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That is all. There is no proposal to protect surface or groundwater from contamination, even though the leach tests indicate that the waste rock ("overburden") has the potential to generate acid and metals in concentrations exceeding water quality standards. Thus, the proposal outlined above cannot meet the requirements of the Amendment 6 Commitments to which it is meant to apply. SUMMARY: Executive Summary We would advise the Division not to accept the proposal outlined in the Executive Summary. INTRODUCTION Section 4, on background chemistry, provides several disingeneous formulas meant to represent the notions of acid production and acid neutralization. The reaction of pyrite with water and oxygen (reaction [1]) expresses only part of the potential for pyrite to produce acid. The reactions shown for the attack of dolomite and calcite by acid are equilibrium reactions: one should not anticipate such reactions in the weathering environment. Equilibrium thermodynamics should not be used to represent the dissolution of minerals where the solutes can be expected to be carried away from the reaction site. Simple addition of acid to carbonate minerals causes effervescence due to the generation of COZ. This is not represented by the reactions shown. The reactions shown for K-feldspar and sericite dissolution also are equilibrium reactions. The conversion of K-spar to sericite and quartz is a high temperature reaction and cannot be used to depict the Cresson situation. The dissolution of sericite by hydrogen ions and water (reaction [8]) is so slow as to be insignificant. Furthermore, because this is a charge balancer! equilibrium reaction, it does not depict the fate of the potassium ion, and its potential effect on metal acidity. In reality, the addition of sulfuric acid to feldspars and micas in natural open systems, if solution pH is low enough, will release potassium, aluminum and silica to solution. Dissolved Al', at least, may cause problems for aquatic life. SUMMARY: Section 4. The section on background chemistry does not correctly represent the weathering environment at Cresson, and should not be consulted for predictive purposes. The better predictive tests are the acid generation and acid neutralization tests themselves. Section 5.1 states that the 2 deep cores are "representative" of the entire diatreme at depth. The text states also that the cores contain 3 to 6 % carbonate, even though the cazbonate minerals were not identified. These statements are not adequate, as expressed in the DMG's reviews of Amendment 6 submittals. Firstly, there is no rational statistical reason to accept that two cores into the deeper part of the diatreme are representative of the entire minerlized portion of the diatreme. Secondly, there is only anecdotal justification -based on a 1906 report -for the notion that the 3-6% of unidentified minerals in the cores are carbonates rather than something else. Following that, if the 3-6% of unidentified minerals were cazbonates in fact, at those abundances they should have shown up on the mineralogical exams. X-Ray Diffraction analyses could easily identify carbonates in concentrations of perhaps 2%. This section also states that jarosite will encapsulate the pyrite crystals and inhibit weathering. This is highly unlikely as jarosite is extremely soluble. Jarosite will release ferric iron and actually promote pyrite solution and acid generation. Section 5.2 states that there is very little potential to generate acid from rocks in the oxidation zone. This is not correct. CC&V's classification of rocks into "oxide," "transitional" and "sulfide" zones reflect an empirical average of pyrite content and other mineralogy. However, it is recognized