[en] As part of the remedial investigation efforts conducted at the Weldon Spring Site Remedial Action Project (WSSRAP), it was recognized that an assessment of the nature and extent of the types of waste in the Weldon Spring Raffinate Pits (WSRP) was necessary to evaluate treatment and disposal alternatives. A sampling plan was developed, therefore, which detailed sample locations, sample parameters, and sampling techniques. The sampling effort consisted of collecting 145 samples from 42 locations. The sampling locations were evenly distributed across each of the four raffinate pits in terms of both area and depth. The samples were analyzed for long-lived radionuclides from the natural uranium and natural thorium transformation series. The average, standard deviation, minimum, and maximum were determined for the selected radionuclides for each pit. The data were then evaluated and interpreted specific to each pit and for each radionuclide. At a later date the surface waters of each pit were sampled and similarly analyzed. 11 refs., 8 figs., 18 tabs