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RE_ Crabtree Detention Outfall-email from EOR.pdf From:Jared Underbrink To:McConnell, Jeanie Cc:Vicky Do;Greg Guillen;Richardson, Zachary Subject:RE: Crabtree Detention Outfall Date:Friday, December 8, 2017 8:28:02 AM Attachments:image002.png That makes sense. I understand they have some utilities to get through along that run. I just put the site in WWHM and the 100 year is 0.13 cfs which should work fine in a 6” pipe at 1% (0.4 cfs capacity). Thanks, Jared Underbrink, PE | Project Manager 250 4th Ave S Ste 200, Edmonds, WA 98020 p. 425.778.8500 | f. 425.778.5536 www.cgengineering.com From: McConnell, Jeanie \[mailto:Jeanie.McConnell@edmondswa.gov\] Sent: Friday, December 08, 2017 7:56 AM To: Jared Underbrink <JaredU@cgengineering.com> Cc: Vicky Do <VickyD@cgengineering.com>; Greg Guillen <GregO@cgengineering.com>; Richardson, Zachary <Zachary.Richardson@edmondswa.gov> Subject: RE: Crabtree Detention Outfall Hi Jared, You are correct that the simplified detention sizing tied to the 2016 storm code says 8” or 10” … in the case of the Crabtree project it would be 10”. There is some debate over whether this is necessary and if you are able to confirm that a smaller pipe size would be adequate for the flows from this project site, the City would approve it. Thanks for checking! -Jeanie From: Jared Underbrink \[mailto:JaredU@cgengineering.com\] Sent: Thursday, December 7, 2017 8:52 AM To: McConnell, Jeanie <Jeanie.McConnell@edmondswa.gov> Cc: Vicky Do <VickyD@cgengineering.com>; Greg Guillen <GregO@cgengineering.com> Subject: Crabtree Detention Outfall Jeanie, On the Crabtree Residence we have the detention outfall called out at 12”. I do not know why we did this but I assume that for whatever reason we thought it was a requirement for a pipe connecting into the right of way? The contractor called and asked if that could be reduced saying that you would approve as low as 6” with an email from me. I just wanted to check in and make sure that sounds right. Looking at the stormwater handout that was in effect at the time it seems like it ought to be 8” or 10” (I think the second “bolded” note is supposed to say 4,000 to 5,000 tributary area). We had just over 4,100 sf, so I think it would only be able to be reduced to a 10”. Thanks, Jared Underbrink, PE | Project Manager 250 4th Ave S Ste 200, Edmonds, WA 98020 p. 425.778.8500 | f. 425.778.5536 www.cgengineering.com