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Soil Gas Trench <br /> Methane continues to be detected in the soil gas trench. Methane content in the gas beneath the <br /> liner of Module 1 is presently between 14% and 37%. When Module 1 liner was first installed in <br /> 2003,the gas beneath the liner was found to vary between 0 and 2%. The HDPE liner was <br /> extended over Module "I"refuse in the fall of 2006. It is possible that placing a HDPE barrier <br /> over Module "I"refuse has trapped landfill gas beneath the liner. <br /> GROUNDWATER DIRECTION AND FLOW RATE <br /> Groundwater elevations were measured in monitoring wells during the first and second quarters. <br /> Groundwater was determined to flow towards the east-southeast(Figures 3 and 4). The calculated <br /> average linear groundwater flow velocity in the first quarter was 117.1 feet per year based on a <br /> hydraulic gradient of 0.0035 foot per foot. The calculated average linear groundwater flow <br /> velocity in the second quarter was 121.2 feet per year based on a hydraulic gradient of 0.0036 foot <br /> per foot(Appendix G). <br /> STANDARD OBSERVATIONS <br /> Regular site inspections were performed during the first semester of 2010. Monthly standard <br /> observations have been summarized(Appendix H). The electronic signatures on the forms certify <br /> that all observations were performed and are accurate. <br /> RUN-OFF/RUN-ON FACILITIES <br /> The Foothill Sanitary Landfill utilizes several methods to control run-on and run-off. The natural <br /> topography of the area controls any run-on into the site. Also,the working area is a significant <br /> distance from the property boundary, so run-on from surrounding properties is minimal. <br /> To control run-off, a perimeter ditch along the north, west and east ends of the unit directs all <br /> storm water run-off into a sedimentation basin on the east side of the site. The rest of the run-off <br /> from the unit gathers into a sedimentation basin at the southeast corner of Module 1. There were <br /> no breeches to any of the run-on/run-off facilities during this monitoring period. <br /> OTHER ANALYSIS <br /> Groundwater samples were collected from landfill supply well LW-1 and analyzed for all <br /> monitoring and field parameters. The well is not a point of compliance, as stated in the WDRs. <br /> Foothill Sanitary Landfill 10 Department of Public Works/Solid Waste <br /> 15`Semester 2010 Groundwater Monitoring County of San Joaquin—July 21,2010 <br />