03 Geotech Letter15365 N.E. 90th Street, Suite 100 • Redmond, WA 98052 • (425) 449-4704 • FAX (425) 449-4711
Earth Solutions NW LLC
Geotechnical Engineering, Construction
Observation/Testing and Environmental Services
February 11, 2020
ES-6375.01
Bush, Roed & Hitchings, Inc.
2009 Minor Avenue East
Seattle, Washington 98102
Attention: Mr. Ted Dimof
Subject: Infiltration Evaluation
Southwest 320th Street Plat
Southwest 320th Street and 21st Avenue Southwest
Federal Way, Washington
Reference: King County
King County Surface Water Design Manual (KCSWDM)
April 24, 2016
Bush, Roed, & Hitchings
Boundary & Topographic Survey
December 3, 2018
R.W. Tabor et al.
Geologic Map of the Tacoma Quadrangle, Washington, 2015
United States Department of Agriculture
Natural Resources Conservation Service
Online Web Soil Survey (WSS) resource
Dear Mr. Dimof:
As requested, Earth Solutions NW, LLC (ESNW) has prepared this infiltration evaluation letter for
the subject site. Our scope of services included subsurface exploration, infiltration testing,
engineering analysis, and preparation of this letter.
Project Description
The subject site is located along the south side of Southwest 320 th Street, approximately 120 feet
west of the intersection with 21st Avenue Southwest, in Federal Way, Washington, as illustrated
on the attached Vicinity Map (Plate 1). The site consists of two adjoined residential tax parcels
(King County Parcel Nos. 132103-9002 and -9091) totaling approximately 2.0 acres of land area.
The subject site is moderately overgrown with trees and brambles and has a remnant foundation
and dilapidated shed along the southern border of the property. We understand a short plat has
been proposed for the subject site and will include multiple single-family lots, a stormwater
management facility, access roads, and related site improvements.
Bush, Roed & Hitchings, Inc. ES-6375.01
February 11, 2020 Page 2
Earth Solutions NW, LLC
If the design assumptions outlined in this section are incorrect or change, or if construction
conditions differ from those encountered during our fieldwork, ESNW should be contacted to
review the recommendations and conclusions provided in this letter.
Subsurface Conditions
As part of this infiltration evaluation, an ESNW representative observed, logged, and sampled
four test pits excavated across the subject site using a mini-trackhoe and operator retained by
our firm on January 17, 2020. The approximate locations of the test pits are depicted on Plate 2
(Test Pit Location Plan). Please refer to the attached test pit logs for a more detailed description
of subsurface conditions. Representative soil samples collected at the test pit locations were
analyzed in accordance with both Unified Soil Classification System (USCS) and United States
Department of Agriculture (USDA) methods and procedures.
Topsoil was encountered in the upper approximate 6 to 18 inches of existing grades at the test
pit locations, characterized by dark brown color, the presence of fine organic material, and small
root intrusions. Fill was encountered at test pit locations TP-101 and TP-102 extending to depths
of roughly six and one-half to eight feet below the existing ground surface (bgs). The fill was
characterized primarily as loose dark brown silty sand with gravel (USCS: SM). Plastic, metal,
rubber, and wood debris was observed in the fill. Where encountered, fill should be evaluated
by ESNW at the time of construction to assess the suitability for use as structural fill and/or
foundation support.
Underlying the topsoil and fill, native soils consisted of a heavily weathered layer of loose to
medium dense silty sand with gravel and sandy silt with gravel (USCS: SM and ML, respectively).
Underlying the weathered layer, native soils consisted of poorly to well-graded gravel, poorly
graded gravel with silt and sand, silty gravel, and poorly graded sand with gravel (USCS: GP,
GW, GP-GW, GM, and SP, respectively). The native soils were generally encountered in a damp
to moist condition and extended to the maximum exploration depth of nine feet bgs.
Geologic Setting
The referenced geologic map identifies Vashon till (Qgt) across the site with Vashon recessional
outwash deposits (Qgo) mapped to the west of the subject site. As described on the geologic
map, Vashon till is typically a compact diamict of subrounded to well-rounded clasts which were
glacially transported and deposited. The diamict is readily comprised of sand, silt, gravel,
pebbles, and cobbles. As described on the geologic map, recessional outwash consists primarily
of moderately sorted to well sorted, stratified sand and gravel.
Groundwater
Groundwater seepage was not encountered at the test pit locations during our exploration on
January 17, 2020. Groundwater seepage rates and elevations fluctuate depending on many
factors, including precipitation duration and intensity, the time of year, and soil conditions. In
general, groundwater flow rates are higher during the winter, spring, and early summer months.
Bush, Roed & Hitchings, Inc. ES-6375.01
February 11, 2020 Page 3
Earth Solutions NW, LLC
Infiltration Evaluation
Our evaluation of the proposed infiltration facilities was completed in general accordance with
applicable requirements and procedures of the referenced 2016 KCSWDM as adopted by the
City of Federal Way. We understand an infiltration facility is proposed for the short plat.
In-situ testing was completed in general accordance with the small-scale Pilot Infiltration Test
(PIT) procedure, as outlined in the 2016 KCSWDM. To evaluate the infiltration capacity of soils,
in-situ testing was completed at TP-103 and TP-104 at a depth of six feet bgs. Our testing
program consisted of a soak period, steady state period, and falling head period. Due to the soil
variability observed at the proposed design depth, two separate preliminary infiltration rates were
calculated for the predominant soil types observed at the property (clean sand deposits and
gravels). The table below summarizes the short-term (measured) rate at each test location, in
units of inches per hour (iph).
Test Pit Measured Rate (iph) Depth (feet) Soil Type
TP-103 60 6 Poorly graded gravel with silt
and sand (GP-GM)
TP-104 24 6 Poorly graded sand (SP)
Per the referenced 2016 KCSWDM, correction factors must be applied to the measured rates to
account for testing methods, facility geometry, and influent control to prevent siltation. In our
opinion, the following correction factors and calculated total correction factor should be applied
to the measured field rates.
Test uncertainty (Ftesting) 0.5
Infiltration facility geometry (Fgeometry) 0.9
Long-term plugging of soils (Fplugging) 1.0 (gravels)
Long-term plugging of soils (Fplugging) 0.9 (medium sands)
Application of the total correction factor to the measured rates are provided in the table below:
Test Pit Design Rate (iph)
TP-103 20
TP-104 10
From a geotechnical standpoint, infiltration is feasible within locations underlain by gravels and
clean sand deposits. The upper silty sand and sandy silt deposits and fill identified at the property
generally exhibit poor infiltration potential and should not be targeted for infiltration facilities.
Minimum vertical separation between the bottoms of the proposed facilities and groundwater
must be considered during design. We recommend provisions for overflow be incorporated into
final designs, wherever practicable.
Bush, Roed & Hitchings, Inc.
February 11, 2020
ES-6375.01
Page4
Given the variability of the site soils infiltration potential, ESNW should be in correspondence with
the facility designer to assist with applying appropriate rates to the targeted infiltrating soils at the
proposed infiltration facility location and acknowledging depth to restrictive layers. Additionally,
ESNW should be retained at the time of facility construction to confirm soils types and provide
additional recommendations as needed.
Limitations
This letter has been prepared for the exclusive use of Bush, Roed, & Hitchings, Inc. and their
representatives. A warranty is neither expressed nor implied. The recommendations and
conclusions provided in this letter are professional opinions consistent with the level of care and
skill that is typical of other members in the profession currently practicing under similar conditions
in this area. Variations in the soil and groundwater conditions encountered at the test pit locations
may exist and may not become evident until construction. ESNW should reevaluate the contents
of this letter if variations are encountered. ESNW should be retained during construction to
observe facility installation and to confirm soil types are as anticipated in this letter.
Supplementary recommendations may be provided during construction, as necessary.
We appreciate the opportunity to be of service to you and trust this letter meets your current
needs. Should you have questions, or if additional information is required, please call.
Sincerely,
EARTH SOLUTIONS NW, LLC
Kyler T. Kelly
Senior Staff Geologist
Attachments: Plate 1 -Vicinity Map
Plate 2 -Test Pit Location Plan
Test Pit Logs
Grain Size Distribution
Raymond A. Coglas, P.E.
Principal Engineer
Earth Solutions NW, LLC
Geotechnical Engineering,Construction
Observation/Testing and Environmental Services
Drwn.CAM
Checked KTK Date Jan.2020
Date 01/29/2020 Proj.No.6375.01
Plate 1
Earth Solutions NWLLCEarthSolutionsNWLLC
EarthSolutions
NW LLC
Vicinity Map
S.W.320th Street Plat
Federal Way,Washington
Reference:
King County,Washington
OpenStreetMap.org
NORTH
NOTE:This plate may contain areas of color.ESNW cannot be
responsible for any subsequent misinterpretation of the information
resulting from black &white reproductions of this plate.
SITE
Plate
Proj.No.
Date
Checked By
Drwn.ByEarthSolutionsNWLLCGeotechnicalEngineering,ConstructionObservation/TestingandEnvironmentalServicesEarthSolutionsNWLLCEarthSolutionsNWLLCCAM
KTK
01/29/2020
6375.01
2TestPitLocationPlan S.W.320thStreetPlatFederalWay,WashingtonNORTH
0 3 0 6 0 1 2 0
Sc ale in Feet1"=6 0 '
NOTE:This plate may contain areas of color.ESNW cannot be
responsible for any subsequent misinterpretation of the information
resulting from black &white reproductions of this plate.
NOTE:The graphics shown on this plate are not intended for design
purposes or precise scale measurements,but only to illustrate the
approximate test locations relative to the approximate locations of
existing and /or proposed site features.The information illustrated
is largely based on data provided by the client at the time of our
study.ESNW cannot be responsible for subsequent design changes
or interpretation of the data by others.
LEGEND
Approximate Location of
ESNW Test Pit,Proj.No.
ES-6375.01,Jan.2020
Approximate Location of
ESNW Test Pit,Proj.No.
ES-6375,Oct.2018
Subject Site
Proposed Infiltration Pond
Existing Building
TP-1
TP-101
TP-101
TP-102TP-103
TP-104
TP-3
TP-1
TP-2
TP-4
TP-5
TP-6
Remnant
Concrete
Foundation
Dilapidated
Shed
S.W. 320TH STREET
21ST AVENUE S.W.350340
330320
350
340
330
320
336.5
331.5
331.0MC = 11.00%
TPSL
SM
GM
Dark brown TOPSOIL (Fill)
-plastic and metal debris
Dark brown silty SAND with gravel, loose, moist (Fill)
-plastic and metal debris to 6.5'
Brown silty GRAVEL with sand, medium dense to dense, moist
Test pit terminated at 7.0 feet below existing grade. No groundwater encountered during
excavation. No caving observed.
Bottom of test pit at 7.0 feet.
1.5
6.5
7.0
NOTES Depth of Topsoil & Sod 18": forest duff
GROUND ELEVATION 338 ft
LOGGED BY KTK
EXCAVATION METHOD AT TIME OF EXCAVATION ---
AT END OF EXCAVATION ---
AFTER EXCAVATION ---
TEST PIT SIZE
EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS:
CHECKED BY HTW
DATE STARTED 1/17/20 COMPLETED 1/17/20
DEPTH(ft)0
5 SAMPLE TYPENUMBERPAGE 1 OF 1
TEST PIT NUMBER TP-101
PROJECT NUMBER ES-6375.01 PROJECT NAME S.W. 320th Street Plat
GENERAL BH / TP / WELL 6375-1.GPJ GINT US.GDT 2/12/20Earth Solutions NW
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
TESTS
U.S.C.S.GRAPHICLOGMATERIAL DESCRIPTION
338.0
331.0
TPSL
SM
Dark brown TOPSOIL (Fill)
-contains gravel
Brown silty SAND with gravel, medium dense, moist (Fill)
-plastic, metal and wood debris to BOH
-minor caving to BOH
Test pit terminated at 8.0 feet below existing grade. No groundwater encountered during excavation. Caving
observed from 3.0 feet to BOH.
Bottom of test pit at 8.0 feet.
1.0
8.0
NOTES Surface Conditions: gravel fill
GROUND ELEVATION 339 ft
LOGGED BY KTK
EXCAVATION METHOD AT TIME OF EXCAVATION ---
AT END OF EXCAVATION ---
AFTER EXCAVATION ---
TEST PIT SIZE
EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS:
CHECKED BY HTW
DATE STARTED 1/17/20 COMPLETED 1/17/20
DEPTH(ft)0
5 SAMPLE TYPENUMBERPAGE 1 OF 1
TEST PIT NUMBER TP-102
PROJECT NUMBER ES-6375.01 PROJECT NAME S.W. 320th Street Plat
GENERAL BH / TP / WELL 6375-1.GPJ GINT US.GDT 2/12/20Earth Solutions NW
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
U.S.C.S.GRAPHICLOGMATERIAL DESCRIPTION
340.5
338.5
333.5
332.0
MC = 7.20%
Fines = 5.70%
MC = 7.30%
Fines = 1.70%
TPSL
SM
GP-
GM
GP
Dark brown TOPSOIL, trace roots to 4.5'
Brown silty SAND with gravel, loose, moist
Brown poorly graded GRAVEL with silt and sand, medium dense, moist
-minor caving to BOH
-infiltration test at 6'
[USDA Classification: extremely gravelly loamy coarse SAND]
Gray poorly graded GRAVEL with sand, medium dense to dense, moist
[USDA Classification: extremely gravelly coarse SAND]
Test pit terminated at 9.0 feet below existing grade. No groundwater encountered during
excavation. Caving observed from 5.0 feet to BOH.
Bottom of test pit at 9.0 feet.
0.5
2.5
7.5
9.0
NOTES Depth of Topsoil & Sod 6": forest duff
GROUND ELEVATION 341 ft
LOGGED BY KTK
EXCAVATION METHOD AT TIME OF EXCAVATION ---
AT END OF EXCAVATION ---
AFTER EXCAVATION ---
TEST PIT SIZE
EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS:
CHECKED BY HTW
DATE STARTED 1/17/20 COMPLETED 1/17/20
DEPTH(ft)0
5 SAMPLE TYPENUMBERPAGE 1 OF 1
TEST PIT NUMBER TP-103
PROJECT NUMBER ES-6375.01 PROJECT NAME S.W. 320th Street Plat
GENERAL BH / TP / WELL 6375-1.GPJ GINT US.GDT 2/12/20Earth Solutions NW
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
TESTS
U.S.C.S.GRAPHICLOGMATERIAL DESCRIPTION
332.0
329.5
326.0
324.0
MC = 3.80%
Fines = 1.70%
MC = 7.20%
Fines = 3.20%
TPSL
SM
SP
GP
Dark brown TOPSOIL, trace roots to 5'
Brown silty SAND with gravel, medium dense, moist
Gray poorly graded SAND with gravel, medium dense, moist
[USDA Classification: very gravelly SAND]
-infiltration test at 6', increased gravel content
-minor caving to BOH
Gray poorly graded GRAVEL with sand, medium dense to dense, moist
[USDA Classification: extremely gravelly coarse SAND]
Test pit terminated at 9.0 feet below existing grade. No groundwater encountered during
excavation. Caving observed from 6.5 feet to BOH.
Bottom of test pit at 9.0 feet.
1.0
3.5
7.0
9.0
NOTES Depth of Topsoil & Sod 12": forest duff
GROUND ELEVATION 333 ft
LOGGED BY KTK
EXCAVATION METHOD AT TIME OF EXCAVATION ---
AT END OF EXCAVATION ---
AFTER EXCAVATION ---
TEST PIT SIZE
EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS:
CHECKED BY HTW
DATE STARTED 1/17/20 COMPLETED 1/17/20
DEPTH(ft)0
5 SAMPLE TYPENUMBERPAGE 1 OF 1
TEST PIT NUMBER TP-104
PROJECT NUMBER ES-6375.01 PROJECT NAME S.W. 320th Street Plat
GENERAL BH / TP / WELL 6375-1.GPJ GINT US.GDT 2/12/20Earth Solutions NW
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
TESTS
U.S.C.S.GRAPHICLOGMATERIAL DESCRIPTION
339.0
337.0
332.5
MC = 2.50%
MC = 1.80%
Fines = 2.50%
MC = 2.00%
TPSL
SM
GW
Dark brown TOPSOIL
-trace roots to 6'
Tan silty SAND with gravel, medium dense, damp
Tan well-graded GRAVEL with sand, dense, damp
[USDA Classification: extremely gravelly coarse SAND]
-slight caving from 3' to 6'
Test pit terminated at 7.5 feet below existing grade. No groundwater encountered during
excavation. Caving observed from 3.0 to 6.0 feet.
Bottom of test pit at 7.5 feet.
1.0
3.0
7.5
NOTES Depth of Topsoil & Sod 6"- 12": forest duff
GROUND ELEVATION 340 ft
LOGGED BY KTK
EXCAVATION METHOD AT TIME OF EXCAVATION ---
AT END OF EXCAVATION ---
AFTER EXCAVATION ---
TEST PIT SIZE
EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS:
CHECKED BY KDH
DATE STARTED 10/26/18 COMPLETED 10/26/18
DEPTH(ft)0
5 SAMPLE TYPENUMBERPAGE 1 OF 1
TEST PIT NUMBER TP-1
PROJECT NUMBER ES-6375 PROJECT NAME S.W. 320th Street Plat
GENERAL BH / TP / WELL 6375.GPJ GINT US.GDT 2/12/20Earth Solutions NW
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
TESTS
U.S.C.S.GRAPHICLOGMATERIAL DESCRIPTION
344.0
342.0
337.0
MC = 8.20%
Fines = 50.40%
MC = 3.10%
TPSL
ML
GP
Dark brown TOPSOIL
-trace roots to 6.5'
Tan sandy SILT with gravel, medium dense, damp
[USDA Classification: gravelly LOAM]
Tan poorly graded GRAVEL with sand, dense, damp
-slight caving to 7'
Test pit terminated at 8.0 feet below existing grade. No groundwater encountered during
excavation. Caving observed from 5.0 to 7.0 feet.
Bottom of test pit at 8.0 feet.
1.0
3.0
8.0
NOTES Depth of Topsoil & Sod 6"- 12": forest duff
GROUND ELEVATION 345 ft
LOGGED BY KTK
EXCAVATION METHOD AT TIME OF EXCAVATION ---
AT END OF EXCAVATION ---
AFTER EXCAVATION ---
TEST PIT SIZE
EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS:
CHECKED BY KDH
DATE STARTED 10/26/18 COMPLETED 10/26/18
DEPTH(ft)0
5 SAMPLE TYPENUMBERPAGE 1 OF 1
TEST PIT NUMBER TP-2
PROJECT NUMBER ES-6375 PROJECT NAME S.W. 320th Street Plat
GENERAL BH / TP / WELL 6375.GPJ GINT US.GDT 2/12/20Earth Solutions NW
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
TESTS
U.S.C.S.GRAPHICLOGMATERIAL DESCRIPTION
344.0
343.0
338.0
MC = 2.10%
MC = 1.80%
Fines = 1.70%
TPSL
SM
SP
Dark brown TOPSOIL
-trace roots to 6'
Brown silty SAND with gravel, loose to medium dense, moist
Tan poorly graded SAND with gravel, dense, damp
-slight caving to BOH
[USDA Classification: very gravelly coarse SAND]
Test pit terminated at 7.0 feet below existing grade. No groundwater encountered during
excavation. Caving observed from 5.0 feet to BOH.
Bottom of test pit at 7.0 feet.
1.0
2.0
7.0
NOTES Depth of Topsoil & Sod 6"- 12": forest duff
GROUND ELEVATION 345 ft
LOGGED BY KTK
EXCAVATION METHOD AT TIME OF EXCAVATION ---
AT END OF EXCAVATION ---
AFTER EXCAVATION ---
TEST PIT SIZE
EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS:
CHECKED BY KDH
DATE STARTED 10/26/18 COMPLETED 10/26/18
DEPTH(ft)0
5 SAMPLE TYPENUMBERPAGE 1 OF 1
TEST PIT NUMBER TP-3
PROJECT NUMBER ES-6375 PROJECT NAME S.W. 320th Street Plat
GENERAL BH / TP / WELL 6375.GPJ GINT US.GDT 2/12/20Earth Solutions NW
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
TESTS
U.S.C.S.GRAPHICLOGMATERIAL DESCRIPTION
349.0
346.0
342.5
MC = 4.60%
MC = 10.20%
TPSL
SM
SP
Dark brown TOPSOIL (Fill)
-trace roots to BOH
Brown silty SAND with gravel, loose to medium dense, moist (Fill)
-plastic and ceramic debris to 4'
-becomes medium dense to dense
Tan poorly graded SAND with gravel, dense, damp
Test pit terminated at 7.5 feet below existing grade. No groundwater encountered during
excavation. No caving observed.
Bottom of test pit at 7.5 feet.
1.0
4.0
7.5
NOTES Depth of Topsoil & Sod 6"- 12": brambles
GROUND ELEVATION 350 ft
LOGGED BY KTK
EXCAVATION METHOD AT TIME OF EXCAVATION ---
AT END OF EXCAVATION ---
AFTER EXCAVATION ---
TEST PIT SIZE
EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS:
CHECKED BY KDH
DATE STARTED 10/26/18 COMPLETED 10/26/18
DEPTH(ft)0
5 SAMPLE TYPENUMBERPAGE 1 OF 1
TEST PIT NUMBER TP-4
PROJECT NUMBER ES-6375 PROJECT NAME S.W. 320th Street Plat
GENERAL BH / TP / WELL 6375.GPJ GINT US.GDT 2/12/20Earth Solutions NW
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
TESTS
U.S.C.S.GRAPHICLOGMATERIAL DESCRIPTION
349.5
348.0
343.0
MC = 3.30%
MC = 4.50%
TPSL
SM
GP
Dark brown TOPSOIL, trace roots to 5'
Tan silty SAND with gravel, medium dense, moist
Tan poorly graded GRAVEL with sand, dense, damp
Test pit terminated at 7.0 feet below existing grade. No groundwater encountered during
excavation. No caving observed.
Bottom of test pit at 7.0 feet.
0.5
2.0
7.0
NOTES Depth of Topsoil & Sod 6": forest duff
GROUND ELEVATION 350 ft
LOGGED BY KTK
EXCAVATION METHOD AT TIME OF EXCAVATION ---
AT END OF EXCAVATION ---
AFTER EXCAVATION ---
TEST PIT SIZE
EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS:
CHECKED BY KDH
DATE STARTED 10/26/18 COMPLETED 10/26/18
DEPTH(ft)0
5 SAMPLE TYPENUMBERPAGE 1 OF 1
TEST PIT NUMBER TP-5
PROJECT NUMBER ES-6375 PROJECT NAME S.W. 320th Street Plat
GENERAL BH / TP / WELL 6375.GPJ GINT US.GDT 2/12/20Earth Solutions NW
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
TESTS
U.S.C.S.GRAPHICLOGMATERIAL DESCRIPTION
344.0
343.0
336.0MC = 2.20%
Fines = 4.10%
TPSL
SM
GP
Dark brown TOPSOIL
-trace roots to BOH
Tan silty SAND with gravel, loose to medium dense, moist
Tan poorly graded GRAVEL with sand, medium dense to dense, damp
[USDA Classification: extremely gravelly coarse SAND]
Test pit terminated at 9.0 feet below existing grade. No groundwater encountered during
excavation. No caving observed.
Bottom of test pit at 9.0 feet.
1.0
2.0
9.0
NOTES Depth of Topsoil & Sod 12": forest duff
GROUND ELEVATION 345 ft
LOGGED BY KTK
EXCAVATION METHOD AT TIME OF EXCAVATION ---
AT END OF EXCAVATION ---
AFTER EXCAVATION ---
TEST PIT SIZE
EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS:
CHECKED BY KDH
DATE STARTED 10/26/18 COMPLETED 10/26/18
DEPTH(ft)0
5 SAMPLE TYPENUMBERPAGE 1 OF 1
TEST PIT NUMBER TP-6
PROJECT NUMBER ES-6375 PROJECT NAME S.W. 320th Street Plat
GENERAL BH / TP / WELL 6375.GPJ GINT US.GDT 2/12/20Earth Solutions NW
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
TESTS
U.S.C.S.GRAPHICLOGMATERIAL DESCRIPTION
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
0.0010.010.1110100
%Silt %ClayD100 D30
1.619
2.289
0.492
1.407
3 100
TP-103
TP-103
TP-104
TP-104
24
406 60
10.501
13.229
3.26
10.86
1.5 8 14
Cc Cu
5.7
1.7
1.7
3.2
COBBLES GRAVELPERCENT FINER BY WEIGHTSAND
GRAIN SIZE IN MILLIMETERS
6.0ft.
9.0ft.
6.0ft.
9.0ft.
coarse
D90
fine
Specimen Identification
PL PI
Classification
Specimen Identification
TP-103
TP-103
TP-104
TP-104
3/4 3/8
6.0ft.
9.0ft.
6.0ft.
9.0ft.
LL
1 2006 10 501/2
HYDROMETERU.S. SIEVE OPENING IN INCHES
14034
U.S. SIEVE NUMBERS
37.5
37.5
37.5
37.5
26.834
30.361
27.536
18.697
D60 D10
0.31
0.578
0.276
0.247
USDA: Gray Extremely Gravelly Loamy Coarse Sand. USCS: GP-GM with Sand.
USDA: Gray Extremely Gravelly Coarse Sand. USCS: GP with Sand.
USDA: Gray Very Gravelly Sand. USCS: SP with Gravel.
USDA: Gray Extremely Gravelly Coarse Sand. USCS: GP with Sand.
33.89
22.90
11.79
44.04
0.81
0.69
0.27
0.74
GRAIN SIZE DISTRIBUTION
coarse SILT OR CLAYfinemedium
16 3020
PROJECT NUMBER ES-6375.01 PROJECT NAME S.W. 320th Street Plat
GRAIN SIZE USDA WITH D90 ES-6375.01 S.W. 320TH STREET PLAT.GPJ GINT US LAB.GDT 1/21/20Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711