Drilling and Coring - Idaho National Laboratory
Science Center Objects
We drill and maintain wells around the INL to monitor and sample groundwater, obtain basalt and sediment cores for study and analysis, and study the physical properties of the subsurface (geophysical logging).
This information helps us to improve the scientific understanding of the eastern Snake River Plain and its aquifer. In particular, we are examining the subsidence of the plain and the movement of groundwater and contaminants within the aquifer.
RESEARCH DRILLING AND CORING
The USGS INL Project Office has its own drillers and drill rigs to drill and core new monitoring and research wells. We drill and core an average of two new wells every year; the INL contractor also drills and cores wells for research purposes. Our scientists and drillers have developed techniques to obtain the best core possible in basalt, consolidated, and unconsolidated sediment. The core drilled from these new wells is archived at the Core Storage Library on the INL site, where it is stored and made available for scientists to study.
In 2010, we obtained two Geoprobe units to collect shallow cores (up to 100 ft deep) from surficial sediment deposits. In addition to other uses around the state, the Geoprobes are being used at the INL to collect samples that will help us determine the hydrologic and geologic properties of subsurface sediment near the proposed location for the Remote Handled-Low-level Waste Disposal Facility. Understanding the hydrogeology of the subsurface will improve the ability to track waste movement in the unsaturated zone at the facility.
Description of the Eastern Snake River Plain
The eastern Snake River Plain is a northeast-trending structural basin, 200 miles long and 50 to 70 miles wide, that occupies much of eastern Idaho. Currently accepted theories for the dramatic subsidence of the eastern Snake River Plain postulate that the plain has been subsiding in the wake of the Yellowstone hot spot caldera eruptions. The eastern Snake River Plain aquifer resides in the thick underground package of rocks and sediment that fills the upper part of this structural downwarp. The part of the basin occupied by the aquifer consists of basalt lava flows and sediment from nearby mountains and rivers. Rhyolitic ash flows and lava flows from the ancient calderas of the Yellowstone volcanic province are found below the base of the aquifer. Total depth of the eastern Snake River Plain structural depression is probably more than 16,000 feet.
The Snake River Plain aquifer is hosted in complex layers of rock and sediment. Most of the rock is basalt erupted from shield volcanoes like those now found on the surface of the present-day eastern Snake River Plain. Basalt is a dark gray or black igneous rock erupted as lava and cooled on the surface of the earth. The eastern Snake River Plain aquifer occupies the upper part of these rocks; alteration almost completely seals off pore space in rocks at depth. The base of the eastern Snake River Plain aquifer is from 1,000 to 4,000 feet below land surface depending on the area.
On the surface and in the subsurface of the eastern Snake River Plain, basalt and sediment layers vary in thickness from less than a foot to tens of feet. Basalt layers vary from solid rock or rubble; most sediment layers are unconsolidated. Basalt and sediment present unique challenges in drilling and core recovery.
For more information about eastern Snake River Plain geohydrology review our Fact Sheet (Bartholomay, 2017) or Professional Paper (Whitehead, 1992). Or visit the following sites for information designed for the general public: