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Whetstone <br />Associates Technical Memorandum <br />SECTION 9. GROUND WATER QUALITY <br />6) Operator states on page 9-49: "Water seeping into the upper levels of the mine is impacted by <br />acid rock drainage... " This statement conflicts with the statement on pg. 6-1 "No acid-forming <br />materials exist on site. " <br />The locations, compositions, quantities, and potential impacts of the acid-generating materials of the <br />mine area do not appear to be well characterized. The water seeping into the upper levels of the <br />mine is described as having pH as low as 2.7, uranium up to 150 mg/L, copper up to 19 mg/L, and <br />total dissolved solids as high as 11, 000 mg/L (pg. 9-49). This is not something that can be easily <br />dismissed. Please provide a more complete characterization of the acid-generating materials, <br />including the possible scenario that, with the workings in a flooded condition, the acid-generating <br />materials are exposed in an unsaturated condition and perhaps preferentially weathered and may be <br />contributing a larger share of loading to the mine pool than in an unflooded condition. <br />All geochemical testing performed on materials from the site indicates that mine rock is classified as <br />having a very low potential to produce acid and a high potential for neutralizing acid. Specifically, <br />the results of the acid-base accounting (ABA) tests indicate that waste rock from the Schwartzwalder <br />Mine is strongly neutralizing with an average net neutralizing (NNP) capacity of 149 t CaC03/kt and <br />an ANP/AGP ratio of 10. The mined rock has a very low potential to generate acidic drainage, and <br />no acidic drainage has been detected from the mine or waste rock facilities to date. <br />Of the five seeps and drips described in the EPP, two had low pH (WASH [3.8], ILLRS [2.7]) and <br />three had near neutral to slightly basic pH (Minnesota [7.9], CO [7.9], and 146 [8.2]). The two seeps <br />with the lowest pH values had the lowest flow rates, measured at 0.03 - 0.05 gpm for the WASH and <br />0.15 gpm for the ILLRS. Two of the seeps with the highest pH had the highest flow rates, measured <br />at 0.8 gpm for the CO and 0.5 gpm for the 146. Therefore, the two low-pH drips were measured at a <br />combined flow rate of less than 0.2 gpm compared to the 1.3 gpm measured at neutral to basic seeps <br />and the unmeasured flow of neutral pH waters near the Minnesota Glory Hole. <br />Overall, the seeps and drips from the unsaturated zone above the mine represent a small quantity of <br />flow through native, in-situ (non-handled) rock materials. Despite these small drips, the pH of the <br />mine pool remains circum-neutral, with no indication that the mine pool will go acid. Bicarbonate <br />alkalinity exceeds 400 mg/L (as CaCO3), which indicates significant buffering capacity within the <br />mine pool. No trends of decreasing pH or alkalinity have been observed to date in mine pool water. <br />The small seeps and drips from the unsaturated workings above the Steve Level contribute <br />significantly less than one gallon per minute annually to the 139 million gallon mine pool, and the <br />alkalinity in the mine pool is sufficient to buffer this small contribution. <br />7) Ground water and surface water monitoring: Phosphorus can exert an important influence on <br />uranium speciation and mobility in natural waters. Although P is not a regulated parameter, the <br />operator must include total P or P04 in all future ground water and surface water samples. <br />Phosphorous has been added to the analytical suites for groundwater, surface water and the mine <br />pool. <br />In the past, phosphorous has been monitored irregularly. Phosphorous has been below detection in <br />50 of 51 samples (98%) from the mine pool. Although very few samples from monitoring wells, <br />4109C.100731 4