Filter Fabric Mass Load Capacity and Long-Term Performance

Underground chamber storage is a popular solution to meet stormwater detention, retention, and water quality requirements in urban settings, however little is known about the long-term viability of geotextiles used as filter fabric to remove stormwater-borne pollutants. Nationally recognized performance verification protocols such as the Washington State TAPE program and the New Jersey Department of Environmental Protection (NJDEP) protocols do not recognize buried filter fabric as an approved treatment solution due to maintenance and access concerns; however, these practices are still widely used across the United States. Issues such as clogging, bio-fouling and operations and maintenance are not wholly understood and resolved. This research examines the long-term water quality performance and maintenance triggers of an underground chamber storage system with filter fabric. Pollutant removal trials were conducted in a laboratory setting per the NJDEP filtration protocol in two phases: the first using inorganic sediment per the protocol, the second phase with the addition of organic sediment and hydrocarbons. Adding hydrocarbons and organics has been demonstrated to clog filters up to 10x faster and can better predict the long-term, in-situ filter fabric response. Results suggest filter fabric may clog quickly if hydrocarbons and organics are present in stormwater, which contradicts the limited existing literature data. In the absence of performance verification under a recognized protocol, understanding the response of filter fabric to long-term pollutant loading can better inform designers and regulators on how and when to use these devices.