SITE INFORMATION AND CORRESPONDENCE

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,....r Site Background Information: California Stop Page 2 of 7 Geomorphic Province of California. The Great Valley Province is a nearly flat, elongated structural trough trending northwest and southeast for approximately 450 miles; it is bounded on the east by the Sierra Nevada mountains and on the west by the Coast Ranges. The Province has been filled to its present elevation with thick sequences of sediment ranging in age from Jurassic to present day, creating a nearly flat-lying alluvial plain extending from the Tehachapi Mountains in the south to the Klamath Mountains in the north. The surficial and upper several hundred feet of subsurface layers consists of a great thickness of predominantly unconsolidated alluvial and flood plain deposits (primarily sands, silts, and clays) of Quaternary age, which are derived from the granitic mountains of the Sierra Nevada. Beneath the upper sedimentary deposits lies a thick sequence of marine deposits of Mesozoic age. These marine deposits are further underlain by a pre- Jurassic complex of igneous and metamorphic basement rock. The Province is subdivided into two major divisions, designated the Sacramento and San Joaquin Valleys. The San Joaquin Valley is drained primarily by the San Joaquin River, and the Modesto, Riverbank, and Turlock Lake Formations and overlying Recent alluvium are the principal sources of domestic groundwater in the 13,500-square mile San Joaquin Valley Ground Water Basin (Basin 5-22). The nearest surface water feature in the vicinity of the property is the San Joaquin River, located approximately '/2-mile south of the site. Based on the U.C. Davis California Resource Lab's Online Soil Survey, surface sediment at the site area is classified as Jacktone-Urban land complex.The Jacktone series consists of moderately deep to hardpan, somewhat poorly drained soils formed in fine textured alluvium from mixed igneous and sedimentary rock sources. Jacktone soils are on basin rims and in basins. Depth to groundwater at the property is approximately 20 feet below surface grade (bsg), based on measurements taken during groundwater monitoring events conducted at the site, and on the map entitled Lines of Equal Depth to Groundwater Spring 1999 published by the San Joaquin County Flood Control District and Water Conservation District (FCD&WCD).The map entitled Lines of Equal Elevation of Groundwater Spring 1999, also published by the FCD&WCD,shows the property to be in an area where groundwater flows toward the east-southeast, but this may be modified by changing recharge and discharge patterns. Groundwater is considered to be of beneficial use in California and is used for domestic, industrial, and commercial purposes. PREVIOUS INVESTIGATIONS January 2002 Dispensers and product lines at the site were removed and upgraded. Pea gravel was removed from beneath the former concrete dispenser Advanced CeoEnvironmental,Inc.