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%6MEMORANDUMft CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD - CENTRAL VALLEY REGION 3443 Routier Road, Suite A Phone: (916) 361-5600 Sacramento, CA 95827-3098 ATSS Phone: 8-495-5600 TO: Antonia K. J. Vorster FROM: Gary A. Reents DATE: 30 March 1990 SIGNATURE: SUBJECT: Phase V Remedial Investigation Report, Nestle foods, San Joaquin County Camp, Dresser, and McKee submitted the subject report, dated 30 January 1990, on behalf of Nestle Foods. A separate letter report describing the results of a soil gas survey dated 16 October 1989, was also submitted at the same time as the RI report. Together, these two reports describe the results of Phase V of the remedial investigation. Phase V work consisted of conducting a soil gas survey west and south of the Nestle facility; installing 12 additional monitoring wells; sampling and analysis of groundwater from monitoring, municipal , and domestic wells; collecting water level data; and conducting a well cycling aquifer "test" . The RI report also includes a proposal and time schedule for additional work. Soil gas samples were collected on the Regal Almond property west of Nestle, and on the Guntert Steel and Ripon Manufacturing properties south of the facility. In all , samples were collected at 35 points. The results do not indicate that volatile organic contamination sources exist on any of these properties. The results do indicate that groundwater contamination levels in the shallow zone are probably substantial to the west/southwest and low to the south. These results correlate with the existing groundwater chemical data. The 12 additional monitoring wells were installed to define the contamination in all aquifer zones, but primarily the C zone. Lithologic and geophysical logging performed as part of well installation added to the definition of the local geology. The results of the well cycling test indicate that at least the A through C zones are interconnected, and that production wells affect groundwater flow directions over substantial distances. Sample results indicate that delineation of the extent of contamination is nearly complete, though some additional work is necessary as described in my comments below. At this point, Nestle proposes to complete the Risk Assessment, collect additional well cycling data, and conduct another round of monitoring well sampling. The Feasiblity Study would then be drafted and submitted by May 1991. My comments regarding the Phase V report results and proposed additional work are as follows: 1. Nestle does not propose any additional monitoring wells in the next phase of work which implies that it considers plume definition complete. Reviewing the levels of total volatile organics of concern (see comment 2a below) , definition appears to be complete in the B-zone, but not in the A and C-zones. Definition of the southwestern extent of contamination in the A-zone (near wells D-1 and D-2) does