Field Evaluation of Low Impact Development Practices for Treatment of Highway Runoff in an Ultra Urban Area

Abstract

The impact of two management practices, gutter filters and bioinlets, on stormwater highway runoff quality at an ultra urban area in Mt. Rainier, MD, was evaluated. The analyses were divided into 3 phases: before construction (32 events) (Flint,2004), gutter filters only (17 events) and gutter filters and bioinlets (14 events). Comparisons between phases 1 and 3 resulted in Total Suspended Solids (83%), cadmium (86-89%) and lead (84%) demonstrating statistically significant removal using the student's t test and the Mann-Whitney U test on the mean event mean concentration (EMC). Total Kjeldahl Nitrogen (12%), nitrite (42%) and copper (29%) demonstrated statistically significant removal, while Total Phosphorus (20-40%) indicated an increase in EMC by the Mann-Whitney U test after phase 3, but these values were insignificant based on the student's t test. Results support the application of these stormwater management practices in urban areas.