ARCHIVED REPORTS XR0000288 - Laserfiche WebLink

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Executive Summary On behalf of the California Department of Transportation (Caltrans), IT Corporation (TT) conducted a groundwater investigation at the Stockton Yard Maintenance Station, in the city of Stockton, California (Figure 1) The site is located at 1604 South B Street,just south of Charter Way The property is an active maintenance yard and is owned by Caltrans The objective of this investigation was to determine the extent of hydrocarbon contamination in groundwater at the site and to calculate the estimated contaminant mass for the encountered water bearing zones On February 11, 2002, an underground utility location survey was conducted to assess the absence or presence of unreported underground utilities at the site The utility survey cleared utilities for the proposed boring locations The boring locations were found to be free of anomalies On February 13 and 14, 2002, IT conducted an investigation that consisted of the advancement of two borings using Cone Penetrometer Testing (CPT) methods for lithologic evaluation and groundwater sample collection The CPT log indicated that potential water bearing zones were located at 19 8 meters (65 feet) below ground surface (BGS), 27 4 meters (90 feet) BGS, and 30 5 meters (100 feet) BGS Based on the CPT data, Zone A includes a very stiff fined grained sand observed between 117 and 13 4 meters (38 5 and 44 feet) BGS, and again between 18 1 and 18 5 meters (59 5 and 61 feet) BGS Zone B includes a silty sand to sandy silt observed between 20 1 to 210 meters (66 to 69 feet) BGS and a very stiff fine grained sand observed between 210 and 25 0 meters (69 and ____ 82 feet)SGS__Chenucal_concentrations detected in the HydroPunch® sample collected at 27 4 meters (90 feet) BGS was applied to this zone Zone C includes very stiff fine-grained sand observed between 27 1 and 30 5 meters (89 and 100 feet) BGS Groundwater samples were collected from each of these zones Total Petroleum Hydrocarbons as gas (TPHg), toluene, ethylbenzene, total xylenes, n-Propylbenzene, tert-Butylbenzene, and 1,2,4-Trimethylbenzene were detected in groundwater samples collected from the boring SC-1 TPHg was detected in the groundwater samples collected from SC-1-65' and SC-1-100' at concentrations of 130 and 84 micrograms per liter (µg/1), respectively Toluene was detected in i SC-1-90' and SC-1-100' at concentrations of 1 1 and 2 2 µg/1, respectively Ethylbenzene was detected in all groundwater samples at concentrations ranging between 14 and 5 2 µg/l Total Xylenes were detected in all groundwater samples at concentrations ranging between 7 6 and 28 6 µg/1 The constituent n-Propylbenzene was detected in SC-1-100' at a concentration of 1 3 µg/1 The constituent tert-Butylbenzene was detected in SC-1-65' at a concentration of N ��2oazwA nP+s+s�4essznzan ex ES-1 �x»