ARCHIVED REPORTS XR0006092 - Laserfiche WebLink

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A WEGE geologist working under the direct supervision of California Registered Geologist #3037 utilized V&W Drilling GeoProbe direct push drilling rig,to continuously core and sample five probes, see Figure 3 and Appendix C - borehole logs All probe holes encountered groundwater between 11 and 12 feet below the surface (bts) The probe holes were destroyed the day they were drilled Probe holes P8 and P9 were sited to define the western edge, lateral extent of the hydrocarbon plume Probe hole P8 was sited approximately 32 feet west of previous probe hole P-3 performed by TEG (October 1995) P8 was necessary to determine the lateral extent of the first water zone (A Zone) hydrocarbon plume extent P8 was continuously cored (four foot sections) to 15 feet bts where a hydropunch water sample was obtained from 15 to 16 feet bts (P8-16W) Probe hole P9 was sited eight feet west of P8 Continuous cores were obtained from 16 feet bts to 26 feet bts Between 26 feet bts to 32 feet bts flowing sands were encountered Jamming the core barrel and no core recovery was possible Continuous cores were then obtained from 32 feet bts to total depth of 36 feet bts Prior to advancing the cores below 30 feet bts a hydropunch water sample was obtained from 30 to 32 feet bts (P9-30W) Probe hole 10 was sited 42 feet west-northwest of monitor well MW3 This probe was sited to detect the upper and lower elevations of the first water zone and to determine the southern extent of the plume downgradient of the site Continuous cores were obtained from 8 feet bts to 24 feet bts The core barrel Jammed at 24 feet bts and the hole was terminated Prior to coring 16 feet bts a hydropunch water sample was obtained from 16 to 17 feet bts (top of water P 10-16W) Probe hole 11 was sited south of P 10 to investigate below where P 10 Jammed, 24 feet bts Continuous cores were obtained from 24 feet to 36 feet bts A hydropunch water sample was obtained between 32 and 36 feet bts prior to coring below the 32 foot depth (P11-32- 36W) A hydropunch water sample was attempted below the 36 foot depth from 36 to 40 feet bts The minibailer came up dry with fine sand on the tip after 15 minutes waiting for water to enter the hydropunch screen Probe hole 12 was sited 44 feet west of MW 1 (most contaminated well onsite) to obtain cores and water samples from the top sand interval Continuous cores were obtained from 8 to 16 feet bts A hydropunch water sample was obtained between 16 and 17 feet bts (P l 2-16W) Based on the inspection of cores from P8 through P12 and laboratory results obtained from the hydropunch water samples it was determined that two distinct water zones were present and that cluster wells would need to be installed to isolate the two zone and to document site remediation and conditions 6 Sanchez 2nd QM 2001