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ATTACHMENT F:MAPS AND CROSS SECTIONS OF GEOLOGIC STRUCTURE OF AREA Physical Extent The Domengine Formation isopach map (Figure F-9), developed for the original permit by examination and correlation of DOGGR well records and geophysical logs (Table F-1),is based on 22 thickness values. The thickness of the injection unit is 831 feet and is not less than 780 feet thick within the AOR. The Domengine thins toward both the Lodi Airport to the east and the East Islands Gas Fields to the northwest. The Domengine Formation structure contour map (Figure F-10) is based on 23 wells that penetrated the top of the formation. The formation dips about 2 degrees uniformly to the southwest. A structural nose 2 to 3 miles to the east of the facility occurs below and, coincidentally,is generally aligned with the railroad line that runs northwest-southeast. A second less prominent structural nose occurs 1 to 2 miles west of the facility,and is oriented to the northeast-southwest. Gas fields appear to be associated with these structural features. The structure contour map does not indicate any closed structural features in the area. Description The Domengine Formation consists of two to three sand intervals separated by siltstone or shale. It is a coarse-grained, gray to brown marine quartz sandstone with feldspar and occasional glauconite. It is exposed to the west in the Mount Diablo area. Physical Properties The hydraulic conductivity and permeability of the injection zone within the Domengine Formation has been measured several times during routine testing since the well was installed in 1994. The averages of these measurements was used to calculate the AOR and are summarized in Tables A-2 and A-3. The hydraulic conductivity of the injection zone is estimated to be 0.591 feet/day and the permeability to be 142 millidarcys. Confining Zones The upper confining zone is the Nortonville Formation. The lower confining zone is the Capay Formation. They are shown in the two cross sections (Figures F-2 and F-3). Nortonville Shale The Nortonville shale is a dark gray marine shale and siltstone that is the upper confining unit for the injection zone. In some areas, minor sandstone,coal,and glauconitic sandstone can also occur within it. In parts of the state,it produces gas. The Nortonville shale isopach map (Figure F-11) has thickness estimates from 24 local wells. The thickness of the Nortonville Shale ranges from 100 to more than 200 feet within the area contoured. This includes a thickness of 117 feet at the STIG-1 well. Overall,the unit thickens to the southeast. Capay Formation The Capay Formation is the lower confining shale unit for the injection zone. It is a marine shale to silty shale with occasional sand stringers. The Capay Formation is being considered and studied for a possible carbon-sequestration project within the sand stringers in the F-4 SAC/371322/082550021(ATTACHMENT-F.DOC)