Agenda - Public Works Committee - 05/15/2007

Home

City Engineer Jankowski indicated 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 of Ford Brook. A sub drainage divide occurs 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 CR 63 and its southern ditch line. The impervious area'ofthe greenhouse property has been calculated to be 24 acres. In comparison the maximum amount of impervious area coming off the county road is less than one acre. City Engineer Jankowski advised 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 of ponding 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 allows the water to flow by gravity toward Trott Brook, a distance of several hundred feet based upon the experience of the Public Works Department through its remedial pumping. Mr. Jankowski advised it is the recommendation of staff that the permanent solution to the drainage problem experienced by the greenhouse should be to implement the drainage plan proposed in the MFRA report. The impact of runoff from the county highway does not appear to be a significant factor in the ponding problem experienced by the greenhouse. The elevation of the county road is virtually the same elevation 400 feet to the east and the runoff from the highway is contained in the county ditch at this location which is adjacent to all open field. Mr. Jankowski indicated the Committee may wish to consider to continue to assist the greenhouse in emergency situations as it has in the past and to provide technical advice if needed. The Committee, staff and Mr. Rowe discussed the layout of the Green Valley Greenhouse site, drainage on the site, the amount of impervious surface, City resources that have been extended to assist in pumping water from the site, and the stormwater utility fee paid by Green Valley Greenhouse, Councilmember Dehen inquired about the cost to complete the plan prepared by MFRA Inc. Public Works Director Olson indicated these costs have not been provided to staff at this time. This information is being presented to the Committee as a first start to determine the interest in assisting with this situation. There has been a lot of discussion about whether there would be a reduction or an increase in the stormwater utility fee for this particular business, which has not been resolved yet. There was not much of a storm drainage system in place here. Mr. Olson pointed out that the purpose of the stormwater utility is to protect drainage issues like this. He indicated staff is interested in the City trying to provide some assistance in this matter commensurate to what portion of the problem is created by the City. Public Works Committee / April 17, 2007 Page 11 of 18