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MEM0RANDU ►�. r <br /> CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD • CENTRAL VALLEY REGION <br /> 3443 Routier Road, Suite A Phone: (916)255-3000 <br /> Sacramento, California 95827-3098 CALNET: 8-494-3000 <br /> TO: Wendy L. Cohen FROM: Jon B. Marshack, D. Env.. <br /> Senior WRC Engineer Senior Environmental Specialist <br /> SLIC Unit Environmentalfrechnical Support Unit <br /> DATE: 7 March 1996 SIGNATURE: <br /> SUBJECT: COMMENTS ON 28 FEBRUARY 1996 SUBMITTAL BY GEOMATRIX FOR <br /> CHEVRON PIPELINE, COMPANY DIVIDEND PROPERTY, TRACY <br /> The following are my comments on Geomatrix Consultants' 28 February 1996 response to our <br /> 1 February request for additional information on the subject site. Additional comments are <br /> included on analytical chromatograms contained in Geomatrix'26 October 1995 Quarterly <br /> Groundwater Monitoring Report and on voice-mail messages left for you by Ms. Zemo of <br /> Geomatrix on 6 March 1996 and forwarded to me. <br /> Requests for Closure Documentation per Tri-Regional Recommendations,Appendix B,page 2 <br /> 1) The well survey submitted by Geomatrix does not clearly show the location of each well and <br /> the distance between pipeline leak locations and each well. Information on how the wells are <br /> sealed would also be helpful. <br /> 2) Geomatrix'response is acceptable. <br /> 3) Historic high and low ground water levels are not represented in the 26 October 1995 report. <br /> Only data for August 1994 through August 1995 are included. These data show a rising <br /> water table over this period. Water level information collected between well installation and <br /> August 1994 should also be presented to demonstrate seasonal fluctuations and overall <br /> trends. The 3 November 1993 Remediation Plan prepared by Erler& Kalinowski, Inc. <br /> shows high levels of hydrocarbons in soils that are now below the water table. We need to <br /> determine whether contaminated soils were part of the vadose zone in earlier years which <br /> have more recently become saturated. This may be contributing to the increasing <br /> concentrations of diesel-range hydrocarbons in MW-13 and MW-23. Will the trend in these <br /> data continue? Could the rising water table have caused the disappearance of free product <br /> shown to exist in earlier reports? <br /> 4) Geomatrix'response is acceptable. <br /> 5) A comparison of the extent of hydrocarbon contaminated soils and ground water initially <br /> found (earliest investigations of the site) and at present are needed to document changes in <br /> plume extent. Contours are useful to indicate where significant data gaps may exist. <br /> The discharger has chosen to implement a passive-bioremediation cleanup method. As stated in <br /> USEPA, Region 9's Fact Sheet on the Lawrence Livermore Report (copy attached), passive <br />