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Remediation of Abandoned Mine Lands |
Thursday, October 2, 2008 : 3:20 p.m.
Risk Management Criteria Determination Using In-Vitro Bioaccessibility Results for Arsenic at Saginaw Hill Mining District, Tucson, Arizona
Recent EPA publications assert that it is best to measure in vivo relative bioavailability (RBA); however, as measurement of arsenic RBA in animals is time-consuming and costly, in vitro procedures are a logical alternative. Dr. John Drexler at the University of Colorado in Boulder has been working cooperatively with EPA Region 8 to develop an in vitro method that can be used to obtain RBA data for lead, arsenic, and other metals in soils. While the in vitro bioaccessibility method was specifically developed for lead, additional research is underway to substantiate the use of the method as a basis for derivation of in vivo RBA data for arsenic. In addition, a 2003 study performed at the University of Florida substantiated the appropriateness of using relative bioavailability data for arsenic in risk assessments as absorption of soil arsenic into the body was found to be less efficient than absorption of arsenic from water.
Four composite surface soil samples from the site were analyzed for bioaccessibility of arsenic. All four samples were collected following the 2004 USGS methodology published by Kathleen Smith that statistically affirms that a 30-increment composite sample can accurately represent 30 individual grab samples. The Drexler in vitro test results indicated a range of bioaccessibility from 3% to 6%. Based on these results, the RMC for arsenic adjusted to reflect site-specific bioaccessibility resulted in a recreational clean-up criterion of 390 mg/kg.
Christine Galli LaBerge, PE, M.B.A., Walsh Environmental Scientists and Engineers LLC Ms. LaBerge has 9 years of experience as an environmental engineer and project manager. She has experience in engineering design, water, wastewater, hazardous materials, mining engineering, and sanitary engineering. She has worked directly with numerous federal clients including the DOD, USFS, EPA, BLM, GSA, NPS and AFCEE. As project manager, Ms. LaBerge provides oversight and technical support on projects involving abandoned mine lands, engineering design, feasibility studies, and hazardous materials management. She has worked on dozens of abandoned mine lands projects throughout the US and has managed high profile, large-scale design projects for several government agencies.
Karl L. Ford, Ph.D., Bureau of Land Management Karl is a National Remediation Advisor for BLM serving the 12 western states. He performs site characterization, risk assessment and remediation for BLM abandoned mine sites. He has a Ph.D in environmental health science from Colorado State University. Karl has previous experience in consulting and university teaching.
Richard Freeman, Ph.D., Ecology & Environment Inc. With 35 years experience, Dr. Freeman provides overall direction and quality assurance for risk management projects. Specializing in toxicological evaluation, he manages and is a key contributor to human health and ecological risk assessments (HHRAs and ERAs), exposure assessments, and the development of risk-based site cleanup criteria. Dr. Freeman has numerous publications to his name and is a well known toxicologist in the environmental remediation field.
Allison Wiman, Ecology & Environment Inc. With 14 years� experience, Ms. Wiman provides support in toxicology and biochemistry to evaluations of commercial/industrial facilities, characterizations of sites containing USTs and pipeline facilities, and field investigations of sites containing hazardous materials and waste. She assists in determinations of contaminant exposure levels and limits, release mechanisms, compound reactions, and sensitive populations; delineates zones of public and environmental impact; helps develop and monitor the implementation of site-specific safety plans; participates in risk assessments; and supports the evaluation of site-specific remedial alternatives.