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Quality Assurance Project Plan: Pilot Study for Non-proprietary Dissolved Metals Treatment: Oyster Shell Retrofits in Catch Basins

Quality Assurance Project Plan: Pilot Study for Non-proprietary Dissolved Metals Treatment: Oyster Shell Retrofits in Catch Basins

This document describes the project plan for an effort to determine the effectiveness of treating stormwater with oyster shells from 2019-2020. In the City of Mercer Island Town Center, two catch basins have been retrofitted to include oyster shell treatment. This retrofit design requires minimal construction, no impacts to above-ground areas, and is expected to have minimal maintenance requirements. Stormwater will be collected before and after passing through the oyster shell treatment for a total of ten storms. These samples will be analyzed for a variety of pollutants, including heavy metals like copper and zinc and compared to samples collected just upstream at catch basins fitted with baffles, but no oyster shells.
This comparison will show how well the crushed oyster shells reduce concentrations of heavy metals and other pollutants. If this pilot project shows that oyster shells successfully reduce heavy metals in stormwater, a more robust analysis could be conducted to have the treatment approved by the Washington State Department of Ecology for wide-spread use through the (TAPE) program.


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    Quality Assurance Project Plan: Pilot Study for Non-proprietary Dissolved Metals Treatment: Oyster Shell Retrofits in Catch Basins (2.21 MB)

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