ARCHIVED REPORTS_2003 FEASABILITY STUDY REPORT AND SITE ASSESSMENT WORK PLAN

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S E C O R 2003 Feasibility Study Report and Site Assessment Work Plan July 18, 2003 Page 19 site hydrocarbons and reduce off-site hydrocarbons to levels near or consistent with the Basin Plan's woos. This remedial alternative will be relatively easy to implement. Upon completion and approval of the remedial action plan and system design, site construction would be coordinated with the preferred contractor. Permits will be minimized with this alternative as an excavation permit and air-monitoring permit will only be required to construct the groundwater barrier. Logistical issues associated with this remedial option will be construction approval, safety compliance, and scheduling with terminal personnel. Thereafter, excavation activities will take place and the groundwater barrier could be installed in approximately four weeks. The present value cost associated with this remedial alternative is approximately $278,000. This cost includes all up front capital costs (remedial action plan, system design, permit fees, construction fees) and long-term costs such as off-site groundwater sampling via hydropunch. This cost evaluation was based on semi-annual groundwater sampling costs over ten year period using a discount rate of 2%. Chevron believes that the local community and State officials would accept this proposed remedial alternative. 7.2 Hydraulic Control Line The proposed hydraulic control line should deter or prevent further off-site migration of hydrocarbons in the saturated zone. Therefore, the proposed hydraulic control line should act as a containment system around the terminal and protect off-site property and sensitive receptors (streams, creeks, rivers, production wells and private wells). This remedial alternative should also actively reduce the off-site and on-site hydrocarbon concentrations in the saturated zone to levels near or consistent with the Basin Plan's WQOs. The hydraulic control line may reverse the existing mass flux of hydrocarbons to off-site properties. Remaining off-site hydrocarbons concentrations would approach the WQO's more rapidly than the passive groundwater barrier. This remedial alternative is considered to have long-term effects on the reduction of off-site hydrocarbon impacts. As long as the hydraulic control line remains in place and operational, off-site properties and sensitive receptors should remain protected. Possible conditions such system operational problems or a dramatic drop in regional groundwater levels could prevent the hydraulic control line from protecting off-site properties and receptors. Possible operational malfunctions (pumps and electrodes, clogging of filters and carbon beds, power shutdowns, etc.) could decrease effectiveness. Groundwater levels would have to drop approximately 20 feet to prevent the hydraulic control line from functioning properly. In either of these two situations, hydrocarbons would have the opportunity to migrate off-site. This remedial alternative is not considered to have short-term effects on the reduction of hydrocarbons in the subsurface. Rather, this remedial alternative is designed to deter or prevent the continued migration (mass flux) of hydrocarbons from the terminal. Therefore, this is a long-term approach, which should contain on-site hydrocarbons and reduce off-site hydrocarbons to levels near or consistent with the Basin Plan's WQOs. This remedial alternative will be more challenging to implement than the groundwater barrier. Upon completion and approval of the remedial action plan and system design, permits and public utility I:\Chevron\1001621\REPORTS\2003\2003FS\FS 2003 revD.doc