The Shiprock uranium-mill tailings remedial action (UMTRA) site, New Mexico
Bernadette Tsosie, Steven Semken, and Bruce Harrison


A uranium mill tailings site on a high terrace adjacent to the San Juan River in Shiprock has been the focus for a Department of Energy remediation program. The mill tailings have been encased within a disposal cell. However, on the lower floodplain a contaminant plume has been identified. Remediation of this plume requires an understanding of the hydrological characteristics of the floodplain and the interaction of flows in the San Juan River and the shallow aquifer. The floodplain consists of alluvial gravels overlying coarser glacial outwash gravels that are sitting on fractured Mancos Shale. Spatial variation of the stratigraphy was determined by analyzing drillers' well logs, and from geophysical surveys. The extent of the contaminant plume has been determined by analysis of groundwater collected from monitoring wells and from electromagnetic (EM) surveys.


  1. Tsosie, Bernadette; Semken, Steven; Harrison, Bruce, 1997, The Shiprock uranium-mill tailings remedial action (UMTRA) site, New Mexico, in: Mesozoic geology and paleontology of the Four Corners Region, Anderson, Orin J.; Kues, Barry S.; Lucas, Spencer G., New Mexico Geological Society, Guidebook, 48th Field Conference, pp. 279-281.

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