STORM APPROVAL MEMO_BLD20191496MEMORANDUM
City of Edmonds
Engineering Division
Date: March 15, 2021
To: BLD2019-1496 File
From: Zachary Richardson, City of Edmoi
Subject: Storm Approval for BLD2019-1496
This memo is intended document the decision process prior to approval of permit
BLD2019-1496 after reviewing the applicant submittal letter dated 1/21/2021. Without
implying any warranty or approval of specifical claims or statements made in said letter,
the City has re -reviewed its role on the referenced permit and believes the permit has
adequately met City code and should be approved.
We find that all drainage requirements per ECDC 18.30 have been satisfied and
provided mitigation exceeds the minimum requirements. The project has demonstrated,
with industry standard hydraulic modelling, that the site will infiltrate flows up to and
including the 100-year flow. The project plans also show 6" of additional ponding depth
provided in the proposed infiltration facility which would be anticipated to manage some
flow in excess of the 100-year storm. An addition dispersion mechanism is also
provided after the infiltration facility overflow spillway to attempt to spread overflow
runoff out to sheet flow and mimic the natural condition as much as feasible. The
mitigation provided here exceeds the minimum required per City code.
The City's role in excess of the 100-year flow is limited to ensuring there is a safe and
certain overflow route as described in ECDC 18.30.060.D.4. It is not the role of the City
to remove any and all potential liability for the developer and/or design engineer.
The project engineer and property owner have both stated in written statements that the
overflow from the infiltration facility will flow in the same manner as the site did prior to
development and will be adequate as a safe and certain overflow path. With a dully
licensed professional making such a statement (see approved drainage report &
appendices in file BLD2019-1496), the City must except this as the safe and certain
overflow route.
As noted in the applicant submitted letter, the City does require owners and operators of
storm water best management practices (BMPs) or facilities to sign and record a
covenant on title to ensure the facility's protection, maintenance, and continued
operation. Said covenant does include a hold harmless clause, which the City believes
would be sufficient to protect itself from future claims which may extend beyond the
City's role of ensuring projects meet City code. The hold harmless appears to
adequately protect the City against future poor construction, maintenance, or operation
of the facility, all of which could potentially result in impacts downstream neighbors.
Accordingly, I recommend that BLD2019-1496 be approved for construction with a
condition of approval to require completion of the LID covenant typically required for
implementation of stormwater BMPs. This approval is only a statement that the
proposed drainage plan appears to meet City drainage code per ECDC 18.30. The City
has based its decision for approval on the limits of the City code, signed statements
from the property owner, and the signed plans and report produced by a civil engineer
appropriately licensed in the State of Washington. This approval shall not be
interpreted to waive or relieve the applicant or the engineer of record of any liability as a
result of the approved drainage plan; such liabilities may still exist and/or may be
beyond the City role in applying the municipal code.
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