HomeMy WebLinkAboutGeoTech Review for BLD2007-01934 - GEO General - 3/14/2008 Mason County Requirements
For Geotechnical Reports
Mason county code 8.52.140 section 5(E)
] 1)A discussion of general geologic conditions,specific soil types,ground water
conditions,the upslope geomorphology and location of upland waterbodies and
wetlands, and history of landslide activity in the vicinity
0 2)A site plan which identifies the important development and geologic features.
Note: No site plan was attached to the Geotechnical Report we received.
] 3) Locations and logs of exploratory holes or probes.
4) The area of the proposed development,the boundaries of the hazard,and associated
buffers and setbacks shall be delineated(top,both sides, and toe)on a geologic map
of the site.
Note: No geologic maps were attached to the Geotechnical Report we received.
5) A minimum of one cross section at a scale which adequately depicts the
subsurface profile,and which incorporates the details of proposed grade changes.
Note: No cross sections were attached to the Geotechnical Report we received.
6) A description and results of slope stability analyses performed for both static and
seismic loading conditions. Analysis should examine worst case failures. The analysis
should include the Simplified Bishop's Method of Circles. The minimum static safety
factor is 1.5,the minimum seismic safety factor is 1.1 and the quasi-static
analysis coefficients should be a value of 0.15.
Note: The results of the slope stability analysis were not clearly defined.
X❑ 7) Appropriate restrictions on placement of drainage features,septic drain fields and
compacted fills and footings, including recommended buffers and setbacks from the
landslide hazard areas.
X❑ 8) Recommendations for the preparation of a detailed clearing and grading plan which
specifically identifies vegetation to be removed,a schedule for vegetation removal and
replanting,and the method of vegetation removal.
i
j X❑ 9) Recommendations for the preparation of a detailed temporary erosion control plan which
identifies the specific mitigating measures to be implemented during construction to
protect the slope from erosion, landslides and harmful construction methods.
i
X❑ 10) An analysis of both on-site and off-site impacts of the proposed development.
] 11) Specifications of final development conditions such as,vegetative management,
drainage,erosion control,and buffer widths.
112) Recommendations for the preparation of structural mitigation or details of other
proposed mitigation.
13)A site map drawn to scale showing the property boundaries,scale, north arrow,and the
location and nature of existing and proposed development on the site.
Note: A site map was not attached to the Geotechnical Report we received.
I'
I'• General Note: Figures 2 and 3 were referenced in the Geotechnical Report but were not
attached to the report that we received dated 12/15/2005.
'�h
A LK A I CONSULTANTS, LLC.
Environmental Engineering • Geotechnical Engineering • Wetland Consulting
March 14, 2008 ; , - Job# 10115
Mason County Department of Community Development
P.O.Box 279 T ,
Shelton,WA 98584
Attn: Kell McAboy
Geotechnical Report Review
Permit#BLD 2007-01934
Applicant: Payson
At your request, we have reviewed a Geotechnical Report for the above referenced permit. The report was
prepared by Geotechnical Testing Laboratory (GTL) dated December 15, 2005 with an update letter that
addressed ALKAI's previous concerns. The report was signed and stamped by Harold Parks, L. G., L.E.G.
(License #827 p t� P Y and the update letter was signed and stamped b Curtis Dean Cushman, Senior Engineering
Geologist(License#2439).
The report with the additional information in the update letter contains the information required in the Mason
! County Code, Landslide Hazardous Areas 8.52.140.E. Further, it is ALKAI's opinion that the report was
prepared to at least the typical standard of practice for geotechnical engineering in this area.
!
We therefore recommend that Mason County accept the geotechnical report.
i
Should you have any questions or concerns, or if we may be of additional assistance, please call our office at
(360)613-2407 or contact us by e-mail at Jim@alkai.net.
Sincerely,
K Co` 0
Donald Balmer,L.G. James Harding,E.I.T
C Senior Hydrogeologist - ' Project Engineer
e Hydruc j,ogist1950
w
sed Ga°�0���.
Donald K Balmer
� lYaB'
Attachments: Geo Tech Work Order
Update letter from GTL
Mason County Requirements Checklist
I
i
9465 Provost Road NW, Suite 202 • Silverdale,Washington 98383 • (360) 613-2407 • Fax: (360) 613-2408
I
i
ALKAI CONSULTANTS, LLC.
Environmental Engineering • Geotechnical Engineering • Wetland Consulting
February 1, 2008 Job# 10115
Mason County Department of Community Development
P.O.Box 279
Shelton,WA 98584
Attn: Kell McAboy 4 f
Geotechnical Report Review
Permit#BLD 2007-01934
Applicant: Payson
At your request, we have reviewed a Geotechnical Report for the above referenced permit. The report was
prepared by Geotechnical Testing Laboratory (GTL) dated December 15, 2005. The report was signed and
stamped by Harold Parks,L.G.,L.E.G. (License#827).
In general, the report contains the information required in the Mason County Code, Landslide Hazardous Areas
8.52.140.E.5 with the following exceptions.
1. Paragraph (2)of the referenced code requires a site plan which identifies the important development and
geologic features. There was no site plan received.
2. Paragraph (4) of the referenced code requires that the area of the proposed development, the boundaries
of the hazard, and associated buffers and setbacks shall be delineated (top, both sides, and toe) on a
geologic map of the site. There was no geologic map received.
3. Paragraph(5)of the referenced code requires a minimum of one cross section at a scale which adequately
depicts the subsurface profile, and which incorporates the details of proposed grade changes. There were
no cross sections received.
4. Paragraph(6)of the referenced code indicates requirements for a description and results of slope stability
analyses performed for both static and seismic loading conditions. Analysis should examine worst case
failures. The analysis should include the Simplified Bishop's Method of Circles. The minimum static
safety factor is 1.5, the minimum seismic safety factor is 1.1 and the quasi-static analysis coefficients
should be a value of 0.15. The results of the slope stability analysis were not clearly defined.
5. Paragraph (13) of the referenced code requires a site map drawn to scale showing the property
boundaries, scale, north arrow, and the location and nature of existing and proposed development on the
site. No site maps were received.
We recommend that Mason County request that Geotechnical Testing Laboratory address the exceptions listed
above in the following manner:
1. Provide the appropriate site plan, geologic map, cross section, and site map that display the requirements
listed above.
9465 Provost Road NW, Suite 202 •Silverdale,Washington 98383 • (360) 613-2407 • Fax: (360) 613-2408
Project No. 10115-001
Mason County Review
February 1,2008
Page No.2
2. Provide the required calculated safety factors clearly labeled.
Should you have any questions or concerns, or if we may be of additional assistance, please call our office at
(360)613-2407 or contact us by e-mail at Jim@alkai.net.
Sincerely,
Donald Balmer,L.G. James Harding,EIT
Senior Hydrogeologist ' Project Engineer
�. HyrjrogF=oi�:q;st �..
'C� 1950 •��
41/o8- Sed Geo��
Donald K. Balmer
Attachments: Geo Tech Work Order
Geotechnical Report by GTL
Mason County Requirements Checklist
9465 Provost Road NW, Suite 202 •Silverdale,Washington 98383 • (360) 613-2407• Fax: (360) 613-2408
A
4
GROTECHNIL TESTING LABORATORY
STEVE PAYSON
3301 W.Hwy 16 �-
PORT ORCHARD,WASHINGTON 98367
f a ,) f '
RE: GEOTECHNICAL REPORT r_�a
SITE INFORMATION: EAST SHERWOOD ROAD
ALLYN,WASHINGTON
PARCEL: 122307590032
ORIGINAL REPORT DATE: 12/15/2005
Mr. Payson:
This is an update letter for the geotechnical report done for the above mentioned parcel dated December 15,
2005. The most recent resources ordinance for landslide hazard critical areas released by Mason County on
December 26, 2006 requires additional information to be addressed in the geotechnical reports. This letter
serves as an addendum to the geotechnical report submitted by us on December 15, 2005.
The letter dated February 1, 2008 from Alkai Consultants, LLC has raised few concerns about the geotechnical
report done for parcel mentioned above. We would like to address those concerns in the following points.
1. The original site plan was submitted along with the report. However, a revised site plan has been
attached with this letter.
2. Revised site plan addresses the concerns about the setbacks and the required buffer zone. Please refer to
the site plan attached.
3. Please refer to Figure 4 attached. Figure 4 depicts the cross section as indicated in the site plan figure 2.
4. Please refer to the attached slope models.
5. Point 1 addresses this issue.
Mason County requires a minimum of 1.10 factor of safety for the slopes for dynamic modeling (Seismic
q
Coefficients= 0.15) and a factor of safety of 1.5 for static modeling (Seismic Coefficients = 0.0). Our models
indicate that the dynamic factor of safety is 1.30 and the static factor of safety is 1.70 for slope A for the above
mentioned parcel. Please note the difference in the dynamic safety factors from the original report dated
December 15, 2005. The difference is explainable due to the use of lower seismic coefficient value i. e. 0.15 as
opposed to used value of 0.3 in the original model.
1001 l Blomberg Street SW,Olympia, WA 98512 1
Phone#: (360)754-4612 Fax#: (360)754-4848
i
w • '
The slope models exhibit that the adjacent slopes at your property are not susceptible to deep seated failure.
However, we have designated the slope as a landslide hazard area and the boundary of landslide hazard area has
been delineated in the attached site plan. We have also proposed a 50 foot vegetative buffer for the landslide
hazard area as shown in the site plan. The necessary setbacks are included in the site plan (Figure 2) as well as
the cross section (Figure 4). We recommend the area designated as a vegetation buffer zone be revegetated and
the buffer be maintained.
If you have any further questions, please call the number listed below.
Respectfully Submitted,
GEOTECHNICAL TESTING LABORATORY
i
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jCurtis D Cushman
Senior Engineering Geologist
I
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Wa h�A
Cc. Kell McAboy, Mason County Planning Department - s"-
ring ciaolo�st �
�s 2439
d GOO
URTIS DEAN CUSNMAN
Attachments: Site Plan
Cross Section
Slope Models
10011 Blomberg Street SW,Olympia, WA 98512 2
Phone#: (360)754-4612 Fax#: (360)754-4848
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East Sherwood Rd. Job 10115 1
Mason County Requirements
For Geotechnical Reports
Mason county code 8.52.140 section 5(E)
XO 1) A discussion of general geologic conditions,specific soil types, ground water
conditions,the upslope geomorphology and location of upland waterbodies and
wetlands, and history of landslide activity in the vicinity
] 2) A site plan which identifies the important development and geologic features.
] 3) Locations and logs of exploratory holes or probes.
] 4) The area of the proposed development,the boundaries of the hazard, and associated
buffers and setbacks shall be delineated(top, both sides, and toe)on a geologic map
of the site.
X❑ 5) A minimum of one cross section at a scale which adequately depicts the
subsurface profile, and which incorporates the details of proposed grade changes.
X❑ 6) A description and results of slope stability analyses performed for both static and
seismic loading conditions. Analysis should examine worst case failures. The analysis
should include the Simplified Bishop's Method of Circles. The minimum static safety
factor is 1.5,the minimum seismic safety factor is 1.1 and the quasi-static
analysis coefficients should be a value of 0.15.
X❑ 7) Appropriate restrictions on placement of drainage features, septic drain fields and
compacted fills and footings, including recommended buffers and setbacks from the
landslide hazard areas.
X❑ 8) Recommendations for the preparation of a detailed clearing and grading plan which
specifically identifies vegetation to be removed, a schedule for vegetation removal and
replanting, and the method of vegetation removal.
X❑ 9) Recommendations for the preparation of a detailed temporary erosion control plan which
identifies the specific mitigating measures to be implemented during construction to
protect the slope from erosion, landslides and harmful construction methods.
X❑ 10) An analysis of both on-site and off-site impacts of the proposed development.
X❑ 11) Specifications of final development conditions such as,vegetative management,
drainage,erosion control,and buffer widths.
112) Recommendations for the preparation of structural mitigation or details of other
proposed mitigation.
] 13) A site map drawn to scale showing the property boundaries, scale, north arrow, and the
location and nature of existing and proposed development on the site.
GEOTECHNICAL TESTING LABORATORY
UPDATE ADDENDUM
STEVE PAYSON
SUNDANCE SOLAR
3301 STATE HIGHWAY 16 W
PORT ORCHARD,WASHINGTON 98367-7505
RE: SITE ADDENDUM
SITE INFORMATION: 560 EAST SHERWOOD ROAD
ALLYN,WASHINGTON 98524
GPS LOCATION: N470 22' 3.3"W1220 50' 55.9"
PARCEL#: 12230750034 9100 1>
REPORT DATE: 12-10-2007
Dear Mr.Payson:
As per your request, Curtis D. Cushman with Wes Parnell came to the above site on 12-05-2007 to look at the
site for which a Geotechnical report was written on 12/15/2005 for the Charles Somers Company. This
addendum is a report of our visit to the site. Current conditions were compared to those in the original report.
As can be seen in the included photos, the site has been generally cleared of vegetation at the building location
and below it, and a building pad has been cut into the soil, with the hogged material pushed out to fill and
flatten the pad. The trailer serves as scale.
Fig 1. Building cut,looking north.
The trailer in Fig. 1 is sitting on a smaller cut that extends past the building cut to the right(east).
As to be expected,there is some slumping in the building cut.
10011 Blomberg Street SW,Olympia, WA 98512 1
Phone#: (360)754-4612 Fax#: (360)754-4848
GEOTECHNICAL TESTING LABORATORY
Fig 2. Building pad looking north of east from road.
rz:
Fig 3. Building pad and cut looking roughly west
Attempts were made to retain the soil as can be seen in Fig 4, below.
Fig 4. Looking roughly east,down slope.
10011 Blomberg Street SW,Olympia, WA 98512 2
Phone#: (360) 754-4612 Fax#: (360)754-4848
r
GEOTECHNICAL TESTING STING LABORATORY
The lobes of material represent some of the pushed-out material, and it appears to be locally seeded to secure it.
The silt-fence, visible at the base of the slope, was intact. No water was seen flowing on-or immediately off-
site.
If you require any further geotechnical work please feel free to contact us work. If you have any questions
contact me at the laboratory number, or call my cell at(360)292-2536.
Respectfully Submitted,
�@ o� was h�� GEOTECHNICAL TESTING LABORATORY
�o
7
ng ri a ist Curtis D Cushman
2439 ��� Senior Engineering Geologist
deed Geo\o
URTIS DEAN CUSNMAN
J
10011 Blomberg Street SW,Olympia, WA 98512 3
Phone#: (360)7544612 Fax#: (360)754-4848
� GEOTECHNICAL REPORT
EAST SHERwooD ROAD
ALLYN, WASHINGTON
' PAxCEL122307590034
' PREPARED FOR
THE CHARI,ES SOMERS COMPANY
' BY
1 GEOTECfINICAL TESTING LABORATORY
OLYMPIA, WASHINGTON
1
1
' DECEMBER 15, 2005
1 GEOTECHNICAL TESTING LABORATORY
1
CONTACT INFORMATION
PREPARER INFORMATION
GTL PROJECT NUMBER: 05-2251-11
t ADDRESS: 10011 BLOMBERG STREET SOUTHWEST
OLYMPIA,WASHINGTON 98512
' TELEPHONE: (360)754-4611
' FACSIMILE: (360)754-4848
' EMAIL ADDRESS: GEOTESTLAB@COMCAST.NET
1 CLIENT INFORMATION
CLIENT: THE CHARLES SOMERS COMPANY
' OFFICE TELEPHONE: (360)275-5413
FACSIMILE: (360)275-0770
' BILLING ADDRESS: P.O.Box 414
GRAPEVIEW,WASHINGTON 98546
SITE ADDRESS: EAST SHERWOOD ROAD
ALLYN,WASHINGTON 98524
PARCEL NUMBER: 122307590034
' GPS LOCATION: N470 22'3.3" W1220 50 55.9"
' 10011 Blomberg Street SW,Olympia,WA 98512 2
Phone#: (360)754-4612 Fax#: (360) 754-4848
1
1 GEOTECHNICAL TESTING LABORATORY
' SCOPE OF UNDERSTANDING
THE CHARLES SOMERS COMPANY
P.O.Box 414
' GRAPEVIEW,WASHINGTON 98546
RE: GEOTECHNICAL REPORT
t EAST SHERWOOD ROAD
ALLYN,WASHINGTON 98524
PARCEL 122307590034
' N470 22'3.3" W 1220 50 55.9"
Gentlemen:
As per your request, we have conducted a soils exploration, foundation evaluation, and slope stability analysis for
the above-mentioned parcel. The results of this investigation,together with our recommendations,are to be found
' in the following report. We have provided three copies for your review and distribution.
During our exploration, a soil boring was advanced at the proposed building location to determine the underlying
geology. Soil samples were collected and submitted for laboratory testing. The data has been carefully analyzed
to determine soils bearing capacities and footing embedment depths. The results of the exploration and analysis
indicate that conventional spread and continuous wall footings appear to be the most suitable type of foundation
t for the support of the proposed structures. Some variability was encountered in comparing the soil profiles of the
site. Net allowable soil pressures, embedment depth, and total expected settlements have been presented for the
site later in the report.
Often, because of design and construction details that occur on a project, questions arise concerning soil
conditions. We would be pleased to continue our role as geotechnical consultants during the project
implementation. We appreciate this opportunity to be of service to you and we look forward to working with you
' in the future. If you have any questions concerning the above items, the procedures used, or if we can be of any
further assistance please call us at the phone number listed below.
1 e�
Respectfully Submitted,
Wash� r GEOTECHNICAL TESTING LABORATORY
' y o�
' Harold Parks,L.G., L.E.G.
��cE� 151 tiy� Senior Engineering Geologist
82
' esed Geo�o
' HAROLD PARKS
' 10011 Blomberg Street SW,Olympia, WA 98512 3
Phone#: (360)754-4612 Fax#: (360)754-4848
1
GrEOTECHNIGAE TESTING LABORATORY
TABLE OF CONTENTS
CONTACT INFORMATION...................................................................................................................... 2
SCOPE OF UNDERSTANDING................................................................................................................ 3
TABLEOF CONTENTS.............................................................................................................................4
1 INTRODUCTION........................................................................................................................................ 5
SITECONDITIONS.................................................................................................................................... 6
SurfaceConditions................................................................................................................................... 6
SiteGeology............................................................................................................................................. 6
SiteSoils................................................................................................................................................... 7
SubsurfaceExplorations............................................ ............................................................................ 8
SubsurfaceConditions.............................................................................................................................. 8
SlopeStability.......................................................................................................................................... 9
CONCLUSIONS AND RECOMMENDATIONS..................................................................................... 10
General ................................................................................................................................................... 10
LANDSLIDE—EROSION HAZARD AREA........................................................................................... 10
Classification.......................................................................................................................................... 10
SlopeStability........................................................................................................................................ 11
BuildingSetback............................................................................................................... ................. 12
Seismic—Liquefaction Hazard............................................................................................................... 14
' Erosion Control ...................................................................................................................................... 15
EARTHWORK.......................................................................................................................................... 15
SitePreparation ...................................................................................................................................... 15
' Structural Fill.......................................................................................................................................... 15
Suitability of Onsite Soils as Fill............................................................................................................ 16
Cutand Fill Slopes................................................................................................................................. 16
Foundation Support. 16
FloorSlab Support.................................................................................................................................. 17
' Retaining Walls...................................................................................................................................... 17
Slope Inclination: Equivalent Fluid Pressure 18
Retaining Wall Alternatives................................................................................................................... 18
' Site Drainage.......................................................................................................................................... 19
SepticImpact.......................................................................................................... ...............................20
LIMITATIONS ..........................................................................................................................................20
' BORING AND LABORATORY RESULTS .................... 21
Boring1, 5 feet.......................................................................................................................................22
Boring 1, 10 feet................................................... .......23
' Boring 1, 15 feet.....................................................................................................................................24
Boring1, 16 feet.....................................................................................................................................25
FIGURE 1 VICINITY MAP......................................................................................................................26
' 10011 Blomberg Street SW,Olympia, WA 98512 4
Phone#: (360)754-4612 Fax#: (360)754-4848
1
GEOTECHNIC L TESTING LABORATORY
INTRODUCTION
This report summarizes the results of our geotechnical consulting services for the proposed single-family
residence to be located along the east-facing hillside overlooking the Sherwood Creek valley, approximately 1.7
miles southwest of Allyn, Washington. The location of the site is shown relative to the surrounding area on the
Vicinity Map, Figure 1.
<o
f
' discussions with n ourexplorations and review of the site.
Our understanding of the project �s based on our discuss o s you and
We understand that the parcel is to be developed as a single-family residence. The site will be accessed by a
' driveway from East Sherwood Road. In general, grading will consist of the excavation of the foundation and
footings. The approximate layout of the site is shown on the Site Plan, Figure 2.
' The site slopes toward the east from the proposed building location. The steepest slope measured onsite exceeds
100 percent. Therefore, Mason County requires that a geotechnical report be prepared in accordance with the
Critical Areas Ordinance.
The purpose of our services is to evaluate the surface and subsurface conditions at the site as a basis for providing
geotechnical recommendations and design criteria for the project and to satisfy the requirements of the Mason
' County Critical Areas Ordinance. Geotechnical Testing Laboratory is therefore providing geologic and
hydrogeologic services for the project. Specifically, our scope of services for this project will include the
following:
' 1. Review the available geologic,hydrogeologic,and geotechnical data for the site area.
2. Conduct a geologic reconnaissance of the site area and surrounding vicinity.
3. Investigate shallow subsurface conditions at the site by observing the exposed soil and reviewing
' published well logs.
4. Evaluate the landslide and erosion hazards at the site per the Mason County Critical Areas Ordinance
regulations.
1 5. Provide geotechnical recommendations for site grading including site preparation, subgrade preparation,
fill placement criteria (including hillside grading), temporary and permanent cut and fill slopes, drainage
and erosion control measures.
' 10011 Blomberg Street SW,Olympia,WA 98512 5
Phone#: (3.60)7544612 Fax#: (360)754-4848
1
GE,OTECHNICAL TESTING LABORATORY
SITE CONDITIONS
' SURFACE CONDITIONS
The proposed building site is located in an area of sparse residential development in the Puget Sound glacial
upland overlooking the Sherwood Creek valley. The site has eastern exposure. We conducted a reconnaissance
of the site area on November 29 and drilled on December 7,2005. Site elevations range from approximately 70 to
240 feet.
' The building area of the site has vegetation common to
the Northwest. The vegetation includes fir, alder, pine,
' hemlock, and madrone trees as well as Scot's broom,
Oregon grape, mullein, holly, sword ferns, bracken
ferns,huckleberry,salal, blackberry, and grasses.
' At the time of the site visit, we observed no evidence of
active surface erosion. No evidence of deep-seated
slope instability was observed onsite. Sloughing and
sliding was observed in the eastern portion of the site.
Surface water flow was not observed onsite at the time
of our reconnaissance. The general topography of the
site area indicates that drainage flows toward the east
from the proposed building location.
SITE GEOLOGY
' The site is generally situated within the Puget Sound glacial upland. The existing topography, as well as the
surFcial and shallow subsurface soils in the area, are the result of the most recent Vashon stade (stage) of the
Fraser glaciation that occurred between about 8,000 and 12,000 years ago, and weathering and erosion that has
occurred since. A description of the surficial soils is included in the"Site Soils" section of this report. In general,
the soils are composed of Vashon glacial till material.
' The Geologic Map of Washington — Northwest Quadrant (2002) has mapped the site geology as glacial till
deposits(Qgt)of continental glacial origin. The report reads:
Till— Unsorted, unstratified, highly compacted mixture of clay, silt, sand, gravel, and boulders
' deposited by glacial ice; may contain interbedded stratified sand, silt, and gravel. Includes part
of the Yashon Drift undivided.
' The Geologic Map of Southeastern Mason County, Washington,
USGS Water-Supply Bulletin 29 by Noble and Molenaar (1970)
describes the site as advance outwash. The advance outwash (Qva)
is described as:
Gravel and sand, with some silt and clay at base.
Unconsolidated and generally is in discontinuous strata.
Underlies till in most of area and up to 200 feet thick.
' Yields moderate to large quantities (20-800 gp.m) of water
where gravel and coarser sand facies below water table.
10011 Blomberg Street SW,Olympia,WA 99512 6
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1
1 GEOTECHNIOAL TESTING LABORATORY
1 SITE SOILS
' The Soil Survey of Mason County, Washington, USDA Soil Conservation Service (1960) has mapped the
site soils as Everett gravelly loamy sand, 5 to 15 percent slopes (Eh). The survey describes the soil as
follows:
' This is the most extensive Everett soil. In undisturbed forests 1 to 2 inches of very dark grayish-
brown material, a mixture of needles, leaves, twigs, cones, moss, and roots, covers the surface.
The surface soil is loose, single-grained, pale-brown, gravelly sandy loam, 6 to 8 inches thick.
The upper 2 or 3 inches normally contains aggregates that are slightly hard and redder than the
others in the layer. To depths ranging from 18 to 24 inches, the subsoil is loose, single grained,
light yellowish-brown gravelly sandy loam or gravelly loamy sand. The amount of shot
decreases with depth, in the lower part only a few shot occur. The subsoil grades to a
substratum of poorly assorted,predominantly yellowish-brown sand, gravel, and cobbly material
that is extremely loose and porous. However, in places, this material will stand in banks. The
color of this material is largely determined by the gravel, course sand, and cobbles which are
' olive gray, pale olive, yellowish brown, light brownish gray, gray, and dark gray. Many of the
cobbles, as well as much of the gravel, are faintly to moderately stained by iron. The amount of
gravel ranges from about 20 percent to 50 percent in the subsoil to as much as 80 percent in the
' substratum. The soil is medium to strongly acid and becomes less acid with depth.
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' 10011 Blomberg Street SW,Olympia, WA 98512 7
Phone#: (360)754-4612 Fax#: (360) 754-4848
1
i VEOTECHNICAL TESTING LABoRA ORY
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SUBSURFACE EXPLORATIONS
Subsurface conditions at the site were evaluated by observing the exposed building site soil, advancing a soil
boring, and reviewing available well logs. Groundwater was not encountered while drilling. Depth to static water
in the onsite well is at 205 feet below the ground surface. Depth to competent soil is approximately 12 inches
throughout the proposed building location.
' SUBSURFACE CONDITIONS
In general, undisturbed dense Everett gravelly sandy loam was observed in the undisturbed portions of the site.
' Glacial till was not encountered to a depth of 20 feet. Groundwater was not observed or encountered.
Groundwater seepage was not observed onsite. Based on the site topography and the nature of the near-surface
soil, seasonally perched groundwater conditions may not be expected during periods of extended wet weather.
i
' 10011 Blomberg Street SW,Olympia, WA 98512 8
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' SLOPE STABILITY
Slopes in excess of 40 percent were observed onsite. Since slopes of 40 percent or greater with 10 feet or more of
vertical relief occur on portions of the site, Mason County requires that a geologic hazards report be completed
according to the Critical Areas Ordinance.
The near-surface soils are in a dense to very dense condition except at the ground surface. The surficial soils are
generally in a medium dense condition.
In general,the undisturbed native soils of the site consist of a mixture of variable amounts of sand, silt,and gravel.
These soil materials are in a dense condition except where they have been disturbed by weathering activity. These
soils are generally stable relative to deep-seated failure. No evidence of deep-seated landslide activity or
significant erosion was observed onsite at the time of our investigation.
' Weathering, erosion, and the resultant sloughing
and shallow landsliding are natural processes that
can affect steep slope areas. Instability of this
nature is typically confined to the upper weathered
' or disturbed zone, which has been disturbed and
has a lower strength. Raveling, sloughing, and
sliding were observed along the eastern slope.
Significant weathering typically occurs in the
upper 2 to 3 feet and is the result of oxidation,root
' penetration, wet/dry cycles, and freeze/thaw
cycles. Erosion in steep slope areas such as this
can be reduced by encouraging vegetation and
1 discouraging runoff from the steep slopes. Erosion
control recommendations for the sloping areas are
provided in the "Erosion Control" section of this Landslide Along Eastern Slope
report.
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' Landslide Offsite to North Along Road Cut
10011 Blomberg Street SW,Olympia, WA 98512 9
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1 GEOTECHNICAL TESTING LABORATORY
1
' CONCLUSIONS AND RECOMMENDATIONS
GENERAL
' Based on the results of our site reconnaissance, subsurface observations, and our experience in the area, it is our
opinion that the site is suitable for the proposed project. The slope is stable relative to deep-seated instability and
will not be affected by the proposed structure. The proposed structure will not undermine adjacent slopes. Proper
drainage control measures will reduce or eliminate the potential for erosion in this area and improve slope
stability. The hazards of the landslide area can be overcome in such a manner as to prevent harm to property and
public health and safety,and the project will cause no significant environmental impact.
In general, the Everett soils observed at the site may be suitable for use as structural fill material. Saturated soil
conditions are not associated with these soils during or following extended periods of rainfall. However, to
reduce grading time and construction costs, we recommend that earthwork be undertaken during favorable
' weather conditions.
1 Conventional construction equipment may be utilized for work at the site. Conventional spread footings may be
utilized at the site for support of the structure. We do recommend that roof and footing drains be installed for the
structure with conventional spread footings. A vapor barrier is recommended for all slab-on-grades.
Pertinent conclusions and geotechnical recommendations regarding the design and construction of the proposed
single-family residence are presented below.
ram., "'"
Proposed Building Location
1
' LANDSLIDE — EROSION HAZARD AREA
CLASSIFICATION
tThe Mason County Critical Areas Ordinance (17.01.100)defines a landslide hazard area as one containing slopes
equal to or greater than 40 percent with more than a 10-foot vertical relief. The eastern slope is in excess of 40
percent and the vertical relief is in excess of 10 feet. Based on this,this site does meet the technical criteria of a
landslide hazard.
10011 1 Blomberg Street SW,Olympia, WA 98512 10
Phone#: (360)754-4612 Fax#: (360) 754-4848
1 �
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GEOTECHNIC L TESTING LABORATORY
The Mason County Critical Areas Ordinance(17.01.104)defines an erosion hazard area as:
Areas in Mason County underlain by soils which are subject to severe erosion when
disturbed. Such soils include, but are not limited to, those for which potential for erosion
is identified in the Soil Survey of Mason County,USDA Soil Conservation Service, 1960,
or any subsequent revisions or additions to this source. These soils include, but are not
' limited to, any occurrence of River Wash ('Ra') or Coastal Beaches ("Cg') and the
following when they occur on slopes 15%or steeper:
a.Alderwood gravelly sandy loam("Ac"and"Ad')
' b. Cloquallum silt loam ("Cd')
c. Harstine gravelly sandy loam ("Hh')
d. Kitsap silt loam ("Kc')
' The soils at the site are mapped as Everett gravelly sandy loam(Eh). Since the soil is very porous, this site does
not meet the technical criteria of an erosion hazard area.
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Landslide Offsite to North Along Road Cut
' SLOPE STABILITY
The Relative Slope Stability of the Southern Hood Canal Area, Washington, (1977) describes the building site
area as Class 1 and the eastern portion of the site as Class 3. Class 1 is expressed as:
Areas believed to be stable. Slopes generally less than 15 percent, but may be greater locally in
' areas too small to be shown at the map scale. Largely comprises rolling uplands underlain by
very stable material such as young glacial till, mantled in places by a thin layer of sandy gravel
or other permeable material; also includes flood plains, deltas, alluvial fans, and some beach
' deposits. Class I areas immediately adjacent to steep slopes of class 3 areas may be threatened
by potential landsliding. Normal,proper engineering practices generally are adequate to insure
stability in these areas.
' 10011 Blomberg Street SW,Olympia,WA 98512 11
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GEOTEcHNicAL TESTING LABORATORY
Class 3 is described as:
' Areas inferred to be unstable because slopes, generally greater than 15 percent, are underlain
by weak, unstable materials in which old or recently active landslides have occurred. Includes
areas of sand and gravel on top of impermeable silt and clay, mostly along steep valley sides.
' Based on our field observations, explorations and our experience with the soil types encountered on the property,
we conclude that although portions of the slopes on the lot exceed 100 percent, they are generally stable relative
to deep-seated failure in their present configuration.
' Excavation and backfillin will occur based on appropriate en ineerin and earthwork recommendations found in
gengineering
' the following"Earthwork"section. Grading in the building portion of.the site should be conducted in accordance
with geotechnical recommendations provided herein.
As previously discussed, weathering, erosion, and the resultant surficial sloughing and landsliding are natural
processes that affect slope areas. Significant weathering typically occurs in the upper 2 to 3 feet and is the result
of oxidation, root penetration, wet/dry cycles and freeze/thaw cycles. Over-excavation may be necessary to
ensure the removal of deleterious material.
1 These processes can be managed and the risk reduced through proper construction of the residence. Erosion
control recommendations in the slope and buffer areas are provided in the "Building Setback" and "Erosion
Control"sections of this report.
BUILDING SETBACK
' A building setback from landslide hazard areas is required unless evaluated and reduced by an engineering
geologist or a licensed professional engineer. Based on our geotechnical evaluation of the site and our experience
in the area, a building setback will be needed for this lot. The building setback may be measured from the bottom
of the footing to the face of the steep slope in accordance with the International Building Code (1805.3.1). The
following figure represents a shear angle for the gravelly sandy loam. Shear angle and cohesion are variables used
to model the site.
' Peak Shear Stress vs. Normal Stress
' 37°
2aW
a
e
d
a 1WO
1 i-ti4 ton
Spa _- - -w-12 ton
-1 ton
1 o
o soo ,am ,soo zoao �soo som
Normal Stress(pst)
' 10011 Blomberg Street SW,Olympia, WA 98512 12
Phone#: (360)754-4612 Fax#: (360)754-4848
Slope stability was modeled using the GEO-SLOPE/W program(version 5.20) in both static and extreme dynamic
conditions (Ca = 0.3). Factors of safety were determined using Bishop's, Janbu, and the Morgenstern-Price
methods. The site was modeled using a monolithic layer of gravelly sandy loam. The glacial till was determined
to have a unit weight of 130 pcf, cohesion of 300 psf, and a shear angle (�) of 41°. Under static conditions, the
slopes remained stable to deep-seated and shallow failure. Under dynamic loading, the 3,328 computations
demonstrated that the slope is not susceptible to surficial raveling and large deep-seated failure. The following
Pi figure illustrates the moment factor of safety for slope "A" under the existing conditions. The figure is the
solution of greatest concern and exhibits the need for a building setback of 25 feet from the crest of the eastern
slope and no closer than 50 feet from the eastern landslide. All foundation elements shall be constructed on native
material or engineered fill material.
Somers Site--Slope A i.
P•. Analysis Method: Morgenstern-Price
Direction of Slip Movement: Left to Right /
Slip Surface Option:Grid and Radius b ' '
Seismic Coefficient: Horizontal and Vertical •^• /•
N �
1.12 .,.
• • • •
230
210
190
p Gravelly Sandy Loam
170 Unit Weight: 129
150 Cohesion:500 \
LLJ 130 Phi:37
110
90
0 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 400 425 450 475 500
Distance (ft)
10011 Blomberg Street SW,Olympia,WA 98512 13
Phone#: (360)754-4612 Fax#: (360)754-4848
GEOTECHNicAL TESTING ]LABORATORY
As previously discussed, weathering, erosion and the resultant surficial sloughing and shallow landsliding are
natural processes that affect slope areas. Surficial raveling and sloughing was observed along the eastern slope.
A To manage and reduce the potential for these natural processes,we recommend the following:
➢ No drainage of concentrated surface water or significant sheet flow onto the sloped areas.
' ➢ No filling within the setback zone unless retained by retaining walls or constructed as an engineered fill.
➢ Trees may be removed on sloped areas as long as the stumps remain. Remaining trees may be limbed.
➢ Selective underbrush may be replaced with desirable vegetation.
SEISMIC—LIQUEFACTION HAZARD
According to the Seismic Zone Map of the United States contained in the 2003 International Building Code(IBC),
the project site is located where the maximum spectral response acceleration is 45 percent of gravity(g).
The Liquefaction Susceptibility Map of Mason County, Washington by Palmer, Magsino, Poelstra, Bilderback,
' Folger,and Niggemann(September 2004)maps the site area as having a very low liquefaction potential.
The Site Class Map of Mason County, Washington by Palmer, Magsino, Bilderback, Poelstra, Folger, and
' Niggemann(September 2004)maps the site area as site class C. Site class C is a very stiff soil or soft rock.
Based on the subsurface conditions observed at the site,we interpret the site conditions to correspond to a seismic
' Soil Profile Type D, for Stiff Soil, as defined by Table 1615.1.1 (IBC). This is based on the range of SPT
(Standard Penetration Test)blow counts and/or probing with a '/a-inch diameter steel probe rod. The shallow soil
conditions were assumed to be representative for the site conditions beyond the depths explored.
' Based on our review of the subsurface conditions, we conclude that the site soils are only mildly susceptible to
liquefaction. The near-surface soils are generally in a dense condition and the static water table is located well
' below the surface. Shaking of the already dense soil is not apt to produce a denser configuration and subsequently
excess pore water pressures are not likely to be produced.
' J
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Proposed Build
' 10011 Blomberg Street SW,Olympia, WA 98512 14
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1
1 GEO'TECHNICAL TESTtNG LABORATORY
EROSION CONTROL
' No onsite erosion was observed at the time of our site reconnaissance. It is our opinion that the potential erosion
hazard of the site is not a limiting factor for the proposed development. Removal of natural vegetation should be
minimized and limited to the active construction areas. Yard landscaping around the home is permissible, but
understory growth on the slopes should be encouraged as much as possible as a deterrent to erosion. Hazard trees
located on steep slopes may be removed only if the stumps remain to deter erosion.
Temporary and permanent erosion control measures should be implemented and maintained during construction
and/or as soon as practical thereafter to limit the additional influx of water to exposed areas and protect potential
receiving waters.
1 Erosion control measures should include, but not be limited to, silt fences, berms, and swales with ground
cover/protection in exposed areas. A typical silt fence detail is included on Figure 2. Any re-contouring of the
site will create a need for erosion control measures as listed above.
1
' EARTHWORK
SITE PREPARATION
All areas to be excavated should be cleared of deleterious matter including any existing structures, debris, duff,
and vegetation. Based on our observations, we estimate that stripping on the order of 6 to 12 inches will be
necessary to remove the root zone and surficial soils containing organics. Areas with deeper, unsuitable organics
should be expected in the vicinity of depressions or heavy vegetation. Stripping depths of up to 2 feet may occur
in these areas. These materials may be stockpiled and later used for erosion control and landscaping. Materials
that cannot be used for landscaping or erosion control should be removed from the project site.
' Where placement of fill material is required, the exposed subgrade areas should be proof-rolled to a firm and
unyielding surface prior to placement of any fill. We recommend that trees be removed with the roots, unless
located on a slope. Excavations for tree stump removal in any building area should be backfilled with structural
' fill,compacted to the density requirements described in the"Structural Fill" section of this report.
If structural fill is needed, we recommend that a member of our staff evaluate the exposed subgrade conditions
' after removal of vegetation and topsoil stripping is completed.
Any soft, loose or otherwise unsuitable areas delineated during foundation preparation or probing should be
' compacted, if practical, or over-excavated and replaced with structural fill, based on the recommendations of our
report.
1 STRUCTURAL FILL
All fill material should be placed as structural fill. The structural fill should be placed in horizontal lifts of
' appropriate thickness to allow adequate and uniform compaction of each lift. Fill should be compacted to at least
90 percent of MDD (maximum dry density as determined in accordance with ASTM D-1557) to within 2 feet of
subgrade and 95 percent MDD in the upper 2 feet.
10011 Blomberg Street SW, Olympia,WA 98512 15
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GEOTECHNICAL TESTING LABORATORY
The appropriate lift thickness will depend on the fill characteristics and compaction equipment used. We
recommend that the appropriate lift thickness be evaluated by our field representative during construction.
' The suitability of material for use as structural fill will depend on the gradation and moisture content of the soil.
As the amount of fines (material passing No. 200 sieve) increases, soil becomes increasingly sensitive to small
changes in moisture content and adequate compaction becomes more difficult to achieve. During wet weather,we
' recommend the use of well-graded sand and gravel with less than 7 percent(by weight)passing the No. 200 sieve
based on that fraction passing the'/4-inch sieve.
' If prolonged dry weather prevails during the earthwork and foundation installation phase of construction, a
somewhat higher(up to 10 percent)fines content will be acceptable.
' Material placed for structural fill should be free of debris, organic matter,trash, and cobbles greater than 6 inches
in diameter. The moisture content of the fill material should be adjusted as necessary for proper compaction.
' SUITABILITY OF ONSITE SOILS AS FILL
Onsite soils may be considered for use as structural fill. In general, the native soils (sand, loam, and gravel)
' encountered on the site must have less than 10 percent fines (material passing the US No. 200 Sieve) to be
suitable for use as structural fill.
CUT AND FILL SLOPES
All job site safety issues and precautions are the responsibility of the contractor providing services and/or work.
i The following cut/fill slope guidelines are provided for planning purposes.
Y.V Temporary cut slopes will likely be necessary during grading operations. As a general guide,temporary slopes of
1.5 to 1 (horizontal to vertical) or flatter may be used for temporary cuts in the upper 3 to 4 feet of the glacially
consolidated soils that are weathered to a loose/medium-dense condition. Temporary slopes of 1 to 1 or flatter
may be used in the unweathered dense to very dense sands and gravel.
These guidelines assume that all surface loads are kept at a minimum distance of at least one-half the depth of the
cut away from the top of the slope and that significant seepage is not present on the slope face. Flatter cut slopes
' will be necessary where significant raveling or seepage occurs.
Surface drainage should be directed away from all slope faces. All slopes should be seeded as soon as practical to
' facilitate the development of a protective vegetative cover or otherwise protected.
FOUNDATION SUPPORT
' Where foundation elements are located near slopes between 5 and 30 percent, the footings should be located a
minimum of 2 times the footing width from the slope face (horizontally), and founded in medium dense or denser
native soils or properly prepared structural fill.
' We recommend a minimum width for isolated and continuous wall footings to meet IBC 2003. Footings founded
as described above can be designed using an allowable soil bearing capacity of 2,000 psf(pounds per square foot)
for combined dead and long-term live loads in areas of medium dense to dense soils.
' 10011 Blomberg Street SW,Olympia, WA 98512 16
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i
1 GEOTECHNICAL TESTING LABORATORY
' The weight of the footing and any overlying backfill may be neglected. The allowable bearing value may be
increased by one-third for transient loads such as those induced by seismic events or wind loads.
' Lateral loads may be resisted by friction on the bases of footings and floor slabs and as passive pressure on the
sides of footings. We recommend that an allowable coefficient of friction of 0.40 be used to calculate friction
' between the concrete and the underlying soil. Active pressure may be determined using an allowable equivalent
fluid density of 150 pcf(pounds per cubic foot).
' We estimate that settlements of footings designed and constructed as recommended will be less than 1 inch, for
the anticipated load conditions, with differential settlements between comparably loaded footings of %z inch or
less.
' Most of the settlements should occur essentially as loads are being applied. However, disturbance of the
foundation subgrade during construction could result in larger settlements than predicted.
FLOOR SLAB SUPPORT
Slabs-on-grade should be supported on medium dense or dense native soils or on structural fill prepared as
' described in the"Structural Fill" section of this report. We recommend that floor slabs be directly underlain by a
minimum 6-inch thickness of coarse sand and/or gravel containing less than 5 percent fines (by weight). The
drainage material should be placed and compacted to an unyielding condition.
A synthetic vapor barrier may be used for the control of moisture migration through the slab, particularly where
adhesives are used to anchor carpet or tile to the slab. A thin layer of sand may be placed over the vapor barrier
and immediately below the slab to protect the liner during steel and/or concrete placement. The lack of a vapor
barrier could result in wet spots on the slab, particularly in storage areas.
fII r,
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View Looking South
RETAINING WALLS
Retaining walls may be utilized on the sloping portion of the site to retain fill material. The lateral pressures
acting on the subgrade and retaining walls will depend upon the nature and density of the soil behind the wall. It
is also dependent upon the presence or absence of hydrostatic pressure. If the adjacent exterior wall space is
backfilled with clean granular, well-drained soil (washed rock), the design active pressure may be determined
using an active pressure coefficient equal to 0.25 (Ka= 0.25). This design value assumes a level backslope and
drained conditions as described below.
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GEOTECHNICAL TESTING ]LABORATORY
Retaining walls located on or near the toe of a slope that extends up behind the wall should be designed for a
lateral pressure, which includes the surcharge effects of the steep slope in proximity to the wall. Although not
' expected at this site,the following data is provided for planning purposes.
For an irregular or composite slope, the equivalent slope angle may be determined by extending a line upward
' from the toe of the wall at an angle of 1 to 1 (Horizontal to Vertical)to a point where the line intersects the ground
surface. The surcharge effects may be modeled by increasing the equivalent fluid pressure for flat ground by the
tpercentage given in the following table:
SLOPE INCLINATION: EQUIVALENT FLUID PRESSURE
' Slope Angle Percent Increase Equivalent Fluid Pressure
Horizontal 0% 35 pcf
3H:1 V 25% 44 pcf
' 2H:1 V 50% 53 pcf
1H:1V 75% 61 pcf
' If the walls are greater than 4 feet in height, exclusive of the footing, additional design considerations should be
applied.
Positive drainage,which controls the development of hydrostatic pressure, can be accomplished by placing a zone
of coarse sand and gravel behind the walls. The granular drainage material should contain less than 5 percent
fines. The drainage zone should extend horizontally at least 18 inches from the back of the wall. The drainage
' zone should also extend from the base of the wall to within 1 foot of the top of the wall. The drainage zone
should be compacted to approximately 90 percent of the MDD. Over-compaction should be avoided as this can
lead to excessive lateral pressures.
' A perforated PVC pipe with a minimum diameter of 4 inches should be placed in the drainage zone along the base
of the wall to direct accumulated water to an appropriate discharge location.
' We recommend that a non-woven geotextile filter fabric be placed between the drainage material and the
remaining wall backfill to reduce silt migration into the drainage zone. The infiltration of silt into the drainage
' zone,with time,can reduce the permeability of the granular material.
The filter fabric should be placed in such a way that it fully separates the drainage material and the backfill, and
' should be extended over the top of the drainage zone.
Lateral loads may be resisted by friction on the bases of footings and as passive pressure on the sides of footings
and the buried portions of the wall. We recommend that an allowable coefficient of friction of 0.40 be used to
tcalculate friction between the concrete and the underlying soil.
RETAINING WALL ALTERNATIVES
Typically, block wall systems are more cost effective for long-term walls than the other options. Specific design
criteria for these options can be provided at your request by the block manufacturers.
1
' 10011 Blomberg Street SW,Olympia,WA 98512 18
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View Looking West at Slope Above Eastern Landslide
SITE DRAINAGE
All ground surfaces, pavements and sidewalks should be sloped away from the residence and associated
structures. Surface water runoff should be controlled by a system of curbs, berms, drainage swales, and/or catch
basins and tight-lined into the appropriate drainage facilities. We recommend that conventional roof drains be
t installed. Footing drains shall be installed for the single-family residence. The roof drain should not be
connected to the footing drain. For footing drains,the drain invert should be below the bottom of the footing.
1 We recommend that the collected stormwater runoff be directed into the appropriate drainage facilities by tight-
line, potentially in the southern portion of the site. Drainage control measures are included on Figure 3. Onsite
irrigation to lawn areas should be closely monitored. We do not expect any adverse affects on the recharge
condition of the groundwater system.
? i
A
Proposed Buildiup'Location
' 10011 Blomberg Street SW,Olympia,WA 98512 19
Phone#: (360)754-4612 Fax#: (360)754-4848
1
' G ° OTECHNICAL TESTING LABORATORY
SEPTIC IMPACT
' The location of the existing septic drainfield was inspected in regards to slope stability. The drainfield will be
located in the southwestern portion of the site. If the septic drainfield location meets our recommended setback,
the slope stability will not be compromised.
1
LIMITATIONS
' We have prepared this report for the use of The Charles Somers Company and members of their design team, to
use in the design of a portion of this project. The data used in preparing this report, and this report, should be
' provided to prospective contractors for their bidding or estimating purposes only. Our report, conclusions and
interpretations are based on data from others and our site reconnaissance, and should not be construed as a
warranty of the subsurface conditions. This report is quantified as a micro-study and not a macro-study.
Geotechnical Testing Laboratory and its personnel cannot be responsible for unforeseen and widespread geologic
events(such as earthquakes, large-scale faulting,and mass wasting)beyond the scope of this project.
Variations in subsurface conditions are possible and may occur with time. A contingency for unanticipated
conditions should be included in the budget and schedule. Sufficient consultation should be made with our firm
during construction to confirm that the conditions encountered are consistent with those indicated by the
recommendations and for design changes should the conditions revealed during the work differ from those
' anticipated,and to evaluate whether earthwork and foundation installation activities comply with contract plans.
If our analysis and recommendations are followed, we do not anticipate any on site or off site impact from the
' construction. It is our conclusion that potential landslide hazards from the landslide area can be overcome so as
not to cause harm to property, public health and safety,or the environment.
The scope of our services does not include services related to environmental remediation and construction safety
precautions. Our recommendations are not intended to direct the contractor's methods, techniques, sequences or
procedures,except as specifically described in our report for consideration in design.
If there are any changes in the loads, grades, locations, configurations or types of facilities to be constructed, the
conclusions and recommendations presented in this report may not be fully applicable. If such changes are made,
we should be given the opportunity to review our recommendations and provide written modifications or
verifications,as appropriate.
1
1
' 10011 Blomberg Street SW,Olympia, WA 98512 ?o
Phone#: (360)754-4612 Fax#: (360) 754-4848
1
' G 'I OTBGRNICAL TESTING LABORATORY
BORING AND LABORATORY RESULTS
Date: 12M2005 File#: 05-2251-11
Boring Log#: B-I N47 22.048 W12250.935 Client: Harley Somers
Boring Type: B-40 Depth Drilled: 21 feet
Depth Change Percent Minus
(feet) Soil Classificationin Soils %M N Q QP V LL PL PI 3/4" #4 #200 Field Description
0.5 2"dark brown duff w/roots
1.0 minor gravels
1.5
2.0 Sandy silt,moist dark yellowish
2.5 brown(10YR4/4),minor clay
3.0
.. . ....... ........ _
3.5
4.0
4.5
5.0 ML,Silty with Sand 29 100.0% 99.4% 71.6% Sandy silt,brown(7.5YR5/2)
5.5 mottling,no gravels.
6.0
6.5
7.0
7.5 -
8.0
8.5
9.0 Increase in gravel concentration
9.5 indicated by drill noise.
10.0 SM,Silty Sand with Gravel 93 90.7% 70.8% 27.9% Sample has wet silty sand above
10.5 gravellayer
11.0
11.5 slow drilling-gravel sounds
12.0
12.5
13.0
13.5
14.0 Grades to silty sandy gravel
14.5 (gravels up to 2"diameter)
15.0 SW-SC,Well graded Sand with 47 100.0% 76.6% 7.6% Silty Sandy Gravel,yellowish-
Sil Clay and Gravel
16.0 Silty Y brown(10Y115;4)interbedded
16.5 GM,Silty Gravel with Sand 93.5% 53.3% 14.1% with Imm thick light gray laminae
_....
17.0
........_........-...- _..
17.5 _.. -
--`- -
18.0
...„ .........
18.5
19.0
---------------------- - - - ----------- --- ---- --------------------=----------------------------------------.
19.5
i i i
20.0 50 ! i ! ! ! ! ! !I"rock in tipof sampler
----- ------------ -------------- -----t _._. ._A-----------� - - ------ --------�------ ----- _
20.5 Silty sandy gravel,limonite
------1-----------------------------.. ........
21.0 Refusal
end of boring--Groundwarer NOT encountered.
1
' 1001 1 Blomberg Street SW, Olympia, WA 98512 21
Phone#: (360) 754-4612 Fax#: (360) 754-4848
1
' BORING 1,5 FEET
U.S.Standard Sieve Opening in Inches U.S.Standard Sieve Numbers Hydrometer Results
100% 20 6 a s v .11 i o s o a i o 0 0%
90% 10%
80% 20%
' r 70% 30%
a�
iv s
3: 60% 40%
m 50% 50%
' m 40% 60%
� m
30% 70%
20% 80%
10% 90%
' 0% 100%
1000 100 10 1 0.1 0.01 0.001
Grain Size in Millimeters
' Cobbles Gravels Sands Silts Clays
Coarse I Fine Coarse I Medium I Fine
Date: 12/07/05 Dlo= 0.01 Classification %Gravel
' Sample#: 1135 D30= 0.03 ML,Silt with Sand 0.59%
Sample ID: D6o= 0.06 Specifications %Sand
Source: Cic= 1.50 No Specs 27.76%
1 Project: Somers Cu- 6.00 %Silt&Clay
Location: Liquid Limit-- 0.00 Dust Ratio= 71.65%
Boring#: B-1 Plastic Limit-- 0.00 Fineness Modulus Sample Meets Specs
Depth: 5' Plasticity Index-- 0.00 0.19 Yes
' Coarse Actual Interpolatedices Actual Interpolated
Section Cumulative Cumulative Section Cumulative Cumulative
Sieve Size Percent Percent Specs Specs Sieve Size Percent Percent Specs Specs
US Metric Passing Passing Max Min US Metric Passing Passing Max Min
6.00" 150.00 100.0% #4 4.750 99.4% 99.4%
4.00" 100.00 100.0% #8 2.360 99.2% 99.2%
3.00" 75.00 100.0% #10 2.000 99.1%
2.50" 63.00 100.00/0 416 1.180 99.0% 99.00/0 1
2.00" 50.00 100.0% 1 #20 0.850 98.8%
1.75" 45.00 100.0% #30 0.600 98.5% 98.5%
1.50" 37.50 100.00/0 #40 0.425 97.5%
1.25" 31.50 100.0% #50 0.300 1 96.8% 96.8%
1.00" 25.00 100.0% #60 0.250 93.7%
7/8" 22.40 100.0% #80 0.180 89.40/6
3/4" 19.00 100.00/0 #100 0.150 87.6% 87.6%
5/8" 16.00 100.00/0 #140 0.106 78.2%
' 1/2" 12.50 100.0% #170 0.090 74 8%
3/8" 9.50 100.0% 100.0% 4200 0.075 71.6% 71.6%
1/4" 6.30 99.6% #270 0.053
' I Copyright Spears Engmeenng&Technical Services PS,I W&2UX
' 10011 Blomberg Street SW,Olympia,WA 98512
Phone#:(360)754-4612 Fax#: (360) 754-4848
1
' GEOTECHNIC L TESTING LABORATORY
1
BORING 1, 10 FEET
U.S.Standard Sieve Opening in Inches U.S.Standard Sieve Numbers Hydrometer Results
100% 20 n. + #4 o s o a a t o a 0%
i90% 10%
80% 20%
70% 30%
.
60% 40%
T �
5
c 50% 50%
40% 60%
cc
-
' 0 30% 70%
20% 80%
' 10% - 90%
0% 100%
1000 100 10 1 0.1 0.01 0.001
' Grain Size in Millimeters
Cobbles Gravels Sands Silts Clays
Coarse I Fine Coarse Medium Fine
' Date: 12 07/05 D10=0.03 Classification o ve
Sample#: 1136 D30=0.09 SK Silty Sand with Gravel 29.18%
Sample ID: D60= 1.79 Specifications %Sand
Source: Cc=0.18 No Specs 42.90%
' Project: Somers Cu=66.48 %Silt&Clay
Location: Liquid Limit= 0.00 Dust Ratio= 0.58 27.92%
Boring#: B-1 Plastic Limit=0.00 Fineness Modulus Sample Meets Specs
Depth: 10' Plasticity Index-- 0.00 3.06 Yes
Coarse Actual InterpolatedFines Actual Interpolated
Section Cumulative Cumulative Section Cumulative Cumulative
Sieve Size Percent Percent Specs Specs Sieve Size Percent Percent Specs Specs
' US Metric Passing Passing Max Min US Metric Passing Passing Max Min
6.00" 150.00 100.00/0 #4 4.750 70.8% 70.8%
4.00" 100.00 100.00/0 #8 2.360 62.5%
3.00" 75.00 100.0% #10 2.000 61.2% 61.2%
2.50" 63.00 100.00/0 #16 1.180 56.5% 56.5%
2.00" 50.00 100.00/0 #20 0.850 53.5%
1.75" 45.00 100.00/0 #30 0.600 51.2% 51.2%
1.50" 37.50 100.0% #40 0.425 48.1% 48.1%
1.25" 31.50 100.0% #50 0.300 44.2% 44.2%
1.00" 25.00 100.0% 100.00/0 #60 0.250 41.7%
7/8" 22.40 96.0% #80 0.180 38.2%
3/4" 19.00 90.7% 90.7%° #100 0.150 36.7% 36.7%
' 5113" 16.00 88.6% 88.6% #140 0.106 31.6%
1/2" 12.50 84.6% 84.6% #170 0.090 29.7%
3/8" 9.50 81.3% 81.3% #200 0.075 27.9% 27.9%
1/4" 6.30 74.2% 4270 0.053
' Copyright Spears Engineering&Technical Services PS,1996-2W4
' 10011 Blomberg Street SW,Olympia,WA 98512 23
Phone#: (360)754-4612 Fax#: (360)7544848
1
GEOTECHNICAL TESTING LABORATORY
BORING 1, 15 FEET
D
U.S.Standard Sieve Opening in Inches l i.S.Standard Sieve Numbers Hydrometer Results
100% 20 s a a i i #a o s o a t o 0 0%
90% 10%
80% 20%
rn 70% 30%
.� t
60% 40%
aT
� 50% 50%
rn
c
a
40% 60%
a
0 30% 70%
20% 80% a
10% 90%
0% 100%
1000 100 10 1 0.1 0.01 0.001
Grain Size in Millimeters
Cobbles Gravels Sands Silts Clays
Coarse Fine Coarse Medium Fine
' Date: 12/ D10= 0.11 Classification /o Gravel
Sample#: 1137 D30=0.36 SW-SC,Well-graded Sand with Silty Clay and Grav 23.37%
Sample ID: Db°= 1.15 Specifications %Sand
Source: Cc= 1.00 No Specs 69.06%
Project: Somers Cu= 10.12 %Silt&ClaN
Location: Liquid Limit= 0.00 Dust Ratio= 7.57%
Boring#: B-1 Plastic Limit-- 0.00 Fineness Modulus Sample Meets Specs
Depth: 15' Plasticity Index--0.00 3.20 Yes
Coarse Actual InterpolatedFines Actual Interpolated
Section Cumulative Cumulative Section Cumulative Cumulative
Sieve Size Percent Percent Specs 1 Specs Sieve Size Percent Percent Sys Specs
' US Metric Passing Passing Max Min US Metric Passing Passing Max Min
6.0 " 150.00 100.0% #4 4.750 76.6% 76.6%
4.00" 100.00 100.0% #8 2.360 68.5% 68.5%
3.00" 75.00 100.0% #10 2.000 66.1%
' 2.50" 63.00 100.0% #16 1.180 60.6% 60.6%
2.00" 50.00 100.0% #20 0.850 54.2%
1.75" 45.00 100.0% #30 0.600 49.3% 49.3%
1.50" 37.50 100.0% #40 0.425 35.2%
1.25" 31.50 100.0% #50 0.300 25.0% 25.0%
1.00" 25.00 100.0% #60 0.250 20.8%
7/8" 22.40 100.0% #80 0.180 14.9%
3/4" 19.00 100.0% 100.0% #100 0.150 12.3% 12.3%
5/8" 16.00 96.4% #140 0.106 9.5%
1/2" 12.50 92.1% 92.1% #170 0.090 8.5%
3/8" 9.50 87.1%a 87.1% #200 0.075 7.6% 7.6%
1/4" 6.30 1 80.0% #270 0.053
Copyright 1 Spears Engineer4&Technical Services PS,1996-2004
10011 Blomberg Street SW,Olympia, WA 98512 24
Phone#: (360)754-4612 Fax#: (360) 754-4848
GEOTECHNICAL TESTING ILABoRA ORY
BORING 1, 16 FEET
U.S.Standard Sieve Opening in Inches U.S.Standard Sieve Numbers Hydrometer Results
100% 20 6 4 3 % 0 t6 ZO 30 4 -1 DO 0 0%
90% 10%
80% 20%
o� 70% 30%
� r
60% 40%
m 50% 50%
c �
m 40% 60% Q,
lL
m
' 0 30% 70%
20% 80%
' 10% 90%
0%" 100%
1000 100 10 1 0.1 0.01 0.001
' Grain Size in Millimeters
Cobbles. Gravels Sands Silts J=ays
Coarse I Fine Coarse Medium Fine
' Date: 12 07 05 Di„= 0.05 Classification %Gravel
Sample#: 1138 D31,= 0.53 GM,Silty Gravel with Sand 46.690N
Sample ID: Dw= 6.38 Specifications %Sand
Source: Cc= 0.84 No Specs 39.19%
' Project: Somers Cu= 120.15 %Silt&Clay
Location: Liquid Limit--0.00 Dust Ratio= 0.50 14.13%
Boring#: B-1 Plastic Limit=0.00 Fineness Modulus Sample Meets Specs
' Depth: 16' Plasticity Index--0.00 4.25 Yes
Coarse Actual Interpolatedroes Actual Interpolated
Section Cumulative Cumulative Section Cumulative Cumulative
Sieve Size Percent Percent Specs Specs Sieve Size Percent Percent Specs Specs
' US Metric Passing Passing Max Min US Metric Passing Passing Max Min
6.00" 150.00 100.0% 4.750 53.3% 53.3%
4.00" 100.00 100.0% #8 2.360 42.9%
3.00" 75.00 100.0% #10 2.000 41.3% 41.3%
' 2.50" 63.00 100.00/0 #16 1.180 36.2% 36.2%
2.00" 50.00 100.00/0 #20 0.850 33.2%
1.75" 45.00 100.00/0 #30 0.600 31.0% 31.00/a
1.50" 37.50 100.0% #40 0.425 28.3% 28.3%
' 1.25" 31.50 100.0% #50 0.300 25.2% 25.2%
1.001, 25.00 100.00/0 100.00/0 #60 0.250 23.4%
7/8" 22.40 97.2% #80 0.180 20.9%
3/4" 19.00 93.5% 93.5% #100 0.150 19.8% 19.8%
5/8" 16.00 90.2% 90.2% #140 0.106 16.5%
1/2" 12.50 83.0% 83.0% #170 0.090 15.3%
3/8" 9.50 72.8% 72.8% #200 0.075 14.1% 14.1%
1/4" 6.30 59.7% #270 0.053
Copyright Spears Engirvering&Techtucal Services PS,1"6-2004
10011 Blomberg Street SW,Olympia,WA 98512 25
Phone#: (360)754-4612 Fax#: (360)754-4848
GEOTECHNICAL TESTING LABORATORY
1 FIGURE 1 VICINITY MAP
.l -r
1 -
l f u t'
1
�/ t
100
Vj r
r.y
' 10011 Blomberg Street SW,Olympia, WA 98512
Phone#: (360)754-4612 Fax#: (360)754-4848
1