Assessment of Bioswale Efficiency in Altering Stormwater Run-off Timing and Duration

Abstract

ABSTRACT Growing land cover and population densities generate increased impervious surface and pollution that deteriorates our water bodies. Impervious surface impedes ground water recharge and instead promotes the discharge of heavy metals, trash, and other pollutants, collected by stormwater runoff, into nearby water bodies. A bioswale has been implemented at SUNY Purchase College Campus in the outermost extent of the W1 parking lot to improve downstream stormwater runoff, as it contributes to the pollution of both Blind Brook and the Long Island Sound. The effectiveness of the bioswale was assessed through a paired watershed study of runoff quality from two similar, large parking lots, W1 and W2, located on the west side of campus. Stormwater runoff events were analyzed to test the effectiveness of the bioswale at increasing discharge durations and delays from rainfall peak to discharge peak. The median values for discharge durations and delays from rainfall peak to peak of W1, W2 and the bioswale were 37.3, 26.5, 17.25, and 1.75, 1.41, 6.2, respectively. W1 and W2 produced indiscernible median values for both analyzed temporal aspects of runoff. Therefore, it is inconclusive that the bioswale provided improvement of stormwater runoff impairment experienced in Blind Brook, or Long Island Sound.