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STAFF REPORT A RESOLUTION APPROVING SINGLE COMPOSITE LINER FOR USE IN A CLASS H WASTE MANAGEMENT UNIT AT FORWARD LANDFILL SAN JOAQUIN COUNTY Background On 4 August 2000, during public testimony concerning revised Waste Discharge Requirements for the UC Davis Landfill, the ability of prescriptive standard landfill liners to meet the liner performance standards required in Title 27 of the California Code of Regulations (Title 27) was questioned. The reasons for questioning the integrity of prescriptive liners include long term decay of synthetic components in liners with resulting increased potential for leaks; and the inability to adequately monitor groundwater impacts from small leaks in liner systems. The Title 27 performance standard for Class H landfill waste containment systems is to prevent migration of wastes from the landfill to adjacent geologic materials, groundwater, or surface water, during the disposal operations, closure, and the post closure maintenance period. In addition to performance standards, Title 27 contains prescriptive design requirements for Class II landfill waste containment systems. The prescriptive design liner for a Class II landfill is a single composite liner. A 19 March 1997 memorandum from Harry M. Schueller, Chief of the Division of Clean Water Programs of the State Board states that for Class II and Class III landfills "It is our opinion that a properly installed single composite liner meets both performance standards"in answer to the question whether State Board staff believes that a single composite liner meets the Chapter 15 (now Title 27)performance standards. Recent studies by the USEPA at double composite lined landfills demonstrated that for approximately half the landfills tested, the upper composite liner leaked and some upper composite liners had significant leakage. In response to questions posed at the 4 August 2000 meeting, on 15 September 2000, the Central Valley Regional Water Quality Control Board (Regional Board) adopted Resolution No. 5-00- 213 requesting the State Water Resources Control Board(State Board) review Title 27 to determine whether the prescriptive design standards are capable of meeting the performance standards. On 9 November 2000, State Board responded that when evaluating liners: "The RWQCB must consider all relevant design-, site-, and operation-specific factors in establishing the appropriate liner and final cover design for a given landfill. " Subsequently, Regional Board staff has requested that landfill operators complete a liner performance appraisal prior to any future expansions. Forward Inc. was informed of the request for a liner performance appraisal on 26 March 2001. On 21 February 2002,Forward Inc. submitted a liner performance evaluation for both construction of the final area D waste management unit(WMU D-02) and for future expansion in the area to the north of area D,between Forward Landfill and Austin Road Landfill. Upon completion of an initial review,Regional Board staff concluded that the evaluation did not