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WASTE DISCHARGE REQUIREMENTS ORDER NO.R5-2002-0219 -7- FOR COUNTY OF SAN JOAQUIN FOR CONSTRUCTION AND OPERATION OF NORTH COUNTY RECYCLING CENTER AND SANITARY LANDFILL FACILITY, SAN JOAQUIN COUNTY quantitation limit(PQL), indicates that a release of waste from a Unit may have occurred. Following an indication of a release,verification testing will be conducted at the same location to determine whether there has been a release from the Unit or the detection was a false detection. Although the detection of one non-naturally occurring waste constituent above its MDL is sufficient to provide for the earliest possible detection of a release, the detection of two non-naturally occurring waste constituents above the MDL as a trigger is appropriate due to the higher risk of false-positive analytical results and the corresponding increase in sampling and analytical expenses from the use of one non- naturally occurring waste constituent above its MDL as a trigger. GROUNDWATER, SURFACE WATER AND UNSATURATED ZONE DEGRADATION 38. Groundwater monitoring through the approved detection-monitoring program has shown sporadic trace detections of several VOCs in groundwater over the past 7 years,none of which have been confirmed by retest. There have been no confirmed (measurably significant)releases from the waste management unit. LINER PERFORMANCE DEMONSTRATION 39. On 15 September 2000 the Board adopted Resolution No. 5-00-213 Request For The State Water Resources Control Board To Review The Adequacy Of The Prescriptive Design Requirements For Landfill Waste Containment Systems To Meet The Performance Standards Of Title 27. The State Board responded, in part,that"a single composite liner system continues to be an adequate minimum standard"however, the Board"should require a more stringent design in a case where it determines that the minimum design will not provide adequate protection to a given body of groundwater." 40. In a letter dated 17 April 2001,the Executive Officer notified Owners and Operators of Solid Waste Landfills that"the Board will require a demonstration that any proposed landfill liner system to be constructed after 1 January 2002 will comply with Title 27 performance standards. A thorough evaluation of site-specific factors and costibenefit analysis of single, double and triple composite liners will likely be necessary." 41. The Discharger provided a single-composite liner system leak performance demonstration. The leakage rate through the proposed liner was calculated from the available head over the liner and assumed quantity of leaks. The maximum available hydraulic head of leachate on the HDPE liner was estimated to be 2.4 inches (HELP-3 model),based on the leachate reaching the LCRS system of Module 4 and the removal of the leachate by the LCRS. These calculations assume that there will be one geomembrane defect of a centimeter diameter hole per acre of liner placed. This geomembrane defect assumption was based on current state-of-practice construction