REVIEWED BLD2024-0473+STATEMENT OF RISK+4.9.2024_1.19.10_PM+4185704RECEIVED
BLD2024-0473
4/11 /2024
-_ REVIEWED -
CITY OF EDMONDS
BY
DEVELOPMENT
CITY OF EDMONDS
SERVICES
DEPARTMENT
? BUILDING DEPARTMENT?
..............................................
COBALT
Cobalt Geosciences, LLC
GEOSCI CES
P.O. Box1792
North Bend, WA 98045
January 29, 2024
RR Foundation Specialist
Attn: Alesha, Ty -Lynn, Jordan, or Amanda
RE: Geotechnical Hazard Statement of Risk
Foundation Mitigation
16o12 74tn Place West
Edmonds, Washington
In accordance with your authorization, Cobalt Geosciences, LLC has prepared this letter to
discuss our review of the provided plans and to provide a statement of risk per City of Edmonds
code requirements.
In preparation of this letter, we have reviewed the following documents:
• Structural plans by Longitude L12o dated September 20, 2023
We have reviewed the provided plans and the information presented appears to include relevant
geotechnical information consistent with our findings, typical engineering standards, and recent
report/evaluation.
The risk of damage to the proposed development and adjacent properties from soil instability will
be minimized subject to the conditions set forth in the geotechnical report prepared by Cobalt
Geosciences, LLC. The proposed foundation mitigation work will not increase the potential for
soil movement provided proper TESC and BMPs are installed properly and maintained until all
landscaping and earthwork is completed. This work is a repair of the existing foundation system
and will not increase or decrease the risk of instability of the soils in this area and nearby areas.
There will always be a risk of soil movements along the slope face where magnitudes exceed about
50 percent and weathered soils are present. At this site, the risk will remain generally low
provided slope areas remain fully vegetated and runoff is fully controlled and directed away from
the slope areas. Provided these conditions are met, the probability of earth movement within a 25
year period is approximately 5 percent. The amount of movement will likely be restricted to near
the slope face and would be less than a few inches over that time period.
The site is situated in the southern one-third of the North Edmonds Earth Subsidence and
Landslide Hazard Area (NEESLH) per the City map.
The work consists of foundation repair and does not include specific measures to mitigate
landslide risks. The pier installation work may provide a limited increase in local stability but is
primarily intended as a mitigation for vertical foundation movements related to soil settlement.
Closure
The information presented herein is based upon professional interpretation utilizing standard
practices and a degree of conservatism deemed proper for this project. We emphasize that this
report is valid for this project as outlined above and for the current site conditions and should not
be used for any other site.
www.cobaltgeo.com (2o6) 331-1097
January 29, 2024
Page 2 of 2
Geotechnical Letter
Sincerely,
Cobalt Geosciences, LLC
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www.cobaltgeo.com (2o6) 331-1097