1610 SE EVERETT MALL WAY 2020-05-18

721k 1i [0, () (1`z) Anthem 13-197 May 1,2014 Response to 2009 City Comments Preface: The 2009 drainage report was edited and revised for this submittal. The original work is owned by HBA Design Group, LLC and by Anthem Self Storage (EM), LLC. Michael E. Ryan owns and maintain the records for HBA Design Group, LLC, and Harmsen &Associates has permission from the original author to use the content for this purpose. To make this report and design compliant with the City of Everett 2010 Drainage manual,we have recalculated all drainage flows and storage values with the use of WWHM2012. Stormwater discharge method has also changed. The 2009 design used a level spreader on the subject property to discharge storm water overland into WSDOT property—per WSDOT's request in 2009. Now, WSDOT has reversed their position and is requesting that we tightline the discharge directly into a WSDOT catch basin. The plans have been revised accordingly and we are in contact with WSDOT at present to obtain easements and temporary construction access. The developed site is relatively flat and nearly all covered with either rooftop or driving surfaces. All runoff is detained, but only runoff from the driving surface is treated and pre-treated,as was the original 2009 system. WWHM2012 has the gift of gab when it comes to generating reports,and uses such robust numerical prose that can only be appreciated by a true stormwater master with secrete ambitions of being an accountant. We are using the DOE provided,free version of WWHM2012 without any program or data alterations. With this in mind,the entire site report includes all talcs necessary to size the detention facility and outflow device, but also incorrectly assumes that all the water is being treated for water quality. We have broken the site into two sub-basins(north and south)for the purposes of collecting,treating and pre-treating the storm runoff from the driving surfaces. We have also created two additional WWHM2012 calculations that quantify the north and south driving surfaces for water quality treatment and pre- treatment. Thus,this drainage report contains three different WWHM2012 reports,one for Site detention and release talcs,and one for each of the two water quality sub-basins. All three reports are contained in the Appendix of the 2014 drainage report. We have removed the inappropriate components from the reports; the site report has been stripped of water quality data and the water quality reports have been stripped of storage data. -//0) X.\Oak I-larborA,I3-197 Anthem Storage\.CI DOCS\2009 City Comments\2014 05 01 Anthem Response to 2009 Comments-Drainage.docx