Hydraulic testing techniques of deep drill holes at Pahute Mesa, Nevada test site

This report describes the testing techniques used by the U. S. Geological Survey to obtain hydrologic data in deep holes drilled in volcanic rocks at Pahute Mesa, Nevada Test Site. The testing program in each hole includes geophysical logging, pumping, and injecting and swabbing between straddle packers.

Rock lithologies and qualitative data on hydrologic conditions in the borehole are obtained from electric, caliper, temperature, and fluid resistivity logs. Quantitative data on major water-yielding intervals in the borehole are obtained from radioactive tracer and spinner surveys.

Pumping tests are made to measure the combined yield of the various aquifers. Injection and swabbing tests are made by adding known volumes of water to, or withdrawing known volumes of water from, straddle-packed intervals and observing the rate of decline or rise in water level resulting from this injection or withdrawal of water. The yield of tested intervals is stated as relative specific capacity, in units of gallons per minute per foot of drawdown.