Green stormwater infrastructure is implemented as part of a distributed stormwater management system meant to mimic natural hydrologic conditions in developed, urban spaces. It consists of infrastructure such as bioretention cells (rain gardens), green roofs, and permeable pavers, all of which use engineering media to remove pollutants and allow stormwater runoff to infiltrate into the ground immediately where it is generated. It also typically provides green space in urban areas, which can lead to improved community health outcomes.
This work was conducted during my master's degree at Virginia Tech. We sampled a bioretention cell (BRC) 7 years post-construction to compare nutrient, peak flow, and volume reductions to data collected immediately after the bioretention cell was built. This was novel at the time (2013-2014), as few BRCs had been sampled several years after installation. We found that the BRC was functioning well, and was not likely to need immediate maintenance via removal and replacement of BRC media, which had been the prevailing thought at the time. We also quantified denitrifying bacteria throughout the BRC media, and found that the highest concentrations were in the top layers of the media, rather than the anoxic layer designed specifically for nitrogen removal.
Publication: Willard, L.L., T. Wynn-Thompson, L.H. Krometis, T.P. Neher, and B.D. Badgley. 2017. “Does it pay to be mature? Evaluation of bioretention cell performance seven years postconstruction.” J. Environ. Eng. 10.1061/(ASCE)EE.1943-7870.0001232.