HomeMy WebLinkAboutBLD2008-00201 Geotechnical Report • • -
-w F a Golder Associates Inc.
18300 NE Union Hill Road,Suite 200 ® _ Golder
Redmond,WA USA 98052-3333 to,
Associates
Telephone(425)883-0777
Fax(425)882-5498
www.golder.com
RECEIVED
September 2, 2008 Our Ref.: 083-93241.000
SEF - 3 200ti
Alan and Bonnie Fure AMEN COUNTY DCD
2114 NW Far Country Lane
Issaquah, Washington 98027
RE: ADDENDUM TO RESULTS OF GEOTECHNICAL INVESTIGATION
TAX PARCEL 821224003
PORT LUDLOW,WASHINGTON
Dear Mr. Fure:
Golder Associates Inc. (Golder) is submitting this addendum to our geotechnical steep slope
reconnaissance report for your proposed garage construction in Port Ludlow. The report was dated
April 21, 2008. The purpose of this report addendum is to address comments received from the
Jefferson County Department of Community Development, dated August 28, 2008. There were four
comments listed on the August 2008 letter. Two comments, numbers 2 and 3, pertained to a landslide
hazard area to the northwest of the proposed garage, and potential impacts from the presence of an
existing trench drain within the footprint of the proposed garage. Comment numbers land 4 are being
addressed by the applicant. Golder's response to comments number 2 and 3 are presented below.
Comment 2
The landslide hazard area referred to being northwest of the garage is a small hill, about ten feet in
height, west of the entrance driveway. The steep portion of the hill facing the proposed garage was
created through excavation for the driveway. The vegetated hill is underlain by dense, Lodgment till,
with no water seepage and does not pose a landside risk. We recommend, in accordance with Section
18.22.170 (6) & (7) of the Jefferson County Critical Areas Ordinance, that the buffer from the toe of
the slope be reduced from the standard 30 feet to the minimum allowable of 15 feet. This will
provide the same protection from landslide hazard as the standard buffer.
Comment 3
The location of the trench drain is shown on the attachments provided by you. I observed this drain at
the ground surface when I made my site visit on March 29, 2008.
The drain consists of an excavated trench backfilled with rounded washed gravel. There was no
observed flow from this drain during my site visit and you have communicated to me that you have
never observed flow from the end of the drain implying the water collected by the drain likely
infiltrates.
We evaluated several potential impacts this drain might have on the proposed construction and steep
slope setback as proposed in our April 2008 letter. Our comments are as follows:
090208jgjl_Fure Addendum Letter.Docx
OFFICES ACROSS AFRICA,ASIA,AUSTRALIA,EUROPE,NORTH AMERICA AND SOUTH AMERICA
•
September 2,2008
Al and Bonnie Fure -2- 083-93241.000
• The presence of the surface drain has no affect on the slope setback distance provided in our
April 2008 report.
• The foundation for the garage can be constructed over the &ravel drain. Care should be taken
during construction not to block the drain. Corvt P. I21 -Qv k,(�� r-p((—1 -p o l l
• The gravel drain could be used to infiltrate/disperse rro'guteer downspout water from the
proposed garage without adverse impact to the landslide hazard area.
We trust this addendum meets your needs. If you have any questions, please give us a call.
Sincerely,
GOLDER ASSOCIATES INC. ' , r= 4,r
Nve
a9,IZ-.---- co ds,,, -..-b is A , t
James G. Johnson L.G. L.E.G. �,�» y' �
Principal and Senior Consultant �''"� ,Inaor / �1.."r �
'' ? lds
James G.Joh son
SEP — 3 2t1g8
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090208jgj 1_Fure Addendum Letter.Docx
Golder Associates
• •
ATTACHMENT
IA ''ED
SrP - 3 20118
090208jgj I_Fuse Addendum Letter.Docu
Golder Associates
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12112 115th Avenue NE \
Kirkland,WA 98034
425.821.8448 TRIAD Land Development Consultants
800.488.0756 toll free ASSOCIATES
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