ENV-11-17 Ozone-Based Remedial Action for Fractured Bedrock Site

Description:

URS Corporation and the Pennsylvania Department of Environmental Protection (PADEP) are currently implementing a remedial action at a former LUST Site located in a rural area in central PA that has impacted the local potable well groundwater supply. Significant issues at the Site include fractured bedrock hydrogeology, constituent distribution and fate, and public health. The former source area represents significant remedial challenges including fractured bedrock, a high hydraulic conductivity, multiple water-bearing zones, incongruent plume migration and groundwater flow direction, and groundwater usage. Several failed pilot studies including pump and treat, dual-phase extraction, modified Fenton's reagent injection, and conventional air-sparge have failed to demonstrate and adequate remedial approach for a timely clean Site cleanup. In 2009, URS installed a low pressure ozone sparging system to perform a pilot study of this technology. A 6-month study was performed and significant VOC reduction was observed throughout the study area. In 2010, URS expanded the ozone sparging system throughout the on-site source area. Since implementation of the ozone sparging technology, significant VOC reduction has been realized throughout the source area and downgradient of the active remediation area. The design of the ozone system is presented along with the performance monitoring results to date.