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T <br />ledesel <br />From; Tyler Mason <Tyler.Maxson@westwoodps.com> <br />Sent: Tuesday, July'31, 2018 9:31 AM <br />To: Tom R€edesel <br />Cc: Daniel Parks <br />suisject: Gem Lake Hy-Vee Plan Changes and Watershed. Approval <br />Attaslimentsi 1845 Permit Withheld Letter 7-12-18.pdf <br />TO m, ` <br />Here's` the list of changes that the watershed requested of us, wh€ch should be all of the changes that were made to the <br />k <br />plans:; <br />I <br />i <br />1.. Submit revised model using the NRC5 MSE3 rainfa11.distributions. <br />f We have changed the rainfall distribution, Gould I ask wily this is required/whore that is <br />confirnunicated? We a runt always use Type 11 and. don't see where MSE3 is required in the <br />E rules. <br />11 Fiftration rate used does not'match the District' s dasign rates. .Based on soil horings, .0,8 in%hr should be used. <br />k <br />Q 'I'lie HydroCAD inodcl's filtration rate has been adjusted to 0.8:11n/hr. <br />3.' When using 0.8 Whr, the maximum.:ponding depth is 1.6 feet. Revise ponds.2 and 3 such that they draw down <br />within 48 hours. <br />3 0 Shouldn't this number be 3.2 feet ME in/hr * 48 .hr 112 in/ft = 3.2 f't)? If so, we sneet'this <br />I drawdown requirement, <br />4. Update. 1007year HWI-s on the plans far the proposed filtration BMPs once revisions are cornplete. <br />a Done <br />5.1 Provide detailed print-out of storage curve from HydrbCAD.to confirm reported storage volume. <br />o Done and included in the report. <br />5.! Revise the overflow..elevation for the south pond. The detail shows 960,31 while the model uses 95.0,21. <br />ip This has been fixed. <br />7.1Revise pipe invert for the south pond: The plans:show 956.5 w€ He the mode€ uses 956.29. <br />I 0 This has been fixed. <br />Some <br />vf these €ssues.were regarding the stormwater narrative or the stormwater model but may have caused small <br />grading changes to the: ponds.. <br />1 also .attached the watershed's.cond€tional approval letter/permit. <br />Pleas let me know if you have a.ny more questlo05.. <br />Thahks;. <br />Ty€er. <br />l <br />Tyler.maxson <br />GRADUATE ENGINEER <br />fy er.ma1(952) <br />son@wesfwoodps.com <br />Uri 697-5748 <br />Main 1 �952) 937-515.0 <br />