2010-05-10_REVISION - M1977300 - Laserfiche WebLink

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Surface Water Ouality Data The water quality data presented in the EPP for Ralston Creek demonstrates an impairment of the water supply use of Ralston Creek due to uranium concentrations exceeding the water quality standard'. The EPP does clearly show that the increased uranium concentrations in Ralston Creek occur as the creek passes through the Schwartzwalder Mine. Therefore, the EPP should state that an impairment of the water supply use of Ralston Creek (WQCC Regulation No. 38) is occurring due to the creek passing through the mine property. Groundwater Oualitv Standards On page 9-3, the EPP states: "The drinking water standards listed in Table 9-1 are not considered to be directly applicable to the alluvial monitoring wells or to groundwater in the underground void, because these are not direct sources of drinking water supply." The WQCD disagrees with this statement and the implications of this statement in the EPP. The Interim Narrative in Regulation No. 41 applies in this instance, meaning that all the standards, including uranium, listed in Tables 1 through 4 in Regulation No. 41 apply at the point of compliance for the mine. For the Schartzwalder Mine, the groundwater point of compliance, which has been determined by DRMS, is Ralston Creek at the lower property boundary. Thus, the EPP needs to reflect that the domestic use groundwater standard for uranium of 30 ug/l does apply the point of compliance. DRMS is obligated to implement that standard through their mine reclamation permit. Mitisation Options and Construction Schedule Cotter presented three mitigation options in the EPP: constructed wetlands, a permeable reactive barrier, and partial source removal. The constructed wetlands and reactive permeable barrier are both passive treatment systems. The EPP does not indicate that either of the treatment systems would result in water quality achieving the uranium standard at a groundwater point of compliance or in surface water. The EPP should be revised to show how the proposed mitigation options detailed in the EPP attain applicable water quality standards. The EPP mitigation options include a discussion on page 15-10 of a partial source removal based upon the decommissioning plan for the Radioactive Materials License (RML) termination. The EPP should discuss this source removal in more detail. The WQCD recommends that the EPP should include a mitigation option that contemplates complete removal of the alluvial fill material coupled with active water collection and treatment of seeps, springs and groundwater to assure attainment of water quality standards in Ralston Creek and at the groundwater point of compliance. The construction schedule for implementing a mitigation option in the EPP is vague. The construction schedule should be revised to be more specific. Also, the implementation of a mitigation option must attain water quality standards as soon as possible. Drinking Water Concerns Ralston Creek flows directly to Ralston Reservoir along with significant water flows from other sources. Ralston Reservoir is a raw water supply for three public drinking water systems that serve large populations. The uranium concentration in Ralston Creek significantly exceeds the water quality standard for uranium. The three water treatment plants that use this water supply are capable of removing uranium, however they are not specifically designed to do so. Additionally, the uranium level in the material filtered out of the raw water will increase. The higher radioactivity level in this material could