SITE INFORMATION AND CORRESPONDENCE

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INFORMATION SHEET WOODBRIDGE SANITARY DISTRICT SAN JOAQUIN COUNTY Woodbridge Sanitary District is presently regulated by Waste Discharge Requirements Order No. 73-66, which prescribes discharge to land. Woodbridge Sanitary District owns and operates the facility that currently discharges an average of 0.34 million gallons per day (mgd) of treated domestic wastewater. The design capacity of the plant is 0.50 mgd. The facility treats domestic wastewater in two Imhoff tanks and two aerated ponds, and dispose of it to five evaporation/percolation ponds adjacent to the Mokelumne River. An average concentration of 290 mg/l (BOD) is received in the influent. Approximately 40 percent of the BOD is removed by the Imhoff tanks. The aeration ponds reduce it to 35 mg/1 prior to discharging to the evaporation/percolation ponds. Four and one-half days of detention time are provided in each aeration pond. The aerators operate for about ten hours under current flows and loads. The evaporation/percolation ponds are used alternatively. The facility has three ground water monitoring wells, one upgradient and two downgradient. Sludge is drawn from the Imhoff tanks monthly. The sludge is dried and composted on-site. Dried sludge has been stored on-site for 12 years and this practice will likely be continued, according to the Mr. George Fiske, plant operator.