Kaiser tested a pilot pump-and-treat system to remove PCBs from groundwater. The system filters groundwater through crushed walnut shells to capture the contaminants. However, new technologies to remove PCBs from groundwater have been identified since the agreed order was first amended to include testing a walnut-shell filtration system. Research shows these new technologies could be more effective and result in a shorter cleanup timeframe, so additional testing is proposed. The testing will help us select the most appropriate cleanup technology for removing PCBs from groundwater at the site.
We will respond to all the comments we receive and publish our responses. If public comments result in substantial changes to our proposal, we will hold another comment period.