Low Impact Development Implementation Studies


This project began in September 2000 and is now complete.  It was funded by the Maryland State Highway Administration.  The purpose of this study was to quantify the improvement in roadway runoff water quality from a highly urbanized area through the installation of LID retrofit technologies.  Storm water quality was monitored before and after LID practice installation.  Specifically, samples were being collected from a commercial/residential watershed located in Mount Rainier, Maryland.  The 1.3 acre drainage area extends along Rhode Island Avenue (U.S. Route 1) between the District of Columbia line and 33RD Street.  This runoff is piped to the Anacostia River, which is part of the Chesapeake Bay watershed.  The contaminants of interest are total suspended solids, heavy metals (copper, lead, and zinc), and nutrients (total phosphorus and nitrogen as nitrate, nitrite and total Kjeldahl).  

Runoff samples were collected for a six-hour duration during storm events.  The sampling protocol is designed to collect more samples at the beginning of the storm event to better characterize any first flush.  In addition, the flow rate is continually monitored, using water level measurements and a Palmer-Bowlus flume.  Flow rate is correlated with rainfall measurements.  Contaminant loadings and event mean concentrations for each storm event are determined using concentration and flow rate measurements.  


Data for 32 storm events have been collected for nearly 1.5 years.  The results show water quality typical for that from roadways and highly developed urban areas.  

In Fall 2003, a set of gutter filters were installed at the site.  Monitoring of runoff flow and quality continued throughout the installation period and beyond during the operation of the filters.  Data suggest water quality improvement after the gutter filter installation.  

In Fall 2004, a set of bioretention inlets was installed and monitoring continued.  Again, water quality improvement has been noted.  

The Low Impact Development Center assisted on this project. 

This work was completed by Master's students Kelly Flint and Ameya Pradhan.

A manuscript is in press describing water quality and pollutant flushing before the LID installation.



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September 26, 2006