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i4 Draft Supplemental Environmental Impact Report Page IV.E-9 Forward Inc. Landfill 2014 Expansion Project collisions,upsets, or other accidents at the landfill. The San Joaquin County Office of Emergency Service signed off on the Forward Landfill plan. y The following procedures are proposed as part of the project: • The Standard Safe Work Practices listed in the Forward, Inc. Site Health and Safety Program and Contingency Plan will be implemented by the operator. • The landfill operator will comply with the provisions of CCR Title 27, Section 20590, which requires that O&M personnel wear and use approved safety equipment for personal heath and safety. • Landfill access will continue to be controlled to limit unauthorized entry by persons or -• vehicles. • The landfill operator will comply with all provisions of CCR, Title 27,Division 2, L Chapter 3, Subchapter 4, Articles 1-3 that apply to landfill health and safety. These procedures also would be included in the JTD being updated by the applicant. The off-site impact is potentially significant therefore the following additional mitigation measure is suggested: Mitigation Measure E.3: (Same as the 2013 EIR Mitigation Measure E.3.) The San Joaquin County Public Works Department shall approve any new waste transport haul routes to the landfill from major arterials,SR 4, or Highway 99. Implementation of the proposed procedures and this mitigation measure would reduce the impact to a less-than-significant level because the County can direct haul trucks to avoid hazardous routes. Impact EA: Additional landfill gas would be generated,thus increasing the potential for landfill gas hazards. (Same as 2013 EIR Impact E.4.) Landfill gas has been reported at less than significant levels at the 28 monitoring points in the most recent(June 2014) sampling of perimeter wells (i.e. outside of the waste) at Forward Landfill, as indicated by the presence of methane and carbon dioxide, the two primary gases that are generated by landfills. Concentrations of landfill gases in perimeter monitoring wells are higher near the Austin Road Landfill unit. The production of landfill gases within a landfill is of concern because landfill gas typically consists of 50 percent methane gas,which is flammable when diluted in air to concentrations of 5 to 15 percent. Landfill gas is also of concern because of the hazardous air pollutants carried with the gas (such as the documented j VOCs in the area of the Austin Landfill unit). Uncontrolled landfill gas emissions could cause 4.. methane gas buildup that could be ignited by machinery or onsite workers,however, the site includes a landfill gas collection system that reduces the chance of a dangerous on-site landfill gas build-up except in the waste mass itself. Perimeter wells have low concentrations of methane indicating that some off-site migration is occurring. Despite the fact that methane is lighter than air(vapor density of 0.55 versus 1), it is concurrently produced with carbon dioxide and will not separate. Instead,both gases will remain mixed and follow pressure and density gradients during transport based on the properties of the mixture,rather than the properties of L