PROJECT HIGHLIGHT
This project aims to evaluate design and maintenance criteria for a category of infrastructure known as low-impact development best management practices (LID BMPs). Few studies have analyzed the extent to which LID BMPs can capture and manage microplastic pollution from stormwater runoff. Through field monitoring and engagement with stormwater regulatory committees and permittees, this research will help fill data gaps needed to develop recommendations for solutions to mitigate microplastic pollution from urban runoff.
PROJECT SUMMARY
In the context of stormwater, the term 'best management practice' (BMP) describes a range of technologies that incorporate physical, chemical or biological processes to treat contaminants in stormwater runoff. Currently, there is no design or maintenance guidance for the BMP industry focused on managing microplastic pollution. Few studies have analyzed the extent to which BMPs retain microplastics.
This project is analyzing existing BMPs to determine their effectiveness at reducing microplastic pollution, with a specific focus on low-impact development best management practices (LID BMPs). These BMPs typically have small footprints, are widely distributed across urban settings, manage runoff close to its sources, and include media-based filters meant to help remove pollutants and contaminants from the water.
Working with Southern California Stormwater Monitoring Coalition (SMC) member agencies participating in a Regional BMP Monitoring Network, researchers have collected samples from six BMPs. The sampling includes 44 water samples (covering untreated runoff entering BMPs and treated runoff discharging from BMPs), 11 engineered media samples and field blanks. The media samples, collected during dry weather, will help reveal long-term accumulation of microplastics and whether current specifications for engineered media design effectively capture microplastics in biofiltration BMPs.
To facilitate analysis of this dataset, researchers have developed an automated tool using open source programming to calculate microplastic concentrations and generate visualization plots. The project also hosted a two-day workshop on stormwater management for 30 undergraduate and graduate civil engineering students from California State University, Long Beach and California State University, Los Angeles. Students learned about the importance of BMPs, state efforts to meet Clean Water Act requirements and emerging concerns about microplastic pollution.
The research will yield evidence-based recommendations for the design, operation and management of LID BMPs, providing essential information to regulatory bodies that oversee stormwater management and BMP designers. These recommendations will help make LID BMPs more effective solutions for mitigating microplastic pollution from urban runoff.