ARCHIVED REPORTS_XR0007376 CASE 2

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PHASE 11 ENVIRONMENTAL SOIL SAMPLING AT&T MICROWAVE RELAY FACILITY 90 WEST TURNER ROAD,SACRAMENTO,CALIFORNIA CONFIDENTIAL AND PRIVILEGED INTRODUCTION This report contains the results of a Phase 11 - Environmental Soil Sampling Investigation conducted by ATC ' Associates Inc (ATC) at the AT&T Microwave Relay Facility located at 90 West Turner Road, Lodi, California (Subject Property, Figure 1 and Figure 2) This work, Initiated by the discovery of diesel fuel in the soil following the removal of a 15,000-gallon underground storage tank (UST), was required by the San Joaquin County Public Health ' Services - Environmental Health Division The scope of work Included completion of 10 Geoprobe soil borings, collection of soil and groundwater samples, analytical testing of the samples, and completion of a report summarizing the findings and results of the investigation This environmental soil and groundwater sampling was conducted under ' the supervision of a California Registered Geologist ' I. BACKGROUND ' The Subject Property is owned by AT&T and is a decommissioned microwave telecommunications relay facility One building exists near the center of the site with a microwave tower located to the north of the building The site is accessed by a gravel road along the east side of the building One 15,000-gallon UST was located adjacent to the northeast corner of the building The UST had been closed in place and it was at least 20 years old,although its exact age was unknown UST removal operations were performed on March 4, 1999 A summary of UST removal and testing activities is presented in an ATC report entitled Report of Findings- UYT Removal,dated July 16, 1999 Excavation activities revealed that the UST was surrounded by pea gravel backfill material Native soil in the was of the excavation consisted of brown silty fine sand Groundwater was not encountered at the base of the UST excavation The UST and/or the piping system associated with the UST appeared to have released petroleum hydrocarbon product into the soil on site Stained and odorous soil was observed in soil samples collected from the base of the UST excavation A visual inspection of the UST upon removal from the excavations found little indication of surface pitting, corrosion, cracking, or holes Moderate staining and petroleum hydrocarbon odors were observed in the soil removed from the excavations A two-foot thick concrete slab was present beneath the base of the UST at a depth of 12 feet below ground surface (bgs) Based on the laboratory analytical results, organic compounds were detected in the soil samples collected at the base of the removed UST and in all the soil stockpiles Confirmatory soil samples indicated that the UST excavation area soil ' had a maximum detected concentration of TPH-D at the south end of the UST at 4,900 ppm at a depth of 16 feet bgs (the maximum depth of the excavation) Elevated TPH-D concentrations were also found in the west and southwest ends of the excavation BTEX and MTBE were not detected in the UST excavation area soil Diesel fuel impacted soil ' was found present primarily at the southern and western ends of the UST excavation Following removal of the UST, approximately 371 tons of diesel fuel-impacted soil were removed from the site and ' disposed at the BFI Landfill located in Livermore, California The UST excavation was backfilled with clean soil imported to the site The conctete slab at the base of the UST was not removed 1 1 1 1