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Chevron ProducLR Company 7 . Chevron Station tl9-5775 '101 W Kettleman Line Lodi ( A At)ku%t 25 2000 Groundwater Extraction Capture Zone Evaluation Operation of the interim GWE system consisting of one extraction well (EX -1) was initiated on July 3, 2000 On August 7, 2000, SECOR measured water levels at the site to evaluate the capture zone of well EX -1 Based upon the water level data collected, the current pumping rate of EX -1 (less than 0 3 gpin), and that wells MW -1 and MW -4 were not accessible due to ongoing site construction, an exact capture zone was not able to be determined Due to the relatively low extraction rate associated with the soil types underlying the site, further capture zone evaluation will be based on data collected over a longer period of time, and from additional monitoring wells upon completion of construction activities at the site Well EX -1 should be redeveloped prior to such testing Additionally, capture zone evaluation could also be performed on additional extraction wells However, this testing was not conducted at this time due to the iequest of Mr Marty Hartzell of the RWQCB in a conversation with Mr Roger Hoffinore of SECOR in June of 2000 (Attachment D) Mr Hartzell stated that pumping from wells other than EX -1 was not approved at this time as such pumping might result in the expansion of the existing plume Mr Hartzell agreed that if frill -time purnprrig from well EX -1 (commenced on July 3, 2000) did not demonstrate control of the plume, pumping from other wells, particularly in the direction of the municipal well, would likely become necessary REMEDIAL OBJECTIVE AND RECOMMENDED REMEDIAL ALTERNATIVE The objective of remediation at this site is to protect existing and potential uses of groundwater Existing uses of relevance to the ai ea include, but ai e not limited to, municipal and drinking water supply Interim remediation has been initiated at the site, as described in G -R's Site Update fbi Foiniel Chew on Station 9.5775, dated July 14, 2000 Based upon the remedial objective and interim remedial work performed to date, SECOR proposes the following Soil Vapor Extraction The interim SVE system operating at the site consists of four SVE wells and a 100-cfm catalytic oxidizer Based upon the data collected by G -R, the interim SVE system operating at the site has a sufficient radius of influence to remediate hydrocarbon impacted soil Figure 16 shows the estimated radius of influence for the SVE system using G -R's 60 -foot radius of influence that was derived from their SVE feasibility test Therefore, SECOR recommends continued operation of the SVE system to address the • secondary source on hydrocarbons in soil SVE data will be collected and evaluated on a bi-monthly basis to verify currently understood influence of the existing wells If ongoing evaluation of this O&M data suggests that the area of influence does not fully 077 41991 043/FRP