Supplement to the site observational work plan for the UMTRA project site at Ambrosia Lake, New Mexico

The purpose of this document is to provide additional and more detailed information to supplement review of the site observational work plan (SOWP) (DOE, 1995) for the Ambrosia Lake, New Mexico, Uranium Mill Tailings Remedial Action (UMTRA) Project site. This document includes a discussion of the average linear velocity of the ground water in the alluvium and a discussion of the ground water quality of the alluvium, weathered Mancos Shale, and the Tres Hermanos-C Member of the Mancos Shale. The data from a 1989 aquifer test were analyzed using the curve-matching software AQTESOLV and then compared with the original results. A hydrograph of the ground water elevations in monitoring wells screened in the alluvium is presented to show how the ground water elevations change with time. Stiff and Piper diagrams were created to describe the changes in ground water geochemistry in the alluvium/weathered Mancos Sahel unit, the Tres Hermanos-C Sandstone unit, the Tres Hermanos-B Sandstone unit, and the Dakota Sandstone. Background information on other related topics such as site history, cell construction, soil characteristics, and well construction are presented in the SOWP. A geologic cross section depicts the conceptual model of the hydrostratigraphy and ground water chemistry of the Ambrosia Lake site. Hydrogeologic information of each hydrostratigraphic unit is presented