ARCHIVED REPORTS XR0000213 - Laserfiche WebLink

Home Browse Search

SECTIONONE OntroducUon • to the north is the District headquarters buildings, to the east is the Caltrans Maintenance Yard, and to the south are open fields The predominant structures located on site include a shop building, a storage building, and an office building There are plans for the construction of a shop building in the center of the site, near the former UST location 9.2 GEOLOGY AND HY®ROGEOLOGY Based on groundwater elevation data collected in 1997, the groundwater flow direction beneath the site is generally to the east with a hydraulic gradient of 0 003 meter per meter (0 003 foot per foot) The histone depth to groundwater ranges from approximately 50 feet below ground surface (bgs)to approximately 68 feet bgs Based on boring logs from previous investigations, the soil predominately consists of a fill material overlying alluvial deposits The fill soil was generally a sandy gravel to a silty sand and was encountered to depths of 3 and feet 15 bgs The soil was classified beneath the fill material as silty clay, clayey silt, clay, sandy silt, sandy clay, and silty sands The site is located near the center of the Great Valley of California, a geomorphic province, that is a nearly flat alluvial plain bounded on the east by the Sierra Nevada and on the west by the Coast Ranges The Great Valley is comprised of a thick sequence of sedimentary rocks of Jurassic to Recent age The Great Valley is a elongated, northwest trending, asymmetric trough with a long stable eastern shelf and a short western flank (Bailey, 1996) The Stockton Arch, an area of uplift, extends from the Sierran slope across to the western flank of the trough The uplift is thought to ' have occurred during Eocene time and may have continued into the Mocene as a result of upward movement on the south side of the Stockton fault ® C%CALMMS&40PIMWRKPLNF D=74CT4W79009NA%MA 1-2