Basic data report for drillhole WIPP 15 (Waste Isolation Pilot Plant-WIPP)

WIPP 15 is a borehole drilled in Marformation.h, 1978, in section 18, T.23S., R. 35E. of south-central Lea County. The purpose of WIPP 15 was to examine fill in San Simon Sink in order to extract climatic information and to attempt to date the collapse of the sink. The borehole was cored to total depth (810.5 feet) and encountered, from top to bottom, Quaternary calcareous clay, marl and sand, the claystones and siltstones of the Triassic Santa Rosa Formation. Neutron and gamma ray geophysical logs were run to measure density and radioactivity. The sink was about 547 feet of Quaternary fill indicating subsidence and deposition. Diatomaceous beds exposed on the sink margin yielded samples dated by 14C at 20,570 +- 540 years BP and greater than 32,000 years BP; these beds are believed stratigraphically equivalent to ditomaceous beds at 153 to 266 feet depth in the core. Aquatic fauna and flora from the upper 98 feet of core indicate a pluvial period (probably Tohokan) followed by an arid or very arid time before the present climate was established. Aquifer pump tests performed in the Quaternary sands and clays show transmissivities to be as high as 600 feet squared per day. As the water quality was good, the borehole was released to the lessee as a potential water well