13_Painted_Hills_Supplemental_Geotechnical_Report_4-19-16IPEC
Inland Pacific Engineering Company
Geotechnical Engineering and Consulting
P.O. Box 1566, Veradale, WA 99037
Phone 509-209-6262
April 19, 2016
Project No. 16-249
NAI Black
c/o Mr. Bryan Walker
107 South Howard
Suite 500
Spokane, WA 99201
Re: Supplemental Geotechnical Evaluation
Painted Hills Golf Course Property
4403 South Dishman-Mica Road
Spokane Valley, WA
Dear Mr. Walker:
As you authorized, we have completed the supplemental geotechnical evaluation for the Painted
Hills Golf Course property at the above-referenced site in Spokane Valley, Washington. The
purpose of the supplemental evaluation is to provide additional soil and groundwater data to
address concerns of the City of Spokane Valley. This report summarizes the results of our field
investigation, laboratory testing, engineering analyses, and our opinions and recommendations
for stormwater management.
PROJECT DESCRIPTION
We understand that the proposed project may consist of a residential development. The site consists
of 91 acres currently developed as a golf course. Stormwater runoff will be treated using drywells
and/or gravel galleries for subsurface infiltration. These type of facilities will also be used to
manage potential floodwaters, if needed. This supplemental evaluation is intended to provide
additional subsurface data at the north end of the site to assist in identifying areas where subsurface
infiltration of stormwater may be feasible due to the presence of suitable soils at depth.
Supplemental Geotechnical Evaluation Project No. 16-249
Painted Hills Golf Course Property Parcel No. 45344.9108
Spokane Valley, WA April 19, 2016
Inland Pacific Engineering Company Page 2
AVAILABLE INFORMATION
We were provided a topographic survey for the project site by Whipple Consulting Engineers, Inc.
(WCE). This topographic survey showed the existing roadways, existing structures, property lines,
and existing ground surface elevation contours. This plan was prepared by WCE and was dated
November 7, 2013. The site was used as a golf course prior to our evaluation. The site is relatively
level with some elevated golf greens and excavated areas for water hazards. The site is primarily
grass-covered with scattered trees along the fairways and pine trees in the undeveloped area to the
northwest. The clubhouse building is present at the southwest corner.
In addition, we performed a preliminary geotechnical evaluation for the property in December 2013.
The results of that evaluation, along with our opinions and recommendations, are summarized in our
Preliminary Geotechnical Evaluation dated December 31, 2013.
We also performed a geotechnical evaluation for certification of the existing levee along Chester
Creek in April 2014. The results of that evaluation are summarized in our Geotechnical Evaluation
report dated February 12, 2015.
Lastly, we performed a geotechnical evaluation in July 2015 consisting of ten 50-foot borings in the
south half of the property. The results of that evaluation are summarized in our Geotechnical
Evaluation Phase 2 report dated July 23, 2015.
FIELD EVALUATION
Procedures
A geotechnical engineer from Inland Pacific Engineering Company (IPEC) observed the drilling of
three penetration test borings at the site. The borings were drilled between March 17 and 19, 2016
using a truck-mounted drill operated by an independent firm working under subcontract to IPEC.
A geotechnical engineer or engineering assistant from IPEC observed the borings and logged the
surface and subsurface conditions. After we logged the borings, they were abandoned in
accordance with state requirements. Ground surface elevations at the borings were provided by
WCE.
The soils encountered in the borings were visually and manually classified in the field by our field
personnel in accordance with ASTM D 2488, “Description and Identification of Soils (Visual-
Manual Procedures)”. The samples were returned to our facility for review of the classification by a
geotechnical engineer and laboratory testing.
Supplemental Geotechnical Evaluation Project No. 16-249
Painted Hills Golf Course Property Parcel No. 45344.9108
Spokane Valley, WA April 19, 2016
Inland Pacific Engineering Company Page 3
Soils Encountered
In general, the borings encountered 2 feet of topsoil at the surface. Below the topsoil, the borings
generally encountered glacially-deposited silty to clayey sands and/or gravels overlying poorly
graded sands to termination depths of the borings. The clayey sands and gravels were generally
encountered in the upper 12 to 18 feet.
Penetration resistances in the sands and gravels ranged from 15 to 90 blows per foot (BPF) and
averaged 37 BPF, indicating that these soils were medium dense to very dense, but were typically
dense.
Geologic maps indicate the soils in this area consist primarily of alluvial and/or glacially
deposited silts, clays, sands, and gravels. According to the Soil Survey of Spokane County, the
site soils are classified by the Natural Resource Conservation Service (NRCS) as Hardesty ashy
silt loam, Narcisse silt loam, Endoaquolls and Fluvaquents, Phoebe ashy sandy loam, and Urban
land-Springdale disturbed complex. The native soils encountered in the borings were consistent
with the NRCS data.
Groundwater was encountered in Boring B-2 at a depth of 71 feet. This depth corresponds to an
elevation of 1934.6. Groundwater was not encountered in the remaining borings. The observed
water levels further indicates that groundwater levels drop generally from south to north with higher
levels near Chester Creek. Fluctuations in the groundwater level may occur due to rainfall,
flooding, irrigation, spring thaw and other seasonal and annual factors not evident at the time the
observations were made.
ANALYSIS, OPINIONS, AND RECOMMENDATIONS
Based on the data obtained from the recent and previous borings, previous test pits, field
permeability tests, and laboratory tests performed, it is our opinion that subsurface infiltration of
stormwater is feasible. The most promising layers are the glacial sands and gravels. These soils
would be suitable for infiltration using standard drywells.
We will perform a mounding analysis for the drywells after the proposed full-scale drywell test is
completed to assess down-gradient impacts
REMARKS
This report is for the exclusive use of the addressee and the copied parties to use in design of the
proposed project and to prepare construction documents. In the absence of our written approval, we
make no representations and assume no responsibility to other parties regarding this report. The
data, analyses, and recommendations may not be appropriate for other structures or purposes. We
recommend that parties contemplating other structures or purposes contact us.
FIGURE 1
Site Location Map
Project No. 16-249
April 19, 2016 Painted Hills Golf Course
4403 South Dishman-Mica Road
Spokane County, WA
FIGURE 2
NRCS Map
Project No. 16-249
April 19, 2016 Painted Hills Golf Course
4403 South Dishman-Mica Road
Spokane County, WA
FIGURE 3
Boring Location Map
Project No. 16-249
April 19, 2016 Painted Hills Golf Course
4403 South Dishman-Mica Road
Spokane County, WA
SS
SS
SS
SS
SS
SS
2003.9
1988.9
SM
SP-SM
SP
2.0
17.0
(SM) SILTY SAND, fine to medium grained, with roots, dark brown,moist.(Topsoil)
(SP-SM) POORLY GRADED SAND with SILT, medium to coarse
grained, a trace of Gravel, brown, moist, medium dense.
(Glacial Outwash)
(SP) POORLY GRADED SAND with GRAVEL, medium to coarse
grained, brown, moist, very dense to medium dense.
(Glacial Outwash)
Fines = 7%
NOTES
GROUND ELEVATION 2005.9 ft
LOGGED BY PRF
DRILLING METHOD Hollow Stem Auger
DRILLING CONTRACTOR Johnson Exploration Drilling GROUND WATER LEVELS:
CHECKED BY PTN
DATE STARTED 3/17/16 COMPLETED 3/17/16
AT TIME OF DRILLING --- Not encountered
AT END OF DRILLING --- Not encountered
AFTER DRILLING --- Not encountered
HOLE SIZE 8 inches
SAMPLE TYPENUMBERDEPTH(ft)0
5
10
15
20
25
30
(Continued Next Page)
PAGE 1 OF 2
BORING NUMBER B-1
CLIENT NAI Black
PROJECT NUMBER 16-249
PROJECT NAME Painted Hills Supplemental
PROJECT LOCATION 4403 South Dishman-Mica Road
GENERAL BH / TP / WELL - GINT STD US LAB.GDT - 4/5/16 11:26 - J:\_IPEC PROJECTS\_2016 PROJECTS\16-249 PAINTED HILLS SUPPLEMENTAL\GINT\16-249 PAINTED HILLS SUPPLEMENTAL.GPJInland Pacific Engineering Company
3012 North Sullivan Road, Suite C
Spokane Valley, WA 99216
Telephone: 509-209-6262
Fax: 509-290-5734
U.S.C.S.GRAPHICLOGMATERIAL DESCRIPTIONTESTS
SS
SS
SS
SS 1955.4
SP
50.5
(SP) POORLY GRADED SAND with GRAVEL, medium to coarsegrained, brown, moist, very dense to medium dense.(Glacial Outwash) (continued)
End of boring.
Groundwater not encountered with 49' of hollow-stem auger in theground.
Groundwater not encountered immediately after withdrawal of the
auger.
Bore hole then abandoned.SAMPLE TYPENUMBERDEPTH(ft)35
40
45
50
PAGE 2 OF 2
BORING NUMBER B-1
CLIENT NAI Black
PROJECT NUMBER 16-249
PROJECT NAME Painted Hills Supplemental
PROJECT LOCATION 4403 South Dishman-Mica Road
GENERAL BH / TP / WELL - GINT STD US LAB.GDT - 4/5/16 11:26 - J:\_IPEC PROJECTS\_2016 PROJECTS\16-249 PAINTED HILLS SUPPLEMENTAL\GINT\16-249 PAINTED HILLS SUPPLEMENTAL.GPJInland Pacific Engineering Company
3012 North Sullivan Road, Suite C
Spokane Valley, WA 99216
Telephone: 509-209-6262
Fax: 509-290-5734
U.S.C.S.GRAPHICLOGMATERIAL DESCRIPTIONTESTS
SS
SS
SS
SS
SS
SS
2003.6
1999.1
1993.6
12-33
(45)
24-20
(44)
24-29(53)
25-28(53)
10-18
(28)
11-13
(24)
SM
SC
GC
SP
2.0
6.5
12.0
(SM) SILTY SAND, fine to medium grained, with roots, darkbrown, moist.(Topsoil)
(SC) CLAYEY SAND with GRAVEL, medium to coarse
grained, brown, moist to wet, dense.
(Glacial Outwash)
(GC) CLAYEY GRAVEL with SAND, fine to coarse grained,
brown, moist, dense.
(Glacial Outwash)
(SP) POORLY GRADED SAND with GRAVEL, medium tocoarse grained, a trace of Cobbles, brown, moist, very denseto medium dense.
(Glacial Outwash)
Fines = 8%
NOTES
GROUND ELEVATION 2005.6 ft
LOGGED BY PRF
DRILLING METHOD Hollow Stem Auger
DRILLING CONTRACTOR Johnson Exploration Drilling GROUND WATER LEVELS:
CHECKED BY PTN
DATE STARTED 3/17/16 COMPLETED 3/18/16
AT TIME OF DRILLING --- Not encontered
AT END OF DRILLING 71.00 ft / Elev 1934.60 ft
AFTER DRILLING 73.50 ft / Elev 1932.10 ft
HOLE SIZE 8 inches
SAMPLE TYPENUMBERDEPTH(ft)0
5
10
15
20
25
30
(Continued Next Page)
PAGE 1 OF 3
BORING NUMBER B-2
CLIENT NAI Black
PROJECT NUMBER 16-249
PROJECT NAME Painted Hills Supplemental
PROJECT LOCATION 4403 South Dishman-Mica Road
GENERAL BH / TP / WELL - GINT STD US LAB.GDT - 4/5/16 11:26 - J:\_IPEC PROJECTS\_2016 PROJECTS\16-249 PAINTED HILLS SUPPLEMENTAL\GINT\16-249 PAINTED HILLS SUPPLEMENTAL.GPJInland Pacific Engineering Company
3012 North Sullivan Road, Suite C
Spokane Valley, WA 99216
Telephone: 509-209-6262
Fax: 509-290-5734
BLOWCOUNTS(N VALUE)U.S.C.S.GRAPHICLOGMATERIAL DESCRIPTIONTESTS
SS
SS
SS
SS
SS
28-37(65)
50/5"
50/5"
50/5"
8-17(25)
SP
(SP) POORLY GRADED SAND with GRAVEL, medium tocoarse grained, a trace of Cobbles, brown, moist, very denseto medium dense.
(Glacial Outwash) (continued)SAMPLE TYPENUMBERDEPTH(ft)35
40
45
50
55
60
65
(Continued Next Page)
PAGE 2 OF 3
BORING NUMBER B-2
CLIENT NAI Black
PROJECT NUMBER 16-249
PROJECT NAME Painted Hills Supplemental
PROJECT LOCATION 4403 South Dishman-Mica Road
GENERAL BH / TP / WELL - GINT STD US LAB.GDT - 4/5/16 11:26 - J:\_IPEC PROJECTS\_2016 PROJECTS\16-249 PAINTED HILLS SUPPLEMENTAL\GINT\16-249 PAINTED HILLS SUPPLEMENTAL.GPJInland Pacific Engineering Company
3012 North Sullivan Road, Suite C
Spokane Valley, WA 99216
Telephone: 509-209-6262
Fax: 509-290-5734
BLOWCOUNTS(N VALUE)U.S.C.S.GRAPHICLOGMATERIAL DESCRIPTIONTESTS
SS
1930.6
21-11
(32)
SP
75.0
(SP) POORLY GRADED SAND with GRAVEL, medium tocoarse grained, a trace of Cobbles, brown, moist, very denseto medium dense.
(Glacial Outwash) (continued)
End of boring.
Groundwater encountered at 71' with 75' of hollow-stem auger
in the ground.
Goundwater encountered at 73.5' 10 minutes later.
Groundwater not encountered to cave-in depth of 15'
immediately after withdrawal of the auger.
Bore hole then abandoned.SAMPLE TYPENUMBERDEPTH(ft)70
75
PAGE 3 OF 3
BORING NUMBER B-2
CLIENT NAI Black
PROJECT NUMBER 16-249
PROJECT NAME Painted Hills Supplemental
PROJECT LOCATION 4403 South Dishman-Mica Road
GENERAL BH / TP / WELL - GINT STD US LAB.GDT - 4/5/16 11:26 - J:\_IPEC PROJECTS\_2016 PROJECTS\16-249 PAINTED HILLS SUPPLEMENTAL\GINT\16-249 PAINTED HILLS SUPPLEMENTAL.GPJInland Pacific Engineering Company
3012 North Sullivan Road, Suite C
Spokane Valley, WA 99216
Telephone: 509-209-6262
Fax: 509-290-5734
BLOWCOUNTS(N VALUE)U.S.C.S.GRAPHICLOGMATERIAL DESCRIPTIONTESTS
SS
SS
SS
SS
SS
SS
2002.5
1996.5
1992.5
1986.5
ML
GC
SC
GC
SP
2.0
8.0
12.0
18.0
(ML) SANDY SILT, with roots, dark brown, moist.(Topsoil)
(GC) CLAYEY GRAVEL with SAND, fine to coarse grained, brown,
moist, dense.
(Glacial Outwash)
(SC) CLAYEY SAND with GRAVEL, medium to coarse grained, brown,moist to wet, dense.(Glacial Outwash)
(GC) SILTY CLAYEY GRAVEL with SAND, fine to coarse grained,brown, moist, medium dense.(Glacial Outwash)
(SP) POORLY GRADED SAND with GRAVEL, medium to coarse
grained, a trace of Cobbles, brown, moist, very dense to medium dense.
(Glacial Outwash)
Fines = 6%
NOTES
GROUND ELEVATION 2004.5 ft
LOGGED BY PRF
DRILLING METHOD Hollow Stem Auger
DRILLING CONTRACTOR Johnson Exploration Drilling GROUND WATER LEVELS:
CHECKED BY PTN
DATE STARTED 3/18/16 COMPLETED 3/19/16
AT TIME OF DRILLING --- Not encountered
AT END OF DRILLING --- Not encountered
AFTER DRILLING --- Not encountered
HOLE SIZE 8 inches
SAMPLE TYPENUMBERDEPTH(ft)0
5
10
15
20
25
30
(Continued Next Page)
PAGE 1 OF 2
BORING NUMBER B-3
CLIENT NAI Black
PROJECT NUMBER 16-249
PROJECT NAME Painted Hills Supplemental
PROJECT LOCATION 4403 South Dishman-Mica Road
GENERAL BH / TP / WELL - GINT STD US LAB.GDT - 4/5/16 11:26 - J:\_IPEC PROJECTS\_2016 PROJECTS\16-249 PAINTED HILLS SUPPLEMENTAL\GINT\16-249 PAINTED HILLS SUPPLEMENTAL.GPJInland Pacific Engineering Company
3012 North Sullivan Road, Suite C
Spokane Valley, WA 99216
Telephone: 509-209-6262
Fax: 509-290-5734
U.S.C.S.GRAPHICLOGMATERIAL DESCRIPTIONTESTS
SS
SS
SS
SS 1954.0
SP
50.5
(SP) POORLY GRADED SAND with GRAVEL, medium to coarsegrained, a trace of Cobbles, brown, moist, very dense to medium dense.(Glacial Outwash) (continued)
End of boring.
Groundwater not encountered with 49' of hollow-stem auger in theground.
Groundwater not encountered immediately after withdrawal of the
auger.
Bore hole then abandoned.SAMPLE TYPENUMBERDEPTH(ft)35
40
45
50
PAGE 2 OF 2
BORING NUMBER B-3
CLIENT NAI Black
PROJECT NUMBER 16-249
PROJECT NAME Painted Hills Supplemental
PROJECT LOCATION 4403 South Dishman-Mica Road
GENERAL BH / TP / WELL - GINT STD US LAB.GDT - 4/5/16 11:26 - J:\_IPEC PROJECTS\_2016 PROJECTS\16-249 PAINTED HILLS SUPPLEMENTAL\GINT\16-249 PAINTED HILLS SUPPLEMENTAL.GPJInland Pacific Engineering Company
3012 North Sullivan Road, Suite C
Spokane Valley, WA 99216
Telephone: 509-209-6262
Fax: 509-290-5734
U.S.C.S.GRAPHICLOGMATERIAL DESCRIPTIONTESTS
DENSITY
Very Loose 0 - 4
Loose 4 - 10
Coarse-Gravel and Gravel GW
Grained Gravelly Soils (with little or no fines)GP
Soils <50% coarse fraction Gravel GM
passes #4 sieve (with >12% fines)GC
<50% Sandy and Sand SW
passes #200 Sandy Soils (with little or no fines)SP
sieve >50% coarse fraction Sand SM
passes #4 sieve (with >12% fines)SC
Fine-ML
Grained CL
Soils OL
>50% MH
passes #200 CH
sieve OH
PT Peat
DESCRIPTION RANGE
Occasional <5%
Trace 5% - 12%
With >12%
Coarse Fine Coarse Medium Fine
MODIFIERS
Hard > 30
USCS SOIL CLASSIFICATION
Liquid Limit > 50
Highly Organic Soils
Silt and Clay
MAJOR DIVISIONS
Liquid Limit < 50
Salt and Clay
Organic Clay and Silt (med to high plasticity)
Muck
Well Graded Sand
Inorganic Silt
Fat Clay
MOISTURE CONTENT
Gravel SandBoulders Cobbles
GRAIN SIZE (INCHES)
Silt and Clay
12 3 0.75 0.19 0.079 0.0171 0.0029
17 - 30
Soft
Rather Soft
Medium
Rather Stiff
Stiff
Very Stiff
2 - 3
4 - 5
6 - 8
9 - 12
RELATIVE DENSITY OR CONSISTENCY VERSUS SPT N-VALVE
FINE-GRAINED SOILS
N(BLOWS/FT) CONSISTENCY N(BLOWS/FT)
Very Soft 0 - 1
MAJOR DIVISIONS WITH GRAIN SIZE
SIEVE SIZE
12" 3" 3/4" 4 10 40 200
COARSE-GRAINED SOILS
Poorly Graded Sand
Silty Sand
Clayey Sand
Silt
Lean Clay
Organic Silt and Clay (low plasticity)
GROUP DESCRIPTIONS
Well Graded Gravel
Poorly Graded Gravel
Silty Gravel
Clayey Gravel
13 - 16
FIELD OBSERVATION
Absence of moisture, dusty, dry to the touch
Dry of optimum moisture content
Wet of optimum moisture content
DESCRIPTION
Dry
Moist
Wet
Very Dense > 50
Dense 31 - 50
Medium-Dense 11 - 30
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
PI Cc CuLLPL
8.65
8.72
9.95
1.37
2.10
1.85
GRAIN SIZE DISTRIBUTION
COBBLES GRAVEL
6.8
8.2
6.2
19
19
19
SAND
GRAIN SIZE IN MILLIMETERS
coarse fine
SP-SM Poorly Graded Sand with Silt
SP-SM Poorly Graded Sand with Silt
SP-SM Poorly Graded Sand with Silt
Classification
D100 D60 D30 D10 %Gravel
2.679
1.992
4.708
B-1
B-2
B-3
coarse SILT OR CLAYfinemedium
30.0
25.0
30.0
%Sand %Silt %Clay
1.065
0.977
2.032
0.31
0.228
0.473
21.9
13.9
39.7
71.2
77.9
54.1
BOREHOLE DEPTH
BOREHOLE DEPTH
3 100
B-1
B-2
B-3
24 16 301 200610501/2 HYDROMETERU.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS 1403420406601.5 8 143/4 3/8
30.0
25.0
30.0PERCENT FINER BY WEIGHTCLIENT NAI Black
PROJECT NUMBER 16-249
PROJECT NAME Painted Hills Supplemental
PROJECT LOCATION 4403 South Dishman-Mica Road
GRAIN SIZE - GINT STD US LAB.GDT - 4/19/16 15:07 - J:\_IPEC PROJECTS\_2016 PROJECTS\16-249 PAINTED HILLS SUPPLEMENTAL\GINT\16-249 PAINTED HILLS SUPPLEMENTAL.GPJInland Pacific Engineering Company
3012 North Sullivan Road, Suite C
Spokane Valley, WA 99216
Telephone: 509-209-6262
Fax: 509-290-5734