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WASTE DISCHARGE REQUIREMENTS ORDER NO. R5-2010-0016 -10- <br />SAN JOAQUIN COUNTY DEPARTMENT OF PUBLIC WORKS <br />NORTH COUNTY LANDFILL <br />SAN JOAQUIN COUNTY <br /> <br /> <br />Leachate and Condensate Management <br />42. Since 2002, the discharger has been pumping collected landfill leachate and LFG <br />condensate back to the landfill, subject to approvals in previous WDRs, which <br />incorporated liquids restrictions in Title 27 and Subtitle D regulations. In the <br />Second Half 2008, approximately 124,000 gallons of leachate (including LFG <br />condensate) were pumped from and returned to the landfill. <br />43. As described in the JTD, LFG condensate is pumped into the LCRS and handled <br />like leachate. Leachate is pumped from the landfill sumps and/or AGTs to <br />dedicated infusion points on the upper elevations of the compositely lined landfill <br />Modules. No liquid is returned to Module 1, however, since it does not comply with <br />Subtitle D. These WDRs allow the Discharger to continue returning landfill <br />leachate and condensate to the landfill, provided that compliance with the <br />applicable liquids restrictions is maintained. See Discharge Prohibition A.3 and <br />Discharge Specification B.4. <br />LANDFILL DESIGN AND CONSTRUCTION <br />Existing Modules <br />Module 1 <br />44. Module 1 (referred to as Modules 1 and 2 in previous WDRs) was constructed in <br />1991 with a non-prescriptive, non-composite containment system, as follows: <br />Component Base Liner Side Slopes <br />Operations Layer ≥ 2’ soil <br />Filter Fabric Geotextile1 <br />LCRS Geonet -------2 <br />Base Liner 60-mil HDPE3 <br />Foundation Layer ≥ 6” compacted soil <br />____________________________ <br />1. 10 oz/yd2 non-woven fabric. <br />2. No LCRS on side slopes. <br />3. HDPE smooth on both sides. <br />The module predated Subtitle D regulations and was therefore not required to <br />have a Subtitle D composite liner (see Finding 5). Further, previous WDRs (Order <br />No. 91-021) included a finding that natural geologic factors at the site (e.g., <br />groundwater separation, soil type) were sufficiently protective of groundwater such <br />that a Chapter 15 containment system was not required (see Title 27, Section <br />20260). Although not required under regulation, a 60-mil HDPE base liner and <br />geonet LCRS were included in the design for additional protection. <br />