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Page IV.F-4 Draft Environmental Impact Report Pa g Forward Inc. Landfill Expansion Ili for protection of water quality. In addition, as described above, the San Joaquin County Public Health Services (SJCPHS)has additional regulatory oversight that could relate to groundwater resources. Landfill Special Waste Program Controls Special treatment programs that are ongoing or would be expanded at the landfill units include ash disposal, sludge solidification, co-generation plant, asbestos disposal, treated wood waste, and landfill gas management. These program elements are summarized in the Project Description. Some such special treatment programs, such as the sludge solidification,have . :. potential for impacts on water quality. However, all such programs have required controls, testing, procedures and protocols that are reviewed and approved by the regulators. For example the sludge solidification agent must use compatible materials allowed for acceptance at the landfill and once solidified,the material to be disposed of in the landfill or stockpiled in the landfill area for potential reuse/recycle pending approval of the local enforcement agency (LEA). i Regional Surface Hydrology Topography and Geography The terrain at the landfill and surrounding vicinity consists of a relatively featureless plain. Both the North and South Branches of the South Fork of Little John's Creek(North and South Branches) traverse the site, generally flowing from the east to the west, however the north branch has been relocated north of the landfill footprint. Original ground surface elevations range from 30 to 40 feet above mean seal level (amsl) (see Figure IV.F-2). Currently developed portions of the site reach a maximum elevation of approximately 137 feet amsl in the former Austin Road Landfill area,and approximately 194 feet amsl in the Forward Landfill area. Surface Water Features The landfill property includes two local drainages,the north and south forks of Littlejohn Creek, which are within the Duck-Littlejohns Hydrologic Area and are tributaries to the San Joaquin River. The south fork of Littlejohns Creek flows within confining levees southwesterly along the southern edge of the landfill and along the south side of the southern expansion area. The North Fork of Littlejohns Creek was realigned to the north and west of the Landfill in 2001, in order to place it outside the footprint of potential floodplain and landfill areas. Flood Hazards With the exception of areas near the creek channels,the Forward Landfill site is within flood zone designation X(Federal Insurance Rate Map, U.S.Dept. of Housing and Urban Development, April 2,2002). Areas designated as Zone X are areas of minimal flooding that lie s outside the 100-year and 500-year floodplain. Some portions of the site along the former course of the North Branch of Littlejohns Creek are mapped as within Zones AE and AO, with 100-year flood depths of 1-3 feet. However,since preparation of the FEMA map,the North Branch has been realigned to the north and west of the landfill fill area,and has been designed to carry the 100-year flood flows. The North and South Branches of the South Fork of Littlejohns Creek on the site are subject to regular maintenance for flood control. This maintenance consists of clearing trees and shrubs from the banks and dense vegetation from the channel. F r