ARCHIVED REPORTS XR0011741 - Laserfiche WebLink

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Site Characterization and So; mediation Plan: 7500 best Eleventh Street, Tracy, Page 3 do business as the Casa Mendoza restaurant. Following closure of the Olympian Service Station, the Navarras contracted with Dietz Irrigation, an experienced contractor holding a general engineering contractor's license with hazardous waste endorsement, to remove four registered underground fuel storage tanks that had been in use by the filling station at the time it ceased operation in 1998. Those tanks were removed from the site on December 9, 1998 under the permit and oversight of the SJCPHS. G< Work to remove the underground piping from the area of the tank pit and dispenser islands of the former filling station revealed the presence of an additional four abandoned, underground storage tanks of considerable age. Those four tanks were removed on December 28, 1998, also under the permit and oversight of the SJCPHS j GEOLOGY AND HYDROGEOLOGY 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. !. l The subject 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 is composed of multiple layers of bituminous macadam and concrete slabs in random fill_ Beneath the paving and fill, to the depth of the bottoms of the pits from which the tanks were removed, the soils are dominantly silty and sandy clays with thin i interbeds of silt and sand. The depth to the groundwater that flowed into one of the opened tank pits was approximately 9 ft. from the ground surface. The precise direction of groundwater flow beneath the site is not currently known, but the general direction of flow in the neighborhood is to the north, so that the down-gradient direction of groundwater flow is away from the subject property, toward the opposite side of West Eleventh Street REMOVAL OF UNDERGROUND TANKS ! A report of tank removal that documented the removal and disposal of the underground tanks and the results of analyses of samples of soil and groundwater recovered from the tank pits, the pipeline trenches, the stockpiles I of soil excavated from the tank pits, and from a zone beneath the pump islands was submitted to the SJCPHS on January 16, 1999 (Dietz Irrigation, 1999) sic i