geotechnical report
August 22, 2024
Garrette Custom Homes
11815 NE 99th St #1200
Vancouver, Washington 98682
Attn: Kimberly Johnson
KimberlyJ@BuildGCH.com
Soils Report
Proposed Residential Plat
xxx – Palisades Street SE
Yelm, Washington
PN: 21725130200
Doc ID: GCH.MattocksPlat.SR
INTRODUCTION
This Soils Report presents the results of our literature review, subsurface explorations,
laboratory testing, and provides geotechnical conclusions and recommendations regarding the
feasibility of onsite stormwater infiltration for the proposed residential plat to be constructed at the
above referenced parcel in the City of Yelm, Washington. The general location of the site is shown on
the attached Site Location Map, Figure 1. Our understanding of the project is based on our
conversations with you; our review of the Preliminary Site Plan prepared by AHBL on November 14,
2023; our January 9 and February 7, 2024 site visits and subsurface explorations; our understanding
of the City of Yelm (the City) development codes; and our experience in the site area.
The site is currently undeveloped. You propose to construct a 39-lot residential plat with a
paved shared access roadway and associated utilities. We anticipate that the proposed residences will
be one- to two-story, wood-framed structures supported by conventional shallow foundations. A copy
of the Preliminary Site Plan is included in the attached Site & Exploration Plan, Figure 2. Because of the
amount of proposed hard surfacing associated with the development, the City will require a Soils
Report be prepared in accordance with the adopted 2019 Stormwater Management Manual for Western
Washington (SWMMWW).
PURPOSE & SCOPE
The purpose of our scope services was to evaluate the surface and subsurface conditions
across the site as a basis for providing stormwater infiltration recommendations and design criteria
for the proposed residential plat. Specifically, the scope of services for this project included the
following:
1. Reviewing the available geologic, hydrogeologic, and geotechnical data for the site area;
2. Exploring surface and subsurface conditions across the site by excavating 19 test pits and 1
hand auger at select locations and installing shallow (less than 10 feet) groundwater
monitoring standpipes in 3 of the test pits;
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August 22, 2024
page | 2
3. While onsite, performing one small-scale Pilot Infiltration Test (PIT) in accordance with the
2019 SWMMWW in a location specified by the civil engineer;
4. Describing surface and subsurface conditions, including soil type, depth to groundwater, and
an estimate of seasonal high groundwater levels based on wet season groundwater
monitoring;
5. Providing our opinion about the feasibility of onsite infiltration in accordance with the 2019
SWMMWW, including a preliminary design infiltration rate based on infiltration testing, as
applicable; and,
6. Preparing this written Soils Report summarizing our site observations and conclusions, and our
recommendations and design criteria, along with the supporting data.
The above scope of work was summarized in our Proposal for Geotechnical Engineering Services
dated December 21, 2023. We received your emailed authorization to proceed on December 26, 2023.
SITE CONDITIONS
Surface Conditions
The site consists of a single unaddressed tax parcel located in the City of Yelm, Washington. The
site is generally rectangular in shape, measures about 400 feet wide (east to west) by about 890 to
1,185 feet long (north to south), and encompasses approximately 9.71 acres. The site is bounded by
State Route 507 to the north and existing single-family residential development to the east, south, and
west. Access to the site is gained from Palisades Street Southeast in the southeast portion of the site.
The site is located on the northern margins of the Yelm glacial upland area. Our site description
is based on 2-foot elevation contours shown on the Thurston County online Show Me Everything map
and our site observations. A storm pond for the residential plat east of the site occupies the northern
corner of the site. South of the storm pond and SR 507, the ground surface slopes up to the south at
about 18 to 20 percent. The central portion of the site slopes up to the southeast at 5 to 10 percent,
and then levels in the southern portion to about 2 percent. Total topographic relief across the site is
on the order of 62 feet. Existing site conditions and topography are shown on the attached Site &
Exploration Plan, Figure 2 and Site Vicinity Map, Figure 3.
Vegetation consists of Douglas fir trees scattered across the site with a dense understory of
grasses, Scotch broom, Himalayan blackberries, and other low growing shrubs. No standing water or
groundwater springs were observed at the ground surface at the time of our site visit. We did observe
some water ponded in the stormwater pond, as it was raining during our January 9, 2024 site visit.
We did not observe signs of slope instability or soil erosion at the time of our site visit.
Site Soils
The USDA Natural Resource Conservation Service (NRCS) Web Soil Survey maps the surficial
soils at the site as Alderwood gravelly sandy loam (2) and Everett very gravelly sandy loam (32).
Detailed descriptions of these soils are included below, and an excerpt of the referenced NRCS map
for the site and adjacent areas is attached as Figure 4.
• Alderwood gravelly sandy loam (2): Mapped throughout the majority of the site, these soils are
derived from glacial drift and/or glacial outwash over dense glaciomarine deposits and are
GCH.MattocksPlat.SR_July2024
August 22, 2024
page | 3
included in hydrologic soil group B. Type 2 soils form on slopes of 8 to 15 percent and are
listed as a “slight” erosion hazard when exposed.
• Everett very gravelly sandy loam (32): Mapped in the northeastern corner of the site, these soils
are derived from sandy and gravelly glacial outwash and are included in hydrologic soil group
A. Type 32 soils form on slopes of 0 to 8 percent and are listed as a “slight” erosion hazard
when exposed.
Site Geology
Based on our review of the Geologic Map of the Centralia Quadrangle, Washington (Schasse,
1987), the site is located in an area mapped as being underlain by Vashon till (Qdvt) and Vashon
outwash gravel (Qdvg). No landslides, colluvial/alluvial fans, or other deposits of mass wastage are
mapped on or within the site vicinity. Detailed descriptions of the mapped geologic units are included
below, and an excerpt of the referenced geologic map is attached as Figure 5.
• Vashon outwash gravel (Qdvg): Recessional outwash was deposited during the end stages of the
Vashon Stade of the Fraser Glaciation, approximately 12,000 to 15,000 years ago by meltwater
streams flowing from the retreating continental ice mass. Recessional outwash typically
consists of well graded, lightly stratified to locally cross-bedded mixtures of sand and gravel.
This unit is considered normally consolidated, offers moderate strength characteristics when
undisturbed, and is loose near the surface and increases in density with depth. The infiltration
potential of recessional outwash is generally favorable.
• Vashon glacial till (Qdvt): Glacial till typically consists of a heterogeneous mixture of clay, silt, sand,
and gravel deposited at the base of the continental ice mass and is subsequently over-ridden.
Accordingly, these deposits are considered to be overconsolidated and typically offer high
strength and low compressibility characteristics, where undisturbed. Infiltration potential within
glacial till is generally limited due to its overconsolidated and fine-grained nature.
Subsurface Explorations
On January 9, 2024, we visited the site and monitored the excavation of 12 test pits to depths
of about 5.0 to 10.0 feet below the existing ground surface. We also performed a small-scale Pilot
Infiltration Test (PIT) in test pit TP-1 at a depth of 4 feet below the ground surface.
On February 7, 2024 we returned to the site and monitored the excavation of 7 additional test
pits to depths of 9.0 to 12.5 feet below the existing ground surface and advanced one hand auger to
a depth of approximately 3.5 feet below the existing ground surface in the existing southern
stormwater pond.
Our field staff logged the subsurface conditions encountered in each exploration and
obtained representative soil samples. The indicated test pit locations were determined by taping or
pacing from existing site features and reference points; as such, the locations should only be
considered as accurate as implied by the measurement method. Elevations for our test pits and in-
situ testing were taken by interpolating between contours from the WA DNR Thurston 2021 DTM 53
LiDAR dataset.
The soils encountered were visually classified in accordance with the Unified Soil Classification
System (USCS) and ASTM D2488. The USCS is included in Appendix A as Figure A-1, while the
descriptive logs of our test pits and hand augers are included as Figures A-2 through A-(. Table 1 below
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summarizes the approximate functional locations, surface elevations, and termination depths of the
explorations.
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 consideration for
underground utilities, existing site conditions, site access limitations and encountered stratigraphy.
The subsurface explorations completed as part of this evaluation indicate the subsurface conditions
at specific locations only, as actual subsurface conditions can vary across the site. The nature and
extent of such variation would not become evident until additional explorations are performed or
until construction activities have begun.
TABLE 1:
APPROXIMATE LOCATIONS, ELEVATIONS, AND DEPTHS OF EXPLORATIONS
Test Pit
Number Functional Location
Surface
Elevation1
(feet)
Termination
Depth
(feet)
Termination
Elevation
(feet)
TP-1 Storm Tract F 360 10.0 350.0
TP-2 Northeast portion of Access Roadway 384 6.0 378.0
TP-3 Proposed Lot 18 394 8.0 386.0
TP-4 Proposed Lots 25, 26, 30, & 31 409 6.0 403.0
TP-5 Proposed Lot 23 401 6.0 395.0
TP-6 Proposed Lot 38 420 6.0 414.0
TP-7 Proposed Lot 1 360 7.0 353.0
TP-8 Proposed Lot 4 405 7.0 398.0
TP-9 Center south portion of Access Roadway 407 5.0 402.0
TP-10 Proposed Lot 10 404 5.0 399.0
TP-11 Proposed Lot 4 405 6.0 399.0
TP-12 Proposed Lot 14 396 5.0 391.0
TP-101 Storm Tract F 360 12.5 347.5
TP-102 Tract E 368 11.5 356.5
TP-103 Tract E 370 10.5 359.5
TP-104 Proposed Lot 16 376 9.5 366.5
TP-105 Northern proposed road 380 11.5 368.5
TP-106 Proposed Lot 23 396 9.5 386.5
TP-107 Proposed Lot 29 404 9.0 395.0
HA-1 Existing stormwater facility 357 3.5 353.5
Notes:
1 = Surface elevations estimated by interpolating between contours derived from WA DNR Thurston 2020 LiDAR (Datum: NAVD88)
Test Pits
The test pits were excavated using a small track-mounted excavator operated by a licensed
earthwork contractor working for GeoResources. Our field representative logged the subsurface
conditions encountered in each test pit and obtained representative soil samples, which were placed
in sealed plastic bags and then taken to our laboratory for further examination and testing as deemed
GCH.MattocksPlat.SR_July2024
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necessary. The soil densities presented on the 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.
Open standpipe piezometers (OSPs) were installed in three of the test pits. The piezometers
consisted of 2-inch PVC pipe, with a perforated or slotted section within the lower 3 feet. The
Piezometer installations were backfilled with the native soils and affixed with a threaded cap for future
measurement of groundwater levels.
Pilot Infiltration Test (PIT)
We performed one small-scale pilot infiltration test (PIT) in accordance with Volume III,
Appendix A of the 2021 Pierce County Stormwater Management and Site Development Manual. The PIT
was completed adjacent to the existing stormwater pond in the northern portion of the site. However,
the PIT was performed at 4.0 feet below the ground surface in what was later determined to be fill
material. The soils at the elevation the test was performed at generally consisted of sandy silt with
gravel, likely placed as part of the construction of the pond berm and previous site grading.
After the PIT was completed, we over excavated the test pit an additional 6.0 feet to a final
depth of 10.0 feet below ground surface and collected representative soil samples. Soil encountered
approximately 6 feet below the ground surface to the full depth explored consisted of poorly graded
gravel with limited amounts of silt.
Subsurface Conditions
At the locations of our test pits, we encountered subsurface conditions that, in our opinion,
generally confirm the mapped stratigraphy at the site. Our test pits encountered soils that appeared to
be consistent with topsoil and undocumented fill soils overlying glacial till. These soil layers are
described below.
• Topsoil: Our test pits encountered about 0.25 to 1.0 feet of dark brown topsoil.
• Undocumented fill: Underlying the topsoil in test pits TP-1, TP-7, TP-101, and TP-106 we observed
2.5 to 5.5 feet of brown-grey sandy silt and medium brown gravelly silty sand in a moist
condition.
• Vashon glacial till: Underlying the topsoil and fill soils in test pits TP-2 through TP-12, TP-104, TP-
106, and TP-107, we observed a medium dense to very dense, grey-brown to grey sandy silty
gravel and gravelly silty sand in a moist to wet condition to the full depth of exploration. We
interpret these soils to be weathered and undisturbed glacial till.
• Weathered Advance Outwash: Underlying the topsoil in test pits TP-102, TP-103, and TP-105, we
encountered brown silty sand with some gravel in a medium dense, moist condition. We
interpret these soils to be weathered advance outwash.
• Advance Outwash: Underlying the weathered advance outwash and the undocumented fill in TP-
1 and TP-101, we encountered grey poorly graded sand with silt and gravel, and grey poorly
graded gravel in a dense to very dense, moist condition. We interpret these soils to be advance
outwash. The advance outwash was encountered to the full depth explored where encountered.
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TABLE 2:
APPROXIMATE DEPTHS AND EXLEVATIONS OF ENCOUNTERED SOILS TYPES
Exploration
Number
Thickness of
(feet) Depth to
Undisturbed Till
(feet)
Depth to
Advance
Outwash
(feet)
Elevation1 of
Advance
Outwash
(feet) Topsoil Fill Weathered
Soils
TP-1 0.5 5.5 NE NE 6.0 354.0
TP-2 0.5 NE 2.0 2.5 NE NE
TP-3 0.75 NE 2.75 3.5 NE NE
TP-4 0.75 NE 3.25 4.0 NE NE
TP-5 0.5 NE 3.5 4.0 NE NE
TP-6 0.5 NE 2.5 3.0 NE NE
TP-7 0.5 2.5 NE 3.0 NE NE
TP-8 0.5 NE 4.5 5.0 NE NE
TP-9 0.75 NE 2.25 3.0 NE NE
TP-10 0.75 NE 1.25 2.0 NE NE
TP-11 0.5 NE 3.5 4.0 NE NE
TP-12 0.75 NE 2.25 3.0 NE NE
TP-101 0.75 4.25 NE NE 5.0 355.0
TP-102 1.0 NE 3.25 NE 4.25 363.75
TP-103 1.0 NE 2.5 NE 3.5 366.5
TP-104 0.75 NE 2.25 3.0 NE NE
TP-105 1.0 NE 2.5 NE 3.5 376.5
TP-106 1.0 2.25 1.75 5.0 NE NE
TP-107 0.5 NE 1.5 2.0 NE NE
HA-1 0.25 NE NE NE 0.25 356.75
Notes:
1 = Surface elevations estimated by interpolating between contours derived from WA DNR Thurston 2020 LiDAR (Datum: NAVD88)
Laboratory Testing
Geotechnical laboratory tests were performed on select samples retrieved from the test pits
to estimate index engineering properties of the soils encountered. Laboratory testing included visual
soil classification per ASTM D2488 and ASTM D2487, moisture content determinations per ASTM
D2216 and grain size analyses per ASTM D6913 standard procedures. Test results are summarized
below in Table 3 and graphical output results are included in Appendix B.
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TABLE 3:
LABORATORY TEST RESULTS FOR ON-SITE SOILS
Sample Soil
Type Lab ID
Gravel
Content
(percent)
Sand
Content
(percent)
Silt/Clay
Content
(percent)
Moisture
Content
(percent)
TP-1, S-2, D: 4ft ML 104657 20.4 28.2 51.4 22.9
TP-5, S-2, D: 3.5ft GP-GM 104658 56.3 32.8 10.9 10.4
TP-9, S-1, D: 2ft GW-GM 104659 64.0 30.9 5.1 6.4
TP-11, S-1, D: 1ft SM 104660 30.5 49.0 20.5 20.8
TP-8, S-1, D: 2ft SM 104663 39.8 44.5 15.7 15.9
TP-101, S-1, D: 8’ GP 104798 83.4 12.6 4.0 3.4
TP-102, S-2, D; 8.5’ SP-SM 104799 28.4 65.0 6.6 7.3
Groundwater Conditions
Groundwater seepage was observed in test pit TP-7 at a depth of 1.5 feet below existing grades
at the time of excavation during our first explorations in January 2024. When we returned to the site
on February 7, 2024 groundwater seepage was observed in test pit TP-101 at approximately 11 feet
below ground surface.
Based on the elevations of the encountered groundwater seepage, we anticipate this is an
inconsistent seasonal perched groundwater table. The groundwater encountered in test pit TP-101 is
likely an unconfined regional groundwater table. As such, we estimate that seasonal high groundwater
within the advance outwash is near elevation 349 feet. We anticipate fluctuations in the local
groundwater levels will occur in response to precipitation patterns, off-site construction activities, and
site utilization. As such, water level observations made at the time of our field investigation may vary
from those encountered during the construction phase.
We performed groundwater monitoring on a bi-weekly basis between January 16, 2024 and
April 29, 2024 to monitor water levels in the 3 open-standpipe piezometers (OSP’s) installed during
our January 9, 2024 site visit. Throughout the monitoring duration we did not observe groundwater
within the OSP’s, which extended about 10, 6, and 7 feet below the ground surface in OSP-1, OSP-2,
and OSP-3, respectively. The locations of the OSP’s are shown on Figure 2.
CONCLUSIONS AND RECOMMENDATIONS
Based on the results of our data review, site reconnaissance, subsurface explorations,
engineering analysis, and our experience in the area, it is our opinion that the on-site management of
stormwater runoff is feasible within the advance outwash soils. Further details are provided below.
Infiltration Recommendations
Test Method
The 2019 SWMMWW, Volume V, Section V-5.4 provides three approved methods to estimate
the design infiltration rate of site soils: 1) Large-Scale Pilot Infiltration Test, 2) Small-Scale Pilot
Infiltration Test, and 3) soil grain size analysis method. Restrictions do apply to the various methods
GCH.MattocksPlat.SR_July2024
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based on soil conditions and type of infiltration facility. We used the grain size analysis method to
develop a preliminary infiltration rate.
Preliminary Design Stormwater Infiltration Rate
We completed soil gradation analyses on two representative soil samples from the advance
outwash soils in the lower, northern portion of the site per the 2019 SWMMWW, Volume V and in
accordance with ASTM D6913. Based on our grain size analysis results, we recommend a preliminary
design infiltration rate of 20.0 inches per hour be used for design of infiltration facilities within the
gravelly advance outwash in the area of TP-1 and TP-101 and 4.2 inches per hour be used for design
of infiltration facilities within the sandy advance outwash observed within test pits TP-102, TP-103,
and TP-105. This rate includes factors of safety for site variability and number of tests (CFv = 0.5), test
method (CFt = 0.4 for grain size analysis), and for potential for siltation and biofouling (CFm = 0.9).
Construction Considerations
If infiltration facilities are proposed, we recommend that a representative from our firm be
onsite at the time of excavation of the proposed stormwater management facilities to verify that the
soils encountered during construction are consistent with the soils observed in our subsurface
explorations. In-situ infiltration testing shall be performed prior to and at the time of construction to
verify the recommended infiltration rate and to determine if a different site-specific infiltration rate
would be more appropriate for the site.
It should be noted that special care is required during the grading and construction periods
to avoid fine sediment contamination. This may be accomplished using an alternative stormwater
management location during construction. All contractors, builders, and subcontractors working on
the site should be advised to avoid allowing “dirty” stormwater or excess sediment to enter the
stormwater facilities during construction and landscaping activities. No concrete trucks should be
washed or cleaned in the vicinity of proposed stormwater systems.
Suspended solids could clog the underlying soil and reduce the infiltration rate of the facilities.
To reduce potential clogging of the infiltration systems, the infiltration system should not be
connected to the stormwater runoff system until after construction is complete and the site area is
landscaped, paved or otherwise protected. Temporary systems may be utilized throughout
construction. Periodic sweeping of the paved areas will help extend the life of the infiltration system.
Additional Services
The City will likely require in-situ infiltration testing be performed in the area of proposed
infiltration facilities. Once the actual size, depth, and location of the gallery has been determined using
the preliminary rate provided above, we should perform in-situ Pilot Infiltration Test per the
stormwater manual. Our final report will then include the final site and grading plans, updated
infiltration rate based on testing, and any additional changes required by the design team.
LIMITATIONS
We have prepared this report for use by Garrette Custom Homes and other members of the
design team for use in the design of a portion of this project. The data used in preparing this report and
this report should be provided to prospective contractors for their bidding or estimating purposes only.
Our report, conclusions and interpretations are based on our subsurface explorations, data from others
GCH.MattocksPlat.SR_July2024
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and limited site reconnaissance, and should not be construed as a warranty of the subsurface
conditions.
Variations in subsurface conditions are possible between the explorations and may also occur
with time. A contingency for unanticipated conditions should be included in the budget and
schedule. Sufficient monitoring, testing and consultation should be provided by our firm during
construction to confirm that the conditions encountered are consistent with those indicated by the
explorations, to provide recommendations for design changes should the conditions revealed during
the work differ from those anticipated, and to evaluate whether earthwork and foundation installation
activities comply with contract plans and specifications.
The scope of our services does not include services related to environmental remediation and
construction safety precautions. Our recommendations are not intended to direct the contractor's
methods, techniques, sequences or procedures, except as specifically described in our report for
consideration in design.
If there are any changes in the loads, grades, locations, configurations or type of facilities to be
constructed, the conclusions and recommendations presented in this report may not be fully
applicable. If such changes are made, we should be given the opportunity to review our
recommendations and provide written modifications or verifications, as appropriate.
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We have appreciated the opportunity to be of service to you on this project. If you have any
questions or comments, please do not hesitate to call at your earliest convenience.
Respectfully submitted,
GeoResources, LLC
Davis W. Carlsen, GIT
Senior Staff Geologist
Kyle E. Billingsley, PE Eric. W. Heller, PE, LG
Senior Geotechnical Engineer Senior Geotechnical Engineer
DWC:KEB:EWH/dwc
Doc ID: GCH.MattocksPlat.SR
Attachments: Figure 1: Site Location Map
Figure 2: Site & Exploration Plan
Figure 3: Site Vicinity Map
Figure 4: NRCS Soils Map
Figure 5: Geologic Map
Appendix A: Subsurface Explorations
Appendix B: Laboratory Test Results
Appendix C: Infiltration Rate Calculations
Approximate Site Location
Figure created from the Pierce County Public GIS website
(https://matterhornwab.co.pierce.wa.us/publicgis/)
Not to Scale
Site Location Map
Proposed Residential Plat
xxx – Palisades Street Southeast
Yelm, Washington
PN: 21725130200
Doc ID: GCH.MattocksPlat.F Aug 2024 Figure 1
EDED
EDED
EDED
ED
ED
ED
ED
ED
ED
ED ED
ED ED
ED ED ED
@A
TP-1 / PIT-1 / OSP-1
HA-1
TP-9
TP-8
TP-6
TP-4 TP-3
TP-2
TP-12
TP-11
TP-10
TP-101TP-102TP-105
TP-103TP-104
TP-106TP-107
TP-7 / OSP-3
TP-5 / OSP-2
Site & Exploration Plan
Proposed Residential Plat
xxx - Palisades Street Southeast
Yelm, Washington
PN: 21725130200
Figure 2Doc ID: GCH.MattocksPlat.F August 2024
0 80 160 24040
Feet1 in = 80 ft
Legend
@A Hand auger ED Infiltration test ED Test pit
Preliminary Site Plan
prepared by AHBL dated
November 14, 2023 µ
Approximate Site Location
Figure created from the Thurston County online Show Me Everything Map
(https://map.co.thurston.wa.us/Html5Viewer/Index.html?viewer=uMap.Main)
Not to Scale
Site Vicinity Map
Proposed Residential Plat
xxx – Palisades Street Southeast
Yelm, Washington
PN: 21725130200
Doc ID: GCH.MattocksPlat.F Aug 2024 Figure 3
Approximate Site Location
Figure created from the Web Soil Survey
(http://websoilsurvey.sc.egov.usda.gov/App/WebSoilSurvey.aspx)
Soil
Type Soil Name Parent Material Slopes Erosion Hazard
(off -road, off-trail)
Hydrologic
Soil Group
2 Alderwood gravelly
sandy loam
Glacial drift and/or glacial outwash
over dense glaciomarine deposits 8 to 15
Slight
B
32 Everett very gravelly
sandy loam Sandy and gravelly glacial outwash 0 to 8 A
Not to Scale
NRCS Soils Map
Proposed Residential Plat
xxx – Palisades Street Southeast
Yelm, Washington
PN: 21725130200
Doc ID: GCH.MattocksPlat.F Aug 2024 Figure 4
Approximate Site Location
An excerpt from the Geologic Map of the Centralia Quadrangle, Washington by Schasse, H.W. (1987)
Symbol Geologic Unit
Qdvg Vashon outwash gravel
Qdvt Vashon till
Not to Scale
Geologic Map
Proposed Residential Plat
xxx – Palisades Street Southeast
Yelm, Washington
PN: 21725130200
Doc ID: GCH.MattocksPlat.F Aug 2024 Figure 5
Appendix A
Subsurface Explorations
SOIL CLASSIFICATION SYSTEM
MAJOR DIVISIONS
GROUP
SYMBOL
GROUP NAME
COARSE
GRAINED
SOILS
GRAVEL CLEAN
GRAVEL
GW WELL-GRADED GRAVEL, FINE TO COARSE GRAVEL
GP POORLY-GRADED GRAVEL
More than 50%
Of Coarse Fraction
Retained on
No. 4 Sieve
GRAVEL
WITH FINES
GM SILTY GRAVEL
GC CLAYEY GRAVEL
More than 50%
Retained on
No. 200 Sieve
SAND CLEAN SAND
SW WELL-GRADED SAND, FINE TO COARSE SAND
SP POORLY-GRADED SAND
More than 50%
Of Coarse Fraction
Passes
No. 4 Sieve
SAND
WITH FINES
SM SILTY SAND
SC CLAYEY SAND
FINE
GRAINED
SOILS
SILT AND CLAY INORGANIC
ML SILT
CL CLAY
Liquid Limit
Less than 50 ORGANIC OL ORGANIC SILT, ORGANIC CLAY
More than 50%
Passes
No. 200 Sieve
SILT AND CLAY INORGANIC
MH SILT OF HIGH PLASTICITY, ELASTIC SILT
CH CLAY OF HIGH PLASTICITY, FAT CLAY
Liquid Limit
50 or more 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 Residential Plat
xxx – Palisades Street Southeast
Yelm, Washington
PN: 21725130200
Doc ID: GCH.MattocksPlat.F Aug
2024 Figure A-1
Test Pit TP-1 / Pilot Infiltration Test PIT-1/OSP-1
Location: Storm Tract F
Approximate Elevation: 360 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88)
Depth (ft) Soil Type Soil Description
0.0 - 0.5 - Topsoil
0.5 - 1.5 ML Grey-brown sandy gravelly SILT (medium stiff, moist)
1.5 - 6.0 ML Grey sandy SILT with gravel (medium stiff, moist)
6.0 - 10.0 GP Grey GRAVEL with sand and trace silt (dense to very dense, moist) (advance outwash)
Pilot Infiltration Test (PIT) performed at 4.0 feet below ground surface (BGS).
Measured infiltration rate: 0.0 in/hr
Terminated at 10.0 feet below the existing ground surface after completion of PIT.
No caving observed at the time of excavation.
Mottling observed from 1.0 to 1.5 feet BGS.
Open standpipe piezometer installed at 10.0 feet BGS.
Test Pit TP-2
Location: Northeast portion of Access Roadway
Approximate Elevation: 384 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88)
Depth (ft) Soil Type Soil Description
0.0 - 0.5 - Topsoil
0.5 - 2.5 GM Medium brown sandy silty GRAVEL (medium dense to dense, moist) (Weathered till)
2.5 - 6.0 GM Grey sandy silty GRAVEL (dense to very dense, moist) (Undisturbed glacial till)
Terminated at 6.0 feet BGS.
No caving observed at the time of excavation.
Mottling observed at 2.0 feet BGS.
No groundwater seepage at time of excavation.
Test Pit TP-3
Location: Proposed Lot 18
Approximate Elevation: 394 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88)
Depth (ft) Soil Type Soil Description
0.0 - 0.75 - Topsoil
0.75 - 3.5 GM Medium brown sandy silty GRAVEL (medium dense to dense, moist) (Weathered till)
3.5 - 8.0 GM Grey sandy silty GRAVEL (dense to very dense, moist) (Undisturbed glacial till)
Terminated at 8.0 feet BGS.
No caving observed at the time of excavation.
No mottling observed.
No groundwater seepage at time of excavation.
Logged by: MAE/DEM Excavated on: January 9, 2024
Test Pit Logs
Proposed Residential Plat
xxx – Palisades Street Southeast
Yelm, Washington
PN: 21725130200
Doc ID: GCH.MattocksPlat.F Aug
2024 Figure A-2
Test Pit TP-4
Location: Intersecting corners of proposed Lots 25, 26, 30, & 31
Approximate Elevation: 409 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88)
Depth (ft) Soil Type Soil Description
0.0 - 0.7
5
-
Topsoil
0.75 - 4.0 GM Medium brown sandy silty GRAVEL (medium dense to dense, moist) (Weathered till)
4.0 - 6.0 GM Grey sandy silty GRAVEL (dense to very dense, moist) (Undisturbed glacial till)
Terminated at 6.0 feet BGS.
No caving observed at the time of excavation.
Mottling observed from 4.0 to 5.0 feet BGS.
No groundwater seepage at time of excavation.
Test Pit TP-5/OSP-2
Location: Proposed Lot 23
Approximate Elevation: 401 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88)
Depth (ft) Soil Type Soil Description
0.0 - 0.5 - Topsoil
0.5 - 3.0 GM Medium brown sandy silty GRAVEL (medium dense to dense, moist) (Weathered till)
3.0 - 4.0 GP-GM Grey-brown sandy poorly graded GRAVEL with silt (medium dense to dense, moist)
(Weathered till)
4.0 - 6.0 GM Grey sandy silty GRAVEL (dense to very dense, moist) (Undisturbed glacial till)
Terminated at 6.0 feet BGS.
No caving observed at the time of excavation.
No mottling observed.
No groundwater seepage at time of excavation.
Open standpipe piezometer installed at 5.0 feet BGS.
Test Pit TP-6
Location: Proposed Lot 38
Approximate Elevation: 420 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88)
Depth (ft) Soil Type Soil Description
0.0 - 0.5 - Topsoil
0.5 - 2.5 GM Medium brown sandy silty GRAVEL (medium dense to dense, moist) (Weathered till)
2.5 - 3.0 SM Grey-brown silty SAND (medium dense to dense, moist) (Weathered till)
3.0 - 6.0 GM Grey sandy silty GRAVEL (dense to very dense, moist) (Undisturbed glacial till)
Terminated at 6.0 feet BGS.
No caving observed at the time of excavation.
No mottling observed.
No groundwater seepage at time of excavation.
Logged by: MAE Excavated on: January 9, 2024
Test Pit Logs
Proposed Residential Plat
xxx – Palisades Street Southeast
Yelm, Washington
PN: 21725130200
Doc ID: GCH.MattocksPlat.F Aug
2024 Figure A-3
Test Pit TP-7/OSP-3
Location: Proposed Lot 1
Approximate Elevation: 360 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88)
Depth (ft) Soil Type Soil Description
0.0 - 0.5 - Topsoil
0.5 - 3.0 GM Medium brown sandy silty GRAVEL (medium dense to dense, moist) (Fill)
3.0 - 7.0 GM Grey sandy silty GRAVEL (dense to very dense, moist) (Undisturbed glacial till)
Terminated at 7.0 feet BGS.
No caving observed at the time of excavation.
No mottling observed.
Slow groundwater seepage observed at about 1.5 feet below existing grades.
Open standpipe piezometer installed at 5.5 feet BGS.
Test Pit TP-8
Location: Proposed Lot 4
Approximate Elevation: 405 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88)
Depth (ft) Soil Type Soil Description
0.0 - 0.5 - Topsoil
0.5 - 5.0 SM Medium brown gravelly silty SAND (medium dense to dense, moist) (Weathered till)
5.0 - 7.0 GM Grey sandy silty GRAVEL (dense to very dense, moist) (Undisturbed glacial till)
Terminated at 7.0 feet BGS.
No caving observed at the time of excavation.
No mottling observed.
No groundwater seepage observed at time of excavation.
Test Pit TP-9
Location: Center south portion of Access Roadway
Approximate Elevation: 407 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88)
Depth (ft) Soil Type Soil Description
0.0 - 0.7
5
-
Topsoil
0.75 - 1.5 GM Medium brown sandy silty GRAVEL (medium dense to dense, moist) (Weathered till)
1.5 - 3.0 GW-GM Grey-brown sandy well-graded GRAVEL with silt (medium dense to dense, moist)
(Weathered glacial till)
3.0 - 5.0 GM Grey sandy silty GRAVEL (dense to very dense, moist) (Undisturbed glacial till)
Terminated at 5.0 feet BGS.
No caving observed at the time of excavation.
No mottling observed.
No groundwater seepage observed at time of excavation.
Logged by: MAE Excavated on: January 9, 2024
Test Pit Logs
Proposed Residential Plat
xxx – Palisades Street Southeast
Yelm, Washington
PN: 21725130200
Doc ID: GCH.MattocksPlat.F Aug
2024 Figure A-4
Test Pit TP-10
Location: Proposed Lot 10
Approximate Elevation: 404 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88)
Depth (ft) Soil Type Soil Description
0.0 - 0.7
5
-
Topsoil
0.75 - 2.0 SM Grey-brown silty SAND (medium dense to dense, moist) (Weathered glacial till)
2.0 - 5.0 GM Grey sandy silty GRAVEL (dense to very dense, moist) (Undisturbed glacial till)
Terminated at 5.0 feet BGS.
No caving observed at the time of excavation.
No mottling observed.
No groundwater seepage at time of excavation.
Test Pit TP-11
Location: Proposed Lot 4
Approximate Elevation: 405 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88)
Depth (ft) Soil Type Soil Description
0.0 - 0.5 - Topsoil
0.5 - 4.0 SM Medium brown gravelly silty SAND (medium dense to dense, moist) (Weathered till)
4.0 - 6.0 GM Grey sandy silty GRAVEL (dense to very dense, moist) (Undisturbed glacial till)
Terminated at 6.0 feet BGS.
No caving observed at the time of excavation.
No mottling observed.
No groundwater seepage at time of excavation.
Test Pit TP-12
Location: Proposed Lot 14
Approximate Elevation: 396 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88)
Depth (ft) Soil Type Soil Description
0.0 - 0.7
5
-
Topsoil
0.75 - 3.0 GM Medium brown sandy silty GRAVEL (medium dense to dense, moist) (Weathered till)
3.0 - 5.0 GM Grey sandy silty GRAVEL (dense to very dense, moist) (Undisturbed glacial till)
Terminated at 5.0 feet BGS.
No caving observed at the time of excavation.
No mottling observed.
No groundwater seepage observed at time of excavation.
Logged by: MAE Excavated on: January 9, 2024
Test Pit Logs
Proposed Residential Plat
xxx – Palisades Street Southeast
Yelm, Washington
PN: 21725130200
Doc ID: GCH.MattocksPlat.F Aug
2024 Figure A-5
Test Pit TP-101
Location: Tract E
Approximate Elevation: 360 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88)
Depth (ft) Soil Type Soil Description
0.0 - 0.75 - Topsoil
0.75 - 5 ML Brown-grey sandy SILT with some gravel (stiff, moist) (undocumented fill)
5 - 12.5 GP Grey GRAVEL with sand and trace silt (dense to very dense, moist) (advance outwash)
Terminated at 12.5 feet BGS.
No caving observed at the time of excavation.
No mottling observed.
Slow groundwater seepage observed at approximately 11 feet BGS
Test Pit TP-102
Location: Proposed Tract D
Approximate Elevation: 368 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88)
Depth (ft) Soil Type Soil Description
0.0 - 1.0 - Topsoil
1.0 - 4.25 SM Brown silty SAND with some gravel (medium dense, moist) (weathered advance
outwash)
4.25 - 11.5 SP-SM Grey gravelly poorly graded SAND with some silt, occasional thin silt lenses (dense,
moist) (advance outwash)
Terminated at 11.5 feet BGS.
No caving observed at the time of excavation.
No mottling observed.
No groundwater seepage at time of excavation.
Logged by: DC Excavated on: February 7, 2024
Test Pit Logs
Proposed Residential Plat
xxx – Palisades Street Southeast
Yelm, Washington
PN: 21725130200
Doc ID: GCH.MattocksPlat.F Aug
2024 Figure A-6
Test Pit TP-103
Location: Proposed Tract D
Approximate Elevation: 370 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88)
Depth (ft) Soil Type Soil Description
0.0 - 1.0 - Topsoil
1.0 - 3.5 SM Brown silty SAND with some gravel (medium dense, moist) (weathered advance
outwash)
3.5 - 10.5 GM Grey sandy silty GRAVEL (dense to very dense, moist) (advance outwash)
Terminated at 10.5 feet BGS.
No caving observed at the time of excavation.
No mottling observed.
No groundwater seepage at time of excavation
Test Pit TP-104
Location: Proposed Tract D
Approximate Elevation: 376 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88)
Depth (ft) Soil Type Soil Description
0.0 - 0.75 - Topsoil
0.75 - 3.0 SM Brown gravelly silty SAND (medium dense, moist) (weathered glacial till)
3.0 - 9.5 SM Grey gravelly silty SAND (very dense, moist) (glacial till)
Terminated at 9.5 feet BGS.
No caving observed at the time of excavation.
Mottling observed at approximately 2.5 feet BGS.
No groundwater seepage at time of excavation.
Refusal in excavation
Logged by: DC Excavated on: February 7, 2024
Test Pit Logs
Proposed Residential Plat
xxx – Palisades Street Southeast
Yelm, Washington
PN: 21725130200
Doc ID: GCH.MattocksPlat.F Aug
2024 Figure A-7
Test Pit TP-105
Location: Northern road area
Approximate Elevation: 380 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88)
Depth (ft) Soil Type Soil Description
0.0 - 1.0 - Topsoil
1.0 - 3.5 SM Brown silty SAND with some gravel (medium dense, moist) (weathered advance
outwash)
3.5 - 7.5 SM Grey fine silty SAND with some gravel (medium dense, moist) (advance outwash)
7.5 - 11.5 GM Grey sandy silty GRAVEL (dense to very dense, moist) (advance outwash)
Terminated at 11.5 feet BGS.
No caving observed at the time of excavation.
Slight mottling observed at 7 feet BGS.
No groundwater seepage at time of excavation
Test Pit TP-106
Location: Proposed Lot 22
Approximate Elevation: 396 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88)
Depth (ft) Soil Type Soil Description
0.0 - 1.0 - Topsoil
1.0 - 3.25 SM Browns silty SAND with some gravel, buried debris (loose to medium dense)
(undocumented fill)
3.25 - 5.0 SM Brown gravelly silty SAND (medium dense, moist) (weathered glacial till)
5.0 - 9.5 SM Grey gravelly silty SAND (very dense, moist) (glacial till)
Terminated at 9.5 feet BGS.
No caving observed at the time of excavation.
Mottling observed at approximately 4.5 feet BGS.
No groundwater seepage at time of excavation.
Refusal in excavation
Logged by: DC Excavated on: February 7, 2024
Test Pit Logs
Proposed Residential Plat
xxx – Palisades Street Southeast
Yelm, Washington
PN: 21725130200
Doc ID: GCH.MattocksPlat.F Aug
2024 Figure A-8
Test Pit TP-107
Location: Proposed lot 29
Approximate Elevation: 404 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88)
Depth (ft) Soil Type Soil Description
0.0 - 0.5 - Topsoil
0.5 - 2.0 SM Brown gravelly silty SAND (medium dense, moist) (weathered glacial till)
2.0 - 9.0 SM Grey gravelly silty SAND (very dense, moist) (glacial till)
Terminated at 9.0 feet BGS.
No caving observed at the time of excavation.
Slight mottling observed at 2 feet BGS.
No groundwater seepage at time of excavation
Logged by: DC Excavated on: February 7, 2024
Test Pit Logs
Proposed Residential Plat
xxx – Palisades Street Southeast
Yelm, Washington
PN: 21725130200
Doc ID: GCH.MattocksPlat.F Aug
2024 Figure A-9
Hand Auger HA-1
Location: Existing stormwater facility
Approximate Elevation: 357 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88)
Depth (ft) Soil Type Soil Description
0.0 - 0.25 - Topsoil
0.25 - 3.5 GM Grey silty GRAVEL with some sand (very dense, moist) (advance outwash)
Terminated at 3.5 feet BGS.
No caving observed at the time of excavation.
No mottling observed at time of excavation
No groundwater seepage at time of excavation
Logged by: DC Excavated on: February 7, 2024
Test Pit Logs
Proposed Residential Plat
xxx – Palisades Street Southeast
Yelm, Washington
PN: 21725130200
Doc ID: GCH.MattocksPlat.F Aug
2024 Figure A-10
Appendix B
Laboratory Test Results
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Tested By: Checked By:
Particle Size Distribution Report
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90
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GRAIN SIZE - mm.
0.0010.010.1110100
% +3"Coarse
% Gravel
Fine Coarse Medium
% Sand
Fine Silt
% Fines
Clay
0.0 13.2 7.2 2.8 6.7 18.7 51.4
6
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#4 #1
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#2
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#3
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#4
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#6
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#1
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#1
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#2
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Test Results (ASTM D 6913 & ASTM D 1140)
Opening Percent Spec.*Pass?
Size Finer (Percent)(X=Fail)
Material Description
Atterberg Limits (ASTM D 4318)
Classification
Coefficients
Date Received:Date Tested:
Tested By:
Checked By:
Title:
Date Sampled:Location: TP-1, S-2
Sample Number: 104657 Depth: 4'
Client:
Project:
Project No:Figure
Sandy SILT with gravel (ML)
2.0
1.5
1.25
1
.75
.5
0.375
#4
#10
#20
#40
#60
#100
#200
100.0
91.2
91.2
91.2
86.8
84.1
82.6
79.6
76.8
74.0
70.1
65.8
60.5
51.4
NP NV NP
ML A-4(0)
23.0729 15.8081 0.1443
Natural Moisture: 22.9%
1/9/24 1/18/24
MAW
KEB
PM
1/9/24
Garrette Custom Homes
Proposed Residential Plat
GarretteCustomHomes.MattocksPlat
PL=LL=PI=
USCS (D 2487)=AASHTO (M 145)=
D90=D85=D60=
D50=D30=D15=
D10=Cu=Cc=
Remarks
*(no specification provided)
GeoResources, LLC
Fife, WA B-1
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Tested By: Checked By:
Particle Size Distribution Report
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GRAIN SIZE - mm.
0.0010.010.1110100
% +3"Coarse
% Gravel
Fine Coarse Medium
% Sand
Fine Silt
% Fines
Clay
0.0 32.6 23.7 9.2 12.8 10.8 10.9
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#6
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Test Results (ASTM D 6913 & ASTM D 1140)
Opening Percent Spec.*Pass?
Size Finer (Percent)(X=Fail)
Material Description
Atterberg Limits (ASTM D 4318)
Classification
Coefficients
Date Received:Date Tested:
Tested By:
Checked By:
Title:
Date Sampled:Location: TP-5, S-2
Sample Number: 104658 Depth: 3.5'
Client:
Project:
Project No:Figure
Poorly graded GRAVEL with silt and sand (GP-GM)
2.0
1.5
1.25
1
.75
.5
0.375
#4
#10
#20
#40
#60
#100
#200
100.0
93.8
89.6
76.8
67.4
58.3
55.6
43.7
34.5
27.9
21.7
17.5
14.2
10.9
NP NV NP
GP-GM A-1-a
32.0590 29.0710 13.9775
6.6497 1.0999 0.1709
Natural Moisture: 10.4%
1/9/24 1/18/24
MAW
KEB
PM
1/9/24
Garrette Custom Homes
Proposed Residential Plat
GarretteCustomHomes.MattocksPlat
PL=LL=PI=
USCS (D 2487)=AASHTO (M 145)=
D90=D85=D60=
D50=D30=D15=
D10=Cu=Cc=
Remarks
*(no specification provided)
GeoResources, LLC
Fife, WA B-2
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Tested By: Checked By:
Particle Size Distribution Report
PE
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GRAIN SIZE - mm.
0.0010.010.1110100
% +3"Coarse
% Gravel
Fine Coarse Medium
% Sand
Fine Silt
% Fines
Clay
0.0 39.8 24.2 7.0 11.9 12.0 5.1
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#6
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#1
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#2
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Test Results (ASTM D 6913 & ASTM D 1140)
Opening Percent Spec.*Pass?
Size Finer (Percent)(X=Fail)
Material Description
Atterberg Limits (ASTM D 4318)
Classification
Coefficients
Date Received:Date Tested:
Tested By:
Checked By:
Title:
Date Sampled:Location: TP-9, S-1
Sample Number: 104659 Depth: 2'
Client:
Project:
Project No:Figure
Well-graded GRAVEL with silt and sand (GW-GM)
2.0
1.5
1.25
1
.75
.5
0.375
#4
#10
#20
#40
#60
#100
#200
100.0
87.1
67.1
64.0
60.2
48.4
44.7
36.0
29.0
22.9
17.1
12.1
8.5
5.1
NP NV NP
GW-GM A-1-a
39.3352 37.3647 18.8871
13.6053 2.3410 0.3411
0.1903 99.25 1.52
Natural Moisture: 6.4%
1/9/24 1/18/24
MAW
KEB
PM
1/9/24
Garrette Custom Homes
Proposed Residential Plat
GarretteCustomHomes.MattocksPlat
PL=LL=PI=
USCS (D 2487)=AASHTO (M 145)=
D90=D85=D60=
D50=D30=D15=
D10=Cu=Cc=
Remarks
*(no specification provided)
GeoResources, LLC
Fife, WA B-3
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s
.
Tested By: Checked By:
Particle Size Distribution Report
PE
R
C
E
N
T
F
I
N
E
R
0
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 7.0 23.5 10.6 16.2 22.2 20.5
6
i
n
.
3
i
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.
2
i
n
.
1½ i
n
.
1
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.
¾ i
n
.
½ i
n
.
3/
8
i
n
.
#4 #1
0
#2
0
#3
0
#4
0
#6
0
#1
0
0
#1
4
0
#2
0
0
Test Results (ASTM D 6913 & ASTM D 1140)
Opening Percent Spec.*Pass?
Size Finer (Percent)(X=Fail)
Material Description
Atterberg Limits (ASTM D 4318)
Classification
Coefficients
Date Received:Date Tested:
Tested By:
Checked By:
Title:
Date Sampled:Location: TP-11, S-1
Sample Number: 104660 Depth: 1'
Client:
Project:
Project No:Figure
Silty SAND with gravel (SM)
1.25
1
.75
.5
0.375
#4
#10
#20
#40
#60
#100
#200
100.0
95.9
93.0
86.0
82.0
69.5
58.9
50.4
42.7
35.1
27.8
20.5
NP NV NP
SM A-1-b
15.8019 11.8879 2.2367
0.8152 0.1770
Natural Moisture: 20.8%
1/9/24 1/18/24
MAW
KEB
PM
1/9/24
Garrette Custom Homes
Proposed Residential Plat
GarretteCustomHomes.MattocksPlat
PL=LL=PI=
USCS (D 2487)=AASHTO (M 145)=
D90=D85=D60=
D50=D30=D15=
D10=Cu=Cc=
Remarks
*(no specification provided)
GeoResources, LLC
Fife, WA B-4
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Tested By: Checked By:
Particle Size Distribution Report
PE
R
C
E
N
T
F
I
N
E
R
0
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 16.1 23.7 12.1 16.5 15.9 15.7
6
i
n
.
3
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.
2
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.
1½ i
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1
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3/
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.
#4 #1
0
#2
0
#3
0
#4
0
#6
0
#1
0
0
#1
4
0
#2
0
0
Test Results (ASTM D 6913 & ASTM D 1140)
Opening Percent Spec.*Pass?
Size Finer (Percent)(X=Fail)
Material Description
Atterberg Limits (ASTM D 4318)
Classification
Coefficients
Date Received:Date Tested:
Tested By:
Checked By:
Title:
Date Sampled:Location: TP-8, S-1
Sample Number: 104663 Depth: 2'
Client:
Project:
Project No:Figure
Silty SAND with gravel (SM)
1.25
1
.75
.5
0.375
#4
#10
#20
#40
#60
#100
#200
100.0
93.1
83.9
74.9
71.9
60.2
48.1
39.2
31.6
25.7
20.8
15.7
NP NV NP
SM A-1-b
23.1091 19.7827 4.7072
2.3489 0.3707
Natural Moisture: 15.9%
1/9/24 1/18/24
MAW
KEB
PM
1/9/24
Garrette Custom Homes
Proposed Residential Plat
GarretteCustomHomes.MattocksPlat
PL=LL=PI=
USCS (D 2487)=AASHTO (M 145)=
D90=D85=D60=
D50=D30=D15=
D10=Cu=Cc=
Remarks
*(no specification provided)
GeoResources, LLC
Fife, WA B-5
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Tested By: Checked By:
Particle Size Distribution Report
PE
R
C
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N
T
F
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E
R
0
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 69.6 13.8 2.4 5.0 5.2 4.0
6
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.
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#4 #1
0
#2
0
#3
0
#4
0
#6
0
#1
0
0
#1
4
0
#2
0
0
Test Results (ASTM D 6913 & ASTM D 1140)
Opening Percent Spec.*Pass?
Size Finer (Percent)(X=Fail)
Material Description
Atterberg Limits (ASTM D 4318)
Classification
Coefficients
Date Received:Date Tested:
Tested By:
Checked By:
Title:
Date Sampled:Location: TP-101, S-1
Sample Number: 104798 Depth: 8'
Client:
Project:
Project No:Figure
Poorly graded GRAVEL (GP)
3.0
2.5
2.0
1.5
1.25
1
.75
.5
0.375
#4
#10
#20
#40
#60
#100
#200
100.0
79.2
68.0
47.1
44.9
34.9
30.4
23.7
20.8
16.6
14.2
11.6
9.2
7.3
5.7
4.0
NP NV NP
GP A-1-a
70.5107 67.5324 45.7374
40.3640 18.3467 2.8544
0.5352 85.46 13.75
Natural Moisture: 3.4%
2/7/24 2/15/24
MAW
KEB
PM
2/7/24
Garrette Custom Homes
Proposed Residential Plat
GarretteCustomHomes.MattocksPlat
PL=LL=PI=
USCS (D 2487)=AASHTO (M 145)=
D90=D85=D60=
D50=D30=D15=
D10=Cu=Cc=
Remarks
*(no specification provided)
GeoResources, LLC
Fife, WA B-6
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Tested By: Checked By:
Particle Size Distribution Report
PE
R
C
E
N
T
F
I
N
E
R
0
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 10.7 17.7 7.1 20.4 37.5 6.6
6
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.
3
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.
2
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.
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1
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#4 #1
0
#2
0
#3
0
#4
0
#6
0
#1
0
0
#1
4
0
#2
0
0
Test Results (ASTM D 6913 & ASTM D 1140)
Opening Percent Spec.*Pass?
Size Finer (Percent)(X=Fail)
Material Description
Atterberg Limits (ASTM D 4318)
Classification
Coefficients
Date Received:Date Tested:
Tested By:
Checked By:
Title:
Date Sampled:Location: TP-102, S-2
Sample Number: 104799 Depth: 8.5'
Client:
Project:
Project No:Figure
Poorly graded SAND with silt and gravel (SP-SM)
1.25
1
.75
.5
0.375
#4
#10
#20
#40
#60
#100
#200
100.0
91.2
89.3
83.3
78.3
71.6
64.5
56.2
44.1
27.5
14.2
6.6
NP NV NP
SP-SM A-1-b
23.7022 13.8854 1.2172
0.5534 0.2702 0.1565
0.1127 10.80 0.53
Natural Moisture: 7.3%
2/7/24 2/15/24
MAW
KEB
PM
2/7/24
Garrette Custom Homes
Proposed Residential Plat
GarretteCustomHomes.MattocksPlat
PL=LL=PI=
USCS (D 2487)=AASHTO (M 145)=
D90=D85=D60=
D50=D30=D15=
D10=Cu=Cc=
Remarks
*(no specification provided)
GeoResources, LLC
Fife, WA B-7
Appendix C
Infiltration Rate Analysis
Soil Grain Size Analysis Method
Procudure based on 2019 SWMMWW, Volume V, Chapter 5, V-5.4
K sat = 10^(-1.57 + 1.90D10 + 0.015D60 - 0.013D90 - 2.08Ffines)(provides Ksat in cm/s)
K sat = [10^(-1.57 + 1.90D10 + 0.015D60 - 0.013D90 - 2.08Ffines)]*1417 (provides Ksat in in/hr)
I.D.Expl.Depth (ft)
Layer
Thickness
(ft)
D10 D60 D90 Ffines
Individual
Ksat (cm/s)
Equivalent Ksat
(in/hr)
104798 TP-101 8 0.535 45.737 70.511 0.040 0.136 192.518
Effective Average Hydraulic Conductivity, K equiv 192.518 Har. Mean
Based on either:192.518 Lowest
1)Average Ksat determined using harmonic mean 192.000 To Use
2)Lowest conductive layer, if within 5ft of bottom of pond
Site variability and number of tests (CFv)
0.25 to 1.0
Factor to use for calculations 0.5
Test Method (CFt)
0.75
0.5
0.4
Factor to use for calculations 0.4
Siltation and bio-buildup (CFm)
0.90
Factor to use for calculations 0.9
Idesign = Imeasured * Ftesting * Fgeometry *Fplugging 34.56 in/hr
Preliminary Design Value 20.00 in/hr
April 2024 Figure C-1
2019 Stormwater Management Manual for Western Washington
Garrette Custom Homes - Mattocks Plat
Yelm, Washington
Massman Calculation Sheet
Proposed Residential Plat
Sample Information Sieve Data Unfactored Rate
Yelm, Washington
PN: 21725130200
DocID: GCH.MattocksPlat.ksat
kequiv=
Large-scale PIT
90% of design capacity
Small-scale PIT
Other small-scale (e.g. Double ring, falling head) & Grain Size
Infiltration Rate Analysis - Shallow Facilities
xxx - Palisades Street Southeast
Soil Grain Size Analysis Method
Procudure based on 2019 SWMMWW, Volume V, Chapter 5, V-5.4
K sat = 10^(-1.57 + 1.90D10 + 0.015D60 - 0.013D90 - 2.08Ffines)(provides Ksat in cm/s)
K sat = [10^(-1.57 + 1.90D10 + 0.015D60 - 0.013D90 - 2.08Ffines)]*1417 (provides Ksat in in/hr)
I.D.Expl.Depth (ft)
Layer
Thickness
(ft)
D10 D60 D90 Ffines
Individual
Ksat (cm/s)
Equivalent Ksat
(in/hr)
104799 TP-102 8.5 0.113 1.217 23.702 0.066 0.016 23.353
Effective Average Hydraulic Conductivity, K equiv 23.353 Har. Mean
Based on either:23.353 Lowest
1)Average Ksat determined using harmonic mean 23.353 To Use
2)Lowest conductive layer, if within 5ft of bottom of pond
Site variability and number of tests (CFv)
0.25 to 1.0
Factor to use for calculations 0.5
Test Method (CFt)
0.75
0.5
0.4
Factor to use for calculations 0.4
Siltation and bio-buildup (CFm)
0.90
Factor to use for calculations 0.9
Idesign = Imeasured * Ftesting * Fgeometry *Fplugging 4.20 in/hr
Preliminary Design Value 4.20 in/hr
April 2024 Figure C-2
xxx - Palisades Street Southeast
Yelm, Washington
PN: 21725130200
DocID: GCH.MattocksPlat.ksat
Infiltration Rate Analysis - Shallow Facilities
Proposed Residential Plat
2019 Stormwater Management Manual for Western Washington
Garrette Custom Homes - Mattocks Plat
Yelm, Washington
Massman Calculation Sheet
kequiv=
Sample Information Sieve Data Unfactored Rate
90% of design capacity
Large-scale PIT
Small-scale PIT
Other small-scale (e.g. Double ring, falling head) & Grain Size