DNS BLD2022-0439 LANDAU Geotechnical Peer Review 3.7.2023LALSANDAU
March 7, 2023
City of Edmonds
121 5th Avenue North
Edmonds, WA 98020
Attn: Ms. Denise Nelson, Senior Permit Coordinator, City of Edmonds, Building Division
Transmitted via email to: denise.nelson@edmondswa.gov
Re: Supplemental Geotechnical Peer Review
Second Revised Permit Submittal Package for Angle Residence
Building Permit No. BLD2022-0439
Edmonds, Washington
Landau Associates Project No. 0074213.040.041
Dear Ms. Nelson:
An applicant proposes to construct a single-family residence at 15724 72nd Avenue West in
Edmonds, Washington (site). The proposed building site is located within the North Edmonds
earth subsidence and landslide hazard area.
Landau Associates, Inc. (Landau) previously reviewed the applicant's permit submittal package
and summarized its findings in letters dated July 12, 2022 (comments on original submittal) and
December 1, 2022 (comments on first revised submittal). The applicant's design consultants have
prepared a second revised permit submittal, based on Landau's December 2022 review
comments.
At the City of Edmonds' (City) request, Landau has reviewed the second revised permit submittal.
The review was completed in accordance with the scope outlined in Task Order No. 23-01, issued
under the amended 2021-2023 Professional Services Agreement between the City and Landau.
Landau reviewed geotechnical portions of the following documents for compliance with Chapters
19.10 and 23.80 of the Edmonds Community Development Code (ECDC):
• CAST Architecture. 2023. Architectural Plans. Revised February 13.
• CAST Architecture. 2023. Corrections Response — Cycle 2 Letter.
• CAST Architecture. 2023. Site Plan. Revised February 13.
• LDC, Inc. 2023. Civil Plans. Revised February 13.
• Swenson Say Faget Structural Engineers. 2023. Structural Plans. Revised February 13.
155 NE 100th St, Ste 302 • Seattle, WA 98125 • 206.631.8680 • www.landauinc.com
Second Revised Permit Submittal Package for Angle Residence
Landau Associates
Select comments from Landau's December 2022 review are reproduced below in italics. The
comments are followed by a brief assessment of the applicant's response:
• Review Comment: Building pad and foundation drainage and slope protection features
have been added to sheet RD-01. Fill stockpile limitations have been added to Sheets ER-01
and ER-02. It should be noted that Note 2 of sheet ER-01 states, "Cut slopes and soil
stockpiles should not be covered each day with plastic during wet weather." This appears
to be an error as it is typically recommended that cut slopes and soil stockpiles are covered
during wet weather. Provided the above error is corrected, it is Landau's opinion that this
comment has been adequately addressed.
Response: Note 2 of Sheet ER-01 has not been updated; at the time of this writing, the
note still reads "Cut slopes and soil stockpiles should not be covered each day with plastic
during wet weather." If the applicant's consultant (LDC, Inc.) revises the note as described
above, Landau will consider the comment to be resolved.
• Review Comment: The geotechnical engineering report has not been updated to include
recommendations for axial and lateral capacity of deep foundations. A cursory review of
the structural engineering calculations suggests that the proposed pile foundations have
been designed using the some allowable bearing capacity that was recommended for use
with shallow foundations. This is likely conservative for axial loading, though no lateral pile
analyses appear to have been completed. Landau recommends the proposed pile
foundations be evaluated for response to lateral loading.
Response: Based on email correspondence with Geotech Consultants, Inc. (GCI) and
Swenson Say Faget (SSF) Structural Engineers,' Landau understands that the lateral earth
pressures in GCI's October 3, 2022 geotechnical engineering study were used to analyze
the lateral response of deep foundations. SSF Structural Engineers has indicated that the
proposed structure will not provide sufficient restraint to require the use of at -rest
conditions. In Landau's opinion, this comment has been adequately addressed.
This letter has been prepared to facilitate the City's evaluation of permit submittal documents for
the proposed single-family residence at 15724 72nd Avenue West in Edmonds, Washington.
Landau reviewed geotechnical portions of the documents for compliance with Chapters 19.10 and
23.80 of the Edmonds Community Development Code and for conformance with conventionally
accepted geotechnical engineering practices. Landau's peer review does not diminish the
responsibility of the applicant's geotechnical consultant to serve as the project's Geotechnical
Engineer of Record. Furthermore, the applicant's consultants are responsible for preparing a
design suitable for the site conditions.
1 "Re: Angle Residence — Corrections Round 2." 2023. E-mail from Rob Ward of Geotech Consultants, Inc. to Sean Gertz of
Landau Associates, Inc. and Greg Coons of Swenson Say Faget Structural Engineers. January 19.
March 7, 2023
Second Revised Permit Submittal Package for Angle Residence
Landau Associates
Closing
If you have questions or comments, please contact Sean Gertz at 206.631.8680 or at
sgertz@landauinc.com.
LANDAU ASSOCIATES, INC.
r
Sean Gertz, PE
Senior Engineer
SC/SMG/SRW/mcs
[P:\074\213.040\R\ANGLE RESIDENCE SUPPLEMENTAL GEOTECHNICAL PEER REVIEW 3.7.2023.DOCX
References
City of Edmonds. Edmonds Community Development Code. Title 19 Building Codes. Chapter 19.10
Building Permits — Earth Subsidence and Landslide Hazard Area.
City of Edmonds. Edmonds Community Development Code. Title 23 Natural Resources. Chapter
23.80 Geologically Hazardous Areas.
Geotech Consultants, Inc. 2022. Geotechnical Engineering Study. October 3.
Landau. 2022. Geotechnical Peer Review: Permit Submittal Package for Angle Residence, Building
Permit No. BLD2022-0439, Edmonds, Washington. Landau Associates, Inc. December 1.
Landau. 2022. Geotechnical Peer Review: Permit Submittal Package for Angle Residence, Building
Permit No. BLD2022-0439, Edmonds, Washington. Landau Associates, Inc. July 12.
March 7, 2023 3