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Chevron <br /> a [heron <br /> Chevron Products Company <br /> February 27, 1997 6001 Bollinger Canyon Road <br /> Building L <br /> San Ramon CA 94563 <br /> P 0 Box 6004 <br /> San Ramon CA 94583-0904 <br /> Mr Ron Rowe <br /> �i <br /> San Joaquin County Public Health Services Marketing—Sales West <br /> PO Box 388 Phone 510 842-9500 <br /> Stockton, CA 95201-0388 <br /> Re Chevron Station# 9-8264 3775 Tragy Blvd Tracy, CA <br /> Attached Groundwater Monitoring Report(Blaine Tech, 1/28/97) <br /> Dear Mr Rowe <br /> Attached you will find a report dated January 28 1997 that was prepared by Chevron's consultant, Blaine <br /> Tech Services, Inc (Blaine Tech), to describe the results of groundwater monitoring that was performed at <br /> the subject site on January 7, 1997 The groundwater analytical results obtained from the previous site <br /> monitoring event were inadvertently omitted from the cumulative table of results appearing in this report <br /> Blaine Tech has been made aware of this omission and will include those data in all subsequent reports <br />• During their January site visit Blaine Tech gauged and sampled all four site-related monitoring wells The <br /> measured direction of groundwater flow was northeasterly Groundwater samples from each well were <br /> analyzed for the presence of TPHGas, BTEX constituents, TPHDiesel, and MTBE In addition, samples <br /> collected from well MW-1 were analyzed for total oil and grease, soluble metals, semi-volatile organic <br /> compounds(SVOC's), and halogenated volatile organic compounds (HVOC's) <br /> Consistent with the findings of the previous monitoring results, there were no motor fuel hydrocarbons <br /> detected at any of the site wells MTBE was detected at wells MW-3 and MW-4 at levels of 780 ppb and <br /> 32 ppb, respectively MTBE was not present at wells MW-1 and MW-2 Samples from well MW-1 did not <br /> defect HVOC's SVOC's or total oil and grease Zinc was detected at 79 ppb in groundwater at well MW- <br /> 1 All other soluble metals were non-detect <br /> The groundwater data collected over the last four quarters has demonstrated an east-northeasterly <br /> direction of flow and has consistently shown an absence of motor fuel hydrocarbons In addition, waste oil <br /> constituents tested for at well MW-1 have been absent These data indicate that there is no widespread <br /> plunie of dissolved hydrocarbons beneath the subject site However there have been consistent detections <br /> of MTBE in groundwater adjacent to and downgradient from the fortner fuel UST complex Considering <br /> these established trends, Chevron proposes the following modifications to the monitoring and sampling <br /> program at the subject site <br /> -measure the depth to groundwater at all site wells quarterly <br /> -sample wells MW-3 and MW-4 quarterly, wells MW-1 and MW-2 annually <br /> -analyze all samples for BTEX constituents and MTBE, discontinue all other analyses <br /> -report results semi-annually, include potent iometric surface maps for the two previous quarters <br /> Pending approval from your agency, Chevron will implement this proposal beginning second quarter of <br /> this year If you have any questions or coninients, please contact me directly at(510) 842-8695 <br />