Agenda - Public Works Committee - 04/17/2007

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CASE # 7 RECEIVE REQUEST FROM GREEN V ALLEY GREENHOUSE FOR DRAINAGE IMPROVEMENTS By: Steven Jankowski, City Engineer Background: Attached to this case is a letter dated March 16, 2007 from Mr. John Rowe ofGfeen Valley Greenhouse requesting the City to address a drainage issue which exists along the portion of the property fronting along CR 63, Green Valley Road. Attached to this case are two photos illustrating the nature of the problem on March 12,2007 during a recent snow melt event. During the March snow melt event the Public Works Department provided equipment to pump the water several hundred feet to the south to a point where the water could flow by gravity to the Trott Brook. The Public Works Department has responded twice to this problem in the last five years as a similar situation occurred several years ago. A drainage plan had been prepared by MFRA Associates, an engineering consulting firm hired by the greenhouse, in 2006 which has been submitted to the City as documentation for a credit toward the storm water utility fee. This drainage plan appears to correct the problem situation described above. Mr. Rowe explained that the concern expressed in his letter centered on the cost of the improvements and whether the proposed drainage system would be handling runoff coming from areas outside of his property, Staff has prepared a cursory review of the area surrounding the greenhouse property utilizing the two foot contour topographic maps prepared in 2003.The greenhouse property is approximately 37,5 acres in size, The general direction of surface flow is from west to east and north to south. The northern limit of the drainage area is the centerline of CR 63 since there are no culverts crossing the highway, The north side of the road drains to County Ditch 14, a tributary ofFord Brook. A subdrainage divide occur approximate 200 feet west of the west property line of the greenhouse. An area of approximately 5 acres drains from this area onto the green house property, Similarly, an area of roughly this size or larger drains from the east side of the greenhouse property onto the neighboring property to the east. The only remaining area which drains onto the greenhouse is the CR 63 and its southern ditch line, The impervious area ofthe greenhouse property has been calculated to be 24 acres. In comparison the maximum amoW1t of impervious area coming off the county road is less than one acre. Observations: One permanent solution to the drainage issue described above would be the installation of the drainage plan prepared by MFRA Inc. This plan was prepared to reduce the storm water charges through the installation ofponding along the south edge of the property. Alternative solutions are also possible and may be as simple as ditching and culvert redirecting water from the low point along the county road to a point where gravity