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WASTE DISCHARGE REQUIREMENTS ORDER NO. R5-2010-0016 -12- <br />SAN JOAQUIN COUNTY DEPARTMENT OF PUBLIC WORKS <br />NORTH COUNTY LANDFILL <br />SAN JOAQUIN COUNTY <br /> <br /> <br /> <br />Module 4 <br />48. A 17 April 2001 letter issued by the Board’s Executive Officer to solid waste landfill <br />owners and operators required a liner performance appraisal for any liner system <br />to be constructed after 1 January 2000, regardless of any liner expansion <br />previously authorized in waste discharge requirements. The performance <br />appraisals were required to include a demonstration that liner systems to be <br />constructed will comply with Title 27 performance standards. <br />49. In response to the Executive Officer’s April 2001 letter, the Discharger submitted a <br />14 May 2002 performance demonstration report for Module 4 and future modules <br />(Liner Performance Demonstration for Module 4 and Future Modules at the North <br />County Sanitary Landfill, prepared by EMCON/OWT, Inc.), which (after revision in <br />response to Board staff comment) was incorporated into a September 2002 Report <br />of Waste Discharge (RWD). The RWD proposed an EAD to the Title 27 <br />prescriptive standard Subtitle D composite liner for Module 4 and future modules <br />(see Construction Specifications D.1 and D.2). <br />50. The results of the Module 4 performance demonstration are summarized in the <br />following table: <br />Data <br />Source <br />Leachate <br />Head <br />Leak <br />Rate1 LCRS Flow Rate2 <br /> Blanket LCRS Piping <br /> Base Liner Gravel Geonet Lateral Header <br /> Inches Gal/acre/day Gal/min <br />Title 27 <12 0.81 --- --- 56.6 145.83 <br />Model 2.4 0.0007 7,295 4,660 28.3 72.9 <br />Design --- --- --- --- 120 500 <br />____________________________ <br />1. Assumed geomembrane defect rate of one hole (1 cm diameter each) per acre of liner placed <br />based on best industry practice CQA. <br />2. Based on anticipated or “worst case” peak conditions (e.g., high precipitation, infiltration and <br />runoff during initial waste filling operations) using Hydraulic Evaluation of Landfill Performance <br />(HELP) Model, Version 3 <br />3. Twice anticipated peak daily flow rates derived from HELP model. <br />The performance demonstration showed that the expected leachate head for the <br />proposed design (2.4 inches) was within the maximum allowed under Title 27 for a <br />MSW landfill (12 inches), and that the calculated leakage rate for the proposed <br />design (0.0007 gal/acre/day) was much less than that for a Title 27 prescriptive <br />MSW landfill (0.81 gal/acre/day). The LCRS lateral and header pipe capacities for <br />the proposed design, 120 gal/min and 500 gal/min, respectively, also exceeded