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• CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD • CENTRAL VALLEY REGION 3443 Routier Road Phone: (91 6) 361-5600 Sacramento, CA 95827-3098 ATSS: 8-495-5600 TO: Kenneth D. Landau FROM: Wendy L. Cohen Senior Engineer Project Engineer DATE: 16 June 1987SIGNATURE: SUBJECT: DRYELL STATUS REPORT, LAWRENCE LIVERMORE NATIONAL LABORATORY SITE 300, SAN JOAQUIN COUNTY I have reviewed Lawrence Livermore National Laboratory's (LLNL) drywell status report dated 14 April 1987 and information submitted previously on drywells at LLNL' s Site 300. The combined submittals list 16 drywells plus two discharges to land for a total of 18 sites. The following comments cover all 18 sites with recommendations for any further actions. 1. Six drywells in the General Services Area (GSA) (at Buildings 872, 873-E, 873-S, 874, 875-S1 and 875-S2) were permanently closed in 1983 and a report submitted in February 1984; no further action was taken. The closure plan submitted in February 1983 shows the wastewater discharged to drywells 873-E and 875-S2 resulted from acid dip tank operations (nitric and chromic acid used with copper parts) , and was hazardous with 8.7 mg/l of chromium. The wastewater discharged to drywell 872-S contained very high BOD, COD, and filtered organic carbon. _ Drywells 875-S1 and 873-S received wastewater which likely would not cause water quality problems , and wastewater directed to drywell 874 was® not characterized. A seventh "drywell " tactually an unlined ditch at Building 879.) also was mentioned in the 1983 closure plan but was not characterized (see item 5 below for a full discussion of this location). The six drywells were closed by removing the gravels, casings, and about three feet of surrounding soil , filling the holes with native soil and compacting, and capping with asphalt for wells that originally were under asphalt. We have no construction details on the wells, and apparently no samples were taken at the bottom of the holes before backfilling. Soil samples were taken from augered holes about one foot and five feet down- gradient of the drywells at depths of six and nine feet (the drywells were reported to be six feet deep) . Samples were analyzed by the EP Toxicity test for chromium, copper, and lead, but the detection limit for lead was 0.16 mg/i , more than three times the drinking water standard. Samples also were analyzed by EPA Method 624 with results showing most of the samples contained toluene (11 out of 15 samples) with values ranging from 30 to 1,000 ppb, and one-half the samples contained methylethyl ketone (MEK) with values ranging from 1 to 6 ppm. One sample from nine feet deep in a borehole near drywell 875-S (the lab sheet does not differentiate between 875-S1 and 875-S2) contained 10 ppb of TCF_.