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Report: Groundwater-quality Monitoring-June 23-28.2005, 7500 West Eleventh Street, Tracy, C4. Page 5 ' highway expansion. Beneath the paving and fill, the soils are composed of alluvial materials consisting of interbedded clays, silts and sands. These materials have been deposited in a complex lenticular form composed of relatively low permeability clays and silty clays inter- bedded with permeable silts and sands. The sizes of individual permeable lenses vary -- ne from relatively large features having considerable es hese lensestmergel mo, loceach othersto of limited extent and thickness. in some j form semi-continuous permeable strata withn�et siee it iesbmat d thale clayey tithese lal u. In�ia1 neighborhood of the 7500 West Eleventh materials are some 100 ft. thick. The stratia nl'area are described above is typical of the alluvial fan upon which Tracy and the surroun g vels of the Beneath the alluvial sediments are the poorly sorted clays, silts sands and Wills that se Tulare Formation that were primarily derived from the Inner Coast Range along the west side of the San Joaquin Val1ny�Th theulLowe°Tularoe Formais tion. into Both two members, the Upper Tulare Formatio permeable and l members of the Formation are, on the regional scale, moderately to highly yield moderate to large quantities of water to the low-permeability,tye Upper T a ustrine Corcoran separated from the Lower Tulare ulare Formation is Formation by p i Clay,which acts as a confining bed within the regional groundwater basin. At the subject site, the top of the Corcoran Clay is estimated to be at a depth of approximately 230 ft. beneath the ground surface and to be some 100 ft. thick. The total this tes suess gthe gest gest Formation is not g underlying Lower Tulare ess from 300 ft to greater than documented;,400 ft.however, that it ranges in thickness Figures 4-9 are hydro strati graphic longitudinal and cross-sections drawn along section lines A-A' through F-F', the locations of which site sothat t istractable hshown Figure otopractical reduce == complexity of the stratigraphy of the Navarra '- interpretation, the sections shown on Figures 4-9 were developed by dividing the sediments into general classes based on their hydraulic conductivity to contas pant transport capacity, which are the sail charactestigravelss of primary , sands and silts have been `} analysis. In the cross-sections, thepermeable segregated from the relatively less permeable clays and silty clays. The depth to groundwater beneath the site varies flow seasonally s tollhe north toward they d Regionally, the general direction of groundwater i River anastomosic branch of the San Joaquin River, the closest tributary of which, the '! Tom Paine Slough, is one and one miles north of the Navarra Site. However, locally, the shallow groundwater gradient tends to follow the topography, which, at the undwater subject property, slopes gentlyto the north-northeast. The local direction of gro geology, articularly where continuous or now is also affected by the local sedimentary g gy, p ide channels far subsurface flow through less semi-continuous sand or gravel strata prov l' permeable facies. sic f%`�