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Stantec PEA WORKPLAN Proposed Lodi Energy Center Site Lodi, California 3.0 GEOLOGY AND HYDROGEOLOGY 3.1 TOPOGRAPHY The Site consists predominantly of exposed soil with low-lying vegetation. The parcel is relatively flat and gently slopes to the west. Berms, drainage channels and lagoons associated with the W PCF border the Site on the north and east. SJCM&VCF ponds border the Site to the south (Figures 1 and 2). The elevation of the Site is approximately 5 feet above mean sea level. 3.2 GEOLOGY The project area is situated in the Great Valley physiographic province. The Great Valley and the adjacent Sierra Nevada to the east form a relatively stable crustal block (Sierran block) composed of Mesozoic crystalline basement that dips gently to the west. The Great Valley physiographic province separates the Coast Ranges to the west from the Sierra Nevada to the east. This province is composed of two elongated northwest- to southeast-trending basins: the Sacramento basin to the northwest and the San Joaquin basin to the southeast. Within the basin deposits, the Site near-surface deposits have been derived from the Sacramento, Mokelumne, and San Joaquin river systems. The Site lies on the eastern edge of the Sacramento-San Joaquin River Delta, and the surficial unit mapped in the Site vicinity is the lower member of the Quaternary Modesto Formation. Deposits of this formation are described as undifferentiated alluvial deposits overlain by Holocene intertidal deposits. Based on prior subsurface assessment of the Site and adjacent WPCF property, the Site subsurface is comprised of fine-grained silty sands/sandy silts to a depth of approximately 10 feet below ground surface (ft bgs). A dense material (cemented or hard pan zone) was reportedly encountered between 2 and 4 ft bgs in the central portion of the Site, as well as between 6 and 10 ft bgs locally onsite and on property east of the Site during a prior investigation. The silty sands/sandy silts are underlain by clayey sand to a depth of approximately 13 ft bgs, and sand was encountered below the clayey sand to a maximum depth of 20 ft bgs. 3.3 HYDROGEOLOGY Based on Carlton's recent geotechnical assessment, historical groundwater levels have ranged between 3 and 20 ft bgs in the Site vicinity over the past 30 years. Carlton reported that that regional groundwater flow direction at the Site is toward the east-southeast through southeast towards a cone of depression located approximately 5 miles to the east-southeast. Locally, groundwater pumping and recharge reportedly cause deflections in groundwater flow direction, and northerly and southwesterly flow direction components have been observed in the past. Based on review of recent shallow groundwater contour maps prepared by West & Yost Associates for fourth quarter 2008 through second quarter 2009, the groundwater elevation at Site monitoring well WSM-3 ranged from -6.89 ft msl (4Q2008) to -3.99 ft msl (2Q2009). Based on these measurements, the groundwater elevation at the Site has increased by approximately 3 feet since fourth quarter 2008. Based on the contour data, the groundwater flow direction has PEA WP-Lodi 4 August 13,2009