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Draft Supplemental Environmental Imact Report Forward Inc.Landfill 2014 Expansion Project Page III-29 L. "Brocchini" parcel to the southwest of the existing landfill site.The main office trailer and maintenance yard are also monitored to assess potential gas accumulations at the foundations. EPA Consent Decree On May 2,2012,Forward, the U.S.EPA and the San Joaquin Valley Air Pollution Control District (District)entered into a stipulated consent decree which was approved by the U.S. District Court for the Eastern District of California,under which Forward will modify the operation of its gas collection and control system with respect to extraction well oxygen levels and temperature, complete Phase II of the planned and ongoing improvement of Forward's landfill gas extraction system,apply for a new Title V air permit from the District that would limit oxygen levels in the landfill gas extraction wells,relocate Forward's perimeter gas probes to the boundary line of the expansion area,and provide for other air quality protection measures. F. PROPOSED PROJECT MODIFICATIONS The proposed physical and operational changes are described below. +.. Development of Additional Landfill Disposal Cells Within Permitted Landfill Boundary t... Development of additional landfill cells would increase the disposal footprint from approximately 355 acres to 370 acres. The proposed additional development area includes two areas within the currently permitted landfill boundary as shown on Figure III.0-4;approximately 8.7 acres in the northeast corner of the site and approximately 6.2 acres in the south area. The acreage added in the south area is gained by shifting the existing disposal footprint north and realigning the creek to the southern and eastern boundaries of the site. The acreage added in the northern area was formerly part of the 100-year flood plain for the North Branch of the South Fork of Littlejohn y' Creek and was not permitted for waste disposal;however,after the North Branch of the creek was realigned, this area is no longer in the 100-year floodplain and can be developed as landfill. The maximum elevation of refuse fill in the additional development areas would be approximately 200 feet above mean sea level(MSL), lower than the permitted maximum height of 210 feet MSL for the existing Forward Landfill. The footprint of the refuse fill would be set back a minimum of 100 feet from the east property boundary. ` The additional development area would have a base liner and Leachate Collection and Recovery System(LCRS)consistent with currently constructed modules and in compliance with pertinent regulatory requirements. The proposed landfill expansion refuse fill Prades meet both State and ►� Federal regulatory criteria under both static and seismic conditions.' The Title 27 regulations governing landfills and Forward's WDRs require a minimum five-foot separation between wastes or leachates and the highest anticipated elevation of underlying groundwater(including the capillary fringe)or the installation of an engineered alternative, such as a subdrain. The regional groundwater in the greater Stockton area,including the vicinity of the Forward Landfill,has been overdrawn for many years and has shown a clear pattern of decreasing groundwater levels. Current groundwater levels at the landfill are approximately 14 to 30 feet below mean sea level (MSL). Based on a review of historic groundwater records,the maximum high groundwater elevation underlying the southern and northeastern development area is %W approximately four feet and ten feet below MSL,respectively. The minimum base grades for the proposed landfill development area have been developed to provide for the required 5-foot separation between historic high groundwater and refuse. 'Z GLA,Inc., Geotechnical Investigation Report,Forward Landfill Expansion,February 2008. a.