[en] This report brings together the most current information on groundwater contamination in the Weldon Spring Chemical Plant/Raffinate Pits (WSCP/WSRP) area and vicinity properties (WSVP) of the Weldon Spring Site (WSS). In 1988 the monitoring well network was extended by the addition of 33 new wells installed at two depths so they could be used for vertical and lateral characterization. The analytical categories for the study were inorganic anions, nitroaromatic compounds, radiochemical parameters, metals, and total organic carbon. Nitrate contamination in groundwater is a result of leaking raffinate pits. The apparent sources of sulfate contamination are associated with the manufacturing of TNT and DNT. Nitroaromatic compounds are present in the groundwater at the WSS as a result of operations at the WSOW during World War II. Historically, only two monitoring wells indicate uranium levels greater than 40 pCi/L which at this time seems to be the most likely drinking water standard the US Environmental Protection Agency (EPA) will establish. Some metals concentrations in groundwater appear to be connected to the raffinate pits as a point source. Other metals are present in the groundwater, not point sources have been identified for them. The contract required detection limits (CRDLs) for some metals higher than regulatory drinking water standards. 19 refs., 24 figs., 13 tabs