Potential environmental threats in old mining areas--The High Rolls (Sacramento) mining district
— Margaret Anne Rogers, William L. Mansker, and Donald W. (Pete) Peters

Margaret Anne Rogers & Associates, Inc. performed a site inspection and Hazard Ranking System (HRS) study within the High Rolls (Sacramento) mining district for the USDA Forest Service. The site inspection involved literature review, interviews, site visits and limited sampling. A site inspection relies on readily available information and/or information which can be collected in a single site visit. The information gathered is then used to do the HRS scoring, a particularly complex exercise. Eight historical mining and prospect sites were chosen to represent the study area outlined by the Forest Service. Dump "soil" samples and vegetation samples were collected to assess contaminant level. All eight sites were (according to an Environmental Protection Agency [EPA] verbal definition) contaminated with aluminum, arsenic, barium, boron, chromium, copper, iron, manganese and zinc. Some sites were contaminated with cadmium, cobalt, fluoride, lead, nickel, nitrate, phenol, radium, selenium, silver, sulfate and uranium. Analyte concentrations in the dump samples correlate well with those in the vegetation samples. Using the 1988 Proposed Rule in conjunction with verbal EPA guidance, the derived HRS score of 50.0 is significantly above the 28.5 required for listing on the National Priorities List (NPL). Using this interim method, the degree of environmental threat may be overestimated for the High Rolls (Sacramento) mining district.