489 - Rapid Assessment of Green Infrastructure to Identify Factors that Affect System Longevity

Impermeable surfaces in urban environments prohibit the natural infiltration of precipitation into the soil. Because infiltration plays a key role in water retention and pollutant removal, urban centers can contribute to flooding and contamination of receiving waters. Green infrastructure (GI) practices have been recognized as effective tools to mitigate some of these consequences and have been widely implemented. A possible shortfall of GI systems is their potential to become ineffective over time. Although many studies have followed the lifespan of individual systems, the diverse design and implementation of GI restricts how broadly these studies can be applied. The goal of this investigation is to identify controlling factors leading to long term functionality of one of the more widely used forms of GI: biofiltration systems. A rapid assessment technique was developed to measure readily available parameters that influence the success or failure of a system. This protocol was utilized by USGS offices in seven states to collect data from biofilters across a variety of soils, age, vegetation, and construction designs. The aggregated data from over one hundred biofilters will be statistically evaluated using a SHAP (SHapley Additive exPlanations) analysis model to identify the which parameters have the most significant influence functionality. Infiltration rate is used to represent the present functionality and is analyzed as a response to the thirty-seven quantitative and qualitative parameters collected for each site. The results will assist the decision-making processes for future implementation of bioretention by identifying parameters that optimize or threaten performance. The rapid assessment protocol can be a useful tool for evaluation of existing GI to identify installations that may be at risk of failure.