ARCHIVED REPORTS XR0009921 - Laserfiche WebLink

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Corrective Action PlanPag e 3 subsurface (Ref 9 ) Groundwater pumping tests to evaluate the hydrogeologic properties of the soils beneath the site have also been conducted (Ref 11 ) Directly north of the subject property (i a 152 East 11th Street), and across 11th Street, there is a Beacon station located at 153 East 11th Street The station is owned by Ultramar Inc (Ultramar) of Hanford, California In connection with investigations of a release of hydrocarbon fuels at the Beacon station, a total of nine ground water monitoring wells have been installed on and around that property The SJCPHS has assigned the Ultramar property Site Code 1389 The locations of the monitonng wells that have been installed on the subject site at 152 East 11th Street that is owned by the Navarras, on the site of Ultramar Inc 's Beacon Station at 153 East 11th Street and in surrounding areas are shown on Figure 2 Wells installed for the Navarras are designated NAV and those installed for Ultramar are designated ULT 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 Logs of the monitoring well borings indicate that the sans beneath the site includes clays, silty clays, sandy clays, clays with gravel, sands, silty sands and sands with gravel These clastic materials are distributed in a complex lenticular structure Areas beneath the streets adjacent to the property have been extensively excavated and backfilled for installation of sewers and other utilities The depth to groundwater is in the range 7 to 9 ft Seasonal variations s in the elevation of the groundwater table are less than one foot (Ref 12 ) The general direction of the groundwater gradient is northwest across the 152 East 11th Street property The slope of the groundwater gradient is typically about 0 003 ft /ft The groundwater contours shown on Figure 2 were constructed from measurements of the depth to groundwater in each of the NAV and ULT series monitoring wells that were made on July 8th 1993 (Ref 9) and are representative of the generally prevailing conditions Additional information about the geology and hydrogeology of the subject site and its environs is detailed in the appropriate sections of this report