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ARCADIS <br />solids and sulfate were lab filtered upon receipt. ARCADIS documented MW -7 <br />sampling activities on a daily log. A copy of the daily log, sampling form and the <br />chain of custody is provided in Attachment 2. <br />Analytical Laboratory Results <br />Laboratory analyses of the 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 Attachment 3. <br />Concentrations of metals and other constituents measured in groundwater at well <br />MW -7 were compared to the compliance standards proposed in the GMP presented <br />to the DRMS in February 2009. Sodium and total iron concentrations exceeded the <br />DRMS- approved compliance standard of 226 and 4.5 milligrams per liter (mg /L), <br />respectively. No other analytes measured at MW -7 exceeded the compliance <br />standards. <br />Per the requirements of the DRMS- approved GMP, if the results of two or more of <br />the selected analytes used for compliance (TDS, sulfate, potassium, sodium, iron, <br />and manganese) exceed their respective compliance values by more than 10 percent <br />in monitoring well MW -7, Holcim is required to modify the sampling frequency from <br />annual to semi - annual in this well. The measured sodium concentration of 250 mg /L <br />was 10.6 percent greater than the compliance value of 226 mg /L. The concentration <br />of iron in the sample collected from MW -7 was 9.91 mg /L, or 120 percent above the <br />compliance value of 4.5 mg /L. <br />Historical groundwater quality data for MW -7 are provided in Table 3 for reference. <br />Summary and Recommendations <br />Redeveloping MW -7 increased the recharge by approximately 0.5 feet per 10 <br />minutes and reduced the cloudy appearance of the water (which may be indicative of <br />a reduction in fine sediments) in MW -7. The concentrations of sodium and total iron <br />were reduced compared to analytical results for March 2012 sampling; however, they <br />still exceed their respective compliance values by more than 10 percent in MW -7. <br />With two analytes exceeding their respective compliance values by more than 10 <br />percent, ARCADIS recommends that the sampling frequency at MW -7 continue to be <br />performed semi - annually. <br />C Users Ir usl.o Documents Holcim 2012 MW -7 Redd clop Summary Letter 2012 1217 Holcim Portland Well Des Sampling Summato Letter doc <br />Mr. Justin Andrews <br />December 17, 2012 <br />Page: <br />3/5 <br />