2013-08-13_HYDROLOGY - M1977348 (2)

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August 2013 7 103- 81640A cored using water to more easily remove the cuttings and reduce dust. Circulation of cuttings and water was not observed during the drilling. Upon removal of the HSA, drill cuttings were observed to be lodged between the outside of the HSA and the fill, suggesting circulation was likely lost due to, and into, the permeable fill. To install monitoring well MW -7, the NQ corehole was abandoned due to drilling difficulties and an offset boring was drilled 20 feet north of the NQ corehole using a 7'/8 -inch air -rotary roller bit to a total depth of 260 feet bls, where the top of the Codell sandstone was observed in the adjacent NQ corehole. Drilling occurred through a string of 81/4 -inch ID HSA set at 30 feet bls to case off the fill. A diverter was installed at the top of the 8'/4 -inch ID HSA to divert cuttings and dust generated from the drilling to a covered roll -off. Water was not added to the air stream while drilling most of this hole to limit introduction of potable water that may impact future groundwater sampling results. A notable amount of groundwater was produced from a depth of about 210 to 215 feet bls, which limited dust generation during drilling of the well borehole. However, at greater depths it was necessary to add water to lift the drill cuttings to the surface and to clear out the borehole before setting the well. Drill cuttings were not sampled from this borehole because the NQ core is representative of the encountered lithology at monitoring well MW -7. 3.1.4 Whole Rock Laboratory Testing A total of seven whole rock samples were collected from the cuttings or core in the screened intervals of each well and submitted to ACZ Laboratories for analysis. The samples were collected for analysis of chemistry to help determine if the geology is contributing to elevated groundwater constituent concentrations. The analysis includes a bulk chemical analysis and the Synthetic Precipitation Leaching Procedure (SPLP) for the same constituents as the groundwater monitoring program. At MW -5, one composite sample was collected from the split -spoon samples from the screened interval. At MW -6 and MW -7, three samples each were collected from distinct rock types in contact with the well screens. Results of the whole rock testing will be discussed in the Site Characterization Report to be prepared after completing quarterly sampling of all seven monitoring wells in 2013. 3.2 Packer Testing Packer injection testing of the bedrock was conducted at select intervals within the NQ corehole as part of the drilling program at monitoring well MW -7. A Longyear NQ Wireline Packer was used as coring progressed to evaluate in -situ hydraulic conductivity of discrete rock intervals. A total of three intervals was tested - -the first between 55 and 61 feet bls (zone of first observed groundwater), the second between 262 and 271 feet bls (the top section of the Codell sandstone), and the last from 251 to 271 feet bls. No other packer testing was conducted because rock coring did not take place at monitoring wells MW -5 (due to high groundwater yields above bedrock) and MW -6. i \10 \81640a\ 0400\ gwcharwellinstallfieldrep_ 09aug13\ gwcharwellinstalifieldrep _09aug13 docx Golder Associates