 Most former manufactured gas plants (MGPs) were abandoned or demolished before the advent of environmental regulations, thereby leaving a legacy of contamination affecting soil, sediment, surface water, and groundwater at sites nationwide. Many former MGPs have been converted to modern facilities, often owned by “successor” gas and electric utility companies, and contamination originating from these sites is an environmental liability for these companies. Critical concerns related to the cleanup of MGP sites include regulatory requirements, future land use, exposure assessment, and feasible remedial options and costs; however, complex issues also arise from equitable liability allocation (cost contribution), cost recovery, and risk management for legal, financial, insurance, and commercial clients.
Exponent provides scientific and engineering expertise specific to MGP sites to help clients develop cost-effective, risk management strategies and solutions. Exponent scientists, physicians, and engineers have provided consulting services at more than 50 former MGP sites in 13 states. Our understanding of issues critical to MGP sites allows us to tailor services specific to clients’ needs, such as developing a programmatic approach for managing multiple MGP sites, implementing risk-based decision making, conducting forensic analysis for liability allocation or dose reconstruction, evaluating PRP history for cost recovery, conducting human health or ecological risk assessment, designing epidemiological studies, or developing remediation initiatives that meet environmentally acceptable endpoints.
Background
From the early 1800s through the mid-1900s, MGPs were operated nationwide to produce gas (from coal, coke, or oil feedstock) as the primary source of energy for lighting and heating in major cities throughout the United States. The number of former MGP sites in the United States has been estimated to range from 2,500 to 5,000 sites, with possibly 10 times this number when considering private manufactured gas works operations that serviced single facilities. Typical chemicals associated with MGP sites include volatile and semivolatile organic compounds, polycyclic aromatic hydrocarbons (PAHs), phenolics, cyanides, thiocyanates, metals (arsenic, chromium, copper, lead, nickel, and zinc), ammoniates, nitrates, and sulfate/sulfides. Coal or water-gas tar, primary by-products of gas manufacture from MGPs, are of particular concern because of the potential for elevated PAH concentrations and the tar form as a dense nonaqueous phase liquid (DNAPL) capable of migrating downward in the subsurface below the water table.
Services
- Process evaluation and historical reconstruction
- Site characterization
- Chemical fingerprinting
- Chemical transport and fate analyses
- Contaminant source allocation
- Cost allocation and apportionment
- Vapor intrusion modeling
- Toxicological analysis of MGP chemicals
- Remedial and feasibility analyses
- Multisite or multiparty strategic and liability consulting
- Litigation Support
Related Links
New York State Department of Environmental Conservation (NYSDEC)
Electric Power Research Institute (EPRI)
Heritage Research Center
Environmental Liabilities at Manufactured Gas Plants Case Studies | top |
