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W W RESOURCE <br /> `� HYDROGEOLOGIC <br /> SERVICES <br /> be placed by pouring 3/8-inch chip bentonite from surface, hydrating with potable water as <br /> necessary. Continuous depth tagging shall be employed to ensure materials bridging does not <br /> occur. <br /> 5. Install appropriate 5-foot length by 4-inch square or round locking environmental monitoring well <br /> head protector set in 3-foot by 3-foot by 4-inch-thick cement pad with 4-inch diameter by 6-foot <br /> length steel pipe protective bollards cemented in-place offset at each pad corner. Each wellhead <br /> shall be clearly labeled by the well name welded either on the top cap or below the locking hasp <br /> prior to arriving onsite. The well names are MW-9, MW-10, MW-11, MW-12, MW-13, MW-14. <br /> The exception to the installation specifications above is for the MW-10 location. As this location is <br /> upgradient of current and future mining,there is interest in collecting adequate rock sample to potentially <br /> conduct whole rock chemical analysis and leachate testing to assist with hydrogeochemical <br /> characterization of the mined Fort Hayes limestone, interburden strata and the underburden Codell <br /> sandstone. To accomplish this, HQ (3.78") wireline core drilling will be performed in lieu of air rotary <br /> drilling from top of bedrock to total depth (base of Codell sandstone). Coring will require injection of <br /> potable water, which will be kept to minimum quantity. As with all of the other bedrock wells, hollow- <br /> stem auger drilling through the unconsolidated colluvium until bedrock refusal is acceptable to effectively <br /> set temporary casing through this interval as needed. Following completion of the core hole, it will be <br /> reamed out to 6-3/8-inch to allow installation of the PVC well as described above. The remainder of the <br /> procedure above, steps 3-5, will be conducted following reaming to complete the Codell sandstone <br /> monitoring well MW-10. <br /> BOREHOLE DRILLING & MONITORING WELL INSTALLATION - COLLUVIUM <br /> In the event significant moisture or free groundwater is encountered in the unconsolidated colluvium <br /> when drilling at the MW-13 and MW-14 locations, a seventh well, MW-15 shall be installed to screen this <br /> material down to the top of bedrock. A nearby existing well, MW-5, has been dry since installation in <br /> 2013 so this is not expected, however plans are to be prepared so, if necessary, it can be completed in the <br /> same mobilization. As the colluvium is fine-grained and unconsolidated,this will require slightly different <br /> specification from the bedrock wells as follows: <br /> 1. Hollow-stem auger drilling through the unconsolidated colluvium until bedrock refusal to <br /> effectively set temporary casing through this interval to enable construction of the well inside. <br /> Following well construction,the hollow-stem augers shall be pulled back to surface and removed, <br /> exposing the newly completed well to the natural formation. As stated previously,the auger inner <br /> diameter must allow a minimum 2-inch annulus per 2 CCR 402-2 State of Colorado Water Well <br /> Construction Rules, which for this project utilizing nominal 2-inch schedule 40 screen and casing <br /> GCC Rio GRANDE,INC.PUEBLO PLANT <br /> 2021 MONITORING WELL INSTALLATION PROGRAM WORK PLAN <br /> 7 <br />