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CLOSE CONSULTING GROUP <br /> Envit(mirTtenta) Science& Engineeing <br /> February 8,2018 <br /> Mr.Edwin Olivares <br /> GCC Rio Grande,Inc. <br /> 3372 Lime Road <br /> Pueblo,CO 81004 <br /> RE: Groundwater Monitoring Well Installation and Baseline Sampling: MW-6 and MW-7 <br /> Dear Mr.Olivares: <br /> This letter provides documentation of the installation and initial sampling of two groundwater monitoring <br /> wells located downdip of the second mine panel at the GCC Rio Grande Inc.(GCC)Pueblo limestone quarry <br /> (Figure 1). Installation activities were completed by Close Consulting Group LLC(CCG)and drilling <br /> contractors(Site Services, Inc.and Dakota Drilling, Inc.)at the request of GCC. The work was completed <br /> pursuant to Technical Revision No.6(TR-06),approved by the Colorado Division of Reclamation,Mining <br /> and Safety(DRMS)on July 28,2017. <br /> The purpose of the work was to investigate the possible presence and nature of groundwater in the Fort Hays <br /> Limestone and Codell Sandstone. The generalized stratigraphy of the site consists of topsoil and colluvium <br /> at the surface,followed by the Smoky Hill Shale,the Fort Hays Limestone,and finally the Codell Sandstone, <br /> which was the deepest unit targeted for drilling. The original scope entailed installation of a single well to <br /> monitor both the Fort Hayes and the Codell if no saturation was apparent at the base of the Fort Hays. If <br /> saturation at the Fort Hayes-Codell contact was observed during drilling,a well cluster was to be installed <br /> to monitor both intervals separately. Drilling was targeted in an area that was approximately along the <br /> projected extension of a fault observed within the second mine panel (Figure 1). Due to other circumstances <br /> and findings during the drilling program,described below,two wells were installed in the Fort Hays. <br /> SITE DRILLING ACTIVITIES: SEPTEMBER 2017 <br /> Prior to drilling activities,GCC personnel contacted the Utility Notification Center of Colorado(UNCC)to <br /> locate any underground utilities at the drilling location and filed a Notice of Intent with the Colorado <br /> Division of Water Resources. Borehole drilling was completed on September 6-7,2017 by Site Services, <br /> Inc.,under observation by CCG, using a CME-55 drill rig and 4.25-inch inner diameter(I.D), 8-inch outer <br /> diameter(O.D)hollow-stem auger. <br /> Soil samples were collected by continuous dry core sampler from ground surface to a depth of 19 feet,where <br /> the auger met refusal. Cores from this interval were collected and logged to obtain stratigraphic and <br /> lithologic data. From there,the borehole was advanced with a rotary drill bit,and cuttings samples that came <br /> to surface were collected and logged for visual descriptions. The upper 12 feet were surface soils and <br /> colluvium,with a limestone gravel layer near the base. The Smoky Hill Shale contact was estimated to be at <br /> 12 feet below ground surface(BGS),extending to approximately 27 feet,where the Fort Hays Limestone <br />