CCP 03-15-1999 - Laserfiche WebLink

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I I I I I I I II I I I I I I ~ I REGIONAL POND CONSIDERATIONS Potential locations of regional storm water detention ponds have also been considered as a part of this report. 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 typically included along with weirs and orifices to control discharge volumes. The Rice Creek Watershed district requires the treatment of storm water runoff, prior to entering water bodies, 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 oflimited 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 to construct. The construction costs are dependent on the size of the 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. In the information, water quality for each lake was quantified using a Trophic State Index (TSI). From the Minnesota Pollution Control Agency recommendations: 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 with in Arden Hills are as follows: Lake Lake Johanna Lake Josephine Karth Lake Little Johanna Round Lake Sunfish Lake Valentine Lake TroD hie State Index ITSn 55 57 65 Unknown 58 Unknown 58 Swimmable Yes Yes No Unknown YeslMarginal Unknown YeslMarginal It is recommended that the City establish periodic monitoring and analysis of the lake water quality. The information gathered from monitoring will allow the City determine the effectiveness of storm water treatment measures and track the general health of the lakes. Table 2. "Proposed Future 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