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TABLE 1 ' POTENTIAL OFFSITE SOURCE AREAS 541 West Grant Line Road . Tracy, California ' Maximum Concentrations } Depth to 1 ' Groundwater,Flow Direction and No Name and Address Potential Contaminant Sources Shallow Soil TvDe Gradient Soil(ppm) Groundwater(ppb) Remediation/Status Concerns ' USTs removed in 1986 and soil and groundwater TPH-gas-5,800 TPH-gas-3,000,000 contamination found Approximately 10,000 gallons of TPH-diesel-10,000 TPH-diesel-NT contaminated water removed from fuel UST excavation and Significant contamination(free product) ' Two former 10,000 gal and one 4 5-6 ft bgs TPH-mo-540 TPH-mo-NT disposed offsite The waste oil tank was observed to have in groundwater Former Mobil Station 5,000 gal fuel USTs and one 250 0->20 ft silty clay g MTBE-NT MTBE-2,470 holes In 1988,floatmg product was found in well MW-3 Evidence of groundwater flow to 5 2375 Tracy Boulevard gal waste oil tank,product luxes and and clay NW with some flow benzene-14 benzene-7,000 and remediated by pump and treat system') In 1992,an northeast as floating and[ugliest ' pump islands to N-NE ethylbenzene-77 ethylbenzene-34,000 automated product recovery system was installed at MW-3, dissolved product located on northeast toluene-3 toluene-9,700 MW-5 and AMW-6 The site is currently part of a Joint corner of site • xylenes-51 xylenes-120,000 Groundwater Monitoring Program with former Chevron ' and Scotties Stations I 'I u 1 In 1986 the USTs were lined with Armor Shield,however TPH-gas-6,500 TPH-gas- 120,000 the product Imes and pump islands were not upgraded at 7' this time In 1998 the gasoline USTs and associated piping• TPH-diesel-NT TPH-diesel-NT and pump islands were removed Approximately 300 tons Significant contamination in ft 0->20 sandy and 5 5-6 feet bgs TPH-mo-NT TPH-mo-NT groundwater of contaminated soil was removed offsite to 2001 Former Scotties Station Three former 8,000 gal gasoline clayey silt, silty NW with some flow MTBE-4 6 MTBE-59,000 1 Cross sections(2000) and potentiometric 6 574 W Grant Line Road USTs and four fuel um islands clay with to W and NE benzene-12 benzene-20,000 groundwater extractor well(EW-1), air sparging well(AS- t pump y 1),and vapor extraction wells(VE-1 andV�-2) stalled maps show general flow to northwest in sandy zones @ 0 008 ethylbenzene-96 ethylbenzene-5,700 and feasibility study conducted In late 20 -2)i ozone and local variations to west and toluene-87 toluene-14,000 northeast xylenes-510 ; xylenes-21,000 sparging remediation was implemented T$ie site is currently part of a Joint Groundwater Monitoring Program ' with former Mobil and Chevron Stations TPH-gas- 1,900 f TPH-13,000 Old gas station(active•-1960s to TPH-diesel-NT TPH-gas-5,200 USTs removed in 1986 and contamination found Holes ' 0-3 ft sands/fill TPH-diesel-NT mid-1980s)and then motorcycle 3-10 ft sandy silty TTotal O&G-�l 0 PH-mo-270 documented in waste oil tank No remediation No wells located downgradient of USTs � 7 Former Wheel Country repair shop 4 0-4 5 ft bgs MTBE-NT MTBE-5 4 Groundwater believed to have been to NE,1so no Pump island and piping were never clay i ' 474 W Grant Line Road Two former 2,000 gal and one NW@0 002 benzene-<2 ! downgradient wells installed for NW flow'direction investigated where most leaks typically 10->15 ft silty benzene-745 f 3,000 gal gasoline USTs,One clay ethylbenzene-23 ethylbenzene-5 5 t occur former 350 gal waste oil UST toluene-7 4 toluenezene SJCEHD and RWQCB closed case in 1997,L xylenes-25 xylenes-9,170 1 I ' Potential Source Areas xls i TREADWELL&ROLLO,INC L 01 5/2'E103