Forensic BMP Investigation

Best management practices (BMPs) include a long list of stormwater runoff treatment technologies that depend upon natural hydrological methods to secure high performance. The natural methods used by BMPs can be described as flow retention, infiltration, evaporation, evapotranspiration, and biologic processes. While the implementation of BMPs has increased over the past years, strategies are still needed to optimize their use in both large and small scales. There are many BMP risks and underperformance scenarios not fully understood or documented, which leads the system to unpredicted failures. Failure in these cases means that the facility could not meet the minimum performance thresholds for pollutant or stormwater volume reduction, and when this happens, a more in-depth investigation to diagnose the causes of failure is needed. This type of investigation is known as Forensic BMP Investigation (FBI). Some examples of FBI are severe inlet obstruction, inadequate pretreatment, sediment caking, standing water, inlet erosion, and/or erroneous design assumptions. There are many individual components that could be causing these failures, once the implementation of BMP’s is largely affected by the characteristics of the local environment, infrastructure, and regulations. There are numerous types of BMP systems, but this round table will focus on the underperformance and failure of bioretention facilities. The stormwater management field has a lot to benefit from understanding failure mechanisms and the ability to predict future failures. Therefore, participants of this roundtable will be presented with the opportunity to share FBI cases and discuss why the bioretention is not working and how it can be fixed.