Publications Details
Intergranular Fluid Compositions from the Waste Isolation Pilot Plant (WIPP), Southeastern New Mexico
The objective of this study was to perform a systematic sampling of the intergranular brines that slowly weep'' from four of the main stratigraphic units exposed in the WIPP. This information was added to the data base on brine compositions used in performance assessment and also employed in characterizing Salado Formation hydrology at the repository horizon. Concentrations of Na, K, Mg, Ca, Cl, SO4, and Br were all highly variable. It was also established that this variability reflects neither post-excavation evaporation nor imprecision in the analytical techniques. Compositional variability on the length scale of a few tens of centimeters is as large as that found over several hundreds of meters. Stratigraphy did not appear to exert any control over weep brine compositions. Programmatically relevant applications of these results are: (1) a valid performance assessment must consider the possibility of a wide range of brines, rather than carry out evaluations using a single best'' average brine, and (2) the Salado appears not to function as a continuous aquifer since brines originating millions of years ago have failed to homogenize though separated by only short distances.