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HomeMy WebLinkAbout2002-05-06 BRAA Email Re Drainage CalculationsKris Danielson From: PosUer, Dennis M[d oom] Sent: Monday, May 08.20025:30 PM To: Mark Vierl|ng (E-mail); Kris Danielson (E-mail); Scott Richards (E-mail) Cc' Kimberly Kamper (E-mail); Jay Johnson (E-mail); Judy Holst (E-mail); Jim Butler (E-mail); Katherine D. Widi Subject: Stillwater H.S. - draina calculations In response to Item No. 7of Mark's 4/25/02 letter to Ms. India Boulton and Mr. Jeffre Carpenter (addressin Para 12 of the CUP), we have reviewed FILE CO the draina calculations for the Stillwater Hi School Stadium Y Improvements as submitted b Anderson-Johnson Associates, Inc. These same draina calculations were submitted to the Valle Branch Watershed District and approved and permitted b VBWD on 3/28/02. The drainage calculations are acceptable as submitted. The school proposes to use two infiltration trenches and an infiltration basin on the west side of the proposed home bleachers bz handle the increased rate of storm water runoff basically not increasing the storm water runoff rate by more than 296 for the 2. 10. and 10O-yoar storm events. We would not normally consider infiltration into our more conservative storm water runoff modeling if this were tobea city-owned and maintained system, however, since these improvements will be privately owned and maintained and have been approved by the VBVVO. the proposed improvements are acceptable. The school will need bo maintain these trenches and basin onan on-going basis boassure infiltration iain fact occurring aamodeled. Dennis As previousl noted, the visitors bleachers are proposed to be constructed on top of an existin 15" storm sewer that is part of the school's privatel owned and maintained football field/track storm sewer s This storm sewer should probabl be relocated around the proposed bleachers to avoid potential future maintenance issues. K4.PosUer Boneatroo Ander1k&Associates 2335 West Highway St. Paul, MN 55113 Direct: (651) 604-4815 Office: (851)836'4600 Fax: (651) 63G-1311 Cellular: (812) 865-8187 E-mail: dpostier@bonestroo.com