20150407134324653.pdfMemorandum
Date: April 1, 2015
To: City of Edmonds Stormwater Engineering Department
Attn: Jerry Shuster
From: Nicole Hernandez, PE
Project: Former Woodway High School Field Improvements
Subject: Response to Comments — BLD20141182
Jerry,
91 1 Western Avenue, Suite 420
Seattle, WA 98104
p. 206.725.121 1
f. 206.973.5344
Ipdengineering. corn
Enclosed please find three (3) copies of the updated Stormwater Site Plan and design drawings for the Former
Woodway High School Field Improvements. Below is a list of your review comments for the permit re -submittal
dated November 11/12/2014 along with our responses which are reflected in the updated plans and report.
® Minimum Requirement # 6/Water quality System Page 12 — The text states that the sizing of the StormFilter®
system by Contech is located in Appendix B. This information was not found the review copy of the
Stormwater Site Plan, please provide. The 2 -year release rate flowing to these filters is stated to be 0.089 cfs.
The modeling in Appendix B has 0.094 cfs, please reconcile.
Response: The StonnIter sizing has been refined based on fisrther coordination with Contech. The current
sizing also reflects the 2 -year release and the flow rate is consistent between the model output, the storrnwater
site plan, and the Contech sizing sheet.
The City approves using the ZPG media cartridges at this point. Contech currently has a different cartridge
using MetalRxTM media that has "Conditional Use" designation from Ecology. The City only accepts
technologies with the "General Use" designation. When the ZPG media cartridges need to be replaced, the
City will require the School District to replace them with the cartridges with MetalRxTM media, if they have
earned the "General Use" designation by Ecology.
Response: Noted. The Stormwater Site Plan has been updated to reflect that the City will require the change
in media type to MetalRx once it has been approved far "General Use ".
® Sheet F-2.3, Detail I — The "Site Specific Data Requirements" for the StormFilter® system are blank and
should be in the detail, especially the invert elevations and the other elevations.
Response: The site specific informationhas now been included in. the StormFilter detail.
As mentioned previously in our email correspondence, we have further refined the modeling, flow control structure
and gravel storage layer of the field section to maximize the efficiency of the system while still meeting the flow
control requirements. Please let me know if you have any questions or need additional information. Thank you.
cc: File