The past and present use of mercury-filled flowmeters (manometers) at gas industry metering stations has resulted in contamination of soils with elemental mercury. These manometers are used throughout the gas industry at production wells, along pipelines, at gas processing plants, at underground storage facilities, and within gas distribution systems.
Soils contaminated with mercury at metering sites may be subject to Resource Conservation and Recovery Act (RCRA) regulations if a sample of the excavated soil exceeds 0.2 mg/L of mercury by the U.S. Environmental Protection Agency (USEPA) toxicity characteristic leaching procedure (TCLP) analysis. Under the Land Disposal Restrictions (Land Ban), mercury-contaminated soils that are determined to be hazardous by TCLP analysis (D009) cannot be landfilled without meeting certain treatment standards. For high-mercury soils (greater than 260 mg/kg total mercury), the Best Demonstrated Available Technology (BDAT) is specified as roasting or retorting.
The mercury research program at the Energy and Environmental Research Center (EERC) is part of a broader, multidisciplinary effort to investigate potential contamination of soil and groundwater at gas industry sites. The primary tasks of this mercury research program include 1) the conduct of a mercury workshop for the gas industry; 2) a literature review and development of a bibliographic database; 3) an assessment of computer models applicable to mercury migration; 4) the development of a risk assessment model for mercury-contaminated sites; 5) the evaluation of sampling, preservation, and analytical protocols for mercury; 6) the characterization and monitoring of field sites; 7) the conduct of laboratory experiments evaluating leaching techniques; and 8) an evaluation of the application of existing or developing remediation technologies with mercury-contaminated soils.
Several of these tasks have been completed, resulting in the distribution of proceedings of the mercury workshop and the bibliographic database. Four field sites have been characterized, and monitoring wells are continuing to be sampled. A mobile prototype of a remediation technology based on physical separation has been tested. Three additional technologies (thermal, chemical, and physicai/chemical) will be tested at the bench scale or as prototype units in early 1993. Most other tasks have resulted in reports that are currently in draft form and will be published in 1993.