geotechnical engineering report, mccormick woods parcel a, …€¦ · lu19-plat prelim-02....
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Corporate Office 17522 Bothell Way Northeast Bothell, Washington 98011 Phone 425.415.0551 ♦ Fax 425.415.0311
www.riley-group.com
June 26, 2019
Mr. James Tosti Windward Real Estate 805 Kirkland Avenue, Suite 200 Kirkland, Washington 98033
Subject: Infiltration Assessment
McCormick Woods Parcel A McCormick Woods Drive SW & St. Andrews Drive SW
Port Orchard, Washington RGI Project No. 2019-088A
As requested, The Riley Group, Inc. (RGI) is pleased to provide the results of our recent infiltration testing at the proposed McCormick Woods Parcel A residential development Site, located in Port Orchard, Washington (Figure 1). RGI previously completed a geotechnical engineering report for the Site which is summarized in our report:
Geotechnical Engineering Report, McCormick Woods Parcel A, McCormick Woods Drive SW & St. Andrews Drive SW, Port Orchard, Washington, dated May 29, 2019.
The results of infiltration testing in the proposed stormwater pond area at the Parcel A site is summarized in this report.
General
The project site is located on the northeast corner of McCormick Woods Drive SW & St. Andrews Drive SW in Port Orchard, Washington. The approximate location of the site is shown on Figure 1.
The site is currently occupied by a vehicle storage lot in the east-central portion of the property. The remainder of the property is forested.
RGI understands the site is to be developed with a 55 lot residential development. An access road will wind through the site with entrance/exit areas on McCormick Woods Drive SW and St. Andrews Drive SW. A stormwater pond will be located in the northern portion of the site.
Geology Review of the Geologic Map of Surficial Deposits in the Seattle 30’ x 60’ Quadrangle, Washington, by James C. Yount, etc. (1993) indicates that the soil in the project vicinity is mapped as Vashon Till (Qvt), which is a nonsorted, nonstratified mixture of clay, silt, sand, and gravel deposited by the Vashon ice sheet. These descriptions are generally similar to the findings in our field explorations.
Infiltration Assessment Page 2 June 26, 2019 McCormick Woods Parcel A, Port Orchard, Washington RGI Project No. 2019-088A
Subsurface Conditions
RGI completed eight test pits (TP-1 through TP-8) at the Site as part of our geotechnical engineering report. Infiltration test pits IT-1 and IT-2 were completed in the area of the proposed stormwater pond during this phase of work. The test pits and infiltration test pits are shown on Figure 2.
Soil conditions documented in the infiltration test pits IT-1 and IT-2 included approximately three feet of reddish brown silty sand underlain by gray sand with some silt to the depths explored. These subsurface conditions were similar to the geotechnical test pits completed in the pond area (IT-3 and IT-4). Test pits IT-3 and IT-4 were completed to depths of 10 and 12.5 feet below grade in the pond area.
Groundwater was not encountered in the test pits completed in the pond area at the time of our explorations.
Infiltration Testing
RGI oversaw the completion of a Pilot Infiltration Tests (PIT), in IT-1 and IT-2 (Figure 2). The infiltration tests were completed at a depth of approximately 6 feet below existing grade in the gray sand unit. The water source for the testing was a water truck. The small scale pilot infiltration test (PIT) was completed per the guidelines in the Washington State Department of Ecology Stormwater Management Manual for Western Washington (SWMMWW).
Infiltration Testing Results
The field measured infiltration rates in IT-1 and IT-2 IT-1 were both 3 inches per hour. We applied the SWMMWW correction factors to the field measured rates to estimate the Ksat design
Ksat design = Ksat initial x (CFv) x (CFt) x (0.9)
Where CFv = Site variability correction factor
CFt = Test method uncertainty
0.9 = Long-term conductivity loss
CFv = 1
CFt = 0.5
Application of the stormwater manual correction factors to the field measured rates yielded recommended long-term design rates as follows:
IT-1/IT-2 (3 inches/hour) x (1) x (0.5) x (0.9) = Ksat design 1.3 inches/hour
USGS, 2014, Bremerton West, WashingtonUSGS, 2017, Burley, Washington
7.5-Minute Quadrangle
Approximate Scale: 1"=1000'
0 500 1000 2000 N
Site Vicinity Map
Figure 1
06/2019
Corporate Office17522 Bothell Way NortheastBothell, Washington 98011Phone: 425.415.0551Fax: 425.415.0311
McCormick Woods Parcel ARGI Project Number:
2019-088ADate Drawn:
Address: McCormick Woods Dr. Southwest & St. Andrews Dr., Port Orchard, Washington 98367
SITE
TP-1
TP-2
TP-3TP-4
TP-5
TP-6
TP-7
TP-8
IT-1
IT-2
N
Geotechnical Exploration Plan
Figure 2
Approximate Scale: 1"=200'
0 100 200 400
= Infiltration test pit by RGI, 06/10/19= Test pit by RGI, 04/30/19= Site boundary
06/2019
Corporate Office17522 Bothell Way NortheastBothell, Washington 98011Phone: 425.415.0551Fax: 425.415.0311
McCormick Woods Parcel ARGI Project Number:
2019-088ADate Drawn:
Address: McCormick Woods Dr. Southwest & St. Andrews Dr., Port Orchard, Washington 98367
Project Name: McCormick Woods
Project Number: 2019-088A
Client: Windward
Test Pit No.: IT-1
Date(s) Excavated: 6/10/2019
Excavation Method: Test Pit
Excavator Type: Tracked Excavator
Groundwater Level: Not Encountered
Test Pit Backfill: Cuttings
Logged By ELW
Bucket Size: 4'
Excavating Contractor: Client Provided
Sampling Method(s)
Location McCormick Woods Drive SW and St. Andrews Drive SW, Port Orchard, WA
Surface Conditions: Mixed Brush/Ferns
Total Depth of Excavation: 6 feet bgs
Approximate Surface Elevation 380
Compaction Method Bucket tamp
US
CS
Sym
bol
TPSL
SM
SP-SM
REMARKS AND OTHER TESTSG
raph
ic L
og
MATERIAL DESCRIPTION
6" topsoil
Reddish brown silty SAND with trace gravel, loose to medium dense, moist
Becomes medium dense
Gray SAND with some silt, medium dense to dense, moist
PIT infiltration test conducted at 6'
PID
Rea
ding
, ppm
Dep
th (
feet
)
0
5
10
Sam
ple
ID
Sam
ple
Typ
e
Ele
vatio
n (f
eet)
380
375
370
Sheet 1 of 1
The Riley Group, Inc. 17522 Bothell Way NE, Bothell, WA 98011
Project Name: McCormick Woods
Project Number: 2019-088A
Client: Windward
Test Pit No.: IT-2
Date(s) Excavated: 6/10/2019
Excavation Method: Test Pit
Excavator Type: Tracked Excavator
Groundwater Level: Not Encountered
Test Pit Backfill: Cuttings
Logged By ELW
Bucket Size: 4'
Excavating Contractor: Client Provided
Sampling Method(s)
Location McCormick Woods Drive SW and St. Andrews Drive SW, Port Orchard, WA
Surface Conditions: Mixed Brush/Ferns
Total Depth of Excavation: 6 feet bgs
Approximate Surface Elevation 380
Compaction Method Bucket tamp
US
CS
Sym
bol
TPSL
SM
SP-SM
REMARKS AND OTHER TESTSG
raph
ic L
og
MATERIAL DESCRIPTION
6" topsoil
Reddish brown silty SAND with trace gravel, loose to medium dense, moist
Gray SAND with some silt, medium dense to dense, moist
Infiltration test conducted at 6'
PID
Rea
ding
, ppm
Dep
th (
feet
)
0
5
10
Sam
ple
ID
Sam
ple
Typ
e
Ele
vatio
n (f
eet)
380
375
370
Sheet 1 of 1
The Riley Group, Inc. 17522 Bothell Way NE, Bothell, WA 98011
Project Name: McCormick Woods
Project Number: 2019-088
Client: Windward
Test Pit No.: TP-1
Date(s) Excavated: 4/30/2019
Excavation Method: Test Pit
Excavator Type: Tracked Excavator
Groundwater Level: Seepage at 5'
Test Pit Backfill: Cuttings
Logged By ELW
Bucket Size: 4'
Excavating Contractor: Client
Sampling Method(s) Grab
Location McCormick Woods Drive SW and St. Andrews Drive SW
Surface Conditions: Mixed Brush/Ferns
Total Depth of Excavation: 7 feet bgs
Approximate Surface Elevation 411
Compaction Method Bucket tampU
SC
S S
ymbo
l
Tpsl
SM
SM
REMARKS AND OTHER TESTS
19% moisture, 19% fines
17% moisture
11% moisture
Gra
phic
Log
MATERIAL DESCRIPTION
8" topsoil
Reddish brown silty SAND with some gravel, loose, moist
Becomes medium dense
Gray silty SAND with trace gravel, dense, moist, (Glacial Till), moderately cemented
Becomes wet
Contains sand lens with light groundwater seepage
Test pit terminated at 7'
Dep
th (
feet
)
0
5
10
15
Sam
ple
Num
ber
Sam
ple
Typ
e
Ele
vatio
n (f
eet)
411
406
401
396
Sheet 1 of 1
The Riley Group, Inc. 17522 Bothell Way NE, Bothell, WA 98011
Project Name: McCormick Woods
Project Number: 2019-088
Client: Windward
Test Pit No.: TP-2
Date(s) Excavated: 4/30/2019
Excavation Method: Test Pit
Excavator Type: Tracked Excavator
Groundwater Level: Not encountered
Test Pit Backfill: Cuttings
Logged By ELW
Bucket Size: 4'
Excavating Contractor: Client
Sampling Method(s) Grab
Location McCormick Woods Drive SW and St. Andrews Drive SW
Surface Conditions: Ferns/Moss
Total Depth of Excavation: 10.5 feet bgs
Approximate Surface Elevation 387
Compaction Method Bucket tampU
SC
S S
ymbo
l
Tpsl
SM
SP
SM
REMARKS AND OTHER TESTS
10% moisture
4% moisture
3% moisture
21% moisture
Gra
phic
Log
MATERIAL DESCRIPTION
6" topsoil
Reddish brown silty SAND with some gravel, loose, moist
Becomes medium dense
Gray SAND with some gravel, medium dense, moist
Increasing in gravel
Tan mottled silty SAND with some gravel, medium dense, moist to wet
Test pit terminated at 10.5'
Dep
th (
feet
)
0
5
10
15
Sam
ple
Num
ber
Sam
ple
Typ
e
Ele
vatio
n (f
eet)
387
382
377
372
Sheet 1 of 1
The Riley Group, Inc. 17522 Bothell Way NE, Bothell, WA 98011
Project Name: McCormick Woods
Project Number: 2019-088
Client: Windward
Test Pit No.: TP-3
Date(s) Excavated: 4/30/2019
Excavation Method: Test Pit
Excavator Type: Tracked Excavator
Groundwater Level: Not encountered
Test Pit Backfill: Cuttings
Logged By ELW
Bucket Size: 4'
Excavating Contractor: Client
Sampling Method(s) Grab
Location McCormick Woods Drive SW and St. Andrews Drive SW
Surface Conditions: Ferns/Mixed Brush
Total Depth of Excavation: 10 feet bgs
Approximate Surface Elevation 386
Compaction Method Bucket tampU
SC
S S
ymbo
l
Tpsl
SM
SP-SM
REMARKS AND OTHER TESTS
11% moisture
18% moisture
10% moisture
Gra
phic
Log
MATERIAL DESCRIPTION
6" topsoil
Reddish brown silty SAND, loose, moist
Becomes medium dense
Gray SAND with some silt, medium dense, moist
Test pit terminated at 10'
Dep
th (
feet
)
0
5
10
15
Sam
ple
Num
ber
Sam
ple
Typ
e
Ele
vatio
n (f
eet)
386
381
376
371
Sheet 1 of 1
The Riley Group, Inc. 17522 Bothell Way NE, Bothell, WA 98011
Project Name: McCormick Woods
Project Number: 2019-088
Client: Windward
Test Pit No.: TP-4
Date(s) Excavated: 4/30/2019
Excavation Method: Test Pit
Excavator Type: Tracked Excavator
Groundwater Level: Not encountered
Test Pit Backfill: Cuttings
Logged By ELW
Bucket Size: 4'
Excavating Contractor: Client
Sampling Method(s) Grab
Location McCormick Woods Drive SW and St. Andrews Drive SW
Surface Conditions: Ferns/Mixed Brush
Total Depth of Excavation: 12.5 feet bgs
Approximate Surface Elevation 379
Compaction Method Bucket tampU
SC
S S
ymbo
l
Tpsl
SM
SM
SP-SM
SW-SM
REMARKS AND OTHER TESTS
11% moisture
7% moisture
7% moisture, 9% fines
9% moisture, 11% fines
8% moisture, 12% fines
6% moisture
7% moisture
Gra
phic
Log
MATERIAL DESCRIPTION
6" topsoil
Reddish brown silty SAND, loose, moist
Becomes medium dense
Tan silty SAND with trace gravel, medium dense, moist, lightly cemented
Gray SAND with some silt and gravel, medium dense to dense, moist
Becomes dense, well cemented
Gray SAND with some silt and trace gravel, medium dense to dense, moist
Test pit terminated at 12.5'
Dep
th (
feet
)
0
5
10
15
Sam
ple
Num
ber
Sam
ple
Typ
e
Ele
vatio
n (f
eet)
379
374
369
364
Sheet 1 of 1
The Riley Group, Inc. 17522 Bothell Way NE, Bothell, WA 98011
Project Name: McCormick Woods
Project Number: 2019-088
Client: Windward
Test Pit No.: TP-5
Date(s) Excavated: 4/30/2019
Excavation Method: Test Pit
Excavator Type: Tracked Excavator
Groundwater Level: Not encountered
Test Pit Backfill: Cuttings
Logged By ELW
Bucket Size: 4'
Excavating Contractor: Client
Sampling Method(s) Grab
Location McCormick Woods Drive SW and St. Andrews Drive SW
Surface Conditions: Ferns/Mixed Brush/Moss
Total Depth of Excavation: 13.5 feet bgs
Approximate Surface Elevation 376
Compaction Method Bucket tampU
SC
S S
ymbo
l
Tpsl
SM
SM
SP-SM
SP-SM
REMARKS AND OTHER TESTS
10% moisture
8% moisture, 23% fines
7% moisture, 8% fines
7% moisture, 7% fines
6% moisture
5% moisture
Gra
phic
Log
MATERIAL DESCRIPTION
6" topsoil
Reddish brown silty SAND with trace gravel, loose, moist
Becomes medium dense
Gray silty SAND with some gravel, dense, moist (Glacial Till)
Moderately cemented
Gray SAND with some silt and trace gravel, dense, moist
Contains silty SAND interbeds
Gray SAND with some silt and gravel, dense, moist
Test pit terminated at 13.5'
Dep
th (
feet
)
0
5
10
15
Sam
ple
Num
ber
Sam
ple
Typ
e
Ele
vatio
n (f
eet)
376
371
366
361
Sheet 1 of 1
The Riley Group, Inc. 17522 Bothell Way NE, Bothell, WA 98011
Project Name: McCormick Woods
Project Number: 2019-088
Client: Windward
Test Pit No.: TP-6
Date(s) Excavated: 4/30/2019
Excavation Method: Test Pit
Excavator Type: Tracked Excavator
Groundwater Level: Not encountered
Test Pit Backfill: Cuttings
Logged By ELW
Bucket Size: 4'
Excavating Contractor: Client
Sampling Method(s) Grab
Location McCormick Woods Drive SW and St. Andrews Drive SW
Surface Conditions: Ferns/Moss
Total Depth of Excavation: 11.5 feet bgs
Approximate Surface Elevation 380
Compaction Method Bucket tampU
SC
S S
ymbo
l
Tpsl
SM
SP-SM
SP
SP-SM
REMARKS AND OTHER TESTS
17% moisture
8% moisture
7% moisture
20% moisture
10% moisture
Gra
phic
Log
MATERIAL DESCRIPTION
6" topsoil
Reddish brown silty SAND, loose, moist
Becomes tan, medium dense
Gray SAND with some silt and trace gravel, medium dense, moist
Lightly cemented
SAND with trace silt, medium dense, moist
Becomes wet
Light groundwater seepage
Gray SAND with some silt, dense, moist to wet, well cemented
Test pit terminated at 11.5'
Dep
th (
feet
)
0
5
10
15
Sam
ple
Num
ber
Sam
ple
Typ
e
Ele
vatio
n (f
eet)
380
375
370
365
Sheet 1 of 1
The Riley Group, Inc. 17522 Bothell Way NE, Bothell, WA 98011
Project Name: McCormick Woods
Project Number: 2019-088
Client: Windward
Test Pit No.: TP-7
Date(s) Excavated: 4/30/2019
Excavation Method: Test Pit
Excavator Type: Tracked Excavator
Groundwater Level: Not encountered
Test Pit Backfill: Cuttings
Logged By ELW
Bucket Size: 4'
Excavating Contractor: Client
Sampling Method(s) Grab
Location McCormick Woods Drive SW and St. Andrews Drive SW
Surface Conditions: Mixed Brush/Ferns/Moss
Total Depth of Excavation: 10 feet bgs
Approximate Surface Elevation 408
Compaction Method Bucket tampU
SC
S S
ymbo
l
Tpsl
SM
SP-SM
SM
REMARKS AND OTHER TESTS
6% moisture
9% moisture
Gra
phic
Log
MATERIAL DESCRIPTION
6" topsoil
Reddish brown silty SAND with some gravel, loose, moist
Becomes medium dense
Gray gravelly SAND with some silt, medium dense, moist
Gray silty SAND with some gravel, very dense, moist (Glacial Till)
Test pit terminated at 10'
Dep
th (
feet
)
0
5
10
15
Sam
ple
Num
ber
Sam
ple
Typ
e
Ele
vatio
n (f
eet)
408
403
398
393
Sheet 1 of 1
The Riley Group, Inc. 17522 Bothell Way NE, Bothell, WA 98011
Project Name: McCormick Woods
Project Number: 2019-088
Client: Windward
Test Pit No.: TP-8
Date(s) Excavated: 4/30/2019
Excavation Method: Test Pit
Excavator Type: Tracked Excavator
Groundwater Level: Not encountered
Test Pit Backfill: Cuttings
Logged By ELW
Bucket Size: 4'
Excavating Contractor: Client
Sampling Method(s) Grab
Location McCormick Woods Drive SW and St. Andrews Drive SW
Surface Conditions: Ferns/Mixed Brush
Total Depth of Excavation: 6 feet bgs
Approximate Surface Elevation 413
Compaction Method Bucket tampU
SC
S S
ymbo
l
Tpsl
SM
SP-SM
REMARKS AND OTHER TESTS
13% moisture
8% moisture, 7% fines
Gra
phic
Log
MATERIAL DESCRIPTION
6" topsoil
Reddish brown silty SAND with some gravel, loose, moist
Becomes medium dense
Gray SAND with some silt and gravel, dense, moist
Very dense, well cemented
Test pit terminated at 6'
Dep
th (
feet
)
0
5
10
15
Sam
ple
Num
ber
Sam
ple
Typ
e
Ele
vatio
n (f
eet)
413
408
403
398
Sheet 1 of 1
The Riley Group, Inc. 17522 Bothell Way NE, Bothell, WA 98011
Project Name: McCormick Woods
Project Number: 2019-088
Client: Windward
Key to Logs
US
CS
Sym
bol
REMARKS AND OTHER TESTSGra
phic
Log
MATERIAL DESCRIPTIONDep
th (
feet
)
Sam
ple
Num
ber
Sam
ple
Typ
e
Ele
vatio
n (f
eet)
1 2 3 4 5 6 7 8
COLUMN DESCRIPTIONS
1 Elevation (feet): Elevation (MSL, feet).2 Depth (feet): Depth in feet below the ground surface.3 Sample Type: Type of soil sample collected at the depth interval
shown.4 Sample Number: Sample identification number.
5 USCS Symbol: USCS symbol of the subsurface material.6 Graphic Log: Graphic depiction of the subsurface material
encountered.7 MATERIAL DESCRIPTION: Description of material encountered.
May include consistency, moisture, color, and other descriptivetext.
8 REMARKS AND OTHER TESTS: Comments and observationsregarding drilling or sampling made by driller or field personnel.
FIELD AND LABORATORY TEST ABBREVIATIONS
CHEM: Chemical tests to assess corrosivityCOMP: Compaction testCONS: One-dimensional consolidation testLL: Liquid Limit, percent
PI: Plasticity Index, percentSA: Sieve analysis (percent passing No. 200 Sieve)UC: Unconfined compressive strength test, Qu, in ksfWA: Wash sieve (percent passing No. 200 Sieve)
MATERIAL GRAPHIC SYMBOLS
Silty SAND (SM)
Poorly graded SAND (SP)
Poorly graded SAND with Silt (SP-SM)
Well graded SAND with Silt (SW-SM)
Topsoil
TYPICAL SAMPLER GRAPHIC SYMBOLS
Auger sampler
Bulk Sample
3-inch-OD California w/brass rings
CME Sampler
Grab Sample
2.5-inch-OD ModifiedCalifornia w/ brass liners
Pitcher Sample
2-inch-OD unlined splitspoon (SPT)
Shelby Tube (Thin-walled,fixed head)
OTHER GRAPHIC SYMBOLS
Water level (at time of drilling, ATD)
Water level (after waiting)
Minor change in material properties within astratum
Inferred/gradational contact between strata
? Queried contact between strata
GENERAL NOTES
1: Soil classifications are based on the Unified Soil Classification System. Descriptions and stratum lines are interpretive, and actual lithologic changes may begradual. Field descriptions may have been modified to reflect results of lab tests.2: Descriptions on these logs apply only at the specific boring locations and at the time the borings were advanced. They are not warranted to be representativeof subsurface conditions at other locations or times.
Sheet 1 of 1
The Riley Group, Inc. 17522 Bothell Way NE, Bothell, WA 98011