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 21 compliance, and scheduling with terminal personnel. Thereafter, remedial system installation will take place and the hydraulic control line can be installed in approximately six weeks. The present value cost associated with this remedial alternative is approximately $540,000. This cost includes all up front capital costs (remedial action plan, system design, permit fees, well installation, remedial system equipment, and construction fees) and long-term costs such as operation and maintenance and off-site groundwater sampling via hydropunch. This cost evaluation was based on monthly operation and maintenance visits and semi-annual groundwater sampling costs over ten year period using a discount rate of 2%. Chevron believes that the local community and State officials will accept this proposed remedial alternative. 7.4 Groundwater Oxygenation System The proposed groundwater oxygenation system should increase dissolved oxygen concentrations in the saturated zone and thus enhance the biodegradation of on-site and off-site hydrocarbons. Oxygen-enriched groundwater should provide the environment for off-site hydrocarbons to degrade to levels near or consistent with the Basin Plan's WQOs. Thus, the proposed groundwater oxygenation should protect off-site properties and sensitive receptors (streams, creeks, rivers, production wells and private wells). This remedial alternative is considered to have long-term effects on the reduction of off-site hydrocarbon impacts. As long as the groundwater oxygenation system 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 groundwater oxygenation system from protecting off-site properties and receptors. Possible system operational problems consist of but are not limited to poor oxygen delivery, malfunctioning air compressor, clogging of filters and auto-drains, and power shutdowns, etc. Groundwater levels would have to drop approximately 15 feet to prevent the groundwater oxygenation system from functioning properly. In either of these two situations, hydrocarbons would have the opportunity to migrate off-site without enhanced degradation. This remedial alternative is not considered to have short-term effects on the reduction of hydrocarbons in the subsurface. This remedial alternative is designed to enhance the degradation of onsite and off-site hydrocarbons. Therefore, this is a long-term approach, which should reduce off- site hydrocarbons to levels near or consistent with the Basin Plan's WQOs. This remedial alternative will be relatively easy to implement rather than previous alternatives (groundwater barrier, hydraulic control line, and combination). Upon completion and approval of the remedial action plan and system design, permits and public utility services will be required to install and operate the groundwater oxygenation system. Permits will consist of well permits, and building permits (electrical, mechanical, and plumbing). Electrical service will also be required. Logistical issues associated with this remedial option will be construction approval, safety compliance, and scheduling with terminal personnel. Thereafter, remedial system installation will take place and the groundwater oxygenation system could be installed in approximately four weeks. The present value cost associated with this remedial alternative is approximately $270,000. This cost includes all up front capital costs (remedial action plan, system design, permit fees, well installation, remedial system equipment, and construction fees) and long-term costs such as operation and maintenance and off-site groundwater sampling. This cost evaluation was based on I:\Chevron\1001621\REPORTST003\2003FS\FS 2003 revD.doc