Geologic and well-construction data for the H-9 borehole complex near the proposed Waste Isolation Pilot Plant site, southeastern New Mexico

Abstract

The H-9 complex, a group of three closely spaced boreholes is located 5.5 miles south of the proposed Waste Isolation Pilot Plant (WIPP) site in east-central Eddy County, New Mexico. The holes were drilled during July, August, and September 1979 to obtain geologic and hydrologic data to better define the regional ground-water-flow system. The geologic data presented in this report are part of a site-characterization study for the possible storage of defense-associated radioactive wastes within salt beds of the Salado Formation of Permian age. The geologic data include detailed descriptions of cores, cutting, and geophysical logs. Each borehole was designed to penetrate a distinct water-bearing zone: H-9a (total depth 559 feet) was completed just below the Magenta Dolomite Member of the Rustler Formation; H-9b (total depth 708 feet) was completed just below the Culebra Dolomite Member of the Rustler Formation; H-9c (total depth 816 feet) was completed below the Rustler Formation-Salado Formation contact. The geologic units penetrated in borehole H-9c are eolian sand of Holocene age (0 to 5 feet); the Gatuna Formation of Pleistocene age (5 to 25 feet); and the Dewey Lake Red Beds (25 to 455 feet), the Rustler Formation (455-791 feet), and part of the Saladomore » Formation (791 to 816 feet), all of Permian age. Three sections (484 to 501 feet, 615 to 625 feet, 692 to 712 feet) in the Rustler Formation penetrated by borehole H-9c are composed of remnant anhydrite (locally altered to gypsum) and clay and silt residue from the dissolution of much thicker seams of argillaceous and silty halite. This residue indicates that the eastward-moving dissolution within the Rustler Formation, found west of the WIPP site, is present at the H-9 site. 12 references, 2 figures, 7 tables.« less