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10/10/00 TUE 17:09 FAX 1 916 861 0430 SECOR-SACRAMENTO Z011 Ch cvron Products Company 2 toner Chevrnn Swtio -5 W t Keak=n Wc.i, Califomin oclQer 9 2000 stabilize the groundwater plume to prevent movement of MIME toward Well 12. A soil vapor extraction system and a groundwater pump and treat system with one extraction well was started on 3 July. Since then the groundwater pumping rate has dropped from approximately 2 gallons per minute (gpm) to less than 0.2 gpm. _ Groundwater contour maps in the .SPAR and FRP show the groundwater plume is moving off` -site to the west and southwest, therefore, the plume has not been stabilized As stated in the RWQCB's Review Problem Assessment Report and Final Remediation Plan, Former Chevron Station #9-5775, 301 West Kettleman Lane, Lodi, Cleanup and Abatement (C&4) Order No. 5-00-704, dated September 22, 2000 (attached to the NOV) operation of a soil vapor extraction system and an interim groundwater extraction were initiated on July 3, 2000, in accordance with the C&A Order compliance date. Gettler-Ryan has indicated that operation of these remedial systems has been continuous to the extent possible since startup, with the exception of short periods of time for re -development of the extraction well and minor routine maintenance of the systems. As noted in the RWQCl3's comment, the groundwater pumping rate in EX -I has declined from 2 gpm to 0.2 gpm. During a telephone conversation with Marty Hartzell of the RWQCB in June 2000, SECOR requested that additional wells (MW -13 and MW -14) be evaluated for pumping • groundwater; however, the RWQCB did not approve the addition of more pumping wells due to their concern of expanding the plume (documented in the FRP, dated August 25, 2000). Prior to this in April 2000, SECOR also requested approval to install remedial oxygen diffusion wells to help prevent the migration of hydrocarbons in groundwater offsite. The RWQCB did not approve the installation of these wells as stated in their letter dated May 19, 2000. • SECOR requested that the extraction wells be re -developed and the RWQCB verbally approved this request on August 23, 2000. In addition, SECOR requested approval to initiate pumping from well N W-14 (renamed as MW-14/EX-2), and the RWQCB agreed at this time. On August 31, 2000, remedial piping was installed for a proposed fixture extraction well (EX -3) to be located near monitoring well MW -1. Between late August and September 19, 2000, access restrictions associated with construction activities slightly delayed the implementation of these approved activities. On September 19, 2000, wells MW- I41EX-2 (located in the southwest corner of the site), MW -13 (located in the southeast corner of the site), and well EX -1 were re -developed. On September 22, 2000, groundwater extraction was initiated from well MW-14/EX-2. A sustainable extraction rate of approximately 0.1 gallons per minute (gpm) was established for both EX -1 and MW-141EX-2. Monitoring and capture zone analysis is ongoing to evaluate plume capture. Preliminary capture zone data (discussed below) suggests that the capture zone resulting from the pumping of wells EX -1 and MW- 14/EX-2 extends from the area of the extraction wells offsite onto and possibly across 077.41991.04310ctober 9, 2000.doc