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MEMORANDUM , - CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD - CENTRAL VALLEY REGION 3443 Routier Road Sacramento, CA 95827-3098 Phone: (916) 361-5600 ATSS Phone: 8-495-5600 TO: GREG K. VAUGHN FROM: ROBERT L. NIBLACK Senior Engineer Engineering Geologist DATE: 30 August 1989 SIGNATURE: SUBJECT: RESULTS OF CHEMICAL ANALYSES ON TWO SAMPLES TAKEN DURING EXCAVATION OF WASTE AT DELTA TRUCK SALES, SAN JOAQUIN COUNTY On 31 May and 1 June 1989 I visited Delta Truck Sales during the excavation of about 5,000 cubic yards of soil . The excavation was in the area of a former surface impoundment used for disposal of steam-cleaning wastewater. The impoundment was buried in 1985. Regional Board staff had determined that the buried waste is hazardous due , to concentrations of soluble lead above the Soluble Threshold Limit Concentration (STLC) . On 1 June 1989 I collected two samples for analyses for trace metals. Waste Extraction Tests (WET) were performed on the samples, and the extracts were analyzed for trace metals. The pH of the samples was also measured. Sample RLN-060189 was taken from about a six foot depth in the northeast corner of the excavation using a backhoe. I took the soil samp�rom the backhoe bucket. The soil appeared to be stained with oil . The results of chemical analyses (laboratory reports are in the file) showed that no metal constituents were present at or near hazardous concentrations. The pH of this samp a was reported to a 8.5. Sample RLN-060189-2 was taken from the ground surface where it had been dropped during excavation. I was looking for a sample of sludge, and this soil appeared to contain the most oil and waste of any soil in the area. Results of chemical analyses on laboratory duplicates of this sample showed that zinc was present at a concentration of 10,000 mg/kg and 7,500 mg/kg. The Total Threshold Limit Concentration as listed in Section 66699, Title 22, California Code of Regulations is 5,000 mg/kg. The WET extract from this sample contained zinc at a concentration of 300 mg/L. The STLC for zinc is 250 mg/L. No other constituents were present at or near hazardous concentrations. The pH of this sample was reported to be 9.2. The total tead concentration in RLN-060189-2 was determined to be ma/kg. The concentration o ead in the WET extract from this sample was 1.8 mg/L. Considering the tenfold dilution which is an element of the WET methodology, the extract concentration indicates that roughly one half of the lead in the sample was soluble under the WET conditions. Lead was not present in these two samples or WET extracts from the samples at or near hazardous levels. Lead in the waste, however, appears to be very soluble under the conditions of the Waste Extraction Test. Hazardous zinc concentrations have not been found in samples taken from the buried impoundment in the past. Some future waste samples should be analyzed for zinc concentrations in order to determine whether the high zinc concentration found in sample RLN-060189-2 is an anomaly. RLN 8/30/89