Evaluation of Regional VOC Plume and Identification of PRPs
- Historical research and analysis and potentially responsible party (PRP) identification
- Evaluation of fate and transport of volatile organic compounds (VOCs) in soil and groundwater
- Database management and preparation of geographic information system (GIS) project
EEC Environmental (EEC) was retained to provide litigation support to identify PRPs and to evaluate the current or potential future impact to underlying groundwater from volatile organic compounds VOCs and hexavalent chromium in a groundwater basin in Southern California. EEC performed in-depth historical research to identify PRPs including an extensive evaluation and review of parcel and address information; review of environmental regulatory agency websites; review of building permits; review of city and business directories; and/or review of historical newspapers, to identify a potential business that may have occupied a property.
An evaluation was then conducted on the nature of operations, hazardous materials used, hazardous waste generated, and other pertinent information to determine if the evidence showed or suggested that chemicals of concern were used on the site based on the types and periods of operations. EEC evaluated the quantities of chemicals used, documented releases to the subsurface, the presence of subsurface conduits, and documented chemical handling practices.
For all sites, EEC compared the available information and triaged the sites based on the strength of the evidence indicating that use of contaminants of concern impacted the subsurface. The PRPs were identified by evaluating the types of businesses, the operational histories, the indication of a potential regulatory file or case at a regulatory agency, and additional evidence of a potential threat to groundwater. Additionally, EEC reviewed historical aerial photographs to identify industrial areas, landfills, railroads, and other features that would indicate potential sources of contaminants.
EEC created a comprehensive GIS project and document management system to manage the voluminous amount of data. This included compiling and processing extensive amounts of data. The GIS data included historical reports and maps; historical aerial photographs; well locations; zoning and land use data; topographic data; and historical aerial photographs dating back to 1909 to aid in the investigation of potential PRP sites. The topographic maps and aerial photographs were also used to identify when potential industrial areas were established.
EEC obtained GIS datasets of sewer infrastructure data, parcel data, zoning and land use data, political boundary data, and groundwater basin data. EEC developed data for use in the investigation of potential PRP sites by geocoding the addresses and parcel assessors identification number. EEC also assisted with data collection and data compilation relating to the geology and hydrogeology of the groundwater basin in support of the development of a groundwater model.