LANDAU REVIEW Larsen Residential Addition Peer Review Letter 8.6.2020LANDAU
AssociATEs
August 6, 2020
City of Edmonds
121 5th Avenue North
Edmonds, WA 98020
Attn: Ms. Kristin Johns, Senior Permit Coordinator, City of Edmonds, Building Division
Transmitted via email to: kristin.johns@edmondswa.gov
Re: Geotechnical Peer Review
Submittal Package for Larsen Residential Addition
Building Permit No. BLD2020-0564
Edmonds, Washington
LAI Project No. 0074207.010.011
Dear Ms. Johns:
An applicant proposes to construct a residential addition at 7329 158th Street Southwest in Edmonds,
Washington (site). At the City of Edmonds' (City) request, Landau Associates, Inc. (LAI) has completed a
third -party review of design/geotechnical documents prepared by the applicant's consultants. The peer
review was completed in accordance with the requirements in Task Order 20-06, issued under the On -Call
Geotechnical and Environmental Engineering Services Agreement between the City and LAI, dated
January 23, 2020.
LAI reviewed the following documents for compliance with standard geotechnical engineering practices in
the Puget Sound Region and with Sections 19.10 and 23.80 of the Edmonds Community Development Code
(ECDC):
• ASPI Land Surveying and Planning. 2018. Short Plat. April 23.
• CG Engineering. 2020. Civil Plan Set. May 5.
• CG Engineering. 2020. Structural Plan Set. March 23.
• H2D Architecture + Design. 2020. Architectural Permit Set. July 1.
• Nelson Geotechnical Associates, Inc. 2019. Preliminary Geotechnical Engineering Evaluation.
February 28.
In LAI's opinion, Nelson Geotechnical Associates' (NGA) preliminary geotechnical engineering evaluation
includes geotechnical design recommendations that are appropriate for the site and the proposed
addition. The evaluation also includes adequate documentation of existing site conditions, based on NGA's
field reconnaissance and subsurface explorations. In its preliminary evaluation, NGA provides an
assessment of seismic, erosion, and landslide hazards present at the site.
NGA's preliminary evaluation satisfies most of the requirements in Sections 19.10 and 23.80 of the ECDC;
however, LAI notes the following deficiencies:
130 2nd Avenue South • Edmonds, Washington 98020 • (425) 778-0907 • www.landauinc.com
Geotechnical Review — Larsen Residential Addition
Landau Associates
• In its preliminary evaluation, NGA recommends constructing a debris catchment wall in, or
adjacent to, the proposed addition; however, the evaluation does not include lateral earth
pressures that can be used to design the wall. The evaluation should be updated to include lateral
earth pressures, consistent with a debris -flow impact against the face of the wall.
• The debris catchment wall recommended by NGA is not identified in the plan sets reviewed by LAI.
The applicant's permit submittal should be updated to include the proposed location and
configuration of the debris catchment wall.
• NGA's preliminary evaluation does not recommend a minimum building setback from the hazard
area, as required in Section 23.80.070.1 of the ECDC. The evaluation should be updated
accordingly.
• NGA's preliminary evaluation does not recommend a buffer distance from the hazard area, as
required in Section 23.80.070.2 of the ECDC. The evaluation should be updated accordingly.
• NGA's preliminary evaluation does not confirm that the proposed addition meets the development
standards in Section 23.80.060 of the ECDC. The evaluation should be updated accordingly.
Landau Associates prepared this geotechnical peer review letter for the exclusive use of the City of
Edmonds to evaluate permit submittal documents related to the proposed residential addition at 7329
158th Street Southwest in Edmonds, Washington. Landau Associates only reviewed geotechnical aspects of
the documents. Review of non-geotechnical documents was performed for the sole purpose of verifying
compliance with the recommendations in Nelson Geotechnical Associates' preliminary geotechnical
engineering evaluation. Landau Associates' review does not relieve Nelson Geotechnical Associates of its
responsibility as the geotechnical engineer of record, nor does it relieve Nelson Geotechnical Associates
and the applicant's other design professionals of their responsibility to prepare a design appropriate to the
site conditions.
We appreciate this opportunity to be of service to the City. Please contact us if you have questions or if we
can be of further service.
LANDAU ASSOCIATES, INC.
Sean Gertz, PE
Senior Project Engineer
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Steven R. Wright, PE
Principal
SMG/SZW/mcs
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August 6, 2020