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Hazards & Hazardous Materials (Continued) If the subsurface investigation programs yield data suggesting that there could be unacceptable risks to future construction workers or residents, a California state environmental regulatory agency will be consulted to provide its opinion on the findings of the subsurface investigations and the assessment of risk. This opinion would be sought prior to initiating construction on either site. The environmental testing programs have not been completed on either of the Sites. However, there are no chemical source areas known to exist on either Site. The mitigation measures presented below are proposed as means to mitigate potential chemical exposures and associated unacceptable risks to human health should COPCs be found at the Sites at levels of concern in soil, soil gas or groundwater. Mitigation Measure #22 Pre Development Mitigation Measures If the subsurface investigation programs yield data suggesting that there could be unacceptable risks to future construction workers or residents and a California state environmental regulatory agency determines that an active remedial response is warranted, the following mitigation measures listed below include methods that may be employed to mitigate unacceptable risks to human health of construction works and future residents. • Remove the impacted soil and dispose of off -Site; • Install a cap to prevent contact with the contamination; Install a physical barrier for vapors such as a vapor barrier or passive venting system, to prevent the accumulation of vapors in indoor environment; • Stockpile soil and aerate on -Site, or in a staging area as may be appropriate, in compliance with all applicable laws and regulations; • Conduct in situ bioremediation measures; or • Implement liquid or vapor extraction measures. The appropriateness of one of the above management measures over another will depend on many factors, such as the type of constituent detected, the size of the identified impacted area, and the estimated cost of implementing the remedy. Results of the sampling activities and the proposed course of action, e.g., no action necessary, soil excavation and off -Site disposal, on -Site treatment and soil reuse, shall be reported to a State environmental regulatory agency and the contractor shall obtain concurrence before implementing the remedial measures. Remedial action plans would be approved in advance by a state environmental regulatory agency. Any cleanup or remediation would be required to meet applicable federal, state and local laws, regulations and requirements. Mitigation Measure #23 Risk Management Measures for Construction Phases The following are risk management procedures to be followed by future contractors during Site preparation and construction activities. General soil management protocols are presented; as well as, protocols for managing fill soils that may be brought to the Sites during filling operations. • Pre -Construction Planning and Notification: Prior to the start of construction activities involving below - ground work, information regarding known areas of contamination shall be provided to the contractor by the Site owner. • Site -Specific Health and Safety Worker Requirements: Each contractor will be responsible for the health and safety of their own workers, including, but not limited to, preparation of their own health and safety plan (HSP) and injury and illness prevention plan (IIPP). The purpose of these documents is to provide general guidance to the work hazards that may be encountered during each phase of construction activities. Cornerstone at San Leandro Crossings Initial Study 17 March 2009 POTENTIALLY ISSUES POTENTIALLY SIGNIFICANT LESS THAN NO SIGNIFICANT UNLESS SIGNIFICANT IMPACT SOURCES ISSUES MITIGATION IMPACT INCORPORATED Hazards & Hazardous Materials (Continued) If the subsurface investigation programs yield data suggesting that there could be unacceptable risks to future construction workers or residents, a California state environmental regulatory agency will be consulted to provide its opinion on the findings of the subsurface investigations and the assessment of risk. This opinion would be sought prior to initiating construction on either site. The environmental testing programs have not been completed on either of the Sites. However, there are no chemical source areas known to exist on either Site. The mitigation measures presented below are proposed as means to mitigate potential chemical exposures and associated unacceptable risks to human health should COPCs be found at the Sites at levels of concern in soil, soil gas or groundwater. Mitigation Measure #22 Pre Development Mitigation Measures If the subsurface investigation programs yield data suggesting that there could be unacceptable risks to future construction workers or residents and a California state environmental regulatory agency determines that an active remedial response is warranted, the following mitigation measures listed below include methods that may be employed to mitigate unacceptable risks to human health of construction works and future residents. • Remove the impacted soil and dispose of off -Site; • Install a cap to prevent contact with the contamination; Install a physical barrier for vapors such as a vapor barrier or passive venting system, to prevent the accumulation of vapors in indoor environment; • Stockpile soil and aerate on -Site, or in a staging area as may be appropriate, in compliance with all applicable laws and regulations; • Conduct in situ bioremediation measures; or • Implement liquid or vapor extraction measures. The appropriateness of one of the above management measures over another will depend on many factors, such as the type of constituent detected, the size of the identified impacted area, and the estimated cost of implementing the remedy. Results of the sampling activities and the proposed course of action, e.g., no action necessary, soil excavation and off -Site disposal, on -Site treatment and soil reuse, shall be reported to a State environmental regulatory agency and the contractor shall obtain concurrence before implementing the remedial measures. Remedial action plans would be approved in advance by a state environmental regulatory agency. Any cleanup or remediation would be required to meet applicable federal, state and local laws, regulations and requirements. Mitigation Measure #23 Risk Management Measures for Construction Phases The following are risk management procedures to be followed by future contractors during Site preparation and construction activities. General soil management protocols are presented; as well as, protocols for managing fill soils that may be brought to the Sites during filling operations. • Pre -Construction Planning and Notification: Prior to the start of construction activities involving below - ground work, information regarding known areas of contamination shall be provided to the contractor by the Site owner. • Site -Specific Health and Safety Worker Requirements: Each contractor will be responsible for the health and safety of their own workers, including, but not limited to, preparation of their own health and safety plan (HSP) and injury and illness prevention plan (IIPP). The purpose of these documents is to provide general guidance to the work hazards that may be encountered during each phase of construction activities. Cornerstone at San Leandro Crossings Initial Study 17 March 2009