Approved Drainage Report Memo For BLD2020-0142, 23517 75th Ave W05/21/20
Mark H. McDowell
McDowell Design Build Inc.
12345 Lake City Way NE #223
Seattle, Wa. 98125
Zachary Richardson, PE
Stormwater Engineer
City of Edmonds
Drainage Report Memo For BLD2020-0142, 23517 75t' Ave W.
The stormwater elements of this building permit proposal rely on and are
consistent with the previously approved civil plans for PLN2017-0065.
The final proposed impervious surfaces total is 2,853 sq ft, 35.6% of the
8,003 sq ft net lot size. The total is broken down into 3 separate areas:
• 2,521 SF of roof area including gutters, which is 18 SF less than the 2,539 SF
basin area shown in Bioretention #1 on the previously approved civil plans.
• 240 SF of hard surfaced driveway which, when combined with the 152 SF of
driveway on the adjacent lot and the 1,276 SF of roadway that is directed
towards Bioretention #3, is consistent with the previously approved civil
plans total of 1,669 SF basin area of bioretention #3.
• 92 SF of pervious surfaced walkway, not shown in the civil plans but added
to the impervious surface calculations on the building plans. It is designed to
be constructed in conformance with Edmonds Standard Detail SD-623,
"Typical Permeable Unit Paver System", including the full depth of the
specified storage rock beneath the pavers as called out in SD-623.
Together, these 3 areas will mitigate 100% of the stormwater generated on
the site, consistent with the previously approved civil plans for PLN2017-0065.
Thank you,
Mark H. McDowell
206 949 9180
COMPLIES WITH APPLICABLE
CITY STORMWAT R CODE
-Ot/21/2020