Pollutant releases from gutter and piping materials into urban stormwater runoff

The primary objective of this research was to examine how different drainage system and tank materials, water characteristics, and exposure time affect contaminants leaching into stormwater runoff. Static leaching tests for eight pipe and gutter materials were conducted over a three month period during which pipe and gutter test materials were immersed in containers with roof runoff water buffered to pH 5 and pH 8. New research was conducted on the same eight gutter and pipe materials using water from Mobile Bay and Black Warrior River in Alabama. In this research, the release of heavy metals is being studied under naturally occurring pH conditions. Water samples were periodically analyzed for a wide range of metallic constituents. As pH decreased, copper concentrations in the copper gutter samples increased. The highest copper release was observed in bay water samples. Galvanized materials resulted in the highest concentrations of zinc. At lower pH conditions, zinc releases from galvanized steel materials increased during the first day of exposure. Zinc releases from galvanized materials were lower in river water samples compared to the bay water samples during short exposure time, however, during long time exposure, zinc concentrations in the river water samples exceeded those in the bay water samples. Galvanized materials were the only source of lead releases.