Laserfiche WebLink
Section 4 <br />Assessment of Potential Toxic-Forming Rock <br />HRMMR §1.1(1) provides the following definition of acid and toxic producing materials: <br />"Acid and toxic producing materials" means natural or reworked earth materials having acid or <br />toxic chemical and physical characteristics that, under mining or post-mining conditions of <br />drainage, exposure, or other processes, produce materials which contain detrimental amounts of <br />chemical constituents such as acids, bases, or metallic compounds. <br />The potential for development rock and ore to be acid-forming has been addressed previously <br />in Section 3, which shows that generation of acid rock drainage is very unlikely at the Sunday <br />Mines Group. Therefore, this section presents evaluation of the potential for development rock <br />and ore to be toxic-forming as defined by HRMMR §1.1(1). <br />This evaluation considers mining conditions related to drainage and exposure, and examines: <br />¦ The potential for development rock and ore to contain detrimental amounts of chemical <br />constituents, which could lead to direct contact risks to humans as a result of incidental <br />ingestion or inhalation; and <br />¦ The potential for development rock and ore to form leachate that contains detrimental <br />amounts of chemical constituents. <br />0 4.1 Potential for Direct Contact Risks <br />As described in Section 1-3, the Sunday Mines Group is located within the San Juan Public <br />Lands and post-mining land use will be managed by BLM. This screening-level evaluation is <br />based on comparison of the total metals concentrations detected in development rock and ore <br />with appropriate screening criteria developed by BLM for metals in soils in Risk Based Criteria <br />for Metals at BLM Mining Sites (BLM 2004). This BLM document provides risk management <br />criteria (RMC) for human exposure to soils for various land uses on BLM property including <br />residents, campers, ATV drivers, workers, and surveyors. In addition, BLM has developed <br />RMCs for wildlife and livestock for ecological risk management on BLM property. The BLM <br />RMC values support land management of former mine sites and are used as a benchmark <br />concentration to which environmental concentrations may be compared, assisting land manager <br />in protecting humans and wildlife on BLM lands. In particular, BLM RMC values were <br />developed such that "people will not experience adverse health effects from metal <br />contamination on BLM lands during their lifetimes if exposure is limited to soil... with <br />concentrations at or less than the RMC" (BLM 2004, p. 3). BLM provides risk management <br />criteria for 11 metals commonly encountered on BLM mining sites: antimony, arsenic, <br />cadmium, copper, lead, manganese, mercury, nickel, selenium, silver and zinc. Other inorganic <br />constituents are addressed separately and are further discussed below. <br />4.1.1 Screening-Level Evaluation using BLM RMCs <br />Table 4-1 provides a summary of total metals concentrations in the Sunday Mines Group ore <br />and development rock compared to corresponding BLM RMCs and wildlife. Regarding ore <br />material, several metals were detected at concentrations exceeding their respective screening <br />C 4-1 <br />T:1649864Denison Mina Task Order 3 - OMO Sampling and Analysis Piw%Task 3.12 - Soil, Ore, Rock Data Assessment ReportlSunday Rock Reporiftfinal repaMeporlWinal Sunday Mines Group Soil Ore Rock <br />Date Assessment Repor1_051509.doc