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MONITORING OF A BEST MANAGEMENT PRACTICE POND IN THE STATEN ISLAND BLUEBELT
Citation:
OCONNOR, T. AND J. ROSSI. MONITORING OF A BEST MANAGEMENT PRACTICE POND IN THE STATEN ISLAND BLUEBELT. Presented at World Environmental & Water Resources Congress in Omaha, Nebraska, Omaha, NE, May 21 - 25, 2006.
Impact/Purpose:
To inform the public
Description:
The USEPA’s Urban Watershed Management Branch has monitored stormwater drainage and best management practices (BMP) as part of its research program. One BMP being monitored is 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 (DEP) as part of the Bluebelt program. The Blubelt incorporates BMPs on a watershed basis; dedicated funding to the DEP programs allows for maintenance of the BMPs. 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 anticipated removals of 55-57%. Of three events monitored for COD, one had no removal, the second negative 146%, and the third 37%. This increase in COD during the second event may be due to biological activity in RC-5 and seasonal considerations, i.e., decaying leaves and wetland vegetation going into dormancy. The largest SS and COD discharges occurred on 12/11/03, which was the largest rain (>1 in.) and flow event monitored. Results indicated that the number of storms monitored was adequate to describe SS removal using a paired t-test on composite influent and effluent data after applying log transformations. Directly calculating the significance using a statistical test for randomly comparing two data sets, non-paired results, indicated a 0.94 significance in the log transformed SS results at a power of 0.5, just shy of 95% confidence. The statistical analysis also implied that obtaining several more storm data might improve the statistical confidence with which the results could be stated. Maintenance activity, cleaning of the forebay and in this case, a good portion of the pond, was performed in the spring of 2005. Almost four truck loads of sediment and leaf litter was removed from the site. As each truck holds about 14 cubic yards of material, about 46 to 48 cubic yards of material was removed. Further monitoring is scheduled for the fall of 2005 to measure the effects of this maintenance activity, to better quantify seasonal effects of leaf decay, and to assess future scheduling of maintenance.