Characteristics of the 3513 impoundment

A characterization study was conducted on a waste settling impoundment (3513 Basin) at the Oak Ridge National Laboratory, to provide information necessary for its proper disposition. The impoundment received laboratory low-level radioactive-waste waters from 1944, the year of its construction, through 1976. The pond is square-shaped and measures approximately 67 m on a side at normal water level. Water in the impoundment overlies 0.6 m of sediment waste. The current conceptual plan for impoundment closure will need to be revised to consider the following: (1) if the waste is solidified in place, remedial actions will have to be taken to isolate the solidified material from the groundwater in both the surrounding clay overburden and underlying limestone bedrock, and (2) the proposal to separate the pond into smaller workable segments by driving sheet piling into the clay may need to be modified for some parts of the pond because of an insufficiently thick clay layer in which to found the piling.