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MONITORING OF A RETENTION POND BEFORE AND AFTER MAINTENANCE
Citation:
OCONNOR, T. AND J. ROSSI. MONITORING OF A RETENTION POND BEFORE AND AFTER MAINTENANCE. In Proceedings, World Environmental and Water Resource Congress 2006: Examining the Confluence of Environmental and Water Concerns, Omaha, NE, May 21 - 25, 2006. American Society of Civil Engineers (ASCE), Reston, VA, ,, (2007).
Impact/Purpose:
To inform the public.
Description:
The USEPA’s Urban Watershed Management Branch monitored a retention pond with wetland plantings in the Richmond Creek (RC) watershed. This BMP, designated RC-5, is owned and operated by the New York City Department of Environmental Protection’s (DEP) as part of the Bluebelt program. During monitoring performed in 2003 and 2004, RC-5 removed suspended solids (SS), but not chemical oxygen demand (COD). Calculated SS loads demonstrated a 61% removal exceeding the anticipated removals of 55-57%, however, COD was not being removed from the pond. Maintenance activity, involving the removal of sediment and organic matter (leaves) by vactor truck and physical labor, was performed in the spring of 2005. About four truck loads of sediment and leaf litter, estimated between 35 m3 (46 cubic yards), was removed from the site. Monitoring during the fall of 2005 measured the effects of this maintenance activity. The effluent concentrations of COD were significantly less after maintenance and calculated influent and effluent COD loading indicated removals. These results were also supported by drops in effluent phosphorous levels. Effluent SS concentrations were not significantly altered, implying the pond still had capacity to remove sediments. Indications are that the maintenance activity significantly reduced the COD effluent and may help communities manage nutrients loadings.
