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kLIFORNIA - Environmental Protth Agency PETE WILSON, Governor <br /> ,NIA REGIONAL WATER QUA TITY CONTROL BOARD <br /> AL VALLEY REGION 00, <br /> ,outier Road, Suite A "IC�C,mento, CA 95827-3098 <br /> JNE: (916) 255-3000 a4. Atic 19 N 14 29 <br /> AX: (916) 255-3015 <br /> 17 August 1994 <br /> Mr. Nick Nickerson <br /> Unocal <br /> 2000 Crow Canyon Road, Suite 450 <br /> San Ramon, CA 94583 <br /> PUREGROIBREA AG BROADWAY: SOIL SAMPLING AND QUARTERLY MONITORING <br /> Thank you for submitting the Soil Sampling Workplan and the Second Quarter 1994 Monitoring Well <br /> Report for the former PureGro/Brea Ag facility on Broadway in Stockton. I have reviewed both- <br /> reports, and have a few comments: <br /> Soil Sampling Workplan: <br /> - The workplan states that samples will be collected from 0-3 feet and from 3-6 feet bgs. There <br /> is also a discussion of the expected soil discoloration and odor which is expected to be noticed <br /> when the pond soils are located. Because the exact depth below ground of the former ponds <br /> are not known, you may wish to revise your sampling depths depending on the depth at which <br /> you find discoloration and/or odor. There does not appear to be a need to collect samples <br /> from the material used to fill in the ponds. <br /> - The workplan is approved. <br /> Monitoring Well Report: <br /> - Table 3, a listing of field parameters, contains some unit inconsistencies in the "Conductivity" <br /> column. This should be corrected before the next quarterly report. <br /> - All analytical data, including halocarbons other than 1,2-DCP, should be included in the <br /> tabulation of analytical results. Were chloroform, dibromochloromethane (DBCM), or other <br /> halocarbons detected in earlier monitoring events, or is this the first time that they have been <br /> found? An updated table should be included in the third quarter monitoring report. <br /> - The water quality goals for chloroform and DBCM are 1.1 µg/1 (Cal/EPA Cancer Potency <br /> Factor) and 14 µg/1 (USEPA IRIS), respectively. Because the levels detected in this <br /> monitoring event meet or exceed these concentrations, these chemicals are also a concern in <br /> thegroundwaterbeneath the site. <br /> If you have any questions, I can be reached at (916) 255-3104. <br /> WENDY "h <br /> Ag Regulatory Unit <br /> cc: Mr. John Rapp, Sierra Pacific Consultants, El Dorado Hills <br /> Mr. Mike Infurna, San Joaquin County Environmental Health, Stockton <br />