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Attachment F Maps and Cross Sections of Geologic Structure of Area Application Requirements Submit maps and cross sections detailing the geologic structure of the local area (including the lithology of injection and confining intervals) and generalized maps and cross sections illustrating the regional geologic setting. Approach This section uses the information from the original maps produced for the 1993 STIG-1 UIC application and combines the geologic information originally included in Attachments D and F of the 1993 STIG-1 application. NCPA's team of consultants provided outstanding support to NCPA by developing numerous cross sections,isopach maps,and structural contour maps using existing well data. Since the time of the original permit application in 1993,no known additional deep wells have been drilled within the AOR, other than the STIG-1 well itself. Although the AOR has increased in size from 1 mile in the original permit to 2 miles in this permit,the 1993 permit had a 2-mile study area in addition to the AOR. Therefore, only supplemental information is provided to enhance the discussion of site conditions. Regional Geology Regional Structural Geology The Southern Sacramento Valley and Sacramento Delta Areas are part of the Great Valley Geomorphic Province,which is a nearly flat alluvial plain that extends from the Klamath Mountains south to the Tehachapi Mountains. To the east are the Sierra Nevada Mountains and to the west are the Coast Ranges (Figure F-1). The Sierra Nevada,Great Valley,and Coast Ranges geologically represent an arc-trench system that resulted from the convergence and subduction of the Pacific oceanic crust underneath the North American Plate during Mesozoic and early Quaternary time. The Great Valley,representing a fore-arc basin,has been filled by a sequence of sediments eroded primarily from the Sierra Nevada arc. The area near Lodi is on the eastern side of this north-south elongated trough,with the deepest part of the basin being about 20 miles further west. The three principal geologic structures in this general region are the Thornton arch(to the north of the site),the Stockton Fault (to the south),and the Midland Fault Zone (to the SAC/371322/082550021(ATTACHMENT-F.DOC) F-1