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r' r'r tA 1-5 and was not renewed. The Stockton Regional Wastewater Control Facility has no established Permissible limits for water containing dissolved hydrocarbons, generally accepting such water when the concentrations remain below the combustible limit. In April 1985, hydrocarbon vapors were detected from a Pacific Bell telephone vault. ARCO personnel purged she area of all vapors, and GR was retained by ARCO to investigate the condition. GR ii established five vapor monitoring points in nearby storm drains. GR vapor monitoring data are included in Appendix B. The locations of these vapor monitoring points are not available to BC at this time. Hydrocarbon vapor concentrations range between 50 and 370 parts per million (ppm) . { GR continued to monitor the recovery system until late March 1987. Appendix B includes a summary of GR data from early May 1986 to late January 1987, and field data from early February through late "'. March 1987. The data show either no free product or a very thin film of product on the groundwater surface. On March 31, 1957, the last day GR monitored the recovery system, 19.842,796 gallons of groundwater and product had been discharged. Upon their removal from the project, GR left the system operational. On May 26, 1987, BC personnel found that the system was no longer operational, and that a total of 19,842,800 gallons had been discharged. The recovery system remains in place on site. The polyvinyl chloride (PVC) in the system is thought by BC personnel to have retained its integrity. A study published in the Spring, 1987 Groundwater Monitoring Review (included in Appendix C) concludes that PVC remains unaffected by contact with aromatic hydrocarbons. The recovery system is not operational at present and has probably not been operating since late March or early April. The free product has been successfully removed from the groundwater surface, and approximately 19,842,800 gallons of product and groundwater containing dissolved hydrocarbons have been removed. Agency Involvement On April 17, 1987, representatives of the California Regional Water Quality Control Board, Central Valley Region, the San Joaquin Local Health District, and BC personnel met to discuss the status and direction of the site investigation. Specific items to be addressed in this preliminary report were determined. On May 21, 1987, the San Joaquin Local Health District reviewed and approved the May 21, 1987, work plan prepared by BC to conduct preliminary investigative work. The work plan is included in Appendix D.