HomeMy WebLinkAboutGEOTech Assessment for BLD98-0908 - BLD Engineering / Geo-tech Reports - 9/5/1998 C014SOLIDATED ENGINEERING
CIVIL - STRUCTURAL - SOILS - PLANNING -
September 5, 1998
Larry Stevens @
Laska, Bonham & Logue
East 8110 Highway 106
Union, WA 98592
LEGAL DESCRIPTION: (See enclosed)
RE: Geo-technical Inspection and Report on Property at the above address.
Dear Mr. Stevens;
The undersigned Geo-technical Engineer, along with Cindy Forbes,
Geo-technician, visited the site of the lot described above on Sep-
tember 2nd to evaluate the geo-technical land stability of the lot.
The slope at the rear of the house is nearly vertical but the soil
is a cemented sandy-gravel glacial till. Photographs illustrating the
slopes were taken for our file and are also enclosed herein.
Tree trunks on the slope at the rear of the house are vertical
indicating a stable history for the slope. The Coastal Zone Atlas of
Mason County, WA indicates the area of the lot as Stable with an
Intermediate Stable area nearby.
Footing details and the retaining wall section for the proposed
addition will provide a sound foundation for this proposed construction.
Soil bearing readings with a penetrometer averaged 2 1/2 tons per square
foot bearing capacity.
In summary, the proposed construction should enhance the stability
of the ground for this lot.
Yours truly, g• B0(l��ti of WASy Dy�
R. B. Boug4, P
Geo-technical & Professional Engineer 0 0048913
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Encls- as listed EXPIRES 00
P.O. Box 2321 • Bremerton, WA 98310 • (360) 479-5598 • FAX (360) 792-0534
MASON COUNTY
PUBLIC WORKS DIRECTORICOUNTY ROAD ENGINEER
Shelton,Washington 98584
DATE: Sept. 16, 1998
INTER-DEPARTMENTAL COMMUNICATIONS
TO: Shandra Fitzpatrick, DCD -Planner
FROM: Alan A. Tahja, P/W- Co. Hydr. Engr. WO#DCD 9827
SUBJ: Geo-Tech Assessment Review NAME: Lasko, Bonham, Logue
BLD98-0908
Shandra,
The slope stability evaluation prepared by Rolla B. Boughan, P.E., of Consolidated Engineering
for the proposed Laska, Bonham& Logue residential addition have been reviewed by Public
Works, and appears to dispel the need for additional geotechnical investigation.
The photographs accompanying the file have been reviewed as well and though there appears to
be a contradiction between Mr. Boughan's assessment that the trees on the slope at the rear of the
house are vertical, and the photographs show a definite bow in the bottom of the tree trunks,I
feel there is not a problem. Surface creep associated with shallow ground movement is common,
and it appears during the trees' early growth they were affected by such shallow movement. It
appears that over the past several years, after the trees had developed deeper roots,they have
been stabile and the tree trunks above the original bow have been able to grow straight without
regular re-straightening. A tree undergoing ongoing sliding would develop a long arch in its
trunk,which is not evidenced in the photographs.
The effectiveness of the 2' high retaining wall seems questionable as to its effectiveness,but its
failure or overturning should not affect the deeper taller foundation wall. Also the length of the
short retaining wall is not indicated anywhere in the submitted materials, but whether it extends
across the full length of the new and existing residence or merely along the back of the addition
doesn't appear to make very much difference.
The geo-technical assessment submitted by Mr. Boughan can be considered adequate.
Please feel free to contact me at County extension 461 if additional comments are needed, or if
you have any questions regarding this review or comments.
Sincerely,
4
Alan A. Tahja
File: H:\WP\GEO\REVIEWS\LASKA. IDC