1998-02-25_HYDROLOGY - M1977493 - Laserfiche WebLink

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reclamation at other site locations while increasing the total Environmental Protection(Nevada Division of Environmental yield of the reservoir. Protection, 1990). This test used lixiviant adjusted to a pH of 7.5 to 8.0 to reflect background water pH ranges measured in Reservoir sediment and Water Ouality Assessment the diversion canals used to fill the reservoir. Further analyses were made for total organic carbon and soil texture. Results Reservoir Sediments of these soil and sediment analyses are provided in Table 2. Early review of the project had determined that Several factors led to the identification that residual residual materials and impacted soils beneath the oxide tailing materials would not pose a threat to ultimate water quality in could pose a concern to water quality of the reservoir the reservoir. First, there was a clear distinction between the following tailing removal. Eagle Park Reservoir,once source tailing material and the underlying soils and rock overlain by tailing material was removed,would not be subject to NPDES tailing deposition. Second, any waters introduced to the permit requirements. Criteria upon which water delivery reservoir that would be in contact with residual materials would be predicated,however,had not been determined. The would be small compared to the overall volume of the concern for ultimate deliverability of impounded freshwater reservoir. Third, following thirty years of tailing storage, from the reservoir culminated in a Sampling and Analysis more soluble components of the tailing had already dissolved. Plan (SAP) to define and measure the chemistry of soils and Mineral components of the remaining tailing were considered waters during and following tailing removal. to be much less soluble than those in the material originally deposited (Titan Environmental Corp., 1996). Other factors Sampling of the reservoir tailing in the that aided in the understanding of low potential soil and prefeasibility stage of the project showed the tailing chemistry sediment impacts to water quality included the presence of to be characteristic of geochemical profiles from the Climax bedrock over much of the reservoir floor, and the removal of orebody. The tailing were non-toxic but acidic due to the growth media as described above. Reservoir configuration nature of the extraction process that used sulfuric acid. The and depth (35 m) were considered favorable in that lake tailing also had a slight neutralization capacity and only turning and stratification (10 in ) would limit the suspension minimal sulfide sulfur, therefore the acidity was borne of the of lake sediments. extraction process, as opposed to the oxidation of sulfide materials. Parameters measured in the pond water and tailing Reservoir Water reflected parameters assigned to Eagle River standards under Aquatic Life Class 1 Cold, Recreation Class 1, and Water Using results of the reservoir sediment analyses, a Supply (Table 1). Initial testing revealed that, as with the straight dilution model assuming 100 percent mobility of Climax Water Treatment System, manganese, iron, zinc, and metals revealed that primary standards for the East Fork of the to a lesser degree aluminum and copper, were the primary Eagle River could be obtained following reservoir fill. constituents found in the tailings and Oxide Pond waters. However, this conservative modeling for secondary drinking water standards for Mn (50 pg/1) showed reservoir levels The Sampling and Analysis Plan (SAP) was designed to slightly above the standard. Freshwater delivery of water into demonstrate source removal and prove limited interaction of Eagle Park Reservoir began in the spring of 1997 through two residual material with the large volume of water storage diversion canals that bracket the Climax water treatment and (Titan Environmental Corp., 1996). The SAP consisted of a process water circuit upgradient of mine facilities. These reservoir bottom material sampling event utilizing composite freshwater sources had previously been used to divert samples taken at a depth of 0 to 15 cm on thirty 0.8 ha sample freshwater around the reservoir to the Eagle River. The 50 ha plots. QA/QC followed EPA's CLP standards to ensure data basin below the diversion canals provided additional water to quality for soil and water samples. Soil samples were fill the reservoir. Figures 2 and 3 show water quality in the subjected total metals analysis and to a modified Meteoric reservoir for selected parameters through the filling period Water Mobility Procedure of the Nevada Division of and SAP sampling conducted in 1997. Table 1. Water Quality Standards for Segment 3 of the Eagle River Physical/Biological Inorganic(mgA) Metals(ug/q D 0=6 0 mg/I NH3(ac/ch)=TVS S=0 002 As(ac)=50(Trec) Fe(ch)=300(dis) Ni(ac/ch)=949 2/988.4 TVS D O(sp)=7 0 mg/I Cl.(ac)=0 019 B=0.75 Cd(ac)=10 3 TVS(tr) Fe(ch)=1000(Trec) Se(ac)=135 TVS pH=6 5-9 0 CI.(ch)=0 011 NO2=0 05 Cd(ch)=1 17TVS Pb(ac/ch)=101 9/4 1 TVS Ag(ac)=2 2 TVS F Colt=200/100 CN" 0 005 CrIII(ac)=50(Trec) Mn(ch)=I000(Trec) Ag(ch)=0.3 TVS C1=250 CrVI(ac/ch)=18 4 TVS Mn(ch)=50(dis) Zn(ac/ch)=120 8/109 5 TVS SO4=250 Cu(ac/ch)=18 4/12 2 TVS Hg(ch)=0 1 TVS=Table Value Standards based on hardness of 103 8 mg/l as CaCO3 ch=Chronic ac=Acute Trec=Total recoverable dis=Dissolved