2015-02-17_HYDROLOGY - M1977348 - Laserfiche WebLink

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Colorado Division of Mining Reclamation and Safety February 17, 2015 Eric Scott 8 1400159 5.0 POTENTIAL NATURAL SOURCES 5.1 Barium Occurrence in Groundwater Since there is not a Site well located outside the areas of CKD disposal screened similarly to the downgradient Site wells, a literature search was conducted to characterize naturally occurring barium and TDS concentrations in groundwater. In Colorado the Niobrara Formation and its surrounding formations are not generally considered good sources of groundwater, due to their low production rates (Pearl 1974). Consequently, information regarding groundwater quality is sparse for the Niobrara in Colorado. The Wyoming State Geological Survey published the Green River Basin Water Plan II, Groundwater Study in 2010 (Surdam 2010). This study assessed groundwater resources in the Greater Green River Basin (GGRB) of southwestern Wyoming and adjacent areas in Colorado and Utah. This study divided the GGRB basin into sub - basins and characterized the aquifers' groundwater chemistry characteristics for water quality purposes. Two of the sub - basins identified are the Washakie and Sand Wash basins. These basins straddle the Wyoming /Colorado border and are approximately 80 miles west and northwest of the Site. The Niobrara Formation occurs as part of the Cody shale unit of the Washakie and Sand Wash basins. Five groundwater chemistry samples of produced water were collected from production well heads from the Niobrara Formation. The samples had concentrations of barium between 0.19 and 42 mg /L, with an average concentration of 15.5 mg /L. TDS concentrations in these samples ranged between 2,270 mg /L and 45,600 mg /L, with an average concentration of 22,200 mg /L. These findings indicate that elevated barium and TDS concentrations are naturally occurring in Niobrara aquifer groundwater. Li (2013) characterized produced water quality within the Wattenberg Field in Colorado from wells screened along the interface of the Niobrara Formation and the Codell Sandstone, and solely in the Codell. For the tested production waters across 66 wells, the average TDS was 18,285 mg /L and the average barium concentration was 18.2 mg /L. Li attributes the presence of barium within the formation water to the surrounding limestone and shale, noting average whole rock barium concentrations of 10 milligrams per kilogram (mg /kg) and 580 mg /kg, respectively. 5.2 Barium Occurrence in Bedrock Barite -rich nodules were identified within the Niobrara Formation at a site in Fairburn, South Dakota (Tourtelot and Cobban 1968). Within the nodules, barite was noted as a replacement for organic constituents within a surrounding matrix of carbonate. Barite mineralization was not found within the deposit outside of the nodules, or in other nodules identified within the Niobrara by Johnson (1930) near Pueblo, Colorado. .' Golder RY_ Q Q rY_ i:\14\1400159\0100\0122\tm-boettchedimestonequarryjnl-17feb fnl- 17feb15 \1400159 tm- boettcherlimestone uar fnl- 17feb15.docx Associates