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In February 2002, the United States Environmental Protection Agency (USEPA) issued a Record of Decision (ROD) for the Hudson River PCBs Superfund Site. In the ROD, USEPA identified several remedial action objectives, including the following:• Reduce PCB levels in sediments in order to reduce PCB concentrations in river (surface) water that are above applicable or relevant and appropriate requirements for surface water; • Reduce the inventory (mass) of PCBs in sediments that are or may be bioavailable; and • Minimize the long-term downstream transport of PCBs in the river.In selecting its cleanup remedy, USEPA required that performance standards for resuspension during dredging, production rates during dredging, and residual sediment contamination after dredging be established. USEPA tasked TAMS/Earth Tech and Malcolm Pirnie with the development of a technically sound standard designed to protect downstream water users as well as the anticipated long-term recovery of the river.Recognizing the need to respond quickly to sediment resuspension events while at the same time satisfying the need to confirm the release of PCBs and not just sediment, two sets of criteria and monitoring frameworks were created. At near-field stations (within a few hundred yards of the dredge), suspended solids are monitored in real-time, providing rapid feedback to the dredge operator. Far-field monitoring at 1 mile or more downstream is performed periodically by collecting samples for PCB analysis to determine concentration and load. The criteria reflect considerations of PCB water quality and PCB loads, with the purpose of protecting public water supplies and the long-term recovery of the river. BACKGROUND

The recently completed aerial survey of the exposed area of Steed Pond showed that the uranium was widely spread in the sediments of Steed Pond. Until ground cover is established over the exposed.pol1d sediments, they will be subject to erosion. As much as 90 tons of sediment could be eroded from the exposed sediments in Steed Pond the first year, but the erosion could be reduced to 5-15 tons by establishing a ground cover such as rye grass. Only about 40% of the eroded sediment would be delivered to Upper Three Runs Creek, because most of the eroded sediment deposited before it reaches Upper Three Runs Creek. Less than 20 mei of uranium would be transported downstream the first year from erosion of Steed Pond sediments, and this could be reduced to 2-5 mei/year if ground cover is established. The preliminary results from these calculations were reported at a Steed Pond review on September 20, 1984. • 3 weekend of September 2-3, 1984, a part of the wooden spillway gave way and the pond slowly drained. The sediments in Steed Pond containing uranium from 300 Area releases are now exposed and subject to erosion. Earlier analyses of a few surface sediment samples from the pond indicate that the uranium concentration ranges from 20 to 531 pCi/gm in the sediments. Since some consideration is being given to leaving the spillway open and the pond drained, an analysis of the amount of uranium that might be transported from the exposed sediment in Steed Pond and the conditions that resulted in uranium originally being deposited in the Tims Branch and Steed Pond stream system was studied. DISCUSSION Alpha Activity Source About 24 curies of alpha activity have been discharged to the Tims Branch system from 300 Area fuel target fabrication operations (Figure 1). From the early 1950's until the mid 1960's, most of the alpha activity discharged was natural uranium (0.72% U-235) along with a small amount of enriched uranium (0.89% U-235). The alpha activity discharged since the mid 1960's is due to depleted uranium (0.2% U-235l. A small amount of alpha activity from Th-232 may have been released in 1967 and 1968. 4 The source of this discharged alpha activity is waste from cleaning and recovery operations in the 300 Area. In the process of making the fuel or target elements, uranium slugs are cleaned in step operations with perchloroethylene, nitric and phosphoric acids. The cleaning removes alpha activity from the surfaces of the slugs used to fabricate fuel or target elements. The used chemicals from this cleaning operation are treated and the waste water containing traces of the residual alpha activity is discharged. Some alpha activity in the waste water was also released from the process used to recover uranium from fuel and target elements that failed specifications or tests. The waste water from all these sources entered a Tims Branch tributary near the 700 Area waste water treatment plant on Road D (Figure 2). An accounting of the gross alpha activity released at the discharge point and the alpha activity in transport in...

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