Laserfiche WebLink
2014 Groundwater <br /> Monitoring Report <br /> ARCADIS <br /> Florence,Colorado <br /> 3. Results <br /> 3.1 Groundwater Elevations and Flow Characteristics <br /> Measured depths to the groundwater surface (Table 1) were used to develop <br /> groundwater elevation contours (Figure 2). The water table is encountered in the <br /> Codell Sandstone Member of the Carlile Formation (RGI 1999), which underlies the <br /> quarried rock. All of the monitoring wells are screened in the Codell Sandstone. The <br /> groundwater flow pattern is similar to what has been observed in the past. <br /> Groundwater generally flows south toward the Arkansas River, which is the major <br /> groundwater discharge zone in the area, as reported by previous investigators (i.e., <br /> BBL 2002, RGI 1999). <br /> Based upon an average measured horizontal groundwater gradient of 0.02 feet per <br /> foot(ft/ft), a reported Codell Sandstone hydraulic conductivity of approximately 4.5x10-6 <br /> centimeters per second (cm/sec; RGI 1999), and a range of effective porosities for <br /> sandstone of five to 30 percent (Freeze and Cherry 1979), the resulting groundwater <br /> velocity is 0.3 to 1.9 feet per year (ft/yr). The resulting groundwater velocity when the <br /> wells installed by Brown and Caldwell, NP-1 and DP-1, are included in the calculations <br /> is 0.3 to 2.0 ft/yr. This range is similar to previously reported values by RGI (1999) and <br /> previous groundwater monitoring reports for this site prepared by ARCADIS. <br /> 3.2 Analytical Results <br /> Laboratory analyses of the 2014 groundwater samples were conducted at ACZ's <br /> Steamboat Springs, Colorado facility. Results of the laboratory analyses are provided <br /> in Table 2. The Laboratory Analytical Results Report is provided as Appendix D. <br /> Historical groundwater quality data are provided in Appendix E (updated with results <br /> through 2013). <br /> Concentrations of metals and other constituents measured in groundwater at well MW- <br /> 7 were compared to the NPLs proposed in the GMP presented to the DRMS in <br /> February 2009. The concentration of sodium (253 mg/L) exceeded the DRMS- <br /> approved compliance standard of 226 milligrams per liter (mg/L) at well MW-7 by <br /> approximately 12%. No other analytes measured at MW-7 exceeded their respective <br /> NPLs. <br /> 8 <br />