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WASTE DISCHARGE REQUIREMENTS ORDER NO. R5-2008-0148 -7- LAWRENCE LIVERMORE NATIONAL SECURITY, LLC AND THE U.S. DEPARTMENT OF ENERGY FOR LAWRENCE LIVERMORE NATIONAL LABORATORY SITE 300 SAN JOAQUIN AND ALAMEDA COUNTIES overlies the regional aquifer, the Tnbsl. The alluvium and Tnbs, are in hydraulic communication. 25.The seasonally highest groundwater level in the alluvium ranges from 10 feet below to even with the base of the sewage ponds. Groundwater flows generally in a northeasterly direction along alluvial paleochannels of Corral Hollow Creek and to the southeast in the Tnbsl. 26.Land within 1,000 feet of the sewage ponds off Site 300 property is used primarily for livestock grazing. One residence is within 1,000 feet of the sewage ponds on the property previously operated as a fire station by the California Department of Forestry. Water supply for this residence is from wells completed in the Tnbsl. Land within 1,000 feet of the sewage ponds within Site 300 is primarily open space, groundwater treatment facilities, and facility maintenance shops and offices. 27.The sewage evaporation pond is lined with catalytically-blown asphalt and is designed to overflow to the sewage percolation pond during periods of high rainfall. The surface area of the sewage evaporation pond is approximately one acre and the surface area of the percolation pond is approximately 0.33 acres. The sewage evaporation pond has a depth of 6.5 feet at the deepest point and four feet near the edges. The Discharger aerates the sewage evaporation pond for odor control as needed. 28.Design capacity of the sewage evaporation pond is 250 people per day at 30 gallons per day (gpd) per person. The sewage evaporation pond receives approximately 4,000 gpd of wastewater. Normal usage is lower than the design capacity. Due to the low flow (less than 10 gallons per minute during the work day), monitoring flow is not practical and no flow meter is installed. 29.The Discharger has only needed to remove sludge from the sewage ponds once since beginning operation. The Discharger sampled the sludge to characterize it for disposal. The sludge was determined to be non-hazardous and was disposed at the Class III BFI Landfill off Vasco Road in Livermore. Future sludge removal would be handled in the same manner. Four metals in the sludge, copper, mercury, silver and zinc, exceed Site 300 soil background levels for these metals. Annual groundwater sampling for metals is required in this Order. 30.The Discharger has registered the sewage percolation pond as a Class V Injection Well with the United States Environmental Protection Agency (US EPA).