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ALKAPcoNsuLTANTs,•
Environmental Engineering • Geotechnical Engineering • Wetland Consulting
December 6, 2005 ACL-05-11-G 110
Page No. 1
Mr. Ray Culver
30 Riverdale Drive
Quilcene, Washington 98376
GEOLOGIC ASSESSMENT REPORT
PROPOSED SINGLE-FAMILY RESIDENCE
JEFFERSON COUNTY PARCEL#'S 950-200-627
SOUTH BEACH PARCEL
JEFFERSON COUNTY,WASHINGTON
Mr. Culver:
This geological report presents the results of a soil and slope assessment directed at evaluating suitability
for proposed development at the above referenced site. The scope of this study was developed during our
telephone conversation on November 14, 2005 and outlined in our proposal to you dated November 15,
2005. The services performed under this authorization were in general compliance with geotechnical
report requirements outlined in the Jefferson County Unified Development Code (UDC), section 3.6.10g.
Fieldwork for this study was undertaken on November 28, 2005.
Site Description
The site is located on a primitive road extending off of South Beach Drive as shown on the Vicinity Map,
Figure 1. The subject parcel is bordered by vacant lots to the north, a steep ascending slope to the west, a
vacant single family residence to the south, and single-family residences with the Hood Canal beyond to
the east. The vertical elevation change from the shoreline to the top of the slope to the west is
approximately 150 feet. The lot to the north is in the planning stages for the construction of a single
family residence.
Proposed Development
It is our understanding that the proposed development will consist of a wood frame single family
residential structure. It is anticipated/recommended that remaining general site grading for development
will be minimal and all disturbed or bare ground areas will be landscaped and/or re-vegetated following
construction.
9465 Provost Road NW, Suite 202•Silverdale,Washington 98383 • (360) 613-2407• Fax: (360) 613-2408
05-11-GI10 Culver SFR
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December 6, 2005
Methodology
The subject property soil and slope conditions were visually examined and evaluated using available
slope exposures in the site vicinity and the site slope itself. This information provided a basis for a
general understanding of the local soil and geologic conditions as discussed below. In addition to the
observation of available soil exposures and reconnaissance of the area the following readily available
resources were reviewed.
Resources used:
• "Soil Survey of Jefferson County Washington", United States Department of Agriculture, 1975.
• "Geologic Map of Washington—Northwest Quadrant", Washington State Department of Natural
Resources, Division of Geology and Earth Resources, GM—50, 2002.
• "Geologic Map of East-Central Jefferson County, Washington", R.U. Birdseye, 1976.
• U.S.G.S. 7.5 minute series topographic map"Lofall", Washington Quadrangle".
• "Coastal Zone Atlas of Washington", Volume 11,Jefferson County, Washington-Department of
Ecology, 1979.
Geologic Setting
The subject site lies within the central Puget Lowland. The lowland is part of a regional north-south
trending trough that extends from southwestern British Columbia to near Eugene, Oregon. North of
Olympia, Washington,this lowland is glacially carved with a depositional and erosional history including
at least four separate glacial advance/retreats. The Puget Lowland is bounded on the west by the Olympic
Mountains and on the east by the Cascade Range. The lowland is filled with glacial and nonglacial
sediments consisting of interbedded gravel, sand, silt,till, and peat lenses.
The Washington Division of Geology and Earth Resource (WDGER), Geologic Map of Washington —
Northwest Quadrant, dated 2002, indicates that the site is mapped as undifferentiated surficial deposits
(Qguc)near glacial till (Qgt). Undifferentiated surficial deposits consist of clay, silt, gravel,till, and peat.
The term undifferentiated is used because steep slopes preclude differentiation at the map scale. Glacial
till consists of an unsorted, unstratified, highly compacted mixture of clay, silt, sand, gravel and boulders
deposited by glacial ice.
The Geologic Map of East-Central Jefferson County, Washington indicated that the site is mapped as pre-
Vashon stratified sediments with beach deposits along the shoreline.
The USDA Soil Conservation Service Soil Survey of Jefferson County Area, Washington, 1975, indicates
the soils of the site are mapped as Cassolary soil with 0 to 15 and 30 to 50 percent slopes originating in
reworked glacial and marine sediments. Permeability is moderately slow, runoff is slow, the erosion
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December 6, 2005
hazard is slight to moderate, and building limitation for dwellings without basements is moderate for 0 to
15 percent slopes. Runoff is rapid, the erosion hazard is severe, and the building limitation for dwellings
without basements is severe for 30 to 50 percent slopes (more specifically, slopes greater than 15
percent).
Surface and Subsurface Conditions
The site slopes upward toward the west. Vegetation consists mostly of blackberries. No evidence of
surficial or deep-seated or rotational landsliding was observed on the property. Soils observed on the
adjacent property to the north consisted of moist to wet surface soils in the upper 2 to 3 feet underlain by
more firm fine grained soil.
Based on the soils exposed on and around the property it is our opinion that the site soil conditions are
generally consistent with those shown on the geologic and SCS maps of the area. Generally differences
between the geologic and soil maps and observed soil conditions occur as a result of mapping scale,
availability of exposures, and intended map usage. These differences are generally minor and not
unexpected.
The "Coastal Zone Atlas of Washington", Volume 11, Jefferson County, Washington Department of
Ecology, 1979 identifies slopes in the site vicinity as stable (S) in the lower portion to the east, unstable
(U) in the slope area of the property, and Modified (M) in the flat area near the shoreline. An area
described as Unstable Recent Slide (Urs) is located to the south of the subject site. Stable slopes are
generally less than 15 percent but can include areas of steeper slopes that are stable due to low
groundwater concentration or competent bedrock. The stable slope designation also includes areas
underlain by weak material such as peat, which are stable because they have no significant slope.
Unstable refers to slopes that are considered unstable due to factors such as steepness, groundwater or
erosion concerns. Modified slopes include areas that have been highly impacted by human activities such
as excavation and fill and performance can be difficult to predict. Unstable recent landslide includes
areas of recent or historically active slides. It should be noted that the mapping was performed in the late
1970's and does not reflect more recent activity.
There was no visible evidence of ground water, springs or seeps observed on the slope face or within
1000 feet of the subject site at the time of the site visit. Our reconnaissance off the subject site was
limited by private property access. Water seepage could occur during periods of heavy rainfall.
Conclusions and Recommendations
It is our opinion that a suitable location for the construction of the proposed structure will be 30 feet from
the toe of slopes steeper than 30 percent as long as any resulting excavations are retained by retaining
walls or foundation walls that retain the soils in the cut areas. It appears that a convenient location would
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December 6, 2005
be starting from approximately 100 feet from the access road and toward the road. Slopes are less steep at
this location and it would provide a setback of approximately 55 feet from slopes steeper than 30 percent.
We recommend that roof drains for any structure be tightlined to the toe of the slope near the primitive
roadway and an energy dissipater such as quarry spalls be utilized to reduce erosion. Infiltration does not
appear to be feasible due to observed slope and soil conditions. Vegetation should be maintained as
currently established outside the building and driveway areas. In our opinion, maintaining vegetation on
the steeper slopes will help maintain to the stability of the moist to wet surface soils which are underlain
by more firm fine grained soil.
At the time of this letter report no building plans were available for review. It is recommended that a`'
representative of Alkai view building plans prior to construction and also the exc4v4ed footings to verify 1
r
that the building is bearing on firm native soil.
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REPORT LIMITATIONS _._.__--= ��
This report has been prepared for the exclusive use of Mr. Ray Culver and his agents for use in planning
of the referenced development. The conclusions and recommendations in this report are based on our
interpretation of site conditions, as they presently exist, anticipated future construction activities, and the
expectation that the investigation adequately defines the subsurface conditions across the site. The soil
conditions described in this report and the conclusions and recommendations contained in this report are
provided for this specific site only and should not be expanded for use on adjacent properties without
additional exploration and review of those sites by our firm. The data and report should be provided to
prospective contractors for their bidding or estimating purposes, but the report conclusions and
interpretations should not be construed as a warranty of the subsurface conditions. There are possible
variations in subsurface conditions. In the event that the scope or location of the project should change or
subsurface conditions different from those encountered during this study be observed or suspected, we
should be advised. At that time a review of the changed conditions will be made, and alternative or
remedial recommendations given as required.
NOTE: We have not explored subsurface conditions as part of this study, nor have we evaluated the site
for the potential presence of contaminated soil, and have not evaluated or addressed ground water
conditions or concerns except as noted in this report. The evaluation of possible environmental or geo-
environmental considerations is beyond the scope of this report.
The owner and the contractor should make themselves aware of and become familiar with applicable
local, state, and federal safety regulations, including current OSHA/WISHA excavation and trench safety
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December 6, 2005
standards. Construction site safety generally is the sole responsibility of the contractor. The contractor
shall also be solely responsible for the means, method, techniques, sequences, and operations of
construction operations. The firm, Alkai Consultants, LLC is providing the preceding information and
recommendations solely as a service to Mr. Ray Culver. Under no circumstances should the provision of
this information or recommendations be construed to mean that the firm Alkai Consultants, LLC (or
subcontractors) are assuming responsibility for construction site safety or the contractor's activities; such
responsibility is not implied and should not be inferred.
Within the limitations of scope, schedule, and budget for this work, it is warranted that the work has been
done in accordance with generally accepted practices followed in this area at the time this is report was
made. No other warranty, expressed or implied is made.
Should you have any questions or concerns, which have not been addressed, or if we may be of additional
assistance, please call our office at(360) 613-2407.
Sincerely,
,,,i0N4s0;\
David Hurum, L.G. t m
Senior Staff Geologist
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I DAVID C. HURUM I
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FIGURE 1 VICINITY MAP
Project Name: South Beach Parcel Z�
ALKAI CONSULTANTS, LLC. Location: Jefferson County,Washington N
Project No.: ACL-05-11-G110
Environmental Engineering• Geotechnical Engineering•Wetland Consulting Client: Mr. Ray Culver
Date: 11/18/05 ! -;,-- ,r __
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