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HERRIGSTAD ENGINEERING PS <br /> Civil Engineer <br /> 4320 Whistle Lake Road Dale Herrigstad, P.E. <br /> Anacortes, WA 98221 (360) 299-8804 <br /> May 12, 2021 <br /> Mr. Steve Lange <br /> Project Manager <br /> City of Anacortes <br /> PO Box 547 <br /> Anacortes, WA 98221 <br /> Subject: 2001 12th Street Drainage Review Response of 2-26-2021. <br /> The following review comments and responses. <br /> 1. Project is not considered "Flow Control Exempt". There are downstream deficiencies downstream, <br /> therefore requiring a downstream analysis to determine Hydraulic Capacity of the system. Or fix the <br /> deficiency as part of this project. <br /> It was a mistake on my part to indicate "Flow Control Exempt". Our proposal is to infiltrate with <br /> a dry well in the southeast corner of the site. <br /> 2. The wrong drainage basin is called out. The actual basin is G11, not G8. <br /> Corrected. <br /> 3. The description of the downstream identifies an impact to two downstream property owners. <br /> Revised the basin description to indicate storm water flow onto property owners on the south side <br /> of the alley. We are proposing infiltration and not impact the downhill neighbors. <br /> 4. The drainage report did not discuss the grade of the alley way correctly. As proposed, the sheet flow <br /> will cross the alley way and onto the adjacent neighbors. <br /> Revised as indicated in #3 above. <br /> Please let us know if you have any additional comments. <br /> Sincerely, <br /> j4_ <br /> Dale Herrigstad PE, PLS <br />