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Amy Eschberger Reference No. 20378105-1-TM-0 ' <br /> Colorado Division of Reclamation, Mining and Safety February 19,2021 <br /> 1.2 Borehole Logging ' <br /> A Golder hydrogeologist was on Site during drilling activities and documented drilling conditions and sample <br /> observations. The borehole log for MW-8 (Attachment A) includes the following pieces of information: ' <br /> ■ Lithologies <br /> • Soil was classified following the Unified Soil Classification System (USCS) ' <br /> ■ Rock type was classified following the Dunham classification scheme for carbonates <br /> ■ Soil or rock color identified by the Munsell color chart ' <br /> ■ Moisture content (dry, moist, wet) , <br /> ■ Rock induration, sedimentary structures, fractures (if visible during air-coring) <br /> ■ Driller observations ' <br /> ■ Drilling methods <br /> Until air-coring was used at 165 ft bgs, lithologic descriptions were based on auger cuttings and air-rotary cuttings. ' <br /> Bedrock was encountered at 2 ft bgs based on driller observation with silt and gravel overburden. Generally, the <br /> auger cuttings and air-rotary cuttings indicated medium gray to light olive gray calcareous shale and limestone'. <br /> A shallow zone of groundwater was encountered at approximately 115 ft bgs. A sample of this water was ' <br /> collected from the open borehole and submitted for laboratory testing, results are provided in Attachment B. <br /> Significant water entered the borehole from this shallow zone, and deeper observations of groundwater ' <br /> occurrences were not possible due to the water infilling from the upper groundwater zone. <br /> Air-coring was used from 165 ft bgs to 235 ft bgs, and no water was added to circulate cuttings. Recovery was ' <br /> poor from approximately 165 ft bgs to 206 ft bgs due to significant mechanical fracturing. Short runs were used in <br /> this Interval to prevent the core from falling out of the core barrel. Bedrock lithology was predominantly medium <br /> light gray, well indurated massive limestone with varying amounts of lamination and bioturbation, few intervals of ' <br /> wackestone and more fossiliferous limestone were observed. Pyrite mineralization was observed primarily along <br /> bedding surfaces. Subvertical joints were observed between 208 ft bgs and 215 ft bgs. A distinct transition at <br /> 215 ft bgs from the overlying medium light gray massive limestone to very light gray, very well indurated massive ' <br /> limestone with sand-filled burrows, rip-up clasts, and stylolites are indicative of the interval directly above the <br /> Niobrara—Codell contact. The Niobrara—Codell contact was observed at 230 ft bgs. The Codell Sandstone was <br /> characterized as a medium light gray, subrounded, well-sorted, very fine—fine grained sandstone dominated by ' <br /> quartz and black lithics. The Codell was heavily bioturbated from 230 ft bgs to 232 ft bgs with a distinct salt and <br /> pepper appearance from 232 ft bgs to 235 ft bgs. <br /> Limestone terminology has been used to describe observed Niobrara Formation to maintain consistency with previous core descriptions ' <br /> completed at the Holcim Boettcher Quarry.Core described in the field as a calcareous mudstone(micrite equivalent)which reflects the <br /> USGS(1988)Laporte Quadrangle description of the two members of the Niobrara Formation,the Smoky Hill Shale Member and the ' <br /> Fort Hays Limestone Member. <br /> GOLDER 2 ' <br />