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SCS ENGINEERS- Health and Safety Considerations Work on or near landfill sites warrants special precautions to mitigate against potential — combustible gas hazards or worker exposure to the trace constituents of LFG. Appendix A of this document provides a H&S Plan for the well installation activities. The H&S plan describes potential hazards and outlines site-specific protection, monitoring and recordkeeping standards. SCS Engineers and the drilling subcontractor will be responsible for implementing these H&S provisions. — 5. PROPOSED LFG MONITORING PARAMETERS AND FREQUENCY Subsurface Gas Monitoring Landfill gas monitoring at the perimeter migration wells will be performed on a quarterly _ basis using field instruments. Parameters to be tested at each well/probe include: • Subsurface pressure. Monitoring shall be performed using a gauge (or combination of gauges) with a suggested range of 0 to 10 inches water column. • Methane concentrations. Monitoring shall be performed using a combustible gas indicator(s) with a dual range of 0-100% LEL and 0-100% v/v. Results will be recorded on field data sheets. Field personnel will record the above information as well as test date, time, weather conditions, and barometric pressure. If methane concentrations above the LEL are detected at any well location, the data will be reviewed for accuracy, and an evaluation will be made to rule out possible interferences. Such interferences could include the presence of subsurface liquids, or previously unidentified combustible gas sources. — Follow-up field testing will be performed if necessary. Depending on field results, confirmatory samples will be obtained for lab analyses. The sample(s) will be analyzed for the major components of LFG (methane, oxygen, nitrogen and carbon dioxide, with a detection limit of 0.1 % v/v). Should the sample results confirm the field readings, the County will notify the LEA and the CIWMB within 5 days of detection. _ If after two consecutive quarterly sampling events the results of monitoring at any single well or probe indicate methane concentrations above the LEL, a confirmatory sample will be obtained for analysis of trace gas constituents. Analyses will be as specified for the Air SWAT "Attachment 1 " compounds, with disposal site detection limits (refer to Table 2). Based on test results, the County will confer with the LEA regarding the need for remedial action (refer to Section 7)• 11 -