ARCHIVED REPORTS_2003 FEASABILITY STUDY REPORT AND SITE ASSESSMENT WORK PLAN

Home Browse Search

S E C O R 2003 Feasibility Study Report and Site Assessment Work Plan July 18, 2003 Page 20 services will be required to install and operate the hydraulic control line. Permits will consist of well permits, building permits (electrical, mechanical, and plumbing), and groundwater discharge permits. 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 could take place and the hydraulic control line could be installed in approximately six weeks. The present value cost associated with this remedial alternative is approximately $1,178,430. 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 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. 7.3 Combination Groundwater Barrier and Hydraulic Control Line The proposed groundwater barrier and hydraulic control line should deter or prevent further off-site migration of hydrocarbons in the saturated zone. Therefore, the proposed groundwater barrier and 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 enhance the off-site degradation of hydrocarbons in the saturated zone and allow current hydrocarbon concentrations to degrade to levels near or consistent with the Basin Plan's WQOs. This outcome would be possible as the groundwater barrier and hydraulic control line prevents or deters the continued migration (mass flux) of hydrocarbons to off- site properties. Thus, existing off-site hydrocarbons could continue to degrade in either an anaerobic and/or aerobic environment without the continued hydrocarbon mass flux originating from the terminal. This remedial alternative is considered to have long-term effects on the reduction of off-site hydrocarbon impacts. As long as the groundwater barrier and hydraulic control line remain in place and operational, off-site properties and sensitive receptors should remain protected. Operational problems described in Section 7.2 may also be experienced with this alternative, which could result in the potential off-site migration of petroleum hydrocarbons. 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 of hydrocarbons from the terminal. Therefore, this is a long-term approach, which should contain on-site hydrocarbon and reduce off-site hydrocarbons to levels near or consistent with the Basin Plan's WQOs. This remedial alternative will be more challenging and complex to implement rather than either the groundwater barrier or hydraulic control line alone. 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 hydraulic control line. Permits will consist of well permits, building permits (electrical, mechanical, and plumbing), and groundwater discharge permits. Electrical service will also be required. Logistical issues associated with this remedial option will be construction approval, safety I AChevron\1001621\REPORTS\2003\2003FS\FS_2003_revD.doc