Atrium Lobby (Hyatt Regency Baltimore on the Inner Harbor)
Full-scale implementation of in situ chemical oxidation (ISCO) remediation of PCE and TCE contaminated groundwater is currently in progress at two fractured bedrock sites. Both sites have suspected DNAPL present in the bedrock, and both sites have completed their first phase of ISCO injections. Site 1, located in Pennsylvania, has TCE concentrations ranging up to 10’s mg/L and has inter-bedded shale and siltstone bedrock. Site 2, located in South Carolina, has PCE concentrations ranging up to 15 mg/L with discretely fractured metagabbro bedrock. At both sites, ISCO implementation was designed to target primary fracture migration pathways with particular focus on the suspected DNAPL source areas to treat as much mass as possible. Recirculation of groundwater with amendment of permanganate was used to deliver permanganate to as wide an area as possible, while preventing the migration of oxidant-laden groundwater off-site and keeping it distributed in the treatment area. Pulsed injection of permanganate in phases followed by rebound monitoring was used to minimize oxidant mass consumption and wastage through targeting only those areas where rebound occurs, which prevents overdosing areas where minimal DNAPL mass is present.
Both sites have undergone two phases of oxidant injections. The results of the first phase of injection was used to focus the second phase of injections. Overall treatment performance and lessons learned will be presented.
