HomeMy WebLinkAbout802274006 Geotech Assessment1451
May 15, 2007
Mike and Sue Joachims
50 Mockingbird Lane
Port Ludlow, WA 98365
Re: Geology Hazard Asse;
Tax Parce1802274006,
Jefferson County, Wasl
Dear Mr. and Ms Joachims:
I visited the Tax Parcel 802274006
stability of the site. The purpose of
and other relevant geologic conditic
Based on my assessment of geologi
failures. Because of potential perch
to foundation drainage will be parti
carefully designed to allow for com
wall. This can be accomplished in
draining gravel and drainage lines 1
foundation. If a daylight basement
the drainage system would be well
foundation remains dry. The extra ~
I suggest that clean out risers be pry
maintained in case of clogging.
RATUM GROUP
~t Street, Bellingham, WA 98225
Phone (360) 714-9409
Lane
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Elkhorn Lane on March 1, 2007 to evaluate the slope
site visit was to assess the slopes on the site and vicinity
at the site.
conditions, the lot is not at risk of being impacted by slope
;d shallow ground water within the soils at the site, attention
~ularly important. The foundation drainage system be
plete drainage from behind the back (upslope) foundation
variety of ways including a well sealed foundation and well
laced along the outside of the walls and beneath the
bundation is used, it is my opinion that some over design of
North the extra costs that may be entailed to ensure that the
esign could include additional drain rock and drain lines; and
wided for the drain lines so that hey can be readily
GEOLOGY
This geology description of the
the site.
Northwestern Washington has beer
the Pleistocene Epoch (1.6 million
interglacial periods, the underlying
Deposits in the Seattle 30' x 60' Q~
indicates that the subject property i
property and in the vicinity-are .con
The till on the site consists of very
and boulders embedded in the silt
is to provide some background regarding the conditions at
occupied by continental glaciers at least four times during
10,000 years ago). During these glacial and accompanying
Bedrock was deeply eroded. The Geologic Map of Surficial
adrangle, Washington (Yount, Minard, and Dembroff, 1993)
underlain by glacial till. Site observations on the subject
istent with the above-described mapping.
~t silt with a poorly mixed assortment of sand, cobbles
Fragments of local basalt bedrock are embedded within
May 15, 2007
Tax Parcel 802274006, Elkhorn Lane
Geology Assessment
the till at the subject property. The
Vashon ice sheet that covered the 1
the present.
was deposited directly by glacial ice associated with the
~t Sound lowland between 20,000 and 13,000 years before
Because the till is very compact an contains a significant percentage of silt and clay, .the till soils
on the site are not well drained and hallow perched ground water is likely present on the site on
a seasonal basis.
Slopes on the site are relatively ger.
site. The property generally slopes
portion of the property. An access ~
Lane. Agrass-covered clearing is l~
remaining areas of the property are
road or possible rail line grade prey
property west of the clearing area.
Site Observations
with slopes generally less than 15 degrees throughout the
~ards the east. Elkhorn Road angles across the eastern
i enters the central portion of the property from Elkhorn
ted in the central portion of the property. Most of the
e covered with alders being the predominant tree. A former
ably associated with past timber harvest cuts across the
Conclusions
No potentially hazardous slopes ar present on the subject property. As noted above attention
should be paid to foundation drain a as soils underlying the site will generally have low
permeability.
Stratum Group appreciates the of
questions regarding our reconnai
Sincerely yours,
atum Group
Dan McShane, L.E.G., M.Sc.
Licensed Engineering Geologist
lity to be of service to you. Should you have any
please contact our office at (360) 714-9409.
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File: 3.1.07
Figure 1. Site Lo~ation 47°52.987' N, 122°54.625' W WGS84
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