ARCHIVED REPORTS XR0011738 - Laserfiche WebLink

Home Browse Search

Report;Groundwater-quality Monitoring-November 28, 2000: 7500 West Eleventh Street, Tracy, CA. Page 2 The restaurant on the property remains in operation and is leased from the Navarras by Able Manzilla Mendoza and Guadeloupe Contrecias, et ux, (the Mendozas) who do business as the Casa Mendoza restaurant. In 2000, the Mendozas leased the rest of the site and plan to expand their business on the property, On December 9, 1998, eight underground fuel storage tanks and 6,000 linear feet of associated piping were removed from the property under the permit and oversight of the SJCPHS. (Dietz Irrigation 1999.) The former locations of the fuel tanks are shown on Figure 2. When the tanks were removed, it was found that fuel hydrocarbons had leaked from underground piping beneath the fuel pump islands of the former fueling station. The former locations of the fuel pump islands are also shown on Figure 2. 1.4 Geology and Hydirogeology The subject property and the surrounding area are situated on level terrain on the distal, northern slope of an alluvial fan. The underlying alluvial sediments are of Quaternary to Recent age. The site and the immediately adjacent property along the south side of West Eleventh Street and the west side of Chrisman Road have been extensively excavated and backfilled during prior filling station construction and remodeling, utility installation, and highway expansion. The.first several feet beneath the surface of the site are composed of multiple layers of i bituminous macadam, concrete slabs and random fill. Beneath the paving and fill, the soils are composed 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 pbrmeable lenses vary from relatively large features having considerable areal extent to small, localized lenses of limited extent and thickness. In some instances, these lenses merge 1 into each other to form semi-continuous permeable strata within the less permeable clayey material. l The depth to groundwater beneath the site varies seasonally between 7 and 11 ft. Regionally, the general direction of groundwater flow is to the.north toward the Old River anastomosis branch of the San Joaquin River, the closest tributary of which, the Tom Paine Slough, is one and one-quarter miles north of the 7500 West Eleventh Street site, However, locally, the shallow groundwater gradient tends to follow the topography, which, at the subject property, slopes gently to the north-northeast. The local direction of groundwater flow is also affected by the local sedimentary geology, particularly where continuous or semi-continuous sand strata provide channels for subsurface flow through i less permeable facies. sic ; i