Black Hills Pioneer (Spearfish, S.D.) October 28, 2005 EPA EXPLAINS GILT EDGE HEALTH RISK ASSESSMENT PROCESS By Donna Smith DEADWOOD -- They already know the soil and the water are contaminated and some cleanup has already been done, but now the Environmental Protection Agency begins the process of assessing the risks to human health posed by the arsenic, lead, mercury and other heavy metal contaminants left behind at the Gilt Edge Mine site near Lead. Advertisement On Wednesday evening, more than 20 citizens gathered in the Galena Room of the Hampton Inn in Deadwood to hear EPA toxicologist Susan Griffin explain the human health risk assessment the EPA will complete at the Gilt Edge site, which is about five miles east of Lead. Griffin began her informal presentation by providing some background information on the mine. She said the mine operated from 1876 to 1998. More than 120 years of mining left scars on the land and contamination in the water and soil. When it was clear that the owners of the property were not going to clean up the site, the government stepped in. In February 2000, then South Dakota Governor Bill Janklow requested that EPA Region 8 propose the site for the Superfund National Priorities List (NPL) and provide emergency response, as well as long- term remedial cleanup at Gilt Edge. The site was proposed for the Superfund NPL in May 2000, and final placement of the site on the NPL was announced in the Federal Register in December 2000. In the months and years since that designation was announced, the EPA has held a number of public information meetings to outline the process the EPA follows when cleaning up a site like Gilt Edge. Gilt Edge is located at the headwaters of cold-water fisheries and municipal water supplies of the northern Black Hills. It was a 258- acre open pit, cyanide heap-leach gold mine, developed in highly sulfidic ore bodies. The operator (Brohm Mining Company of Canada) became insolvent, leaving 150 million gallons of acidic, heavy-metal- laden water in three open pits, as well as millions of cubic yards of acid-generating waste rock that need cleanup and long-term treatment. The EPA has already done a significant amount of work at the Gilt Edge site. "The 70-acre Ruby Gulch Waste Rock Repository is 95 percent completed. A new water treatment plant has been built (lime/high- density-sludge process) to more cost-effectively treat the ongoing acid-rock drainage (ARD) that will result from rainfall and snow until remaining portions of the site are remediated, further reducing ARD treatment requirements," according to EPA records. As the EPA continues its work, the agency also assesses possible future uses for the site and any potential health risks posed for future visitors, recreational guests or residents. Citizen Dan Leikvold, who is also superintendent of the Lead-Deadwood Schools, asked Griffin on Wednesday what sort of timeline the EPA has for completing the human health risk assessment. Griffin responded that in four-to-six months the EPA will have a baseline risk assessment. The EPA tests contamination levels in surface water and soil at Gilt Edge. Then the agency's toxicologists develop a "site conceptual model" or graphic illustration of where the contamination originates, how it moves through the environment and how humans come into contact with the contaminants, Griffin said. Human exposure can occur through the air by inhalation of the dust, by ingestion of soil, sediment, surface water, groundwater, fish and produce, or through dermal or skin exposure to contaminants. Testing by either direct (blood and urine) sampling or indirect means (using equations to estimate site-specific exposure) then helps the EPA compare the likely levels of contaminants exposure at Gilt Edge to known medical benchmarks for toxic levels of the various contaminants. Griffin used the known adverse health effects of arsenic as an example. Arsenic is a human carcinogen, meaning overexposure to the toxic chemical is associated with increased incidents of lung, skin, liver and bladder cancer. Other non-cancerous effects are also listed. Because the scientists know at what concentrations the adverse effects of arsenic occur, they can then compare those known levels to the exposure levels calculated at the Gilt Edge Mine site to estimate the risk. Testing for the arsenic levels can be expensive, and Griffin said the human testing is up to the county or state health officials. The county and state can get financial support for such testing, and that is an area the EPA can help explore for the Gilt Edge project. Citizens also raised questions about the possibility that contaminated water could leak far beyond EPA sample testing sites. Griffin said that the agency welcomes ideas from citizens about the right places and ways to test for contamination. The EPA might also consider formation of a group to meet regularly to discuss issues at the Gilt Edge site. Griffin said the agency values public input on the process, and she asked if those present would have any interest in such a group. EPA representatives may return to the Northern Hills one more time before the end of the year, but that will be announced in plenty of time to allow more public input, Griffin said. Exploration of potential future uses for the cleaned up land continues, and citizen input is welcome throughout the process. Copyright The Black Hills Pioneer 2005