MTC Memo #1 - Mock Res CA Commentary (16B186) 4-27-19.pdfMaterials Testing & Consulting, Inc.
Geotechnical Engineering • Materials Testing • Special Inspection • Environmental Consulting
April 27, 2019
GEOTECHNICAL MEMORANDUM #1
To: Darrin Mock
Property Owner
Cc: Greg Guillen, PE, SE; CG Engineering
Mike Clugston, et al.; City of Edmonds
Re: Proposed Residential Structure Repairs — Critical Area Commentary
21100 88th Place West, Edmonds, Washington
MTC Project No.: 1813291
Dear Mr. Mock and Project Team:
At your request, Materials Testing & Consulting, Inc. (MTC) provides this memorandum regarding
suitability of the proposed project with respect to the bordering critical area slope at the project site, an
existing single-family residence. The project generally entails partial reconstruction of a failing dry -
stacked retaining wall and replacement of select isolated column footings supporting a second story
overhang related to the wall in the same location. The work area resides in close proximity to a
designated critical area slope (of natural grade) as a result of prior construction at that location. We
understand that the work is undergoing final permitting for construction, and the local municipality has
requested that MTC verify the project will meet applicable standards for critical area protection.
Site investigation and engineering work by MTC for the repair project is presented in the letter of
Geotechnical Evaluation — Mock Property Existing Residence (October 29, 2018) for the subject
property. The prior work generally included targeted explorations at the repair area, visual assessment of
adjacent slope conditions for critical area concerns, and block wall section design. Following report
submittal, MTC held discussions with and provided consultation to the project structural engineer. To
our knowledge, since our previous visits there have been no changes of significance to the project design,
nor to the site conditions, that would require further commentary or review. Therefore, the previous
recommendations and design parameters provided by MTC as well as our understanding of site critical
area conditions are considered to remain valid.
From a geotechnical perspective, the proposed improvements constitute a necessary repair to the existing
structure that intends to implement a permanent improvement to the stability of the affected portion of
the residence foundation and the adjacent exterior wall supporting the rear patio apron that is closely
associated with the main structure. It is our understanding that the repairs will not decrease existing
structure setbacks or increase encroachments upon the adjacent slope, but that the repairs will
unavoidably constitute work directly at the boundary of the critical area slope. Assuming proper care is
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Mock Residence Repairs — Memorandum #1: Critical Area Commentary Materials Testing & Consulting, Inc.
April 27, 2019 1813291
taken during construction and appropriate restorations to the work area (top -dressing, replanting, etc.) are
done following construction, it is our opinion that the project will adhere to City of Edmonds
Development Standard 23.80.060 by avoiding adverse impact to the critical area slope and not increasing
the threat of hazard to adjacent properties. In fact, the repairs are intended to improve the stability from
the existing conditions, and as a result are expected to reduce the level of hazard from those present.
Furthermore, no alterations or clearing are proposed to the critical area slope itself, the project is
designed to minimize the load placed upon sensitive surface soils (via use of pin piles), and the current
scope of improvement will not alter site stormwater conditions. Thus the project adheres to City of
Edmonds Development Standard 23.80.070.
It is our understanding that MTC will be retained for construction phase testing, observation, and
geotechnical consultation services on an as -needed basis to address permit requirements as well as any
unanticipated issues that may arise during construction. For this project, such services may include but
are not limited to earthwork support consulting, footing subgrade verifications, compaction testing of
common site fills and structural fills, observing pile installations, laboratory materials testing, and special
inspections as may be required.
Mr. Mock, we trust this correspondence will satisfy your needs. If you have further questions, please feel
free to call. We appreciate the opportunity to be of further service to your project.
Respectfully Submitted,
MATERIALS TESTING & CONSULTING, INC.
019
John R. Gillaspy, L.E.G.
NW Region Geotechnical Division Manager
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