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Section 2 <br />Potential for Adverse Impacts <br />2.2.1 Designated Chemicals <br />As defined in the HRMMR §1.1(13): <br />"Designated Chemicals" are toxic or acidic chemicals used within the permit <br />area in extractive metallurgical processing, the use of which, at certain <br />concentrations, represents a potential threat to human health, property, or the <br />environment. <br />By definition, designated chemicals are chemicals used in extractive metallurgical <br />processing, and as previously stated, extractive metallurgical processing is not <br />conducted at the Sunday Mine Group. Therefore, no designated chemicals are present <br />on site. <br />2.2.2 Acid and Toxic Producing Materials <br />As defined in the HRMMR § 1.1 (1): <br />"Acid and Toxic Producing Materials" means natural or reworked earth <br />materials having acid or toxic chemical and physical characteristics that, <br />under mining or post-mining conditions of drainage, exposure, or other <br />processes, produce materials which contain detrimental amounts of chemical <br />constituents such as acids, bases, or metallic compounds." <br />Detailed evaluation of acid base accounting (ABA) data, field observations, and <br />meteoric water mobility procedure (MWMP) data indicate that the development rock <br />and ore are extremely unlikely to generate acid rock drainage and are not considered <br />acid-forming material. <br />The potential for stockpiled development rock and ore to be classified as toxic- <br />forming was evaluated by considering two pathways for potential toxic effects: <br />¦ Direct contact risks; and <br />¦ Potential development of toxic leachate. <br />Preliminary screening of direct contact risks based on comparison of total metals <br />concentrations to toxicity screening levels provided by U.S. Bureau of Land <br />Management (BLM) and EPA indicate that most metals, including uranium and <br />vanadium, do not exceed the screening criteria, and therefore do not present direct <br />contact risks. However, this preliminary screening indicated that potential arsenic <br />risks related to direct contact with arsenic should be investigated further. Therefore, <br />additional evaluation of potential direct contact risks related to arsenic was conducted <br />to evaluate the bicavailability of arsenic in stockpiled ore and development rock. This <br />assessment included specific in-vitro assays, electron microbe analyses, and detailed <br />evaluation of potential direct contact risks. This work concludes that available data for <br />development rock present at the Sunday Mines Group does not suggest significant <br />toxic-forming potential. <br />2-4 <br />TA64986-Denison MineslTask Order 4- EPP Sunday Mines GroupTINAL EPP\FINAL - Environmental Protection Plan Sunday Mines.doc