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11AW11ERS ESIG4ERSGONSULi+uiS ' mineral content, etc. and classified according to the Unified Soil Classification System (USCS). • Borehole logs are presented in Appendix of this report. 1 Monitor wells were constructed of 4-inch diameter PVC screen and blank casing MW-2A and ' MW-3A were installed to approximately 60 and 57 feet bgs, respectively, using 20 feet of .01 - inch slot PVC screen with a #lc Lonestar sand The top of the screen was set approximately 5 feet above the saturated zone The sand pack was slowly placed through the augers across the ' screened interval and extend at least 2 feet above the top of the screen A 2-foot thick bentomte seal was placed above the sand pack and hydrated for at least 30 minutes, prior to grouting the ' remaining annular space with cement/bentonite grout mixture Both wells were completed at the surface with traffic-rated utility boxes, mounted flush with the ground surface ' After well construction was completed and the grout seals had been allowed approximately 24 hours to harden, each well was developed using a combination of bailing and surging until the ' water was relatively free of sediments Over 10 wells volumes were removed from each well during development The elevation of the top of the PVC casing at each well was surveyed ' relative to mean sea level. Soil cuttings were contained in labelled 55 gallon drums and transported for storage inside the San Joaquin County motor pool building at 100 N. Hunter Street Monitor Well Abandonment One dry monitor well was abandoned during this field effort As requested by PHSEHD, MW-2 ' was not abandoned during this field effort as originally proposed Well abandonment was completed by emplacement of a bentonite-cement grout mixture from the bottom of the well, ' upward. The well was not grouted under pressure, other than the weight of the grout column, because the well was located beneath an overhang of the Building which prevented ng access The well casing was refilled to the surface as necessary and surface patched with a concrete ' mixture. ' Groundwater Sam lin ' Groundwater sampling was conducted on 25 and 26 July 1995, after the aquifer surrounding the newly installed and developed monitor wells had been allowed to equilibrate for 2 weeks Before sampling, the depth to water was measured and the well volume was computed using the 1 well diameter and the height to the water column A minimum of three casing volumes were purged from each well in order to obtain a representative groundwater sample Groundwater 1 LTR0JEcrs%VU0Q+HS"R SE m A-2 29 Augmt 190