THE BUTTE PRIORITY SOILS OPERABLE UNIT(BPSOU) CONSISTS OF FORMER AND/OR ACTIVE MINING, MILLING, SMELTING AND RELATED FACILITIES. IT'S A NETWORK OF RAILROAD TRACKS AND SPURS CON- STRUCTED OR CONTAMINATED WITH MINING RELATED WASTES. THESE MINE WASTE DUMPS, MILL WASTES & ASSOCIATED CONTAMINATED SOILS SURROUNDING THE AREA ARE CONTAMINATED WITH LEAD AND ARSENIC. THE POTENTIAL HEALTH THREAT TO THE RESIDENTS CONSISTS PRI- MARILY OF INGESTION AND/OR INHALATION OF THESE CONTAMINANTS.