Arsenic/Mine Tailings Study Q & A
Q. Why was a special study undertaken at the Ringwood Site to evaluate the potential sources of arsenic on the Site?
A. During the course of the removal work at the Ringwood Site, some samples were collected from areas that had formerly been used as depositories for mine tailings. (Mine tailings are small pieces of mined materials that were discarded after separation from iron ore during the mining process.) EPA-approved testing of the samples, which uses a strong acid to extract constituents from the samples, showed somewhat elevated arsenic concentrations. Based on these results, EPA required that Ford develop a work plan that would determine whether the elevated arsenic concentrations were associated with mine tailings, paint sludge or with 'background' conditions. After extensive input from experts at the United States and the New Jersey Geological Surveys, and other outside parties, a work plan to test the mine tailings was developed and finalized.
Q. Has the mine tailings testing been completed?
A. Yes, the testing program has been completed, and a draft report with the findings has been submitted to EPA. The report will be published once it has been approved by EPA.
Q. What do the results of the testing show?
A. The testing shows that elevated arsenic concentrations are present in mine tailings on the Ringwood Site. The testing confirmed, more specifically, that apatite, which is a naturally occurring mineral found in mine tailings at the Site, contains arsenic as part of its chemical makeup. Apatite is a very stable mineral. As a result, arsenic is not available to leach under natural conditions into soils, surface waters, sediments or groundwater. That is why arsenic above the background concentrations has only been found in areas where mine tailings deposits are located.
Q. Does paint sludge contain arsenic? If so, how do we know that the arsenic levels on the Site are not associated with paint sludge?
A. Arsenic is found in some paint sludge deposits, but elevated arsenic concentrations remaining after paint sludge removal typically were found in mine tailings areas. Where paint sludge deposits were removed from areas that did not have mine tailings – such as the SR-6 area, behind the Cannon Mine Pit -- there was no pattern of elevated arsenic concentrations. (Indeed, none of the samples in the SR-6 area showed arsenic above background concentrations, despite the presence of paint sludge in that area.) Also, the mine tailings study showed that the arsenic in mine tailings has a distinct chemical 'signature' that is quite different from paint sludge. (The arsenic in paint sludge appears in the form of a very fine-grained, tin-lead mineral phase that is part of the organic carbon matrix; arsenic in mine tailings typically appears in conjunction with calcium and phosphorous – a combination that is not associated with paint sludge, and the trace element vanadium.) It is the mine tailings’ 'signature' that has been found on the Site where most arsenic concentrations above background or New Jersey soil standards have been detected.
Q. Do the elevated levels of arsenic on the Site pose a health risk?
A. No. The levels of arsenic found through EPA-approved testing are not particularly high. Background levels of naturally occurring arsenic in the area approach 10 mg/kg, and the mine tailings typically are ranging 20 mg/kg and 50 mg/kg. Even more important, because the arsenic is bound up in the mineral lattice of apatite and only shows evidence of arsenic in these concentrations following exposure to a strong acid, the arsenic in the mine tailings cannot easily migrate into water or soils on the Site.
