Bypass flow.pdfi......
MI
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MEMORANDUM
June 21, 2006
File
Don Fiene, Assistant City Engineer
Lyle Chrisman, Engineering Program %M/anager
Damon Roth, Stormwater Engineer 1 l
Bypass Flow — Michel Single Family Residence @ 15911 74th Pl. W
A proposed single family residence at 1591174"" Pl. W includes approximately 1,240 square feet
of pavement installed in City ROW that cannot be directed to the private detention system
because of grading. Typically, the increase in flow from this bypass area would need to be
accounted for in the detention calculations and the total flow from the site (bypass + detained)
would need to match that from the predeveloped site (bypass + detained). However, in this
instance, it was determined that the additional impervious surface area would only increase the
flow from the bypass area by 0.01 cfs. Therefore, in this instance, it was determined that it was
not necessary to offset the increase in flow from the bypass area by the detention system because
the increase in flow was so minor.
City of Edmonds