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Memorandum1b CALIFORNIA REGIONAL MATER QUALITY CONTROL BOARD . CENTRAL VALLEY REGIO 3201 S Street Sacramento, California 95816 Phone: 445-0270 TO: Antonia Vorster FROM: Daniel Ward Senior Engineer Area Engineer 1 DATE: 12 December 1985 SIGNATURE: _ v L�-r,LC (d(L SUBJECT: "GROUNDWATER QUALITY AND SOIL ANALYSIS FOR CLOSURE OF ARCADY OIL COMPANY DISPOSAL SITE, HOLT, CALIFORNIA", BY ALVIN L. FRANKS, Ph.D The subject report summarizes the soil and ground water sampling at the Arcady site. The report also proposes to close a major portion of the site and further investigate an area which is contaminated with lead. Soil samples were taken from borings at 11 locations over the site, as shown on the attached figure. Two to five samples were taken, with depth, at each boring. Ten monitoring wells were drilled, constructed and developed at the locations shown on the attached figure. Soil samples were extracted and analyzed according to the WET test in Title 22. Using this citric acid ex- traction, 'designated' levels of chromium, lead, and barium were detected in all 11 borings. ' Hazardous' levels (above the STLC) of lead, nickel , and cobalt were detected in boring No. 11. 'Hazardous' levels of barium were detected in boring No. 10. Arsenic was detected at below the 'designated' level of 0.5 ppm in all but boring No. 9. Arsenic levels were from <0.04 to 0.44 ppm. Zinc was detected in all borings at below the 'designated' level of 500 ppm. Zinc levels were from 1. 32 ppm to 12. 7 ppm. The "native materials" underlying the site contained up to 56 ppm zinc. The drinking water standard for lead was exceeded in the water samples taken from wells 5 and 6. These wells appear to be downgradient of borings 10 and 11, respectively. Barium was detected in all wells sampled at 0.05 to 0.35 ppm. The drinking water standard for barium is 1 ppm. Arsenic was detected in well No. 6 at 0.004 ppm, well below the drinking water standard of 0.05 ppm. Zinc was found in all wells sampled at 0.04 to 0.2 ppm. The secondary drinking water standard for zinc is 5 ppm. My comments on the subject report are as follows: 1. The tables, well logs, and figures submitted are handwritten and xeroxed, and are not completely legible. 2. The figures do not include a scale, so that distances can be determined. 3. Only one set of ground water samples was taken. Additional samples must be taken to confirm or refute the results already received. It would be imprudent to formulate conclusions, and plan closure activities on one set of ground water samples.