SITE INFORMATION AND CORRESPONDENCE

Home Browse Search

Defense Depot Tracy -2- 26 July 1989 Cooling waters from the vapor degreaser and heat sealing machines. Spillage from the recouping operations. Domestic sewage from on-site personnel . Domestic sewage and small quantities of industrial wastewater including effluent from the motor pool ' s oil/water separator, boiler blowdown (7800 gallons per year) , and photographic chemicals (60 gallons per year) are discharged to an on-site treatment plant'. The plant consists of primary sedimentation, two trickling filters in series, secondary sedimentation, chlorination, and disposal into two evaporation/percolation ponds. One pond is used each year while the other is dried and disced. The two ponds have a combined capacity of 12.8 acre-ft. The treatment plant has a design flow of 0.5 mgd. The current average flow is estimated at between 90,000 to 140,000 gpd'. The flow meters were not operational during the inspection. Samples of the effluent from the on-site treatment plant were taken and the results are attached. The major findings were: Constituent Concentration Units BOD 4.3 mg/1 SS 5.8 mg/1 Settleable Solids <0.1 ml/l/hr Volatile Or anics None detected except for 84 ppb of trihalomethanes (EPA 601 (likely from the chlorination process) . The treatment plant appeared to be operating smoothly, except for floc carryover in the secondary clarifier (apparently due to the inefficiency of the solids removal system) . Flowmeters were not operable. No odors were noticeable at the treatment plant nor at the domestic disposal ponds. All other liquid waste streams are discharged into one of two industrial waste ponds. These ponds are single lined with 30 mil Hypalon liners and have a combined storage capacity of approximately 850,000 gallons. Discharge has been estimated at 192,000 gallons per year (1) . Previous analyses of the industrial ponds' liquid and sludge have detected low levels of pesticides within the sludge (chlordane = 0.25 ppb, diazinon = 0.13 ppb, and chloropyritus = 0.07 ppb) , and in the liquid (aldrin = 1.33 ppb) . In 1987, the liquid in the ponds had 1, 1 ,1- trichloroethane = 12 ppb, benzene = 0.06 ppb, and toluene = 0.028 ppb. During this inspection samples were taken of the influent to the small industrial pond and of the sludge on the floor of the small pond (see attached figure) . The ' Draft Volume I , RI/FS Engineering Report, Defense Depot Tracy, Woodward-Clyde Consultants, 3 July 1989.