Oral Presentation Freshwater Sciences 2023

Performance of stormwater retention basins constructed using different techniques in an urban environment prone to flash flooding (#174)

Brian Laub 1 , Melissa Garcia 1 , Lani May 1
  1. The University of Texas at San Antonio, San Antonio, TX, United States

There is growing interest in using green infrastructure, or low impact development (LID) facilities to help manage stormwater runoff and pollutant loading from newly constructed and existing urban areas. However, the feasibility and benefits of implementing such facilities across climate types and in multi-use urban environments, such as university campuses, needs to be demonstrated. We discuss the hydrologic retention, water quality improvement, aesthetic, and learning benefits of four bioretention basins constructed on a university campus in south-central Texas, a region prone to periods of extended drought and flash flooding. Water samples were collected at the inlet and outlet of each basin for at least four runoff events and measured for multiple water quality parameters including total dissolved solids (TDS), total suspended solids, turbidity, E. coli, nitrate, total nitrogen, total phosphorus, and several metals. Flow level monitoring was also conducted at the inlet and outlet of two basins and in a grassy channel that existed prior to construction of one of the basins. All basins effectively captured stormwater runoff and attenuated peakflows downstream. Water quality impacts were variable between basins, with the only consistent response across all four basins being an increase in concentrations and loads of TDS in outlet compared to inlet water. Two basins reduced loads of E. coli, two basins reduced first-flush concentrations of sediments and some nutrients, and one basin showed no significant improvement in any measured water quality parameter. Differences in water quality improvement between basins is likely attributable to differences in construction and materials. The most effective basin, although the most costly, is located on a highly-trafficked area of campus where signs provide information to students and visitors. This basin in particular shows that multi-functional LID facilities can be effectively integrated into urban environments such as university campuses.