SITE INFORMATION AND CORRESPONDENCE_FILE 1

Home Browse Search

MEMORANDUM CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD * CENTRAL VALLEY REGION 3443 Routier Road, Suite A Phone: (916)255-3000 Sacramento, California 95827-3098 CALNET: 8-494-3000 TO: Wendy Cohen FROM: Jon B. Marshack, D. Env. Senior WRC Engineer Senior Environmental Specialist SLIC Unit EnvironmentaUTechnical Support Unit GATE: 1 February 1996 SIGNATURE: SUBJECT: CHEVRON PIPELINE COMPANYAND TEXACO TRADING AND TRANSPORTATION, INC., DIVIDEND PROPERTY, TRACY At your request, I reviewed the 26 October 1995 report,titled Quarterly Groundwater Monitoring Report, July—September 1995 and Annual Progress Summary, prepared by Geomatrix Consultants for the subject site. This report focuses on ground water monitoring performed pursuant to Regional Water Board Monitoring and Reporting Program No. 95-801 to assess the water quality impact of leaks from petroleum pipelines that ran along the southwest boundary of the subject property. My review of the case has been limited to this report and discussions with you, John Moody, May Hoe, and Gordon Lee Boggs of this office. I have focused mainly on the ground water monitoring data, since that is the subject of the Geomatrix report. The Geomatrix report concludes that petroleum hydrocarbons in soil and ground water are "not providing a continuing source of dissolved-phase hydrocarbon constituents to ground water" and "pose no threat to waters of the state." For this reason,the report recommends that the ground water monitoring program be discontinued and, pending DTSC's approval of the health risk assessment, that the site be closed by the Regional Water Board. Monitoring data contained in the report demonstrate that hydrocarbon pollutants exceed applicable beneficial use-protective water quality objectives in two locations, MW-13 and MW-23. To determine that closure is appropriate for such a site, Regional Water Board staff must be able to find that the site presents "low risk" for water quality,i.e., that pollution is of limited extent and that pollutants in soil and ground water are being treated/attenuated/degraded at a sufficient rate that beneficial uses of ground water will be restored within a reasonable period of time. There are some deficiencies that make the existing body of monitoring data insufficient for me to be able to make the necessary finding as stated above. While Geomatrix'conclusions may be valid, the report does not provide sufficient support for me to recommend closure without additional monitoring and documentation. To provide complete closure-supporting documentation for our files and to be consistent with the manner in which similar cases are handled by our Underground Tank Program, the closure documentation called for in Appendix B, Requests for Closure,to the Tri-Regional Board Staff Recommendations for Preliminary Investigation and Evaluation of Underground Tank Sites should be submitted. A copy of Appendix B is enclosed.