I have tried to track down such systems and learned that the success rate
with such systems is fairly low and the maintenance requirements quite
high. My recommendation is to design grass swales and infiltration trenches
into the parking lot so that sheet runoff passes across a section of turf
then into an infiltration trench or basin--instead of going into storm
sewers. I have seen a nice design in which strips of pavement were
interspersed with strips of vegetated (attractive) infiltration trench.
The Washington State Department of Ecology has done considerable research
on pollutant removal from stormwater and may be worth contacting in this
regard. The contact I have (some years old) is Helen Pressley, Stormwater
Unit, Water Quality Program, Department of Ecology, P.O. Box 47600,
Olympia, WA; 206/407-6456. They published a very good "Stormwater
Management Manual for the Puget Sound Basin."
The issue of frozen ground in New England, of course, complicates the
run-off situation.
>If the lot is not paved, has anyone had experience with using a membrane
>beneath gravel to keep run-off water from sinking into the ground, presumably
>carrying the pollutant with it?
>
Andropogon Associates in Philadelphia has done some very sophisticated
stormwater management systems for parking lots in which stormwater was
collected in reservoirs beneath the pavement and allowed to flow to
infiltration basins. They may have some materials available on this
(215/487-0700), but remember that they are in the business of selling
design services and may not be willing to volunteer too much information.
Contacts there is Carol Franklin and Rolf Sauer (pronounced "sour").
Alex Wilson
Environmental Building News
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