SITE INFORMATION AND CORRESPONDENCE_FILE 1

Home Browse Search

CIIEVRON PIPELINE CO.,-DIVIDEND PROPERTY, TRACY Regional 11hier Board Staff Position: a) This case is not a "soil-only" case, since pollutants have reached ground water. b) Based on the information provided to date, this case may be a"low-risk" case. c) To clearly demonstrate that the case is "low-risk" and to document remaining contaminants at the site being considered for closure, more information is needed, as outlined below. i Information Needs to Assess This Case for Closure: t) Well Survey —Identify the location of the well relative to the pipeline in the 1/4 of 1/4 of section labeled "19, U on the Figure 1 map in Geomatrix' 28 February 1996 submittal and describe its construction and use. 2) Ground lilater Sampling — Perform two additional quarters of ground water sampling from wells MW-13, MNV-16, MW-17, MW-18 and MW-19 during the first two quarters of 1996. Samples should be analyzed for diesel-range and gasoline-range petroleum hydrocarbons by GC-FID and for BTEX by USE-PA Method 8020 without filtration. Centrifugation and silica gel cleanup of diesel-range hydrocarbon samples are acceptable, but not necessary. Diesel- range (extractable) hydrocarbons should be limited to hydrocarbons with C10 through CID chain lengths. Gasoline-range (purgeable) hydrocarbons should be limited to hydrocarbons with C4 through C12 chain lengths. Analytical quantitation limits should match those of the Tri-Regional Recommendations. Chromatographic conditions (e.g., oven temperature program) should be adjusted so that the initial solvent peak is clearly separated from the i analyte peaks. 3) Geologic Cross Section —The cross-section along the pipeline in Geomatrix' 28 February 1996 submittal should be modified to include existing analytical data from soil and ground Nvater and high and low ground water table elevations that have existed since well installation. 4) Remaining Soil Contamination -- Present graphical representations (concentration contours) of the vertical and lateral extent.of soil contaminants proposed to be left in place, using existing data. i 5) Remediation Alternatives —Present the rationale for not implementing active remedial measures that were proposed and approved by Regional Water Board staff in 1.991. 6) Remaining Contaminants— Present the rationale for leaving soil and ground water contaminants in place. The discussion should address the protection afforded to existing and potential beneficial uses of ground water in the area of the release and an estimate (with rationale) of the expected time period for passive remediation measures to reduce pollutants below beneficial use-protective levels. 7) Properly O nerAcceptance —Concurrence from the property owner, Dividend Development Corporation, that the discharger's conclusions and recommendations for case closure are acceptable. 20 March 1996