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Taj M. Bahadori -2- 18 March 2015 Foothill Landfill San Joaquin County the above State and Federal regulations for MSW landfills, it appears that the RWQCB can allow condensate from LF-1 to be discharged into LF-2. Staff Response —As noted in Finding 63 of the proposed WDRs, Subtitle D regulations (40 CFR 258.28) prohibit the discharge of leachate and landfill gas condensate from one landfill unit to another, but allow these liquids to be returned to the unit from which they were derived, provided that the landfill unit has a Subtitle D-compliant base liner and leachate collection and recovery system (LCRS). Since LF-1 is unlined and does not have an LCRS, these liquids cannot be returned to LF-1, and, consistent with the general prohibition, cannot be discharged to another landfill unit. The WDRs therefore prohibit the discharge of LF-1 leachate and/or gas condensate to either unit and require that the Discharger submit an Operations and Maintenance (O&M) Plan for the gas controls at the site, including plans for appropriate handling and disposal of leachate and/or landfill gas condensate collected from LF-1. To allow the Discharger more time to reconfigure the landfill gas controls per above, the due date for cessation of LF-1 condensate discharges to LF-2 was extended by one year to 15 October 2016. The due date for submission of the gas controls O&M plan was also correspondingly extended. See Discharge Prohibition A.3.b and Provision H.B. 3. LF-2 Construction Specifications Several comments took issue with engineered alternative design (EAD) component specifications included in Construction Specifications D.1 through DA for LF-2 expansion modules (e.g., base liner, side slope liner, LCRS,, and sump). In general, the comments stated that the specifications or design criteria did not allow enough flexibility to allow for design modifications that might be necessary to take into account differences in future modules (e.g., size, configuration, drainage). The comments requested that such specifications be removed or modified so as to be more general or standard-based. Staff Response —The above WDR construction specifications reflect Title 27 prescriptive standards and previously-approved engineered alternative designs (EADs) for existing landfill modules at the site. Such previously-approved EADs are typically included in WDR construction specifications to avoid the need for re-evaluation of designs as a Title 27 EAD each time an expansion module, or module phase, is proposed. The design report fora future module may simply recite that the design is consistent with the prescriptive standard or EAD specified under the WDR's construction specifications and provide supporting information. Minor variations from the designs specified in the WDRs (e.g., moisture specification for clay component) could also be considered for approval under Construction Specification D.6 without requiring revision of the WDRs. Significant modifications to the required designs (e.g., elimination of a required containment system component) would need to be re-evaluated as an EAD and approved under revised WDRs, however. The WDRs are also reviewed every 5 years to determine whether they need to be updated or revised (e.g., to reflect a new EAD for an expansion module). Minor edits were made in response to comments on this item. See Construction Specifications D.1 through b.4.