Engineering comment.pdf1 J
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January 13, 2010
Mike Clugston, Planner
JoAnne Zulauf, Engineering Technician
PLN20090056, Accessory Dwelling
18106 Andover Street
Engineering has reviewed and approved the subject application with the following condition
to be noted in the staff report.
At this time the applicant proposes to add a total impervious area equal to 1400 square feet.
Existing impervious surface is noted as 4129 sf constructed in the year 2000. Per Edmonds
Community Development Code (ECDC) Chapter 18.30, all impervious surface area
constructed after July 7, 1977 requires on site detention. A review of the site plan and the
June 8, 1995 AGRA geotechnical report shows that the drainage of the existing home conveys
directly into the City storm system without being detained on property. Therefore
construction of this addition would require the construction of a detention system sized for the
cumulative 5,529 sf of impervious surface. See attached Storm Water Management Drainage
Planning handout #E72 for more information. Verification of the impervious surface area
and sizing of the storm detention system will be reviewed by the Engineering Division at the
time of building permit submittal. Since the total impervious area exceeds 5000 square feet
the storm detention system will need to be designed and stamped by a licensed engineer.
Thank you.
City of Edmonds