2010-08-02_REVISION - M1977300 (25)

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Environmental Protection Plan, Schwartzwalder Mine 11-7 9 (b) Surface Water Quality Data (i) Previous Studies of Surface Water Quality The USGS and others have performed several studies of water quality in Ralston Creek. Most of these studies were associated with the Schwartzwalder Mine discharge permit. US EPA (1972). EPA Region VIII initiated a limiting monitoring effort to supplement the State/Water Board program. Monitoring was conducted from May through September, 1972, with a goal of determining radioactivity concentrations in the waters of Ralston Reservoir and Upper Long Lake. In addition to the grab water samples collected from these impoundments, sample collection included the mine effluent, water and bottom sediment samples from Ralston Creek and Long Lake ditch, and bottom sediment samples from the two impoundments. Yang20 and Edwards21 (1984) collected water samples and bed sediment samples from Ralston Creek and Reservoir during the winter of 1980 and spring of 1981 for uranium and radium analyses. They determined that the concentrations of uranium and radium in Ralston Creek, 400 feet upgradient of the Schwartzwalder mine, were 4.0 µg/L (0.004 mg/L) and 0.13 pCi/L, respectively. R.G. Otto & Associates (1984) performed a detailed survey of surface and groundwater quality to assess the impact of runoff and seepage from the waste rock piles on the water quality in Ralston Creek. Surface water samples were collected upstream and downstream of the waste rock piles and groundwater samples were collected downslope of the disposal site from September 1983 through August 1984. The study concluded that the waste rock piles had no measurable impact on water quality in the stream, with the possible exception of stream uranium levels. The uranium data were inconclusive for determining impact, and the uranium levels in Ralston Creek downstream of the waste rock piles were well below the Colorado Basic Stream Standards. USGS (Zielinski, et al., 2005) conducted geochemical sampling of 82 stream waters and 87 stream sediments in the mountainous areas west of Denver. The sampling was conducted in 1994, and a publication on uranium in surface waters and sediments affected by historical mining was published in 2005 (Zielinski, et al., 2005). Results indicated that the spatial distribution of Precambrian granites and metamorphic rocks strongly influences the concentration of uranium in stream sediments. Stream water and sediments collected downstream of the Schwartzwalder Mine, as part of this larger study, showed locally anomalous concentrations of uranium. (ii) Surface Water Sampling Locations The locations of current surface water monitoring stations are provided in the Monitoring Plan (Section 12 of this EPP). Surface water monitoring has been conducted for over 30 years at the designated point of compliance in Ralston Creek (Station SW-BPL), and at five other stations for the purpose of understanding upstream sources, further characterizing the creek, and evaluating the potential effects of an ore truck spill on the creek (Station SW-ARH). Two of the historical monitoring stations are located above the point of compliance: Station SW-AWD (located above the waste rock dumps) and Station SW-A001 (located above the former water treatment plant discharge). Three of the stations are located downstream of the point of compliance: SW-ARH (above Red Hill), SW-FBRG (at the first bridge), and SW-LLHG (on Ralston Creek at the Long Lake Head Gate, approximately 1.5 miles downstream from the Schwartzwalder Mine). 20 Affiliated with the USGS at the time. 2' Affiliated with the Colorado School of mines at the time 4109C.100731 Whetstone Associates