2010-08-02_REVISION - M1977300 (35)

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Environmental Protection Plan, Schwartzwalder Mine 4-2 . (e) Air Quality Permits Two air permits are currently active: (1) 97JE0037F and (2) 85MO184-2P. (if) Storm Water Discharge Permit The Colorado stormwater discharge permit #COR-040046 has been in effect since March 19, 1993. The stormwater management plan (updated in May of 2010) identifies potential sources of pollution (including sediment) which may reasonably be expected to affect the quality of stormwater discharges associated with the mine and describes the best management practices (BMPs) used to reduce pollutants in stormwater discharge. (g) Well Permit Water Resource Permit Number 64684, issued September 22, 1972, by the Office of the State Engineer for the non-industrial domestic water well. No other air, water quality, or solid and hazardous waste permits are in effect for the reclaimed Schwartzwalder Mine. The Schwartwalder does not currently use, handle, store, or disposal of designated chemicals. No acid mine drainage-forming materials have been handled or stored within the permit area3. Additional permits may be required in the future, related to mitigation options under consideration for groundwater in the alluvium and fill material (Section 15). • 3 All geochemical testing performed on materials from the site indicates that mine rock is classified as having a very low potential to produce acid and a high potential for neutralizing acid. Specifically, the results of the acid-base accounting (ABA) tests indicate that waste rock from the Schwartzwalder Mine is strongly neutralizing with an average net neutralizing (NNP) capacity of 149 t CaC03/kt and an ANP/AGP ratio of 10. The mined rock has a very low potential to generate acidic drainage, and no acidic drainage has been detected from the mine or waste rock facilities to date. Of the five seeps and drips described in Section 9(b)(iv).3, two had low pH (WASH [3.8], ILLRS [2.71) and three had near neutral to slightly basic pH (Minnesota [7.9], CO [7.9], and 146 [8.2]). The two seeps with the lowest pH values had the lowest flow rates, measured at 0.03 - 0.05 gpm for the WASH and 0.15 gpm for the ILLRS. Two of the seeps with the highest pH had the highest flow rates, measured at 0.8 gpm for the CO and 0.5 gpm for the 146. Therefore, the two low-pH drips were measured at a combined flow rate of less than 0.2 gpm compared to the 1.3 gpm measured at neutral to basic seeps and the unmeasured flow of neutral pH waters near the Minnesota Glory Hole. Overall, the seeps and drips from the unsaturated zone above the mine represent a small quantity of flow through native, in-situ (non-handled) rock materials. Despite these small drips, the pH of the mine pool remains circum-neutral, with no indication that the mine pool will go acid. Bicarbonate alkalinity exceeds 400 mg/L (as CaCOO, which indicates significant buffering capacity within the mine pool. No trends of decreasing pH or alkalinity have been observed to date in mine pool water (Section 9(b)(iv).2). The small seeps and drips from the unsaturated workings above the Steve Level contribute significantly less than one gallon per minute annually to the 139 million gallon mine pool, and the alkalinity in the mine pool is sufficient to buffer this small contribution. 4109C.100731 WiietstoneAssociates