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HomeMy WebLinkAbout2002-06-14 BRAA Email Re Grading & SW-SS CalculationsKris Danielson From: Postler, Dennis M [d postler a@bonestroo. com] Sent: Friday, June 14, 2002 2:09 PM To: Kris Danielson (E- mail); Scott Richards (E -mail) Cc: Kimberly Kamper (E- mail); Judy Holst (E- mail); Jay Johnson (E- mail); Jim Butler (E- mail); Mark Vierling (E- mail); Katherine D. Widin (E -mail) Subject: Century Power & Equipment - Building Addition & Remodeling t] Century Power Equipment - Bldg... Kris: I received the fax you forwarded with updated plans and drainage calculations. The faxed plan sheets are too small to read relative to verifying previous comments regarding utilities. Stormwater Calculations /Storm Sewer: The updated drainage talcs show storm water runoff for existing and proposed conditions for 2, 10 and Igo - year storm events. These talcs are acceptable as submitted relative to storm water runoff for the entire site. A drainage area map was included (Sheet D1) It appears the rate of runoff is increasing by over 3 112 times for all rainfall frequencies. We normally require post development rates of runoff to be equal or less than existing conditions. This condition is waived for individual sites if a downstream storm water pond is in place to handle rate control. In this case, no downstream storm water pond exists to handle the increased flow (other than Long Lake in Stillwater). As such, we, and I'm sure BCWD, will want to see how this additional runoff is proposed to be controlled to existing rates. (Previous comment regarding existing surge basin still applies.) Parking Lot/Grading: The new grading plan shows significantly more grading into the existing raving at two locations -- 1) At the proposed trash enclosure area and 2) at the northwesterly bituminous driveway /parking area. The original plans had a retaining wall at the 2nd location to help minimize grading which now appears to have been removed. The 1st area has presumably increased due to now utilizing proper grading slopes. We would recommend either pulling improvements back from these areas to minimize grading /tree removals (particularly the trash enclosure area - -does it need to extend that far west ?), or installing retaining walls at these locations. Their proof of parking area would require additional grading /filling in of the existing ravine. Previous comments attached: << Century Power Equipment - Bldg Addn — email to Cityj- 5- 02.rtf» Dennis M. Postler Bonestroo, Rosene, Anderlik & Associates 2335 West Highway 36, St. Paul, MN 55113 Direct: (651) 604 -4815 Office: (651) 636-4600, x4815 Fax: (651) 636 -1311 Cellular: (612) 865 -9187 E -mail: dpostler @bonestroo.com