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<br /> E-''MEMORANDUM Cal/EPA
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<br /> CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD `
<br /> ' CENTRAL VALLEY REGION
<br /> SS ROUA 0 .i
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<br /> (916)255-3000 • CALNET 8-494-3004 • FAX(916)255-3015 Pete Wilson,Governor
<br /> TO: Gordon L. Boggs FROM: Patricia A.Anderson
<br /> DATE: 23 February 1998 SIGNATURE: r
<br /> SUBJECT. REVIEW FOR'NO FURTHER A CTIONREQ UIRED,ARTS&ARTISTS, 204 EAST LODI
<br /> AVENUE, LODI, SAN JOA QUIN COUNTY
<br /> Based on limy review of the case file, concerning the above site, I have noted the following:
<br /> Background,:9In`January,1987;`a'550-gallon leaded gasoline tank-was-removed from:-the.above-site-Soil-
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<br /> samples, collected beneath the tank, had 1,400 mg/kg total petroleum hydrocarbons as gasoline (TPH-g),
<br /> 270 mg/kg toluene, and 18 mg/kg xylenes. Nevertheless, impacted soil was returned to the excavation and
<br /> not overexcavated from the area.
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<br /> From July 1987 through August 1996, eight monitoring wells, soil borings, soil probes, a remediation well,
<br /> i and air sparging wells were installed to investigate the extent of soil and groundwater contamination and to
<br /> design a remediation system.`Data showed that contaminated soil extends laterally in a 65 ft diameter with a
<br /> maximum concentration of 13,000 mg/kg total petroleum hydrocarbons as gasoline (TPH-g),
<br /> 22 mg/kg benzene, 510 mg/kg toluene, 170 mg/kg ethylbenzene, 890 mg/kg xylene. This contamination
<br /> extends vertically to 50 ft bgs'with 3,900 mg/kg (TPH-g}, 1.7 mg/kg benzene, 190 mg/kg toluene,
<br /> 61 mg/kg ethylbenzene, and 290 mg/kg xylenes.
<br /> Data from monitoring wells, MW-1 through MW-3, shows that in August and September 1987, groundwater
<br /> occurred at 50 ft bgs with flow towards the northeast. In June and August 1992, groundwater occurred at
<br />= 60 ft bgs; ith flow towards the northwest. Since August 1992, groundwater has risen to 55 ft bgs with flow
<br /> consistently,towards the south to southwest. This change in the direction of groundwater flow is probably
<br /> due to the pumping influence from municipal wells located 350 ft east(Municipal well No. 01),
<br /> 1,500 ft west, and 2,000 ft north of this site. Municipal well No. 01 was abandoned in June 1992, and the
<br /> other two wells are "off-line." Ground water samples from Municipal ViWeIl No. 01 were nondetect for
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<br /> hydrocarbons in1987. Construcf�an and operating data for these r�iunicipal wells are unknown. The nearest
<br /> operating downgradient municipal well is 3,500 ft south of the site and does not influence the direction of
<br /> ground water flow.
<br /> Initial groundwater data shows that the highest levels of contamination occurred in MW-1 (total depth
<br /> (TD)65 ft, screened interval 31 to 65 ft bgs)with 100 mg/l TPH-g, 21 mg/1 benzene, 17 mg/1 toluene,
<br /> 2.3 mg/1'ethylbenzene, and 7.0 mg/1 xylene. This contamination extends to MW-3 (TD 59 ft, screened
<br /> interval 37 to 59 ft bgs) and MW-4 (TD 74 ft, screened interval 49 to 74 ft bgs), which had consistent
<br /> detection's of contamination,'and MW-5 (TD 75 ft, screened interval 50 to 75 ft bgs), which had sporadic
<br /> detections of contamination., This contamination extends further to MW-6, MW-7, and MW_8 (TD 70 ft,
<br /> screenedCiriterval 50 to 70 ft bgs),which have only occasional detections of contamination. The nearby
<br /> operating municipal wells influenced the direction of ground water flow and consequently the plume of
<br /> contamination both of which extended northward. San Joaquin County's interpretation of the data is that the
<br /> .plume of contamination extended laterally to these wells and vertically to 75 ft bgs. However, my
<br /> Our mission 1,to preserve and enhance the quality of California's water resources,and
<br /> ensure their proper allocation and efficient use for the benefit of present and future generations.
<br /> Recycled Paper
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