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FWMA NSA Working to Restore Nature Quik Stop Market No. 132 Project No. F7132.93 June 8, 1993 This pumping was agreed upon with the SJCPHS in August 1991 as a temporary:interim remedial activity pending receipt of permission to enter adjacent downgradient properties. When well sampling purge water and equipment rinse water is transported from the site by Exceltrans (a licensed hauler), monitoring well MW-5 is pumped using a vacuum truck with a clean PVC-extension. During the pumping, water in the well is kept at a low level by periodic pumping over a period of about 3 hours. Previous measurements indicate that pumping for 3 hours removes approximately 200 gallons of groundwater. Groundwater 11 samples are obtained prior to and at the completion of pumping. The groundwater samples are collected following the procedures outlined in the RESNA groundwater sampling j protocol (Appendix B). The samples were transported to RESNA Environmental Laboratories, a state-certified laboratory located in Fremont, California and analyzed for TPHG and BTEX. The results of these analysis are included in Table 1. f In an effort to further delineate the off-site extent of contamination, RESNA and Quik Stop Markets, with the approval of SJCPHS, elected to conduct a soil gas and shallow groundwater survey along the eastern side of the Taco Bell site and that portion of West Hammer Lane which fronts the Taco Bell site. This survey was conducted'on April 29, 1992 with a specially equipped van operated by Tracer Research Corporation(Tracer) of Tucson, Arizona,under the direction of a RESNA geologist. The results of this survey indicated that the upper aquifer and the contamination detected in it did not extend into the areas investigated in this survey. This may indicate that the upper aquifer is limited in extent and isolated from the lower aquifer (RESNA,July 1992) and/or that the contamination detected in the upper aquifer is localized. 1' In view of the information obtained in the Tracer survey, RESNA recommended the ' installation of two groundwater monitoring wells on the Taco Bell property. It was clear that obtaining access for the installation of two groundwater monitoring wells on the Taco Bell property would require the assistance of the SJCPHS. Scheduled quarterly groundwater sampling and analysis were continued. ' In our June 1992 quarterly report (RESNA, October 1992) RESNA recommended that on the basis of an established history of nondetectable TPHG and BTEX the sampling frequency for wells MW-3 and MW-4 be reduced from quarterly to semi-annually. In a jletter dated November 17, 1992 to Mr. Jack Griffith of Quik Stop Markets the SJCPHS approved the semi-annual sampling and analysis of these two wells. During a phone conversation on December 3, 1992 with Mr.Steven Schneider of the SJCPHS,Mr. Schneider 1, reduced the fecal coliform sampling and analysis of well MW-2 from semi-annually to annually. A-3