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Mr. John Moody -2- PLACING ADDITIONAL REFUSE ON EXISTING UNLINED FOOTPRINT AT FOOTHILL SANITARY LANDFILL Relevant Regulatory References In 1989, Waste Discharge Requirements (WDRs) were issued to the County for this site under Central Valley Region Order 89-018 (attached). This Order specifies the active fill area of "approximately 85 acres", now called Area "I", as the actual waste boundary existing at that time. In 1991, federal regulations were promulgated under 40 Code of Federal Regulations (CFR) Part 258 (commonly referred to as "Subtitle D"). This regulation required, among other things, that all new landfills be constructed with liner and leachate collection and removal systems. In anticipation of these federal regulations, the State of California Water Resources Control Board (SWRCB) issued Resolution 93-62 requiring amended WDRs for all landfills. Item ILA of that Resolution (excerpted below) defines a lateral expansion as any area "outside the actual waste boundaries of an MSW landfill as it exists on October 9, 1993". MSW landfills -- By the Federal Deadline (e.g., October 9, 1993), each Regional Water Board shall amend the waste discharge requirements for discharges of waste at all MSW landfills in its region (including discharges to any area outside the actual waste boundaries of an MSW landfill as they exist on that date ["lateral expansion" hereinafter]), to require persons who own or operate such landfills to.... (underline emphasis added). Based on the above, placement of additional refuse within the actual waste boundaries of Area "I" is not a lateral expansion, but rather continuing refuse placement within the waste boundaries existing prior to 1993. In addition, the present WDRs (Order No. R5-2003-0020) do not require installing impermeable membrane within the actual waste boundaries of Area "I" before placing additional refuse. Planned Continued Refuse Placement Within Area "I" Waste Boundary Based on consideration of the above, the County intends to continue placing refuse within the boundaries of Area "I". Standard refuse placement procedures will be used, including: • Maximizing available airspace by removing as much cover soil as possible from the existing fill surfaces before placing refuse. • Placing refuse using standard landfill placement and compaction equipment. • Covering the placed refuse with daily cover (soil or tarps) in accordance with the Operating Permit. • Placing intermediate cover over daily cover when appropriate. • Retaining existing landfill gas (LFG) wells and geomembrane in fill areas. The fill area under discussion is adjacent to an area over which a geomembrane was placed in 2006 (Figures 2 and 3). This membrane was placed to address a past concern that landfill gas from newly -placed refuse could penetrate through older refuse, into the soil and to groundwater below. To address this concern and prevent gas produced by refuse placed in the future from entering beneath that geomembrane, the County will install a horizontal LFG collector at the edge of the membrane (Figure 3).