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Three main areas of investigation will occur to develop the final design: 1) hydrologic regime, 2) hydraulic modeling, and 3) managing riparian revegetation that are in accordance with the specified flood control goals. The conceptual design, based on preliminary investigations, is shown on Figures D-1 and D-2. The proposed relocated channel will exceed the flood control ability of the old channel and result in the net creation of approximately nine acres of riparian woodland habitat. 5.2 LATERAL EXPANSION The proposed lateral expansion will increase the disposal footprint from 354.5 acres to 551.8 acres and the total permitted area of the site from 558.9 acres to 743.6 acres. The proposed expansion area is primarily located south and west of the current permitted landfill areas, and also includes approximately 9.75 acres in the northeast corner of the site, as shown on Figure C. The proposed base grading plan is shown on Figure E. The proposed final grading plan and landfill cross-sections are shown on Figures F and G). Typical details showing the proposed liner and cover systems are shown on Figure G. 5.2.1 ENGINEERED ALTERNATIVE LINER AND FINAL COVER Current groundwater levels at FL are approximately minus 10 to minus 25 feet MSL. However, based on a review of the groundwater contour maps for several periods of high groundwater, including the highest recorded elevations since 1974, GLA concluded in letter reports to the RWQCB dated May 9, 2007 and November 30, 2007, that the reasonable high groundwater conditions for FL vary from an elevation of minus 2-ft to minus 5-ft MSL along the west side, and minus 6-ft MSL east of WMU FU-06, respectively. They also noted that considering the overdraft condition of the San Joaquin hydrologic basin, these elevations are considered conservative and are not likely to be attained again, even following unusually heavy rains. In letters dated May 15, 2007 and December 14, 2007 the RWQCB concurred that valid estimates of the maximum high groundwater elevation underlying the expansion area are minus 2-ft MSL west and south of the existing landfill and minus 6-ft MSL in the area east of WMU FU-06. Forward Landfill Project Description 5-2 BRYAN A.STIRRAT&ASSOCIATES (J:\Allied\Forward\2007.0018 Lateral Expansion\Reports\Proj Descrip\021308 Final Proj Des\Sec 5.doc:2/13/2008)