Minnesota Department of Transportation
This study provides design information for temporary stormwater ponds with floating head skimmers. The purpose of the ponds is to remove suspended sediment and nutrient loads from stormwater runoff on active construction sites. The design information is directed at meeting the standards in the National Pollution Discharge Elimination System (NPDES) general permit which includes storing runoff from the 2-year, 24-hour rainfall event or providing the equivalent sediment control. The study results include: Research of currently available floating head skimmers, Estimation of runoff hydrology and hydraulics from active constructions sites using HydroCAD, Estimation of water quality improvements using P8, and Design plans. The study shows several available technologies for pond skimming. The pond and skimmer design manages a 2- year, 24-hour rainfall event while removing an average of 80 percent of total suspended solids (TSS) from runoff. Smaller systems do not operate equivalently without additional treatment such as adding flocculants. Plans, maintenance requirements, and special provisions are included.
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