5.2. PCSR 06-10-2008 - Laserfiche WebLink

Home Browse Search

Civil Engineering Land Surveying Land Planning Apri125, 2008 Mr. Dennis Sharp Sharp and Associates 10907- - 93rd Avenue North Maple Grove, MN 55369 ,john OIIVer &Assvclates, Inc. 580 Dodge Avenue, Elk River,llIl~T 55330 (763) 441-2072 • Fax (763) 441-5665 eriverLa7er. joliverassoc. com Re: RENNER 4TH ADDITION -Elk River, Minnesota Dear Dennis: Enclosed are copies of drawings and applications for submittal to the City of Elk River. We have included Preliminary Plat, Grading, Drainage and Erosion Control Plan and Utility Plan. Drainage Calculations are also enclosed demonstrating ponding capability and storm sewer sizing. The Preliminary Plat creates five new lots and replats Raymond Renner lot shown as Lot 1, Block 1. The existing pond has been enlarged in a manner consistent with direction received from Raymond Renner and yourself. The pond as shown has sufficient volume without discharge to retain the runoff from the 3.0 inch rainfall event. Subsequently, a dead storage volume of 1,800 cubic feet per acre of drainage area to the pond is provided. The water quality volume is discharged at a rate not exceeding 5.66 cfs per acre of surface area at the water quality volume elevation. The water quality volume is calculated as 1/2 inch of runoff from the new impervious surfaces under developed conditions. The rear lot area of Lots 2 and 3 drain to an in-place pond on the adjoining Hutton and Rowe parcel. We are of the understanding that whatever agreement(s) may be required to facilitate this drainage pattern, they can be easily obtained as the property ownerships of Hutton and Rowe and Renner Properties, LLC are family members. There is no discharge from the Hutton and Rowe pond under the 100 year event. The development of Lot 6 provides for a future pond facility if needed. The proposed design provides for a discharge of 6.7 cfs from Lot 6 (subcatchment 16s; 10 year storm sewer). If this discharge and volume are insufficient for the full development of Lot 6, then additional ponding would be needed. The 100 year storm event is a backward flow from pond 1 to pond 2 to its point of discharge at 888.03 (a culvert under the driveway to Furniture and Things adjacent to Jarvis Street). ~~~~~ ~ t~,~t.'~1~~~ Offices in ilk River • Burnsville • Brooklyn Center • St. Cloud ti~~~: joli~Terassoc.com