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WASTE DISCHARGE REQUIREMENTS ORDER NO.R5-2002-0219 -5- FOR COUNTY OF SAN JOAQUIN FOR CONSTRUCTION AND OPERATION OF NORTH COUNTY RECYCLING CENTER AND SANITARY LANDFILL FACILITY, SAN JOAQUIN COUNTY 22. The direction of groundwater flow is toward the southwest. The average groundwater gradient is approximately 0.0004 foot per foot. The average groundwater velocity is 13.5 feet per year. 23. Monitoring data indicates background groundwater quality has an electrical conductivity (EC) ranging between 60 and 480 micromhos/cm,with total dissolved solids (TDS) ranging between 134 and 250 mg/l. 24. The designated beneficial uses of the groundwater, as specified in the Basin Plan, are domestic and municipal, agricultural, and industrial supply. GROUNDWATER, SURFACE WATER AND UNSATURATED ZONE MONITORING 25. The current groundwater monitoring system is comprised of an upgradient,background well G-1 and downgradient wells G-31), G-4, and G-5. The Discharger proposes to install a groundwater monitoring well G-6 downgradient from Module 4. 26. The current unsaturated zone monitoring system is composed of suction lysimeters strategically located beneath the landfill modules. VZ-1 is the background lysimeter located adjacent to G-1 on the upgradient(eastern) side of the facility. VZ-2 through VZ- 5 monitors Modules 1, 2, &3. VZ-6 though VZ-8 are proposed to be installed beneath Module 4; under the leachate sump (LZ-6),under one LCRS trench(LZ-7), and under the northeast portion of the base liner system(LZ-8). The secondary containment system beneath the leachate sump for Module 4 is identified as L-3. The lysimeters have access ports available at the surface for sampling of soil-pore liquids. 27. South Paddy Creek flows from north to south along the eastern boundary of the facility. The upgradient monitoring point in South Paddy Creek is S-1, and downstream monitoring point is S-2. S-4 surface water sampling point is located on the northwestern comer of the facility adjacent to Module 1 &2. S-4 monitors stormwater in a ditch that flows north along the perimeter of the facility boundary,which eventually flows to a wetlands area northeast of Module 1 &2. There is also a wetlands area west of S-1,north of the recycling center. A stormwater Retention Pond is located downgradient from the groundwater-monitoring well G-1 (upgradient) and west of S-2. Water from the Retention Pond is used for dust control and other activities on site. 28. The Discharger's proposed detection monitoring program for groundwater and soil-pore liquids in the unsaturated zone satisfies the requirements of Title 27. 29. The Discharger proposes to install a landfill gas (LFG)monitoring system beneath the single-composite liner as horizontal soil gas piping around the base of the perimeter and below the center of Module 4 to monitor the unsaturated zone for the presence of VOCs. Horizontal LFG collectors will also be installed in the first refuse lift, a minimum 15 feet