2002-06-26 CC Packet - Laserfiche WebLink

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.. Retention_Svstems - werponas Reftuir~ments Iftunftnance Tconlinued) 1[' tree growth on the embankment; damage to the emergency spillway; sediment accumulation around the outlet; and erosion within the basin and banks. Any necessary repairs should be made immediately. During inspec- tions, changes to the wet pond or the contributing watershed should be noted, as these may affect basin performance. ~. Sediment should be removed from the pond as necessary, ans! at least once eve 5 25 years (usually more frequently than once every 25 years). The frequency of sediment removal depen s on the years of gdiment accumulation that were incorporated into the design volume of the wet pond's permanent pool and forebay and on the OCCUrrence of any high-loading events. In most cases, no specific limitations have been placed on disposal of sediments removed from wet detention ponds. Studies to date indicate that pond sediments are likely to meet toxicity limits and can be safely landfilled. On-site sediment disposal is always preferable (iflocal authorities permit) as long as the sediments are deposited away from the shoreline to prevent their reenlly into the pond and away from recreation areas, where they could possibly be ingested by young children. . Sediments should be tested for toxicants in compliance with current disposal requirements if land uses in the catchment include commercial or industrial zones, or ifvisual or olfactory indications of pollution are noticed. Mosquito control, if necessary. 3-264 Minnesota Urban Smal~ Sites BMP Manual