CCP 05-10-1999 - Laserfiche WebLink

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I I , I I I I I I '- I I I I I I I , I REGIONAL POND CONSIDERA nONS Potential locations of regional detention ponds have also been considered as part of this project. Regional ponds can help to increase storm water runoff quality and control discharge rates into receiving waters such as streams, ditches, wetlands and lakes, Detention ponds are designed to trap sediment and pollutants in runoff water, Oil and grease skimmers are also included along with weirs and orifices to control discharge volumes, The Rice Creek Watershed district requires the treatment of storm water runoff from all new construction projects and reconstruction projects when possible. The City to date has constructed a number of storm water treatment ponds most recently in the Gateway Business District. Typically, storm water detention/retention ponds are the most economical and efficient way to remove pollutants from storm water runoff. In areas of limited land availability sump manholes and grit chambers have been used as well to improve water quality, The regional ponds would vary in size depending on the runoff area and type of land use, The regional ponds identified on the masterplan would typically require 1 to 2 acres ofland and cost between $50,000 and $200,000 each to construct. The construction costs are dependent on the size ofthe pond and site preparation and earthwork required in constructing each particular pond, This price range does not include property acquisition costs, In several cases the pond construction could be included in a road construction or reconstruction project in conjunction with the construction of a storm sewer system, In the City of Arden Hills 1998 Comprehensive Plan, lake characteristics were listed for all the lakes within the city. Water quality for each lake was quantified using the Trophic State Index (TSI), Based upon recommendations from the Minnesota Pollution Control Agency: a TSI less than 59 is swimmable, a TSI between 60-65 partially supports swimming and a TSI greater than 65 does not support swimming, The TSI for the lakes within Arden Hills are as follows: Lake Lake Johanna Lake Josephine Karth Lake Little Johanna Round Lake Sunfish Lake Valentine Lake Trophic State Index (TSI) 55 57 65 Unknown 58 Unknown 58 Swimmable Yes Yes No Unknown YesIMarginal Unknown YesIMarginal The City is currently in the process of establishing a Water Quality Task Force, which will be charged with developing systematic means to determine the health of the above lakes and recommend measures to be taken in order to improve the health of the lakes, The task force recommendations will playa major role in determining which regional ponds would be the most effective and therefor assist with setting priorities on pond construction and associated roadway reconstruction, Table 1.2 "Proposed Futnre Storm Water Treatment Pond Locations" lists the possible storm water ponds as shown on the masterplan and indicates approximate drainage areas, pond sizes, the receiving waters from the pond and potential means of construction. 10