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S <br /> REPORT OF FINDINGS <br /> QUARTERLY GROUNDWATER MONITORING REPORT NO. 4 <br /> REQUEST FOR SITE CLOSURE <br /> APRIL 2001 —JUNE 2001 <br /> AT&T, MICROWAVE RELAY FACILITY <br /> 90 WEST TURNER ROAD, LODI, CALIFORNIA <br /> ATC PROJECT NO. 75.75128.0001 <br /> November 14, 2001 <br /> 1.0 INTRODUCTION <br /> The purpose of this report is to document activities related to quarterly sampling of three groundwater momtormg <br /> wells at the AT&T microwave relay facility located at 90 West Turner Road, Lode, California (Figure 1) <br /> AT&T authorized ATC Associates Inc (ATC)to perforin quarterly groundwater monitoring by Work Order No <br /> CA-8-PF2M6 dated August 30,2000 <br /> 2.0 BACKGROUND <br /> The site is owned b AT&T and is a decommissioned microwave telecommunications rely facile One <br /> Y Y t5' <br /> building exists near the center of the site with a microwave tower located to the north of the building The site is <br /> accessed by a gravel road along the east side of the building One 15,000-gallon diesel fuel underground storage <br /> tank(UST)was located adjacent to the northeast comer of the building The age of the UST was unknown <br /> 1 The UST was removed by ATC on Marchi 4, 1999 The UST and/or the piping system associated with the UST <br /> appeared to have released petroletun hydrocarbon product into the soil on site Dark-stained and petroleum <br /> odorous soil was observed in soil samples collected from the base of the UST excavation The UST excavation <br /> area soil had a maximum detected concentration of total petroleum hydrocarbons — diesel fuel (r?H-D) at the <br /> south end of the UST at 4,900 milligrams per kilogram(mg/kg)at a depth of 16 feet below ground surface(bgs), <br /> the maximum depth of the excavation Elevated TPH-D concentrations were also found in soil at the west and <br /> southwest ends of the excavation Benzene, toluene, ethylbenzene, and total xylenes (BTEX) and methyl tert <br /> butyl ether(MTBE)were not detected in the UST excavation area soil <br /> Following removal of the UST, approximately 371 tons of diesel fuel-impacted soil were removed from the site <br /> and disposed at the BFl Landfill located in Livermore, California on March 23, 1999 The UST excavation was <br /> backfilled with clean soil imported to the site <br /> A soil boring investigation by ATC, described in a report dated April 6, 2000, found that diesel impacted soil <br /> appears to be confined to the immediate vicinity of the former UST excavation in an area approximately 25 feet <br /> long by 25 feet wide Analytical results of groundwater samples from that investigation indicate that diesel fuel in <br /> the groundwater migrated from the former UST excavation to the south and east The diesel fuel impaarW <br /> groundwater appeared to be laterally confirmed to an area approximately 60 feet long by 35 feet wide Diesel fuel <br /> was found in groundwater at a maximum reported concentration of 150 micrograms per titer(ug/L) adjacent to <br /> the UST excavation, and decreased to a concentration of 58 ug/L, 20 feet farther to the south No BTEX or <br /> MTBE were detected in grab groundwater samples collected from the borings, with the exception of total xylenes <br /> detected in the grab sample from one boring at 12 ug/L <br /> AT&T—Lodi,Quarterly Groundwater Monitoring Report No J <br /> NATC ATC Project No 75 75128 0001 <br /> November 14,2041 <br /> Page 1 of 7 <br />