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Drainage Area <br />Pretreatment Device <br />1" Event Peak <br />Runoff Rate (cfs) <br />Design Treatment <br />Capacity (cfs) <br />Drainage Area 1 <br />ecoStorm Model #1 <br />0.42 <br />1.9 <br />Drainage Area 2 <br />Aqua -Swirl #1 AS -3 Model <br />0.88 <br />1.8 <br />Drainage Area 3 <br />Aqua Swirl #2 AS -3 Model <br />1.39 <br />1.8 <br />Drainage Area 4 <br />ecoStorm Model #1.5 <br />1.07 <br />2.6 <br />Event <br />Existing Runoff <br />Rate (cfs) <br />Proposed Runoff <br />Rate (cfs) to <br />Regoinal Ponds <br />2 -yr (2.75 ") event <br />1.56 <br />16.27 <br />10 -yr (4.1") event <br />6.98 <br />26.16 <br />100 -yr (5.9 ") event <br />16.85 <br />39.27 <br />Table 1: Runoff Rates Summary <br />Table 2: Pretreatment Summary <br />The ecoStorm and Aqua -Swirl structures have been sized adequately enough to treat the 1" event and convey <br />the 10 -year rainfall events. A diversion weir was used for each system to contain and treat the 1" event, but <br />also to allow stormwater to by -pass during larger events. <br />CONCLUSION <br />The proposed design will provide pretreatment of storm water runoff prior to entering the City's stormwater <br />system. The proposed design meets the intent of the LRRWMO and City of Ramsey regulations which dictate <br />at least 80% of total suspended solids based on a 1" rain event. <br />CONTACT INFORMATION <br />This document was prepared by: <br />Landform <br />105 South 5 Avenue, Suite 513 <br />Minneapolis, MN 55401 <br />Please direct any questions regarding this narrative to Steve Sabraski, PE at ssabraski@landform.net or <br />612.638.0243. <br />Project No. UWA10002 <br />Suite Living at the COR <br />Stormwater Narrative <br />L AN D F OR M December 3, 2010 <br />2 <br />