HomeMy WebLinkAboutMISCr
1945 S. h Street
FederalWayay,WA 98003
Schweikl & Associates, pile Phone: (253) 815 1700
Civil Engineering, Project iWanagement and Consulting Fax (752) 815-1701
November 16, 2006i1 .?
C17Y 0, ,7`
Drainage Report 1V0V 2 7 2o06
Project: SK - Preliminary Short Plat RECEWED
Overview
The following drainage report is provided to the City of Renton as part of the short plat
submittal process for the proposed SK Short Plat. The project lies in the East Lake
Washington -Renton drainage basin, which is part of the Cedar River/Lake Washington
watershed. The proposed project consists of three existing parcels, Lot 5 (Parcel No.
9526400050) of the Woodland Terrace Plat and two unplatted parcels (numbers
3343900985 and 3343900981) of the original C. D. Hillman's Lake Washington Garden
of Eden Division No. 4. Lot 5 fronts Camas Avenue N.E. at the southeast portion of a
cul-de-sac directly south of the N.E. 20ffi Street intersection. The other two parcels do not
front Camas Avenue or any other existing road, but are adjacent to Lot 5 immediately to
the south and southwest. Total area of the three parcels is 27,424 sf (.63 acres). The
current City of Renton zoning classification is R-8 Single -Family Residential. At present
all three parcels are owned by Larry and Sharon Samples, who reside in the existing
house on parcel 9526400050 (Lot 5). The other two parcels are landscaped and well
maintained by the Samples as part of their backyard. The surrounding land uses are all
established single-family residential plats, including Eden's Garden to the east, Powell's
I" Addition to the south and the remainder of Woodland Terrace to the north and west.
All utilities exist in the Camas Avenue ROW. An eight inch sanitary sewer stub extends
to the site and is currently capped. The Samples existing house has an onsite system
(septic tank and drain field). There also exists a ten foot utilities easement from the
Camas Avenue ROW, southward to the southern property boundary of the project. This
was originally intended to provide utility access to the two parcels that do not have
frontage on Camas Avenue.
The project proposes to short plat the three existing parcels into four single-family lots in
the R-S Residential zone and a 26 foot wide tract. The Samples existing house will
remain on what is to become the new Lot 1. Lots 2, 3 and 4 will be south of Lot l and
access Camas Avenue via a 20 foot wide private access drive across the tract. All four
lots will receive their utility services from Camas Avenue. Because concrete curbs,
gutters and sidewalks already exist along this section of Camas Avenue, no street
improvements are required by the City of Renton for this project.
The 2005 King County Surface Water Design Manual (KCSWDM) is the storm drainage
regulatory manual adopted by the City of Renton. In accordance with the 2005
KCSWDM, this project is subject to a small project drainage review. The Best
Management Practice (BMP) for controlling runoff from the impervious areas of the
project and the preferred method of the City of Renton is infiltration. This is providing
the onsite soils will permit it. A soils report was required by the City of Renton and was
performed by Goetech Consultants, Inc. This report confirms that the soils do support
infiltration and in fact have a calculated infiltration rate of I 1 inches per hour.
The King County Soils Survey Maps provided by the United States Department of
Agriculture Soil Conservation Service were reviewed to determine the soil characteristics
within the projects drainage basin. The survey maps indicate the soils of the basin belong
to the Indianola Series soils classification. More, specifically, they call it Indianola loamy
fine sand. Indianola soils are excessively drained soils that were formed under ancient
conifer forests in sandy, recessional, stratified glacial drift. The Indianola type soils in
the projects basin are characteristically very dark brown at the surface, dark grayish
brown to brown just under the surface, turning to dark yellowish brown around fifteen
inches below the surface, and finally ranging from light olive -brown at thirty inches to
pale olive at depths of sixty or more inches. The soil near the surface is loamy fine sand
and becomes just sand as depth increases. Common traits include dry, nonsticky,
nonplastic and slightly acid soil. Soil permeability is rapid, and available water capacity
is moderate. Runoff is slow to medium, and the erosion hazard is slight to moderate
Resource Review
The available resources were reviewed and a summary of the resultant research follows:
The project does not lie in either a FEMA flood plain, a Critical Drainage Area or an
adopted Basin Plan.
The King County Sensitive Areas portfolio was reviewed with the use of the iMap
website and there are no sensitive areas located onsite. There are no mapped sensitive
areas in the surrounding vicinity within a half mile radius. The closest being a sensitive
landslide area approximately one half mile to the northeast that parallels Honey Creek.
Two recorded Department of Natural Resources and Parks (DNRP) Drainage Complaints,
both to the southwest about one half mile from the project, were identified but have no
relevance to the project.
There are no reports of the existence of any wetlands on or in the project area.
Desi ng Plan
The conceptual storm drainage plan will be to use onsite infiltration. The existing
residence on Lot 1 will continue with its present method. New residences on Lots 2, 3
and 4 wilI have their individual roof drains collected and conveyed through a storm
drainage structure with a sump, to infiltration drywells. Sizing the drywells per section
C.2.2.4 of the KCSWDM-Appendix C, requires 90cf of volume for every 1000sf of roof
area, given the onsite medium sand soils. Designing for the house with the greatest roof
area, that being 1809sf on Lot 4, and assuming two drywells per house, leads to each
drywell servicing 905sf of roof area and needing a volume of at least 81.5cf. Using five
foot diameter drywells would then require a four foot two inch minimum depth of gravel
in each drywell.
Runoff from the new residences driveways and the proposed 20 foot wide access drive
will be conveyed by design as surface flow to a Type 1 Catch Basin and distributed to an
infiltration trench located under a portion of the access drive. Sizing of the trench was
done using the King County Runoff Time Series (KCRTS) Hydrologic Simulation Model.
For the projects proposed 5,406sf of impervious driveway area, the model calculated that
a trench 48'L x 3'W x 2.5'D, would be needed to infiltrate the predicted stormwater
without causing flooding.
Summary
In summary, the project proposes to install six infiltration drywells and one infiltration
trench to address the drainage requirements associated with the development of this site.
All design work was prepared in accordance with the 2005 KCSWDM, the accepted City
of Renton drainage design manual.
If you should have any questions or require additional information please do not hesitate
to contact me, Brant A. Schweikl, at (253) 815-1700, and I will do my best to assist you
in any way possible.
�N7
Schweikl & Associates, 1i 11c
Civil Engineering, Project Management and Consulting
SIC SHORT PLAT - 0 6 0 7 8
INFILTRATION TRENCH DESIGN DATA
Retention/Detention Facility
Type of Facility:
Facility Length:
Facility Width:
Facility Area:
Effective Storage Depth:
Stage 0 Elevation:
Storage Volume:
vertical Permeability:
Permeable Surfaces:
Riser Head:
Riser Diameter:
Top Notch Weir:
Outflow Rating Curve:
Gravel Infiltration Trench
48.00 ft
3.00 ft
144. sq. ft
2.50 ft
100.00 ft
108. cu. ft
5.40 min/in
Bottom
Bone
None
2.50 ft
4.00 inches
1945 S. 375th Street
Federal Wa)MA 98003
Phone:(253) 815-170D
Fax: (252) 815-1701
Stage
Elevation
Storage
Discharge
Percolation
(ft)
(ft)
(cu. ft)
(ac-ft)
(cfs)
(cfs)
0.00
100.00
0.
0.000
0.000
0.04
0.10
100.10
4.
0.000
0.000
0.04
0.20
100.20
9.
0.000
0.000
0.04
0.30
100.30
13.
0.000
0.000
0.04
0.40
100.40
17.
0.000
0-000
0.04
0.50
100.50
22.
0.000
0.000
0.04
0.60
100.60
26.
0.001
0.000
0.04
0.70
100.70
30.
0.001
0.000
0.04
0.80
100.80
35.
0.001
0.000
0.04
0.90
100.90
39.
0.001
0.000
0.04
1.00
101.00
43.
0.001
0.000
0.04
1.10
101.10
48.
0.001
0.000
0.04
1.20
101.20
52.
0.001
0.000
0.04
1.30
101.30
56.
0.001
0.000
0.04
1.40
101.40
61.
0.001
0.000
0.04
1.50
101.50
65.
0.001
0.000
0.04
1.60
101.60
69.
0-002
0.000
0.04
1.70
101.70
73.
0.002
0.000
0.04
1.80
101.80
78.
0.002
0.000
0.04
1.90
101.90
82.
0.002
0.000
0.04
2.00
102.00
86.
0.002
0.000
0.04
2.10
102.10
91,
0.002
0.000
0.04
2.20
102.20
95.
0.002
0.000
0.04
2.30
102.30
99.
0.002
0.000
0.04
2.40
102.40
104.
0.002
0.000
0.04
2.50
102.50
108.
0.002
0.000
0.04
2.60
102.60
108.
0.002
0.103
0.04
2.70
102.70
108.
0.002
0.188
0.04
2.80
102.80
108.
0.002
0.230
0.04
2.90
102.90
108.
0.002
0.266
0.04
3.00
103.00
108.
0.002
0.297
0.04
3.10
103.10
108.
0.002
0.326
0.04
3.20
103.20
108.
0.002
0.352
0.04
3.30
103.30
108.
0.002
0.376
0.04
3.40
103.40
108.
0.002
0.399
0.04
3.50
103.50
108.
0.002
0.420
0.04
3.60
103.60
108.
0.002
0.441
0.04
3.70
103.70
108.
0.002
0.460
0.04
3.80
103.80
108.
0.002
0.479
0.04
3.90
103.90
108.
0.002
0.497
0.04
4.00
104.00
108.
0.002
0.515
0.04
4.10
104.10
108.
0.002
0.532
0.04
4.20
104.20
108.
0.002
0.548
0.04
4.30
104.30
108.
0.002
0.564
0.04
4.40
104.40
108_
0.002
0.579
0.04
4.50
104.50
108_
0.002
0.594
0.04
Hyd
Inflow
Outflow
Peak
Storage
Target
Calc
Stage
Elev
(Cu-Ft)
(Ac-Ft)
1
0.05
0.06
0.00
1.16
101.16
50.
0.001
2
0.05
*******
0.00
2.32
102.32
100.
0.002
3
0.05
*******
0.00
0.68
100.68
29.
0.001
4
0.05
****x**
0.00
0.55
100.55
24.
0.001
5
0.04
*******
0.00
0.21
100.21
9.
0.000
6
0.04
*******
0.00
0.04
100.04
2.
0.000
7
0.03
*******
0.00
0.00
100.00
0.
0.000
8
0.03
*******
0.00
0.00
100.00
0.
0.000
----------------------------------
Route Time Series through Facility
Inflow Time Series File:dev.tsf
Outflow Time Series File:rdout.tsf
Inflow/Outflow Analysis
Peak Inflow Discharge:
0.050
CFS
at 0:00 on Oct 6 in 1981
Peak Outflow Discharge:
0.000
CFS
at 16:00 on Oct 6 in 1981
Peak Reservoir Stage:
2.32
Ft
Peak Reservoir Elev:
102.32
Ft
Peak Reservoir Storage:
100.
Cu-Ft
0.002
Ac-Ft
Flow Frequency Analysis
Time Series File:rdout_tsf
Project Location:Sea-Tac
---Annual Peak Flow Rates--- -----Flow Frequency Analysis-------
FlowRate Rank Time of Peak - - Peaks - - Rank Return Prob
(CFS) (CFS) (ft) Period
0.000 2 10/01/48 0:00 0.000 0.53 1 89.50 0.989
0.000
3
10/01/49
0:00
0.000
0.00
2
32.13
0.969
0.000
4
10/01/50
0:00
0.000
0.00
3
19.58
0.949
0.000
5
10/01/51
0:00
0.000
0.00
4
14.08
0.929
0.000
6
10/01/52
0:00
0.000
0.00
5
10.99
0.909
0.000
7
10/01/53
0:00
0.000
0.00
6
9.01
0.889
0.000
8
10/01/54
0:00
0.000
0.00
7
7.64
0.869
0.000
9
10/01/55
0:00
0.000
0.00
8
6.63
0.849
0.000
10
10/01/56
0:00
0.000
0.00
9
5.86
0.829
0.000
11
10/01/57
0:00
0.000
0.00
10
5.24
0.809
0.000
12
10/01/58
0:00
0.000
0.00
11
4.75
0.789
0.000
13
10/01/59
0:00
0.000
0.00
12
4.34
0.769
0.000
14
10/01/60
0:00
0.000
0.00
13
3.99
0.749
0.000
15
10/01/61
0:00
0.000
0.00
14
3.70
0.729
0.000
16
10/01/62
0:00
0.000
0.00
15
3.44
0.709
0.000
17
10/01/63
0:00
0.000
0.00
16
3.22
0.690
0.000
18
10/01/64
0:00
0.000
0.00
17
3.03
0.670
0.000
19
10/01/65
0:00
0.000
0.00
18
2.85
0.650
0.000
20
10/01/66
0:00
0.000
O.Oo
19
2.70
0.630
0.000
21
10/01/67
0:00
0.000
0.00
20
2.56
0.610
0.000
22
10/01/68
0:00
0.000
0.00
21
2.44
0.590
0.000
23
10/01/69
0:00
0.000
0.00
22
2.32
0.570
0.000
24
10/01/70
0:00
0.000
0.00
23
2.22
0.550
0.000
25
10/01/71
0:00
0.000
0.00
24
2.13
0.530
0.000
26
10/01/72
0:00
0.000
0.00
25
2.04
0.510
0.000
27
10/01/73
0:00
0.000
0.00
26
1.96
0.490
0.000
28
10/01/74
0:00
0.000
0.00
27
1.89
0.470
0.000
29
10/01/75
0:00
0.000
0.00
28
1.82
0.450
0.000
30
10/01/76
0:00
0.000
0.00
29
1.75
0.430
0.000
31
10/01/77
0:00
0.000
0.00
30
1.70
0.410
0.000
32
10/01/78
0:00
0.000
0.00
31
1.64
0.390
0.000
33
10/01/79
0:00
0.000
0.00
32
1.59
0.370
0.000
34
10/01/80
0:00
0.000
0.00
33
1.54
0.350
0.000
1
10/06/81
16:00
0.000
0.00
34
1.49
0.330
0.000
35
10/01/82
0:00
0.000
0.00
35
1.45
0.310
0.000
36
10/01/83
0:00
0.000
0.00
36
1.41
0.291
0.000
37
10/01/84
0:00
0.000
0.00
37
1.37
0.271
0.000
38
10/01/85
0:00
0.000
0.00
38
1.33
0.251
0.000
39
10/01/86
0:00
0.000
0.00
39
1.30
0.231
0.000
40
10/01/87
0:00
0.000
0.00
40
1.27
0.211
0.000
41
10/01/88
0:00
0.000
0.00
41
1.24
0.191
0.000
42
10/01/89
0:00
0.000
0.00
42
1.21
0.171
0.000
43
10/01/90
0:00
0.000
0.00
43
1.18
0.151
0.000
44
10/01/91
0:00
0.000
0.00
44
1.15
0.131
0.000
45
10/01/92
0:00
0.000
0.00
45
1.12
0.111
0.000
46
10/01/93
0:00
0.000
0.00
46
1.10
0.091
0.000
47
10/01/94
0:00
0.000
0.00
47
1.08
0.071
0.000
48
10/01/95
0:00
0.000
0.00
48
1.05
0.051
0.000
49
10/01/96
0:00
0.000
0.00
49
1.03
0.031
0.000
50
10/01/97
0:00
0.000
0.00
50
1.01
0.011
Schweikl & Associates, puc
Civil Engineering, Project Management and Consulting
SK SHORT PLAT-06078
INFILTRATION TRENCH INPUT DATA
1945 S. 375th Street
Federal Way,WA 98003
Phone:(253) 815-1700
Fax: (252)815-1701
NASchweikl & Associates,pile
Civil Engineering, Prr feet Management and Consulting
SK SHORT PLAT-06078
INFILTRATION TRENCH INPUT DATA
1945 S.375th Street
Federal Way,WA 98003
Phone:(253) 815-1700
Fax: (252)815-1701
Bottom length (F4 48.000
Bottom Width (IF#( 13.000
Bottom Area (Sq Fq E�
Effective Storage Depth before Dverflow WJ 2.5QQ
Elevation at 0 Stage (Ft] 1100.000
Vertical PermeabililyNinjln] 5.40Q
Riser Head (F4 2.500
Riser Diameter on) 4600
Number of Orifices
rTop of Riser----__�-- - --.- - --
t Notched Flat
MNT of Compliance Setup
Edit Test UYDROGRAPti Parameters
Define RISER Orifices and Notch
$AVE to TRENCH DW.rdf
Define how the Point of Compliance is Reached
Flow Frequency Analysis
Time Series File:dev.tsf
Project Location:Sea-Tac
---Annual
Peak
Flow Rates ---
Flaw Rate
Rank
Time of
Peak
(CFS)
0.031
21
2/16/49
21:00
0.045
6
3/03/50
16:00
0.030
25
2/09/51
2:00
0.027
35
10/15/51
13:00
0.025
43
3/24/53
15:00
0.029
28
12/19/53
19:00
0.031
22
11/25/54
2:00
0.031
23
11/18/55
15:00
0.034
15
12/09/56
14:00
0.032
20
12/25/57
16:00
LogPearson III Coefficients
Mean= -1.505 StdDev= 0.095
Skew 0.553
-----Flow
Frequency
Analysis -------
- - Peaks
- - Rank
Return
Prob
(CFS)
Period
0.050
1
89.50
0.989
0.050
2
32.13
0.969
0.047
3
19.58
0.949
0.047
4
14.08
0.929
0.045
5
10.99
0.909
0.045
6
9.01
0.889
0.043
7
7.64
0.869
0.041
8
6.63
0.849
0.038
9
5.86
0.829
0.038
10
5.24
0.809
0.024 47
0.030 27
0.027 39
0.027 36
0.026 42
0.030 26
0.028 34
0.027 37
0.041 8
0.045 5
0.025 44
0.027 38
0.027 40
0.037 11
0.024 46
0.028 32
0.036 14
0.025 45
0.031 24
0.043 7
0.038 9
0.034 16
0.037 12
0.050 1
0.038 10
0.028 31
0.027 41
0.032 18
0.047 3
0.023 49
0.029 29
0.050 2
0.047 4
0.028 33
0.020 50
0.023 48
0.029 30
0.033 17
0.032 19
0.036 13
Computed Peaks
Computed Peaks
Computed Peaks
Computed Peaks
Computed Peaks
Computed Peaks
Computed Peaks
Computed Peaks
11/03/58 17:00
11/20/59 5:00
2/14/61 21:00
11/22/61 2:00
12/15/62 2:00
12/31/63 23:00
12/21/64 4:00
1/05/66 16:00
11/13/66 19:00
8/24/68 16:00
12/03/68 16:00
1/13/70 22:00
12/05/70 9:00
12/08/71 18:00
1/13/73 2:00
11/28/73 9:00
12/26/74 23:00
11/13/75 19:00
8/26/77 2:00
9/17/78 2:00
9/08/79 15:00
12/14/79 21:00
11/21/80 11:00
10/06/81 0:00
10/28/82 16:00
1/03/84 1:00
6/06/85 22:00
1/18/86 16:00
10/26/86 0:00
11/11/87 0:00
8/21/89 17:00
1/09/90 6:00
11/24/90 8:00
1127/92 15:00
11/01/92 16:00
11/30/93 22:00
11/30/94 4:00
2/08/96 10:00
1/02/97 6:00
10/04/97 15:00
0.037
11
4.75
0.789
0.037
12
4.34
0.769
0.036
13
3.99
0.749
0.036
14
3.70
0.729
0.034
15
3.44
0.709
0.034
16
3.22
0.690
0.033
17
3.03
0.670
0.032
18
2.85
0.650
0.032
19
2.70
0.630
0.032
20
2.56
0.610
0.031
21
2.44
0.590
0.031
22
2.32
0.570
0.031
23
2.22
0.550
0.031
24
2.13
0.530
0.030
25
2.04
0.510
0.030
26
1.96
0.490
0.030
27
1.89
0.470
0.029
28
1.82
0.450
0.029
29
1.75
0.430
0.029
30
1.70
0.410
0.028
31
1.64
0.390
0.028
32
1.59
0.370
0.028
33
1.54
0.350
0.028
34
1.49
0.330
0.027
35
1.45
0.310
0.027
36
1.41
0.291
0.027
37
1.37
0.271
0.027
38
1.33
0.251
0.027
39
1.30
0.231
0.027
40
1.27
0.211
0.027
41
1.24
0.191
0.026
42
1.21
0.171
0.025
43
1.18
0.151
0.025
44
1.15
0.131
0.025
45
1.12
0.111
0.024
46
1.10
0.091
0.024
47
1.08
0.071
0.023
48
1.05
0.051
0.023
49
1.03
0.031
0.020
50
1.01
0.011
0.057
100.00
0.990
0.052
50.00
0.980
0.048
25.00
0.960
0.042
10.00
0.900
0.041
8.00
0.875
0.037
5.00
0.800
0.031
2.00
0.500
0.026
1.30
0.231
1945 S.375th Street
Federal Way,WA 98W3
AWASchweikl & Associates, puc Phone. (253) 815-1700
Civil Engineering, Project Management and Consulting Fax. (252) 815-1701
SK SHORT PLAT--06078
DEVELOPED BASIN INPUT DATA
Land Use Typo--- - -
Area Jacrez)::
Till Forest 19.800
Till Pasture
Till Grass
Outwash Forest
Outwash Pasture
Outwash Grass
Wetland
Impervious
Scale Factor
1' Hourly 15-minute
Data Type .--..... _ _ ........... .
r Reduced
�' Hfstori
Compute Total Area
Reduced is 0 years simulating Historic record
I
Till Forest)
0.00 acres)
Till Pasture
0.011 acres)
Till Grass
0.110 acres)
Outwash Forest
0.00 acres]
Outwash Pasture
0.00 acres]
Outwash Gress
0.00 acres)
Wetland
0.00 acres)
Impervious)
0.12 acres
Total
0.12 acres
Scale Factor : 1.00 Hourly Historic
Timc Series_ DEY
Compute Time Series
Modify User Input
T File for computed Time Series [.TSF]
CEOTECH
CONSULTANTS, INC_
LDK Construction, Inc.
PO Box 2764
Renton, Washington 98056
Attention: Larry Kupferer
Subject: Transmittal letter — Geotechnical Engineering Study
Proposed Residential Short Plat
1824 Camas Avenue Northeast
Renton, Washington
Dear Mr. Kupferer:
13256 Northeast 20th Street, Suite 16
Bellevue, Washington 98005
(425) 747-5618 FAX (425) 747-8561
November 10, 2006
Cr Fy o� RENTOn, JN 06366
NOV 2 7 2006
RECE11JED
via facsimile (425) 255-6416
We are pleased to present this geotechnical engineering report for the proposed residential short
plat to be constructed in Renton. The scope of our services consisted of exploring site surface and
subsurface conditions, and then developing this report to provide recommendations for general
earthwork, design criteria for foundations and retaining walls, and infiltration considerations. This
work was authorized by your acceptance of our proposal, P-7166, dated September 29, 2006.
The attached report contains a discussion of the study and our recommendations. Please contact
us if there are any questions regarding this report, or for further assistance during the design and
construction phases of this project.
Respectfully submitted,
GEOTECH CONSULTANTS, INC.
Marc R. McGinnis, P.E.
Principal
cc: Schweikl & Associates
via facsimile (25. j 815-1701
ZJMIMRM: jyb
GEOTECHNICAL ENGINEERING STUDY
Proposed Residential Short Plat
1824 Camas Avenue Northeast
Renton, Washington
This report presents the findings and recommendations of our geotechnical engineering study for
the site of the proposed short plat to be located in Renton.
We were provided with a preliminary site plan and a topographic map. Schweikl & Associates,
PLLC developed these plans. We understand that the development will consist of dividing the
property into four lots, regrading the southem portion . of the site and building three new single-
family residences. From the plan, the new construction would require relatively small cuts and fills,
on the order of 1 to 2 feet. The existing house to the north (#1824), adjacent to Camas Avenue
Northeast is to remain. We also understand that you propose to develop several infiltration
trenches to disperse of stormwater on -site.
If the scope of the project changes from what we have described above, we should be provided
with revised plans in order to determine if modifications to the recommendations and conclusions of
this report are warranted_
SITE CONDITIONS
SURFACE
The Vicinity Map, Plate 1, illustrates the general location of the site. The property is located near
the southern extent of Camas Avenue Northeast in Renton. The site is irregularly shaped, with
approximately 50 feet of frontage along the Camas Avenue cul-de-sac. The property site widens
out to the south and covers nearly 27,500 square feet. The northern end of the site is relatively flat,
then a moderate slope begins to rise up to the south and southeast beyond the existing house and
detached garage. The house is one-story, and the existing garage has been set into the slope.
The southern slope remains landscaped but mostly undeveloped, except for a small shed in the
southwest comer of the site. A short gravel driveway connects Camas Avenue Northeast to a
small concrete pad in front of the garage. There are also several small rockeries on the site.
The site is surrounded on all sides by single family residences, except for the portion in the north
that connects to Camas Avenue Northeast. There is a large rockery east of the site that ranges in
height from 12 feet tall in the north end of the property down to 2 feet at the south end. The grade
on the site is lower than the property to the east.
r
We observed no signs of slope instability on, or adjacent to, the subject property.
SUBSURFACE
The subsurface conditions were explored by excavating test pits at the approximate locations
shown on the Site Exploration Plan, Plate 2. Our exploration program was based on the proposed
construction, anticipated subsurface conditions and those encountered during exploration, and the
scope of work outlined in our proposal.
LDK Construction JN 06366
November 10, 2006 Page 2
The test pits were excavated on October 3, 2006 with a rubber -tired backhoe provided by LDK
Construction. A geotechnical engineer from our staff observed the excavation process, logged the
test pits, and obtained representative samples of the soil encountered. "Grab" samples of selected
subsurface soil were collected from the backhoe bucket. The Test Pit togs are attached to this
report as Plates 3 through 5.
Soil Conditions
We excavated five test pits at various locations around the property. in the test pits we
encountered loose slightly silty sands overlying medium -dense sand with occasional
gravels. The depth to the medium -dense sands varied across the site, from 2.5 to 4.5 feet,
and became dense with depth. The excavation depth was limited to a maximum of 6 feet by
the small size of the backhoe. Caving conditions were encountered in the upper, loose,
soils.
No obstructions were revealed by our explorations. However, debris, buried utilities, and old
foundation and slab elements are commonly encountered on sites that have had previous
development.
Groundwater Conditions
No groundwater seepage was observed during excavation. The test pits were left open for
only a short time period and it was only possible to reach a depth of 6 feet. It should be
noted that groundwater levels vary seasonally with rainfall and other factors.
The stratification lines on the logs represent the approximate boundaries between soil types at the
exploration locations. The actual transition between soil types may be gradual, and subsurface
conditions can vary between exploration locations. The logs provide specific subsurface
information only at the locations tested. The relative densities and moisture descriptions indicated
on the test pit logs are interpretive descriptions based on the conditions observed during
excavation.
The compaction of backfill was not in the scope of our services. Loose soil will therefore be found
in the area of the test pits. If this presents a problem, the backfill will need to be removed and
replaced with structural fill during construction.
CONCLUSIONS AND RECOMMENDATIONS
GENERAL
THIS SECTION CONTAINS A SUMMARY OF OUR STUDY AND FINDINGS FOR THE PURPOSES OF A
GENERAL OVERVIEW ONLY. MORE SPECIFIC RECOMMENDATIONS AND CONCLUSIONS ARE
CONTAINED IN THE REMAINDER OF THIS REPORT. ANY PARTY RELYING ON THIS REPORT SHOULD
READ THE ENTIRE DOCUMENT.
The test pits conducted for this study encountered loose slightly silty sand overlying medium -dense
sand that became dense with depth. It is our professional opinion that the proposed single family
residences can bear on the medium -dense to dense sand underlying the loose, slightly silty sands.
LDK Construction JN 06366
November 10, 2006 Page 3
It will be important that any soils loosened by the teeth of the backhoe bucket be removed from
foundation subgrades before concrete is poured.
Excavation must not undermine adjacent existing structures, such as the rockery to the east. In
general, temporary cuts should not extend below a 2:1 (Hodzontal:Vertical) zone sloping from
footings, wails or rockeries, unless shoring is provided.
We also conducted infiltration tests in Test Pits 1 and 2 by the method outlined in King County's
Surface Water Design Manual (SWDM). Each test was conducted at 5.5 to 6 feet, near the bottom
depth of the proposed infiltration facilities. After a period of soaking's; three trials were performed
in each of the two test pits. From the data obtained from the infiltration tests and what we
understand about the planned facilities' geometry, we recommend a design infiltration rate of no
more than 11 inches per hour. Under the King County SWDM, a geometry correction would need
to be applied to this value once the preliminary system geometry has been determined. The
performance of any subsurface infiltration system will degrade over time, due to clogging of the
surrounding soil with silt and debris carried in by the runoff. The effective life of an infiltration
system can be prolonged by frequent cleaning of gutters and surface drains.
Storm detention/retention facilities and other utilities are often installed below, or near, structures.
The walls of storm vaults must be designed as either cantilever or restrained retaining walls, as
appropriate. Wall pressures for the expected soil conditions are presented in the permanent
foundation and retaining walls section of this report. It is important that the portion of the structure
above the permanent detained water level be backfilled with free -draining soil, as recommended for
retaining walls. Should drainage not be provided, the walls must be designed for hydrostatic forces
acting on the outside of the structure. The backfiil for all underground structures must be
compacted in lifts according to the criteria in the pervious section of this report. Trenches for
underground structures and utilities should not cross a line extending downwards from a new or
existing footing at an inclination of (1:1) (Horizontal:Vertical), or a line extending downwards from a
property line at an inclination of 1:1 (H:V). We should be consulted if these excavation zones will
be exceeded for installation of storm facilities or other utilities.
The erosion control measures needed during the site development will depend heavily on the
weather conditions that are encountered. We anticipate that a silt fence will be needed around the
downslope sides of any cleared areas. Rocked construction access roads should be extended into
the site to reduce the amount of soil or mud carried off the property by trucks and equipment.
Wherever possible, these roads should follow the alignment of planned pavements, and trucks
should not be allowed to drive off of the rock -covered areas. Existing catch basins in, and
immediately downslope of, the planned work areas should be protected with pre -manufactured silt
socks. Cut slopes and soil stockpiles should be covered with plastic during wet weather. Following
rough grading, it may be necessary to mulch or hydroseed bare areas that will not be immediately
covered with landscaping or an impervious surface.
The drainage and/or waterproofing recommendations presented in this report are intended only to
prevent active seepage from flowing through concrete walls or slabs. Even in the absence of active
seepage into and beneath structures, water vapor can migrate through walls, slabs, and floors from
the surrounding soil, and can even be transmitted from slabs and foundation walls due to the
concrete curing process. Water vapor also results from occupant uses, such as cooking and
bathing. Excessive water vapor trapped within structures can result in a variety of undesirable
conditions, including, but not limited to, moisture problems with flooring systems, excessively moist
air within occupied areas, and the growth of molds, fungi, and other biological organisms that may
be harmful to the health of the occupants. The designer or architect must consider the potential
LDK Construction JN 06366
November 10, 2006 Page 4
vapor sources and likely occupant uses, and provide sufficient ventilation, either passive or
mechanical, to prevent a build up of excessive water vapor within the planned structure.
Geotech Consultants, Inc. should be allowed to review the final development plans to verify that the
recommendations presented in this report are adequately addressed in the design. Such a plan
review would be additional work beyond the current scope of work for this study, and it may include
revisions to our recommendations to accommodate site, development, and geotechnical
constraints that become more evident during the review process.
We recommend including this report, in its entirety, in the project contract documents_ This report
should also be provided to any future property owners so they will be aware of our findings and
recommendations.
SEISMIC CONSIDERATIONS
In accordance with Table 1615.1.1 of the 2003 International Building Code (IBC), the site soil pro-
file within 100 feet of the ground surface is best represented by Soil Profile Type C (Very Dense
Soil. The site soils are not susceptible to seismic liquefaction because of their dense nature and
the absence of near -surface groundwater.
CONVENTIONAL FOUNDATIONS
The proposed structures can be supported on conventional continuous and spread footings Dearing
on undisturbed, native sand, or on structural fill placed above this competent native soil. See the
section entitled General Earthwork and Structural Fill for recommendations regarding the
placement and compaction of structural fill beneath structures. Adequate compaction of structural
fill should be verified with frequent density testing during fill placement. Prior to placing structural fill
beneath foundations, the excavation should be observed by the geotechnical engineer to document
that adequate bearing soils have been exposed. We recommend that continuous and individual
spread footings have minimum widths of 16 and 24 inches, respectively. Exterior footings should
also be bottomed at least 18 inches below the lowest adjacent finish ground surface for protection
against frost and erosion. The local building codes should be reviewed to determine if different
footing widths or embedment depths are required. Footing subgrades must be cleaned of loose or
disturbed soil prior to pouring concrete. Depending upon site and equipment constraints, this may
require removing the disturbed soil by hand.
Depending on the final site grades, overexcavation may be required below the footings to expose
competent native soil. Unless lean concrete is used to fill an overexcavated hole, the
overexcavation must be at least as wide at the bottom as the sum of the depth of the
overexcavation and the footing width. For example, an overexcavation extending 2 feet below the
bottom of a 2-foot-wide footing must be at least 4 feet wide at the base of the excavation. If lean
concrete is used, the overexcavation need only extend 6 inches beyond the edges of the footing_
An allowable bearing pressure of 2,500 pounds per square foot (psf) is appropriate for footings
supported on competent native soil. A one-third increase in this design bearing pressure may be
used when considering short-term wind or seismic loads. For the above design criteria, it is
anticipated that the total post -construction settlement of footings founded on competent native soil,
or on structural fill up to 5 feet in thickness, will be about one inch, with differential settlements on
the order of half an inch in a distance of 50 feet along a continuous footing with a uniform load.
LDK Construction JN 06366
November 10, 2006 Page 5
Lateral loads due to wind or seismic forces may be resisted by friction between the foundation and
the bearing soil, or by passive earth pressure acting on the vertical, embedded portions of the
foundation. For the latter condition, the foundation must be either poured directly against relatively
level, undisturbed soil or be surrounded by level structural fill. We recommend using the following
ultimate values for the foundation's resistance to lateral loading:
Coefficient of Friction 0.a0
Passive Earth Pressure 300 pcf
Where. (1) pcf is pounds per cubic foot, and (11) passive earth
pressure is computed using the equivalard fluid density.
If the ground in front of a foundation is loose or sloping, the passive earth pressure given above will
not be appropriate. We recommend maintaining a safety factor of at least 1.5 for the foundation's
resistance to lateral loading, when using the above ultimate values.
PERMANENT FOUNDATION AND RETAINING WALLS
Retaining walls backfilled on only one side should be designed to resist the lateral earth pressures
imposed by the soil they retain. The following recommended parameters are for walls that restrain
level backfill:
= MW I
Active Earth Pressure
35 pcf
Passive Earth Pressure
300 pcf
Coefficient of Friction
0.50
Soil Unit Weight
130 pcf
Where: (1) pcf is pounds per tunic foot, and (ii) active and passive
earth pressures am computed using the equivalent fluid
pressures.
' For a restrained wall that cannot deflect at least 0.002 times tts
height, a uniform lateral pressure equal to 10 pat times the height
of the wall should be added to the above active equivalent fluid
pressure.
i
The values given above are to be used to design permanent foundation and retaining walls only.
The passive pressure given is appropriate for the depth of level structural fill placed in front of a
retaining or foundation wall only. The values for friction and passive resistance are ultimate values
and do not include a safety factor. We recommend a safety factor of at least 1.5 for overtuming
and sliding, when using the above values to design the walls. Restrained wall soil parameters
should be utilized for a distance of 1.5 times the wall height from comers or bends in the walls.
This is intended to reduce the amount of cracking that can occur where a wall is restrained by a
corner.
LDK Construction JN 06366
November 10, 2006 Page 6
The design values given above do not include the effects of any hydrostatic pressures behind the
walls and assume that no surcharges, such as those caused by slopes, vehicles, or adjacent
foundations will be exerted on the walls_ If these conditions exist, those pressures should be added
to the above lateral soil pressures. Where sloping backfill is desired behind the walls, we will need
to be given the wall dimensions and the slope of the backfill in order to provide the appropriate
design earth pressures. The surcharge due to traffic loads behind a wall can typically be
accounted for by adding a uniform pressure equal to 2 feet multiplied by the above active fluid
density.
Heavy construction equipment should not be operated behind retaining and foundation wails within
a distance equal to the height of a wall, unless the walls are designed for the additional lateral
pressures resulting from the equipment. The wall design criteria assume that the backfill will be
well -compacted in lifts no thicker than 12 inches. The compaction of backfill near the walls should
be accomplished with hand -operated equipment to prevent the walls from being overloaded by the
higher soil forces that occur during compaction.
Retaining Wall Backfill and Waterproofiny
Backfill placed behind retaining or foundation walls should be coarse, free -draining
structural fill containing no organics. This backfill should contain no more than 5 percent silt
or clay particles and have no gravel greater than 4 inches in diameter. The percentage of
particles passing the No. 4 sieve should be between 25 and 70 percent. If the native sand
is used as backfill, a drainage composite similar to Miradrain 6000 should be placed against
the backfilled retaining walls. The drainage composites should be hydraulically connected
to the foundation drain system. Free -draining backfill or gravel should be used for the entire
width of the backfill where seepage is encountered. For increased protection, drainage
composites should be placed along cut slope faces, and the walls should be backfilled
entirely with free -draining soil
The purpose of these backfill requirements is to ensure that the design criteria for a
retaining wall are not exceeded because of a build-up of hydrostatic pressure behind the
wall_ The top 12 to 18 inches of the backfill should consist .of a compacted, relatively
impermeable soil or topsoil, or the surface should be paved. The ground surface must also
slope away from backfilled walls to reduce the potential for surface water to percolate into
the backfill. The section entitled General Earthwork and Structural Fill contains
recommendations regarding the placement and compaction of structural fill behind retaining
and foundation walls.
The above recommendations are not intended to waterproof below -grade walls, or to
prevent the formation of mold, mildew or fungi in interior spaces. Over time, the
performance of subsurface drainage systems can degrade, subsurface groundwater flow
patterns can change, and utilities can break or develop leaks. Therefore, waterproofing
should be provided where future seepage through the walls is not acceptable. This typically
includes limiting cold -joints and wall penetrations, and using bentonite panels or membranes
on the outside of the walls. There are a variety of different waterproofing materials and
systems, which should be installed by an experienced contractor familiar with the
anticipated construction and subsurface conditions. Applying a thin coat of asphalt emulsion
to the outside face of a wall is not considered waterproofing, and will only help to reduce
moisture generated from water vapor or capillary action from seeping through the concrete.
As with any project, adequate ventilation of basement and crawl space areas is important to
LDK Construction
November 10, 2006
JN 06366
Page 7
important to prevent a build up of water vapor that is commonly transmitted through
concrete walls from the surrounding soil, even when seepage is not present. This is
appropriate even when waterproofing is applied to the outside of foundation and retaining
walls. We recommend that you contact a specialty consultant if detailed recommendations
or specifications related to waterproofing design, or minimizing the potential for infestations
of mold and mildew are desired.
The General, Slabs -On -Grade, and Drainage Considerations sections should be
reviewed for additional recommendations related to the control of groundwater and excess
water vapor for the anticipated construction,
SLABS -ON -GRADE
The building floors can be constructed as slabs -on -grade atop the native sand, or on structural fill.
The subgrade soil must be in a firm, non -yielding condition at the time of slab construction or
underslab fill placement. Any soft areas encountered should be excavated and replaced with
select, imported structural fill.
Even where the exposed soils appear dry, water vapor will tend to naturally migrate upward through
the soil to the new constructed space above it. All interior slabs -on -grade must be underlain by a
capillary break or drainage layer consisting of a minimum 4-inch thickness of gravel or crushed
rock that has a fines content (percent passing the No. 200 sieve) of less than 3 percent and a sand
content (percent passing the No. 4 sieve) of no more than 10 percent. As noted by the American
Concrete Institute (ACI) in the Guides for Concrete Floor and Slab Structures, proper moisture
protection is desirable immediately below any on -grade slab that will be covered by tile, wood,
carpet, impermeable floor coverings, or any moisture -sensitive equipment or products. ACI also
notes that vapor retarders, such as 6-mil plastic sheeting, are typically used. A vapor retarder is
defined as a material with a permeance of less than 0.3 US perms per square foot (psf) per hour,
as determined by ASTM E 96. It is possible that concrete admixtures may meet this specification,
although the manufacturers of the admixtures should be consulted. Where plastic sheeting is used
under slabs, joints should overlap by at least 6 inches and be sealed with adhesive tape. The
sheeting should extend to the foundation walls for maximum vapor protection. If no potential for
vapor passage through the slab is desired, a vapor barrier should be used. A vapor barrier, as
defined by ACI, is a product with a water transmission rate of 0.00 perms per square foot per hour
when tested in accordance with ASTM E 96. Reinforced membranes having sealed overlaps can
meet this requirement.
ROCKERIES
We anticipate that rockeries may be used in the site development. A rockery is not intended to
function as an engineered structure to resist lateral earth pressures, as a retaining wall would do_
The primary function of a rockery is to cover the exposed, excavated surface and thereby retard the
erosion process. We recommend limiting rockeries to an exposed height of 8 feet and placing
them against only dense, competent, native soil. The lower 12 inches of any rockery must be
embedded below the finish grade that will exist at the face of the rockery. Rockeries that are taller
than 8 feet, or that are placed in front of loose soil or in areas of compacted fill will require
additional engineering. Special design will also be required for rockeries that would support
surcharges from vehicles or other load -bearing elements.
LDK Construction JN 06366
November 10, 2006 Page 8
The construction of rockeries is, to a large extent, an art not entirely controllable by engineering
methods and standards. It is imperative that rockeries, if used, are constructed with care and in a
proper manner by an experienced contractor with proven ability in rockery construction_ The
rockeries should be constructed with hard, sound, durable rock in accordance with accepted local
practice and standards. In general, the lowest two rows of rocks should have a minimum depth (as
measured perpendicular to the rockery's face) of 1I3 of the rockery's height. Soft rock, or rock with
a significant number of fractures or inclusions, should not be used, in order to limit the amount of
maintenance and repair needed over time. Provisions for maintenance, such as access to the
rockery, should be considered in the design. In general, we recommend that rockeries have a
minimum dimension of one-third the height of the slope cut above them.
EXCAVATIONS AND SLOPES
Excavation slopes should not exceed the limits specified in local, state, and national government
safety regulations. Temporary cuts to a depth of about 4 feet may be attempted vertically in
unsaturated soil, if there are no indications of slope instability. The upper soils are loose and prone
to caving, vertical cuts in this sand may not maintain stability for long periods of time. Vertical cuts
should not be made near property boundaries, or existing utilities and structures. Based upon
Washington Administrative Code (WAC) 296, Part N, the sail at the subject site would generally be
classified as Type A. Therefore, temporary cut slopes greater than 4 feet in height should not be
excavated at an inclination steeper than 1:1 (Horiaontal:Vertical), extending continuously between
the top and the bottom of a cut.
The above -recommended temporary slope inclination is based on the conditions exposed in our
explorations, and on what has been successful at other sites with similar soil conditions. It is
possible that variations in soil and groundwater conditions will require modifications to the
inclination at which temporary slopes can stand. Temporary cuts are those that will remain
unsupported for a relatively short duration to allow for the construction of foundations, retaining
walls, or utilities. Temporary cut slopes should be protected with plastic sheeting during wet
weather. It is also important that surface water be directed away from temporary slope cuts. The
cut slopes should also be backfilled or retained as soon as possible to reduce the potential for
instability. Please note that sand can cave suddenly and without warning. Excavation, foundation,
and utility contractors should be made especially aware of this potential danger. These
recommendations may need to be modified if the area near the potential cuts has been disturbed in
the past by utility installation, or if settlement -sensitive utilities are located nearby.
All permanent cuts into native soil should be inclined no steeper than 2:1 (H:V). Water should not
be allowed to flow uncontrolled over the top of any temporary or permanent slope. All permanently
exposed slopes should be seeded with an appropriate species of vegetation to reduce erosion and
improve the stability of the surfsciai layer of soil.
DRAINAGE CONSIDERATIONS
Foundation drains should be used where (1) crawl spaces or basements will be below a structure,
(2) a slab is below the outside grade, or (3) the outside grade does not slope downward from a
building. Drains should also be placed at the base of all earth -retaining walls. These drains should
be surrounded by at least 6 inches of 1-inch-minus, washed rock and then wrapped in non -woven,
geotextile filter fabric (Mirafi 140N, Supac 4NP, or similar material)_ At its highest point, a
perforated pipe invert should be at least 6 inches below the bottom of a slab floor or the level of a
LDK Construction A 06366
November 10, 2006 Page 9
crawl space, and it should be sloped for drainage. All roof and surface water drains must be kept
separate from the foundation drain system. A typical drain detail is attached to this report as Plate
fi. For the best long-term performance, perforated PVC pipe is recommended for all subsurface
drains.
Drainage inside the building's footprint should also be provided where (1) a crawl space will slope
or be lower than the surrounding ground surface, (2) an excavation encounters significant seepage,
or (3) an excavation for a building will be close to the expected high groundwater elevations. We
can provide recommendations for interior drains, should they become necessary, during excavation
and foundation construction_
As a minimum, a vapor retarder, as defined in the Slabs -On -Grade section, should be provided in
any crawl space area to limit the transmission of water vapor from the undertying soils. Also, an
outlet drain is recommended for all crawl spaces to prevent a build up of any water that may bypass
the footing drains_
No groundwater was observed during our field work. If seepage is encountered in an excavation, it
should be drained from the site by directing it through drainage ditches, perforated pipe, or French
drains, or by pumping it from sumps interconnected by shallow connector trenches at the bottom of
the excavation.
The excavation and site should be graded so that surface water is directed off the site and away
from the tops of slopes. Water should not be allowed to stand in any area where foundations,
slabs, or pavements are to be constructed. Final site grading in areas adjacent to buildings should
slope away at least 2 percent, except where the area is paved. Surface drains should be provided
where necessary to prevent ponding of water behind foundation or retaining walls. Additionally, a
drainage swale should be provided upslope of the buildings to intercept surface nun -off and direct i#
into the storm drains. Water from roof, storm water, and foundation drains should not be
discharged onto slopes; it should be tightlined to a suitable outfall located away from any slopes.
,�►fir 1��T� i�it,'1: lflft�l�dti:�l'l�i►1�7- LS�L�J
All building and pavement areas should be stripped of surface vegetation, topsoil, organic soil, and
other deleterious material. The stripped or removed materials should not be mixed with any
materials to be used as structural fill, but they could be used in non-structural areas, such as
landscape beds.
Structural fill is defined as any fill, including utility backfill, placed under, or close to, a building,
behind permanent retaining or foundation walls, or in other areas where the underlying soil needs
to support loads. All structural fill should be placed in horizontal lifts with a moisture content at, or
near, the optimum moOsture content. The optimum moisture content is that moisture content that
results in the greatest compacted dry density. The moisture content of fill is very important and
must be closely controlled during the filling and compaction process.
The allowable thickness of the fill lift will depend on the material type selected, the compaction
equipment used, and the number of passes made to compact the lift. The loose lift thickness
should not exceed 12 inches. We recommend testing the fill as it is placed. If the fill is not
sufficiently compacted, it can be recompacted before another lift is placed_ This eliminates the
need to remove the fill to achieve the required compaction. The following table presents
recommended relative compactions for structural fill:
LDK Construction
November 10, 2006
Beneath footings, slabs 95%
or walkways
Filled slopes and behind 90% LA
retaining walls
95% for upper 12 inches of
Beneath pavements subgrade; 90% below that
level
Where. Minimum Relative compaction is the ratio, expressed in
Percentages, of the compacted dry density to the maximum dry
density, as determined in accordance with AM Test
Designation D 1567-91 (Modified Proctor).
JN 06366
Page 10
Structural fill that will be placed in wet weather should consist of a coarse, granular soil with a silt or
clay content of no more than 5 percent. The percentage of particles passing the No. 200 sieve
should be measured from that portion of soil passing the three -quarter -inch sieve.
LIMITATIONS
The conclusions and recommendations contained in this report are based on site conditions as they
existed at the time of our exploration and assume that the soil and groundwater conditions
encountered in the test pits are representative of subsurface conditions on the site. If the
subsurface conditions encountered during construction are significantly different from those
observed in our explorations, we should be advised at once so that we can review these conditions
and reconsider our recommendations where necessary. Unanticipated soil conditions are
commonly encountered on construction sites and cannot be fully anticipated by merely taking soil
samples in test pits. Subsurface conditions can also vary between exploration locations. Such
unexpected conditions frequently require making additional expenditures to attain a properly
constructed project. It is recommended that the owner consider providing a contingency fund to
accommodate such potential extra costs and risks. This is a standard recommendation for all
projects.
This report has been prepared for the exclusive use of LDK Construction, and its representatives,
for specific application to this project and site. Our recommendations and conclusions are based
on observed site materials, and selective laboratory testing and engineering analyses. Our
conclusions and recommendations are professional opinions derived in accordance with current
standards of practice within the scope of our services and within budget and time constraints. No
warranty is expressed or implied. The scope of our services does not include services related to
construction safety precautions, and 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. Our services also do not include assessing or minimizing the
potential for biological hazards, such as mold, bacteria, mildew and fungi in either the existing or
proposed site development.
LDK Construction
November 10, 2006
ADDITIONAL SERVICES
J N 06366
Page 11
In addition to reviewing the final plans, Geotech Consultants, Inc. should be retained to provide
geotechnical consultation, testing, and observation services during construction. This is to confirm
that subsurface conditions are consistent with those indicated by our exploration, to evaluate
whether earthwork and foundation construction activities comply with the general intent. of the
recommendations presented in this report, and to provide suggestions for design changes in the
event subsurface conditions differ from those anticipated prior to the start of construction.
However, our work would not include the supervision or direction of the actual work of the
contractor and its employees or agents. Also, job and site safety, and dimensional measurements,
will be the responsibility of the contractor.
During the construction phase, we will provide geotechnical observation and testing services when
requested by you or your representatives. Please be aware that we can only document site work
we actually observe. It is still the responsibility of your contractor or on -site construction team to
verify that our recommendations are being followed, whether we are present at the site or not.
The following plates are attached to complete this report:
Plate 1 Vicinity Map
Plate 2 Site Plan
Plates 3 - 5 Test Pit togs
Plate 6 Typical Footing Drain Detail
LDK Construction
November 10, 2006
J N 06366
Page 12
We appreciate the opportunity to be of service on this project. If you have any questions, or if we
may be of further service, please do not hesitate to contact us.
Respectfully submitted,
GEOTECH CONSULTANTS, INC.
Zack J. Munstermann
Geotechnical Engineer
Marc R. McGinnis, P.E.
Principal
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GEOTECH
CONSULTANTS, INC.
Vicinity Map
1824 Camas Ave NE
Renton, WA
E-mdTP4
1
TP I
0
Existing House
=6 8 9k]
Property Line
0 -- Approximate test pit location
GEOTECH
CONSULTANTS, INC.
� TP 2
TP 5 0
SITE PLAN
1824 Camas Ave NE
Renton, WA
Job No: I Date: a e:
06366 Nov2006 No Scale 2
5
10
15
5
10
15
�o��o-�5CP
TEST PIT I
Description
Crushed gravel over
Brown, slightly silty SAND, medium- to fine-agrained, organics, moist,
SP medium -dense
* Test Pit was terminated at 6 feet on October 3, 2006.
* No groundwater seepage was observed during excavation.
* Caving was observed from 0 to 2.5 feet
during excavation.
TEST PIT 2
Grass over
Description
Brown, slightly silty SAND with organics, medium- to fine-grained, moist,
loose
- becomes medium -dense, no silt, no organics
- becomes gray, dense at bottom of hole
* Test Pit was terminated at 5.5 feet on October 3, 2006.
* No groundwater seepage was observed during excavation.
* No caving was observed during excavation.
GEUTECH
CONSULTANTS, INC.
TEST PIT LUGS
1824 Camas Avenue NE
Renton, Washington
=AN&De e: Lagged 6r: ► ub:
Nov. 2006 ZJM 3
CP z
E
10
15
\
� l
5
10
15
TEST PIT 3
Description
crass over
SP
Brown, slightly silty SAND, organics, medium- to fine-grained, moist, loose
- no silt, no organics, becomes gray, medium -dense
* Test Pit was terminated at 4 feet on October 3, 2006.
* No groundwater seepage was observed during excavation.
* Caving was observed in the upper 2 feet during excavation.
TEST PIT 4
Description
Brown, slightly silty SAND with organics, medium- to fine-grained, moist,
loose
- no organics, no silt, becomes medium -dense, gray
* Test Pit was terminated at 4 feet on October 3, 2006.
* No groundwater seepage was observed during excavation.
No caving was observed during excavation.
GEOTECH
CONSULTANTS, INC.
TEST PIT LOGS
1824 Camas Avenue NE
Renton, Washington
rub n n t�,r by: �rere:
06366 i ov. 2DOG ZJM 3
5
10
15
TEST PIT 5
Description
Brown, slightly silty SAND with organics, medium- to fine-grained, moist,
loose
- becomes light gray, medium -dense, no silt, no organics
- becomes gray
* Test Pit was terminated at 6 feet on October 3, 2006.
* No groundwater seepage was observed during excavation.
* No staving was observed during excavation.
GEOTECH
CONSULTANT'S, INC.
TEST PIT LOGS
1824 Camas Avenue NE
Renton, Washington
Job NM_ nan:; I19990d er. PWO:
06366 1 Nov.20D6 I ZJM 1 3
Slope backlfiill away from
foundation. Provide surface
drains where necessary.
Washed Roc
(718" min. size)
4"
Tightline Roof Drain
(Do not connect to footing drain)
Backfill
(See text for
requirements)
Nonwoven Geotextile _.
Filter Fabric
p Possible Slab
I +x •Q.��.Q •�.' •D.'Q:O••D•' Q.b.-G1.D�.Q.'�1:q�.Q,.O
�'POv.a�'}POc.;�06°•�0a
glZiOo °s 3_ a o_.ro.4 »b. .o . •ro. �° .,.b.°:o . .ti.s.o .
e e o ev blFl10 x
4" Perforated Hard PVC Pipe
(Invert at least 8 inches below
slab or crawl space. Slope to
drain to appropriate outfall.
Place holes downward.)
Vapor Retarder/Barrier and
Capillary Break/Drainage Layer
(Refer to Report text)
NOTES:
(1) In crawl spaces, provide an outlet drain to prevent buildup of water that
bypasses the perimeter footing drains.
(2) Refer to report text for additional drainage, waterproofing, and slab considerations.
GEOTECH
CONSULTANT'S, INC.
FOOTING DRAIN DETAIL
1 824 Camas Ave NE
Renton, WA
FOW63M616
Date: ca ate:
Nov. 2006 Not to Scale 6