Interdependence of variables influencing pollutant removal performance of an infiltration garden treating parking lot runoff

Urbanization develops problems on non-point source and deterioration of the urban water cycle. (Hyun & Lee, 2013). Infiltration gardens have been recommended as a best management practices (BMPs) that uses natural processes to sustainably treat urban stormwater runoff. Since varying factors have interaction which affects the pollutant removal capability of a facility, this research was conducted to identify the factors that would yield an optimum removal performance of an infiltration garden (6 m x 1.2 m x 1.2 m) treating stormwater runoff from a 481 m2 asphalt parking lot located in Kongju National University, Cheonan City, South Korea. A total of 13 storm events from 2014 to 2015 were monitored. Statistical analyses using Pearson correlation was conducted and correlations with 95% confidence level are considered significant. Total sediment solid (TSS) was found to be significantly interrelated with turbidity, chemical oxygen demand (COD) and total nitrogen (TN) (r = 0.959 to 0.987; p<0.0001) implying that the removal of solid-phase material within the water column highly affected the performance of the facility for the reduction of other pollutants. In addition, the inflow rate of the runoff was found to be highly correlated with pH (r = 0.998; p<0.0001). It was evident through the conducted sensitivity analysis that investing on the treatment mechanisms of both TSS and COD to achieve removal capabilities to at least 90% of the facility will be beneficial for the overall removal performance of the system.