Four Levels of Assessment for LID Practices

The capacity to infiltrate stormwater is an important aspect of many low impact development practices. Quantitative evaluation of infiltration capacity has typically been performed by monitoring the inflow and outflow of various storms, and determining the infiltration through a mass balance. Monitoring programs, however, are typically of long duration (i.e. one or more field seasons), require intensive effort, and frequently do not yield useful data for individual LID practices. We propose a new approach for assessment of stormwater LID practices that includes controlled testing as a key component in a Four Level assessment program. In increasing order of effort, the four levels are: (1) visual inspection, (2) infiltration capacity testing, (3) synthetic runoff testing, and (4) monitoring.