood
Material Description
Atterberg Limits (ASTM D 4318)
Classification
Coefficients
Date Received:Date Tested:
Tested By:
Checked By:
Title:
Date Sampled:Source of Sample: B-5 Depth: 35Sample Number: 9
Client:
Project:
Project No:Figure
TEST RESULTS
Opening Percent Spec.
*Pass?
Size Finer (Percent) (X=Fail)PERCENT FINER0
10
20
30
40
50
60
70
80
90
100
GRAIN SIZE - mm.
0.0010.010.1110100
% +3"Coarse
% Gravel
Fine Coarse Medium
% Sand
Fine Silt
% Fines
Clay
0.0 0.0 0.5 0.6 19.5 71.3 8.16 in.3 in.2 in.1½ in.1 in.¾ in.½ in.3/8 in.#4#10#20#30#40#60#100#140#200Particle Size Distribution Report
These results are for the exclusive use of the client for whom they were obtained. They apply only to the samples tested and are not indicitive of apparently identical samples.Tested By: Checked By:
GeoResources, LLC
Fife, WA
(no specification provided)*
PL=LL=PI=
USCS (D 2487)=AASHTO (M 145)=
D90=D85=D60=
D50=D30=D15=
D10=Cu=Cc=
Remarks
Grey medium SAND with trace silt and occ gravel(very dense,
wet)(advance outwash?
NM-14.7%1.25
1
.75
.5
.375
#4
#10
#20
#40
#60
#100
#200
100.0
100.0
93.4
90.7
86.0
82.4
80.6
77.8
68.5
29.0
14.4
9.4
SP-SM
11.9804 8.8857 0.3736
0.3295 0.2539 0.1584
0.0844 4.42 2.04
JPK
Amalani, LLC
Creekwood Residential Plat
Amalani.Creekwood
Material Description
Atterberg Limits (ASTM D 4318)
Classification
Coefficients
Date Received:Date Tested:
Tested By:
Checked By:
Title:
Date Sampled:Source of Sample: B-5 Depth: 40Sample Number: 10
Client:
Project:
Project No:Figure
TEST RESULTS
Opening Percent Spec.
*Pass?
Size Finer (Percent) (X=Fail)PERCENT FINER0
10
20
30
40
50
60
70
80
90
100
GRAIN SIZE - mm.
0.0010.010.1110100
% +3"Coarse
% Gravel
Fine Coarse Medium
% Sand
Fine Silt
% Fines
Clay
0.0 6.6 11.0 1.8 12.1 59.1 9.46 in.3 in.2 in.1½ in.1 in.¾ in.½ in.3/8 in.#4#10#20#30#40#60#100#140#200Particle Size Distribution Report
These results are for the exclusive use of the client for whom they were obtained. They apply only to the samples tested and are not indicitive of apparently identical samples.Tested By: Checked By:
GeoResources, LLC
Fife, WA
(no specification provided)*
PL=LL=PI=
USCS (D 2487)=AASHTO (M 145)=
D90=D85=D60=
D50=D30=D15=
D10=Cu=Cc=
Remarks
NM-4.3
1.25
1
.75
.5
.375
#4
#10
#20
#40
#60
#100
#200
100.0
100.0
100.0
100.0
100.0
99.7
99.0
94.5
67.5
27.8
14.9
10.5
SP-SM
0.6897 0.5915 0.3845
0.3398 0.2598 0.1509
JPK
Amalani, LLC
Creekwood Residential Plat
Amalani.Creekwood
Material Description
Atterberg Limits (ASTM D 4318)
Classification
Coefficients
Date Received:Date Tested:
Tested By:
Checked By:
Title:
Date Sampled:Source of Sample: B-6 Depth: 5Sample Number: 2
Client:
Project:
Project No:Figure
TEST RESULTS
Opening Percent Spec.
*Pass?
Size Finer (Percent) (X=Fail)PERCENT FINER0
10
20
30
40
50
60
70
80
90
100
GRAIN SIZE - mm.
0.0010.010.1110100
% +3"Coarse
% Gravel
Fine Coarse Medium
% Sand
Fine Silt
% Fines
Clay
0.0 0.0 0.3 0.7 31.5 57.0 10.56 in.3 in.2 in.1½ in.1 in.¾ in.½ in.3/8 in.#4#10#20#30#40#60#100#140#200Particle Size Distribution Report
These results are for the exclusive use of the client for whom they were obtained. They apply only to the samples tested and are not indicitive of apparently identical samples.Tested By: Checked By:
GeoResources, LLC
Fife, WA
(no specification provided)*
PL=LL=PI=
USCS (D 2487)=AASHTO (M 145)=
D90=D85=D60=
D50=D30=D15=
D10=Cu=Cc=
Remarks
NM-5.7%
1.25
1
.75
.5
.375
#4
#10
#20
#40
#60
#100
#200
100.0
100.0
100.0
100.0
98.7
95.5
91.8
85.0
61.6
29.0
19.2
14.2
SP-SM
1.3614 0.8487 0.4135
0.3545 0.2557 0.0838
JPK
Amalani, LLC
Creekwood Residential Plat
Amalani.Creekwood
Material Description
Atterberg Limits (ASTM D 4318)
Classification
Coefficients
Date Received:Date Tested:
Tested By:
Checked By:
Title:
Date Sampled:Source of Sample: B-8 Depth: 5Sample Number: 1
Client:
Project:
Project No:Figure
TEST RESULTS
Opening Percent Spec.
*Pass?
Size Finer (Percent) (X=Fail)PERCENT FINER0
10
20
30
40
50
60
70
80
90
100
GRAIN SIZE - mm.
0.0010.010.1110100
% +3"Coarse
% Gravel
Fine Coarse Medium
% Sand
Fine Silt
% Fines
Clay
0.0 0.0 4.5 3.7 30.2 47.4 14.26 in.3 in.2 in.1½ in.1 in.¾ in.½ in.3/8 in.#4#10#20#30#40#60#100#140#200Particle Size Distribution Report
These results are for the exclusive use of the client for whom they were obtained. They apply only to the samples tested and are not indicitive of apparently identical samples.Tested By: Checked By:
GeoResources, LLC
Fife, WA
(no specification provided)*
PL=LL=PI=
USCS (D 2487)=AASHTO (M 145)=
D90=D85=D60=
D50=D30=D15=
D10=Cu=Cc=
Remarks
NM-19.4%
1.25
1
.75
.5
.375
#4
#10
#20
#40
#60
#100
#200
100.0
100.0
95.2
87.2
86.5
83.5
80.5
76.8
61.2
30.1
16.9
11.4
15.1849 6.1890 0.4151
0.3498 0.2496 0.1261
JPK
Amalani, LLC
Creekwood Residential Plat
Amalani.Creekwood
Material Description
Atterberg Limits (ASTM D 4318)
Classification
Coefficients
Date Received:Date Tested:
Tested By:
Checked By:
Title:
Date Sampled:Source of Sample: B-9 Depth: 5Sample Number: 2
Client:
Project:
Project No:Figure
TEST RESULTS
Opening Percent Spec.
*Pass?
Size Finer (Percent) (X=Fail)PERCENT FINER0
10
20
30
40
50
60
70
80
90
100
GRAIN SIZE - mm.
0.0010.010.1110100
% +3"Coarse
% Gravel
Fine Coarse Medium
% Sand
Fine Silt
% Fines
Clay
0.0 4.8 11.7 3.0 19.3 49.8 11.46 in.3 in.2 in.1½ in.1 in.¾ in.½ in.3/8 in.#4#10#20#30#40#60#100#140#200Particle Size Distribution Report
These results are for the exclusive use of the client for whom they were obtained. They apply only to the samples tested and are not indicitive of apparently identical samples.Tested By: Checked By:
GeoResources, LLC
Fife, WA
(no specification provided)*
PL=LL=PI=
USCS (D 2487)=AASHTO (M 145)=
D90=D85=D60=
D50=D30=D15=
D10=Cu=Cc=
Remarks
Light gray medium SAND (dense, wet)
NM-18.9%
1.25
1
.75
.5
.375
#4
#10
#20
#40
#60
#100
#200
100.0
100.0
100.0
100.0
99.4
97.1
94.8
88.2
46.7
14.7
7.4
4.6
SP
1.0282 0.7843 0.5121
0.4447 0.3343 0.2520
0.2092 2.45 1.04
JPK
Amalani, LLC
Creekwood Residential Plat
Amalani.Creekwood
Material Description
Atterberg Limits (ASTM D 4318)
Classification
Coefficients
Date Received:Date Tested:
Tested By:
Checked By:
Title:
Date Sampled:Source of Sample: B-9 Depth: 12.5Sample Number: 5
Client:
Project:
Project No:Figure
TEST RESULTS
Opening Percent Spec.
*Pass?
Size Finer (Percent) (X=Fail)PERCENT FINER0
10
20
30
40
50
60
70
80
90
100
GRAIN SIZE - mm.
0.0010.010.1110100
% +3"Coarse
% Gravel
Fine Coarse Medium
% Sand
Fine Silt
% Fines
Clay
0.0 0.0 2.9 2.3 48.1 42.1 4.66 in.3 in.2 in.1½ in.1 in.¾ in.½ in.3/8 in.#4#10#20#30#40#60#100#140#200Particle Size Distribution Report
Proposed Creekwood Page | B
December 22, 2022
Appendix C – Slope Stability Analyses
1.31.3WW1.31.3Phi (deg)Cohesion (psf)Strength TypeSat. Unit Weight (lbs/ft3)Unit Weight (lbs/ft3)ColorMaterial Name38350Mohr‐Coulomb140135Qva3050Mohr‐Coulomb90Duff40500Mohr‐Coulomb140Qvt31250Mohr‐Coulomb120115Weathered Till40030020010000100200300400500600700ScenarioMaster ScenarioGroupAA' 2022CompanyDrawn ByFile NameDecember 2022.aesrevision.slmdDate12/15/2022, 12:34:25 PMProjectSlide2 - An Interactive Slope Stability ProgramSLIDEINTERPRET 9.025
0.60.6WW0.60.6 0.325004003002001000-1000100200300400500600700800ScenarioDynamicGroupAA' 2022CompanyDrawn ByFile NameDecember 2022.aesrevision.slmdDate12/15/2022, 12:34:25 PMProjectSlide2 - An Interactive Slope Stability ProgramSLIDEINTERPRET 9.025
2.32.3WW2.32.3Phi (deg)Cohesion (psf)Strength TypeSat. Unit Weight (lbs/ft3)Unit Weight (lbs/ft3)ColorMaterial Name340Mohr‐Coulomb125120Qvr38350Mohr‐Coulomb140135Qva3050Mohr‐Coulomb90Duff370Mohr‐Coulomb130Structural Fill40500Mohr‐Coulomb140Qvt31250Mohr‐Coulomb120115Weathered TillEFP (lbs/ft3)Pressure Profile TypeConnection Strength (lbs/ft)Connection Strength InputTensile Strength (lbs/ft)Strip Coverage (%)AnchorageForce OrientationLocation of ForceFriction FactorInput TypeMaterial DependentForce ApplicationTypeColorSupport Name35TriangularHorizontalCentroid of the Pressure DiagramActive (Method A)Retaining Wall (EFP)Retaining Wall1000Constant2000100Slope FaceParallel to Reinforcement0.4Friction FactorNoActive (Method A)GeosyntheticMSE4003002001000100200300400500600ScenarioMaster ScenarioGroupAA' Proposed 2022CompanyDrawn ByFile NameDecember 2022.aesrevision.slmdDate12/15/2022, 12:34:25 PMProjectSlide2 - An Interactive Slope Stability ProgramSLIDEINTERPRET 9.025
1.21.2WW1.21.2 0.324030020010000100200300400500600ScenarioDynamicGroupAA' Proposed 2022CompanyDrawn ByFile NameDecember 2022.aesrevision.slmdDate12/15/2022, 12:34:25 PMProjectSlide2 - An Interactive Slope Stability ProgramSLIDEINTERPRET 9.025
2.92.9WW2.92.9Phi (deg)Cohesion (psf)Strength TypeSat. Unit Weight (lbs/ft3)Unit Weight (lbs/ft3)ColorMaterial Name340Mohr‐Coulomb125120Qvr38350Mohr‐Coulomb140135Qva3050Mohr‐Coulomb90Duff40500Mohr‐Coulomb140Qvt31250Mohr‐Coulomb120115Weathered Till350300250200150100150200250300350400450ScenarioMaster ScenarioGroupBB' 2022CompanyDrawn ByFile NameDecember 2022.aesrevision.slmdDate12/15/2022, 12:34:25 PMProjectSlide2 - An Interactive Slope Stability ProgramSLIDEINTERPRET 9.025
1.21.2WW1.21.2 0.32350300250200100150200250300350400450ScenarioDynamicGroupBB' 2022CompanyDrawn ByFile NameDecember 2022.aesrevision.slmdDate12/15/2022, 12:34:25 PMProjectSlide2 - An Interactive Slope Stability ProgramSLIDEINTERPRET 9.025
2.82.8WW2.82.8Phi (deg)Cohesion (psf)Strength TypeSat. Unit Weight (lbs/ft3)Unit Weight (lbs/ft3)ColorMaterial Name340Mohr‐Coulomb125120Qvr38350Mohr‐Coulomb140135Qva370Mohr‐Coulomb130Structural Fill40500Mohr‐Coulomb140Qvt31250Mohr‐Coulomb120115Weathered Till300250200150100150200250300350400450ScenarioMaster ScenarioGroupBB' 2022 ProposedCompanyDrawn ByFile NameDecember 2022.aesrevision.slmdDate12/15/2022, 12:34:25 PMProjectSlide2 - An Interactive Slope Stability ProgramSLIDEINTERPRET 9.025
1.21.2WW1.21.2 0.32400350300250200100150200250300350400450ScenarioDynamicGroupBB' 2022 ProposedCompanyDrawn ByFile NameDecember 2022.aesrevision.slmdDate12/15/2022, 12:34:25 PMProjectSlide2 - An Interactive Slope Stability ProgramSLIDEINTERPRET 9.025
2.02.0WW2.02.0Phi (deg)Cohesion (psf)Strength TypeSat. Unit Weight (lbs/ft3)Unit Weight (lbs/ft3)ColorMaterial Name3050Mohr‐Coulomb90Duff40500Mohr‐Coulomb140Qvt31250Mohr‐Coulomb120115Weathered Till2502001500255075100125150175200225250275300ScenarioMaster ScenarioGroupCC' 2022CompanyDrawn ByFile NameDecember 2022.aesrevision.slmdDate12/15/2022, 12:34:25 PMProjectSlide2 - An Interactive Slope Stability ProgramSLIDEINTERPRET 9.025
1.31.3WW1.31.3 0.322502001500255075100125150175200225250275300ScenarioDynamicGroupCC' 2022CompanyDrawn ByFile NameDecember 2022.aesrevision.slmdDate12/15/2022, 12:34:25 PMProjectSlide2 - An Interactive Slope Stability ProgramSLIDEINTERPRET 9.025
4.54.5WW4.54.5Phi (deg)Cohesion (psf)Strength TypeSat. Unit Weight (lbs/ft3)Unit Weight (lbs/ft3)ColorMaterial Name370Mohr‐Coulomb130Structural Fill40500Mohr‐Coulomb140Qvt31250Mohr‐Coulomb120115Weathered Till3002502001500255075100125150175200225250275300ScenarioMaster ScenarioGroupCC' 2022 ProposedCompanyDrawn ByFile NameDecember 2022.aesrevision.slmdDate12/15/2022, 12:34:25 PMProjectSlide2 - An Interactive Slope Stability ProgramSLIDEINTERPRET 9.025
2.12.1WW2.12.1 0.32400350300250200150-100-50050100150200250300350400ScenarioDynamicGroupCC' 2022 ProposedCompanyDrawn ByFile NameDecember 2022.aesrevision.slmdDate12/15/2022, 12:34:25 PMProjectSlide2 - An Interactive Slope Stability ProgramSLIDEINTERPRET 9.025
2.22.2WW2.22.2Phi (deg)Cohesion (psf)Strength TypeSat. Unit Weight (lbs/ft3)Unit Weight (lbs/ft3)ColorMaterial Name38350Mohr‐Coulomb140135Qva3050Mohr‐Coulomb90Duff40500Mohr‐Coulomb140Qvt31250Mohr‐Coulomb120115Weathered Till30025020015010050050100150200250300350400450ScenarioMaster ScenarioGroupDD' 2022CompanyDrawn ByFile NameDecember 2022.aesrevision.slmdDate12/15/2022, 12:34:25 PMProjectSlide2 - An Interactive Slope Stability ProgramSLIDEINTERPRET 9.025
1.41.4WW1.41.4 0.32300250200150100050100150200250300350400450ScenarioDynamicGroupDD' 2022CompanyDrawn ByFile NameDecember 2022.aesrevision.slmdDate12/15/2022, 12:34:25 PMProjectSlide2 - An Interactive Slope Stability ProgramSLIDEINTERPRET 9.025
2.22.2WW2.22.2Phi (deg)Cohesion (psf)Strength TypeSat. Unit Weight (lbs/ft3)Unit Weight (lbs/ft3)ColorMaterial Name38350Mohr‐Coulomb140135Qva370Mohr‐Coulomb130Structural Fill40500Mohr‐Coulomb140Qvt31250Mohr‐Coulomb120115Weathered Till30025020015010050050100150200250300350400450ScenarioMaster ScenarioGroupDD' 2022 ProposedCompanyDrawn ByFile NameDecember 2022.aesrevision.slmdDate12/15/2022, 12:34:25 PMProjectSlide2 - An Interactive Slope Stability ProgramSLIDEINTERPRET 9.025
1.31.3WW1.31.3 0.32300250200150100050100150200250300350400450ScenarioDynamicGroupDD' 2022 ProposedCompanyDrawn ByFile NameDecember 2022.aesrevision.slmdDate12/15/2022, 12:34:25 PMProjectSlide2 - An Interactive Slope Stability ProgramSLIDEINTERPRET 9.025
1.21.21.21.2Phi (deg)Cohesion (psf)Strength TypeUnit Weight (lbs/ft3)ColorMaterial Name340Mohr‐Coulomb120Qvr38350Mohr‐Coulomb135Qva3050Mohr‐Coulomb90Duff3002001000050100150200250300350400450500550600ScenarioMaster ScenarioGroupEE' 2022CompanyDrawn ByFile NameDecember 2022.aesrevision.slmdDate12/15/2022, 12:34:25 PMProjectSlide2 - An Interactive Slope Stability ProgramSLIDEINTERPRET 9.025
0.70.70.70.7 0.323002001000050100150200250300350400450500550600ScenarioDynamicGroupEE' 2022CompanyDrawn ByFile NameDecember 2022.aesrevision.slmdDate12/15/2022, 12:34:25 PMProjectSlide2 - An Interactive Slope Stability ProgramSLIDEINTERPRET 9.025
1.23.51.2 200.00 lbs/ft21.23.51.2139.8Phi (deg)Cohesion (psf)Strength TypeUnit Weight (lbs/ft3)ColorMaterial Name340Mohr‐Coulomb120Qvr38350Mohr‐Coulomb135Qva3050Mohr‐Coulomb90Duff500400300200100-1000100200300400500600700ScenarioMaster ScenarioGroupEE' 2022 ProposedCompanyDrawn ByFile NameDecember 2022.aesrevision.slmdDate12/15/2022, 12:34:25 PMProjectSlide2 - An Interactive Slope Stability ProgramSLIDEINTERPRET 9.025
0.71.50.7 200.00 lbs/ft20.71.50.7 0.32500400300200100-1000100200300400500600700ScenarioDynamicGroupEE' 2022 ProposedCompanyDrawn ByFile NameDecember 2022.aesrevision.slmdDate12/15/2022, 12:34:25 PMProjectSlide2 - An Interactive Slope Stability ProgramSLIDEINTERPRET 9.025
1.41.41.41.4Phi (deg)Cohesion (psf)Strength TypeUnit Weight (lbs/ft3)ColorMaterial Name340Mohr‐Coulomb120Qvr38350Mohr‐Coulomb135Qva3050Mohr‐Coulomb90Duff35030025020015010050050100150200250300350400450500ScenarioMaster ScenarioGroupFF' 2022CompanyDrawn ByFile NameDecember 2022.aesrevision.slmdDate12/15/2022, 12:34:25 PMProjectSlide2 - An Interactive Slope Stability ProgramSLIDEINTERPRET 9.025
0.70.70.70.7 0.32400300200100-50050100150200250300350400450500550ScenarioDynamicGroupFF' 2022CompanyDrawn ByFile NameDecember 2022.aesrevision.slmdDate12/15/2022, 12:34:25 PMProjectSlide2 - An Interactive Slope Stability ProgramSLIDEINTERPRET 9.025
1.42.01.4WW 200.00 lbs/ft21.42.01.4Phi (deg)Cohesion (psf)Strength TypeSat. Unit Weight (lbs/ft3)Unit Weight (lbs/ft3)ColorMaterial Name340Mohr‐Coulomb125120Qvr38350Mohr‐Coulomb140135Qva3050Mohr‐Coulomb90DuffInfinite strength150Concrete147.0003530025020015010050050100150200250300350400450500ScenarioMaster ScenarioGroupFF' 2022 ProposedCompanyDrawn ByFile NameDecember 2022.aesrevision.slmdDate12/15/2022, 12:34:25 PMProjectSlide2 - An Interactive Slope Stability ProgramSLIDEINTERPRET 9.025
0.71.20.7WW 200.00 lbs/ft20.71.20.7 0.3235030025020015010050-50050100150200250300350400450500550ScenarioDynamicGroupFF' 2022 ProposedCompanyDrawn ByFile NameDecember 2022.aesrevision.slmdDate12/15/2022, 12:34:25 PMProjectSlide2 - An Interactive Slope Stability ProgramSLIDEINTERPRET 9.025
2.62.6WW2.62.6Phi (deg)Cohesion (psf)Strength TypeSat. Unit Weight (lbs/ft3)Unit Weight (lbs/ft3)ColorMaterial Name38350Mohr‐Coulomb140135Qva3050Mohr‐Coulomb90Duff40500Mohr‐Coulomb140Qvt31250Mohr‐Coulomb120115Weathered Till300250200150100500050100150200250300350400450500550ScenarioMaster ScenarioGroupGG' 2022CompanyDrawn ByFile NameDecember 2022.aesrevision.slmdDate12/15/2022, 12:34:25 PMProjectSlide2 - An Interactive Slope Stability ProgramSLIDEINTERPRET 9.025
1.41.4WW1.41.4 0.3235030025020015010050050100150200250300350400450500550ScenarioDynamicGroupGG' 2022CompanyDrawn ByFile NameDecember 2022.aesrevision.slmdDate12/15/2022, 12:34:25 PMProjectSlide2 - An Interactive Slope Stability ProgramSLIDEINTERPRET 9.025
2.62.6WW 200.00 lbs/ft22.62.6Phi (deg)Cohesion (psf)Strength TypeSat. Unit Weight (lbs/ft3)Unit Weight (lbs/ft3)ColorMaterial Name38350Mohr‐Coulomb140135Qva3050Mohr‐Coulomb90Duff40500Mohr‐Coulomb140Qvt31250Mohr‐Coulomb120115Weathered Till300250200150100500050100150200250300350400450500550ScenarioMaster ScenarioGroupGG' 2022 ProposedCompanyDrawn ByFile NameDecember 2022.aesrevision.slmdDate12/15/2022, 12:34:25 PMProjectSlide2 - An Interactive Slope Stability ProgramSLIDEINTERPRET 9.025
1.41.4WW 200.00 lbs/ft21.41.4 0.3235030025020015010050050100150200250300350400450500550ScenarioDynamicGroupGG' 2022 ProposedCompanyDrawn ByFile NameDecember 2022.aesrevision.slmdDate12/15/2022, 12:34:25 PMProjectSlide2 - An Interactive Slope Stability ProgramSLIDEINTERPRET 9.025
2.22.2W2.22.2Phi (deg)Cohesion (psf)Strength TypeSat. Unit Weight (lbs/ft3)Unit Weight (lbs/ft3)ColorMaterial Name38350Mohr‐Coulomb140135Qva3050Mohr‐Coulomb90Duff31250Mohr‐Coulomb120115Weathered Till2402302202102001901800102030405060708090100110ScenarioMaster ScenarioGroupSPSP' 2022CompanyDrawn ByFile NameDecember 2022.aesrevision.slmdDate12/15/2022, 12:34:25 PMProjectSlide2 - An Interactive Slope Stability ProgramSLIDEINTERPRET 9.025
1.31.3W1.31.3 0.322402202000102030405060708090100110ScenarioDynamicGroupSPSP' 2022CompanyDrawn ByFile NameDecember 2022.aesrevision.slmdDate12/15/2022, 12:34:25 PMProjectSlide2 - An Interactive Slope Stability ProgramSLIDEINTERPRET 9.025
2.62.6 200.00 lbs/ft2 200.00 lbs/ft22.62.6Phi (deg)Cohesion (psf)Strength TypeUnit Weight (lbs/ft3)ColorMaterial Name38350Mohr‐Coulomb135Qva370Mohr‐Coulomb130Structural FillInfinite strength150Concrete31250Mohr‐Coulomb115Weathered TillForce OrientationPile Shear Strength (lbs)Failure ModeOut‐Of‐Plane Spacing (ft)Force ApplicationTypeColorSupport NameParallel to surface20000Shear5Active (Method A)Pile/Micro Pile4 inch pins2502402302202102001900102030405060708090100110ScenarioMaster ScenarioGroupSPSP' 2022 ProposedCompanyDrawn ByFile NameDecember 2022.aesrevision.slmdDate12/15/2022, 12:34:25 PMProjectSlide2 - An Interactive Slope Stability ProgramSLIDEINTERPRET 9.025
1.31.3 200.00 lbs/ft21.31.3 0.32280260240220200-20020406080100120140ScenarioDynamicGroupSPSP' 2022 ProposedCompanyDrawn ByFile NameDecember 2022.aesrevision.slmdDate12/15/2022, 12:34:25 PMProjectSlide2 - An Interactive Slope Stability ProgramSLIDEINTERPRET 9.025
2.22.22.22.2Phi (deg)Cohesion (psf)Strength TypeUnit Weight (lbs/ft3)ColorMaterial Name340Mohr‐Coulomb120Qvr38350Mohr‐Coulomb135Qva3050Mohr‐Coulomb90Duff30020010000100200300400500600ScenarioMaster ScenarioGroupNDND' 2022CompanyDrawn ByFile NameDecember 2022.aesrevision.slmdDate12/15/2022, 12:34:25 PMProjectSlide2 - An Interactive Slope Stability ProgramSLIDEINTERPRET 9.025
1.31.31.31.3 0.3230020010000100200300400500600ScenarioDynamicGroupNDND' 2022CompanyDrawn ByFile NameDecember 2022.aesrevision.slmdDate12/15/2022, 12:34:25 PMProjectSlide2 - An Interactive Slope Stability ProgramSLIDEINTERPRET 9.025
2.22.2 200.00 lbs/ft22.22.2Phi (deg)Cohesion (psf)Strength TypeUnit Weight (lbs/ft3)ColorMaterial Name340Mohr‐Coulomb120Qvr38350Mohr‐Coulomb135Qva3050Mohr‐Coulomb90Duff30020010000100200300400500600ScenarioMaster ScenarioGroupNDND' 2022 ProposedCompanyDrawn ByFile NameDecember 2022.aesrevision.slmdDate12/15/2022, 12:34:25 PMProjectSlide2 - An Interactive Slope Stability ProgramSLIDEINTERPRET 9.025
1.31.3 200.00 lbs/ft21.31.3 0.3230020010000100200300400500600ScenarioDynamicGroupNDND' 2022 ProposedCompanyDrawn ByFile NameDecember 2022.aesrevision.slmdDate12/15/2022, 12:34:25 PMProjectSlide2 - An Interactive Slope Stability ProgramSLIDEINTERPRET 9.025