Proposed Guidelines for Monitoring Stormwater Gross Solids

Stormwater gross solids are the coarse sediments, leaves, organic debris and human derived trash that are washed off during rain events, but are rarely quantified in stormwater studies. As part of ASCE/EWRI's Urban Water Research Resources Council, the Gross Solids Technical Committee is in the final stage of developing guidelines for measuring stormwater gross solids. The purpose of these guidelines is to standardize data collection procedures used in evaluating the removal of Gross Solids by Best Management Practices (BMPs) and to allow for direct comparison of field data from separate studies by using the same collection methodologies. This guideline does not address the pollutants in the water column since these methods have been well described elsewhere, but focuses on particles greater than 75 microns that are not measured using standard monitoring techniques. There are many variables to consider in monitoring gross pollutants. These include the purpose of the monitoring program, fiscal constraints, desired accuracy, parameters to be monitored, whether the BMPs traps Gross Solids in a wet, dry, or combined condition, and time constraints for completion of the program. Three program levels have been defined. Level 1 is basic collection of samples with a minimal amount of laboratory analysis. Level 2 starts with Level 1 and adds intensive techniques to separate litter, debris, and sediment, and uses laboratory analysis to quantify basic individual parameters of concern. Level 3 programs are research programs customized for specific goals. Note that the collection and analysis in each Level are minimum criteria, and additional techniques or parameters may be added as needed. These guidelines are preliminary and some of the recommendations have not been finalized. Also suggestions from other researchers in the field are encouraged.