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Working to Restore Nature Quarterly Groundwater Monitoring, Fourth Quarter 1993 February 2, 1994 Quik Stop Market No 132, Stockton, California F7132 93 Quarterly Well Pumping As agreed upon with the San Joaquin County Public Health Services (SJCPHS), groundwater is pumped out of monitoring well MW-5 on a quarterly basis as an interim remedial measure (RESNA, November 1991) For this quarter, well MW-5 was pumped on November 10, 1993 As agreed, prior to pumping, a groundwater sample designated as MW-5A was collected from the well. After pumping MW-5 for about 3 hours and extracting approximately 300 gallons of water, another groundwater sample designated as MW-5B was collected The groundwater extracted from MW-5 was transported by Erickson Inc , a licensed trucking company from Richmond California, to Gibson Environmental, a licensed recycling facility located in Redwood City, Califorrua Groundwater Sampling On December 17, 1993, groundwater samples were collected from five (MW-1R, MW-2, MW-5, MW-6, and MW-7) of the seven monitoring wells in accordance with RESNA's field protocol (Appendix A) In November 1992, the SJCPHS approved semiannual sampling of monitoring wells MW-3 and MW-4 (SJCPHS, November 17, 1992) and in February 1993, they approved discontinuing sampling of these wells (Personal Communication, February 2, t 1993) Groundwater purged from the wells and equipment decontamination water were placed in a licensed, trailer-mounted container and disposed of at Gibson Environmental, a licensed recycling facility located in Redwood City, California Well and water depth information are shown on the Field Report/Data Sheets and, the volume of groundwater removed from each well and other measured sampling parameters are noted on the Well Purge Data Sheets, included in Appendix B Laboratory Analyses IThe groundwater samples were transported to Sequoia Analytical, a state-certified laboratory, located in Redwood City, California Samples were analyzed for the presence ' of TPHg following modified Environmental Protection Agency (EPA) Methods 3050/8015 and for BTEX following EPA Methods 3050/8020 The laboratory analytical reports and chain-of-custody records are attached in Appendix C ' Summary of Results and Discussion A summary of the analytical results from current and past well samplings is presented in Table 1 Based on the water level data for December 17, 1993, (Table 1), RESNA has ' 2