Stormwater Hydraulic Detention and Pollutant Removal Properties of Compost Blankets on Highway Fill Slopes

Focus Area

Water Quality/Wetlands


Natural Resources







Research Idea Scope

The compost blanket is a low impact development (LID) approach to flow control. Compost blankets could be used for stormwater hydraulic detention Best Management Practices (BMPs) to reduce the size requirements of conventional stormwater detention ponds, or even eliminate the need for them completely. At the same time, they have the potential for pollutant removal.
The most cost-effective stormwater treatment systems for linear highway projects may also be the simplest. Basic sheetflow off the roadway surface and dispersion over highway fill slopes is a centuries-old technique for drainage. However, this simple practice has been replaced in recent years by a preference for more elaborate stormwater treatment systems including ponds, swales, vaults, sand-filters, and other BMPs.
Transportation agencies currently provide landscaping for aesthetics on some projects. Compost blankets and compost soil amendments are commonly included as part of the landscaping. Also, use of compost blankets for temporary erosion-control BMPs instead of silt fencing is becoming more popular (Faucette et al., 2004; Middleton and King, 2003; Goldstein, 2002; Tyler, 2001). Often these installations are done independently from drainage design, and a separate stormwater treatment system is developed for the project. Designers could be taking advantage of these applications of landscaping and compost blankets by putting them to work as stormwater BMPs. 
Compost is already known for its ability to filter and remove pollutants from highway runoff (McDonald, 2005; Glanville et al., 2004; Nikolaidis and Chheda, 2001; Richman, 1997). We also know it promotes infiltration and holds water like a sponge. But little research has been done to evaluate how much detention value compost provides for highways.
 If designers and permitting resource agencies had hydraulic coefficient numbers for equations or models to show how much stormwater detention is provided by compost, the result could be simpler, more effective stormwater treatment systems that are also less expensive to build and maintain than currently conventional systems.

Suggested By

RNS. Sponsoring Committee: AFB40, Landscape and Environmental Design