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March 17, 2016 Page 3 Also in 2002,Codell Sandstone monitoring well MW-001 was installed within the Years I -5 mine panel (Figure 1). Because the well was within the initial quarry excavation area it was removed before or during the beginning of mining. In 2003,MW-OOIA,MW-002,MW-003 and MW-004 were installed(Brown&Caldwell,2003). MW- OOIA was installed as a replacement Codell Sandstone well for MW-001. The screen in the well specifically isolated the Codell Sandstone. The geologist' log for the well indicates 3 feet of Juana Lopez shale between the Fort Hayes and Codell. The well also screened this shale interval. The bottom of the bentonite seal in the well was at the contact between this reported shale layer and the base of the Fort Hayes. MW-OOIA was found to remain dry for its entire life until it was plugged and abandoned in accordance with DRMS approval in April 2013 (GCC,2013). The absence of water encountered during quarrying the Fort Hayes and the dry conditions in MW-001 A substantiate the absence of water in both the Fort Hayes and Codell intervals in the vicinity of present mining. Wells MW-002,MW-003 and MW-004 were also plugged and abandoned in April 2013 in accordance with DRMS approval(GCC,2013),after studies revealed that they were installed in the alluvium within a losing reach of the St.Charles River(i.e. sourced by recharge from the river),and did not serve any purpose in monitoring for potential water quality impacts from the GCC plant or quarry(Contour Consulting Engineering,2013). Well MW-005 was installed between the plant site and the Edson Arroyo in July of 2008(Contour Consulting Engineering,2013). The well is completed in claystone(weathered shale)beneath a surficial clayey soil and screened from 9 to 25 feet. The borehole extended to 29 feet,but was terminated in the same claystone. Well MW-005 has been dry since it was installed. DISCUSSION ON GEOCHEMISTRY The relatively unique feature of the Fort Hayes Limestone at the GCC quarry is its high purity. It consists of relatively thick(30 to 40 feet)limestone beds with very thin shale interbeds. Collom(2000)prepared a geological report on the Fort Hayes Limestone for GCC in which it is noted that the limestone is relatively pure calcium carbonate(approximately 95%). The remaining mass is most entirely silica and alumina. Testing of the unit indicated that it contained exceptionally low concentrations of kerogens and sulfur. Kerogens are<0.10%in limestone and—0.2% in shale. The very thin shale interbeds in the Fort Hayes Limestone,which are a potential host for sulfide minerals,were noted to be free of excessive quantities of pyrite and other associated sulfide minerals. This was likely due to the well-oxygenated depositional environment. The average sulfur content of the limestone was reported as 0.07%dry weight as sulfide and sulfate,which is in the lower 20%of cement producing sources(Collom,2000). The metal content of the limestone was tested by GCC and reported to the DRMS(GCC,2015). Analyses of total metals were performed on the limestone,as well metals in Multiple Extraction Procedure(MEP) effluent. The MEP subjects the sample to multiple extractions using simulated precipitation(pH adjusted deionized water). The material tested was limestone collected from the initial crushing process and from the quarry floor. These results are shown in Table 1. The results are compared to published average and ranges of metal concentrations in limestone. This comparison indicates that concentrations in the GCC quarry limestone appear average for typical limestones,with possibly slightly above average concentrations of barium and selenium. MEP leachate concentrations for barium and selenium are still both well below Federal drinking water standards(Maximum Contaminant Levels,or MCLs)of 2 mg/L and 0.05 mg/L, respectively. With the exception of barium,very low metals concentrations were reported in the MEP effluent;mostly below or near the detection limit. Close Consulting Group LLC