SITE INFORMATION PACKAGE FOR NATIONAL REMEDY REVIEW BOARD PART B, SECTION 1: SITE NAME, LOCATION, AND BRIEF HISTORY <strong>In<strong>for</strong>mation</strong> <strong>Package</strong>, the FFS Report, and the <strong>for</strong>thcoming ROD Amendment extends approximately 1 mile to the west beyond the confluence of the SFCDR and the North Fork of the Coeur d’Alene River. Figure A-2 provides a map of the Upper Basin. The topographic relief in the Upper Basin ranges from approximately 2,000 to 7,000 feet above mean sea level. 1.2 Mining History The Bunker Hill Superfund <strong>Site</strong> has a long history of mining and related metals-processing activities. Mining and smelting within the Coeur d’Alene Basin began more than 100 years ago, and the region became one of the leading silver-, lead-, and zinc-producing areas in the world. The area surrounding the SFCDR produced over 97 percent of the ore mined in the entire Basin (Science Applications International Corporation [SAIC], 1993). Approximately 1.2 billion ounces (34,000 tons) of silver, 8 million tons of lead, and 3.2 million tons of zinc were produced (Long, 1998). The Bureau of Land Management (BLM) of the U.S. Department of the Interior identified more than 1,000 mining or milling-related features in the region surrounding the SFCDR (BLM, 1999). Several of the features were metals-processing facilities that were constructed at various times, including an electrolytic zinc plant, a lead smelter plant, three sulfuric acid plants , a phosphoric acid plant , and a fertilizer plant. As a result of past mining, milling, and smelting practices, substantial portions of the Coeur d’Alene Basin contain elevated concentrations of lead, zinc, cadmium, and other metals. Within the Upper Basin, elevated concentrations of metals resulted primarily from the discharge or erosion of mill tailings and other mine-generated waste into rivers and streams. These water bodies, in turn, deposited millions of tons of mine tailings into streambeds, floodplains, and shorelines throughout the Upper and Lower Basins. The history of milling and tailings disposal practices in the Basin is summarized in Table B1-1; some significant details are summarized below. • Approximately 62 million tons of tailings were discharged to the Coeur d’Alene Basin after mining began. • Tailings were frequently used as fill material <strong>for</strong> residential and commercial construction projects. • Until 1968, tailings tended to be discharged directly into the SFCDR or its tributaries. Most of the tailings were transported downstream, particularly during high-flow events, and deposited as solid tailings or as tailings/sediment mixtures in beds, banks, and floodplain areas. Since 1968, all mill tailings have been placed in impoundments or returned as fill to provide structural support to active mines. • Mining activities generated large volumes of waste rock and discharged water from mine openings (adits) that contained high concentrations of metals. • Particulates released to the air from smelting operations contained high concentrations of metals. The particulates were transported by the wind and were deposited throughout the Bunker Hill Box area. (The Bunker Hill “Box” is a 21-square-mile area surrounding the <strong>for</strong>mer smelter complex.) B1-2
SITE INFORMATION PACKAGE FOR NATIONAL REMEDY REVIEW BOARD PART B, SECTION 1: SITE NAME, LOCATION, AND BRIEF HISTORY • High concentrations of metals are pervasive in the soil, sediments, surface water and groundwater in the Basin; these metals pose substantial risks to the people, plants, and animals that inhabit the Basin. • Elevated blood levels in children living in the Basin have been documented <strong>for</strong> more than 15 years. • Migratory birds and mammals have died due to ingestion of lead-contaminated soil and sediments in the Basin. • Contamination from mining activities to surface water, soil, sediments, and biotic tissues have caused increased mortality and decreased survival, growth, and reproduction to various plant and animals, particularly fish and waterfowl (Stratus, 2000; USEPA, 2001c, 2001d). B1-3