2013-08-13_HYDROLOGY - M1977348 (2)

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August 2013 8 103- 81640A To conduct the tests, the packer system was inflated at the surface within a section of NQ drill pipe to test and repair leaks. Golder checked the flow meter calibration by pumping water through the flow meter and timing how long it took to fill a 5- gallon bucket and comparing to the meter reading. The meter was found to be in calibration. Following system checks, the core barrel was removed from the NQ drill stem, the drill stem raised to set the bit at the desired depth, and then the packer assembly was lowered on to the bit. The packer was then inflated to a pressure adequate for the depth of the test interval and water was pumped through the system. After adequate flushing of the zone was achieved and steady flow was observed, Golder recorded injection pressures and flow rates. After pressure and flow readings stabilized, the injection pressure was increased incrementally until three or four steps were completed. The flow and pressure readings were used to estimate the hydraulic conductivity using the following equation for Method 1 Zone 3 tests (U.S. Department of the Interior 1977): Where: Q K __ [(Cs + 4)rH] K: hydraulic conductivity, feet/second Q: water injection flow rate (cubic feet/second) Cs: conductivity coefficient r: borehole radius, feet H: effective head, feet. The solutions for each interval are provided in Appendix C, and the results are present in Table 2 to compare with slug test data and data from monitoring wells MW -1 through MW -4. 3.3 Monitoring Well Installation Monitoring wells were installed in the boreholes following completion of drilling and packer testing. In general, the wells were constructed with either 2- or 4 -inch diameter ID, flush threaded, Schedule 40 PVC 20 -slot screen and riser lowered in the borehole until the casing protruded above the land surface. The annular space around the screen and end cap was filled with clean, washed, well- rounded #10 -20 Colorado silica sand by gravity feed to approximately 2 to 4 feet above the top perforation. A hydraulic seal was created with CETCOO medium bentonite chips gravity -fed into the annular space above the screen and filter pack. CETCOO Puregold0 bentonite grout was placed in the annular space above the bentonite seal. The grout was mixed and placed in accordance with the State of Colorado Division of Water Resources (DWR) Water Well Construction Rules 2 CCR 402 -2. A 4- or 6 -inch square protective steel casing was placed around the PVC riser such that the bottom extends into the annular space to the top of the bentonite grout and the top rises above the PVC casing several inches. Concrete was placed at the top of the bentonite grout to land surface. A concrete pad, approximately 3 -foot square and about 6 inches thick was constructed around the protective casing. The i \10 \81640a\ 0400\ gwcharwellinstallfeldrep_ 09aug13\ gwcharwellinstallfieldrep _09aug13 docx Golder Associates