GeotPeerReview Comments 1.pdf
Structural Plans for Isaacson Residence, including Sheets S-0 through S-8, prepared by Reed
& Associates, PS, dated June 3, 2009.
Structural Calculations for Brian & Cindy Isaacson, Isaacson Residence, Lot 2, Lorian
Woods, Edmonds, prepared by Reed & Associates, PS, dated June 3, 2009.
Concept Landscape Plan (one sheet), prepared by R. W. Thorpe & Associates, Inc., dated
August 1, 2008.
Plan Sheets (including Sheet 1 - Existing Conditions Plan, Sheet 2 – Grading & TESC Plan,
Sheet 3 – Grading & TESC Notes & Details, Sheet 4 – Site Drainage Plan, Sheet 5 –
Residence Drainage Plan, and Sheet 6 – Drainage Details Plan, prepared for Brian & Cindy
Isaacson by Western Engineers, Inc., latest revision dated May 21, 2009.
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Targeted Storm Drainage Study for Brian & Cindy Isaacson, 16007 73 Place West,
Edmonds, Washington, report prepared by Western Engineers, Inc., dated May 13, 2009.
Applicant/Owner Liability & Landslide Acknowledgment, signed by Brian Isaacson and Cindy
Isaacson, dated June 1, 2009.
Isaacson Residence, Lot #2 – Lorian Woods (PRD-1981-2), Lead Design Professional
Designation and Statement, letter addressed to the City of Edmonds prepared by O’Brien &
Associates, dated May 26, 2009.
City Review Comments, Letter of Release of Liability, Letter addressed to the City of Edmonds
prepared by Western Engineers, Inc., dated May 21, 2009.
R & A Job#07-789, SFR to be constructed at Lot 2, Plat of Lorian Woods, Edmonds, WA,
Permit #: BLD2007-0833, STRUCTURAL ENGINEER DECLARATION (City Ordinance
#2661 and #3632), letter to Brian & Cindy Isaacson prepared by Reed & Associates, PS, dated
June 3, 2009.
The focus of the current peer review is on the house and retaining wall plans. The applicant has
previously submitted permit application packages for other elements of the site development that includes
tree cutting, and grading, drainage and replanting elements of the project. Each of those previous permit
application submittals has undergone geotechnical peer review by Landau Associates and our previous
review comments have been addressed as appropriate in the earlier submittals and subsequent permits.
GR
EOTECHNICAL EPORTS
The geotechnical report prepared by Terra Associates dated March 31, 2008 provides a
reasonably comprehensive evaluation and discussion of site conditions and risks, and provides
geotechnical recommendations for grading, drainage, foundation and retaining wall design, and other
design elements of the project. The March 31, 2008 report, along with the June 2 and June 5, 2009
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supplemental letters by Terra Associates appear to adequately address the City’s geotechnical report
requirements for development within the ESLHA.
CP
IVIL LANS
Sheet 1, General Note 22 references Chenowyth Land Surveying, but the Survey Notes and
Datum on the same sheet reference a survey completed by Group 4, Inc. The correct reference for the
survey should be noted.
Sheet 5 of the civil plans show the location for a perimeter footing drain on each side of the
residence. Sections on Sheets A-5 through A-7 of the architectural plans show a similar footing drain
scheme in cross section view. Because the lower level of the residence is at two elevations, there is a
potential for groundwater seepage to be below the elevation of the drain on the east side of the residence,
but above the lower level of the residence. In this case, groundwater pressures could build up behind the
interior foundation wall. Groundwater buildup behind the wall could also result in a damp wall or
seepage through the wall in any cracks or joints. To address this potential issue, in our opinion it would
be prudent to install a foundation drain behind the interior foundation wall. Structural details on Sheet S-
6 show footing drains behind all foundation walls, including the interior foundation wall. We recommend
that the civil, architectural, and structural drawings be reviewed by the design team for consistency with
respect to the location of footing drains and that a footing drain be included behind the interior foundation
wall.
SP
TRUCTURAL LANS
Our review of the structural plans and calculations were limited to a cursory review to see that the
geotechnical recommendations have been addressed in the design.
We note that the geotechnical report recommends an allowable foundation soil bearing pressure
of 1,200 psf and provides recommendations for active pressure and passive resistance against retaining
walls. Our brief review of the retaining wall design calculations indicates that some of the wall sections
have apparently used an allowable soil bearing pressure of 1,800 psf in the design. The geotechnical
report also recommends that the upper one foot of soil be ignored for passive resistance, but it appears
that the retaining wall structural calculations have not ignored the upper one foot of soil. We recommend
that the structural engineer review the calculations to either confirm that these discrepancies do not affect
the retaining wall foundation design or revise the design as appropriate to be consistent with the
geotechnical recommendations.
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* * * * * *
This technical memorandum has been prepared for the exclusive use by the City of Edmonds in
evaluating the adequacy of permit submittal documents related to the proposed Issacson single family
residence building permit for property at Lot 2 and adjacent common area of the Plat of Lorian Woods on
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73 Place West in Edmonds, Washington. The focus of this review was the geotechnical aspects of the
application. The purpose of the review was to assess the adequacy of the application documents for
compliance with City requirements contained in ECDC 23.80 and ECDC 19.10 and conformance with
conventionally accepted geotechnical engineering practices. This geotechnical peer review by Landau
Associates does not lessen the requirements for the applicant’s geotechnical consultant and other design
professionals to prepare an appropriate design for the site conditions.
We appreciate this opportunity to be of service to the City. Please contact us if you have any
questions or if we may be of further service.
DRS/rgm
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