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Mr. Don O. Culbertson Proposal P95-060.56 June 29, 1995 Page 5 Polyvinyl Chloride (PVC) casing. Twenty feet of slotted casing (screened interval) will be placed at the approximate bottom of each boring and situated such that a portion of the screened interval extends above first-encountered groundwater which will allow for seasonal fluctuations in the groundwater and provide the ability to monitor for floating petroleum hydrocarbons. An appropriately sized sand pack will be placed in the annular space from the bottom of each boring to approximately 3 feet above the top of the screened interval. A bentonite seal will be placed above the sand pack and a cement grout containing approximately 4% bentonite will be placed above the bentonite to approximately 1 foot below grade (bg). The remainder of the annular space will be completed with a concrete grout. The well will be secured with either a locking at-grade, traffic-rated well cover or a metal riser set in a concrete pad, and graded to insure that surface water drainage occurs away from the well. A locking device will be installed to prevent access by unauthorized personnel. The location and elevation of each monitoring well will be surveyed and this information, in conjunction with depth to groundwater measurements, will be used to construct a groundwater contour map. Subtask 3.2 Monitoring well development and sampling. After the monitoring wells have been installed and the grout has been allow to set for at least 48 hours, they will be developed. Before development, the depth to groundwater will be measured and recorded and the well will be checked for free-phase petroleum hydrocarbons using an interface probe or a clear acrylic bailer. If free-phase petroleum hydrocarbons are observed, the thickness of this phase will be measured but the well will not be developed or sampled. If free-phase petroleum hydrocarbons are not observed in the well, it will be developed by surging, bailing, pumping, or a combination of these techniques until relatively non-turbid water is obtained. After the well has been developed and groundwater levels in the well have stabilized, they will be purged of at least three casing volumes of water and sampled by methods described in Appendix A. During groundwater sampling, a duplicate groundwater sample will be collected from one of the wells and an equipment blank will collected from the Teflon® bailer prior to sampling the first well. Task 4 Chemical Analysis Soil and groundwater samples collected during completion of Task 2 will be submitted to a California-certified laboratory for analysis. Soil and groundwater samples, including the duplicate groundwater and the equipment blank samples, will be analyzed for total extractable petroleum hydrocarbons as crude by EPA method 8015 modified, and for benzene, toluene, ethylbenzene, and total xylenes (BTEX) by EPA method 8020. One FRF/H:\wp\proposal\P9506056.wp5-95 gtf:l