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
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.
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.
work was completed by Master's students Kelly Flint and Ameya Pradhan.
manuscript is in press describing water quality and pollutant flushing
before the LID installation.