5
The most commonly used RC drill bits are five to eight inches in diameter and have round metal
buttons that protrude from the bit. These buttons are required to drill through rock. RC rig setups
usually consist of a support vehicle, an auxiliary vehicle, as well as the rig itself. The support
vehicle, normally a truck, holds diesel and water tanks for resupplying the rig and also holds
other supplies needed for maintenance on the rig. The auxiliary is a vehicle carrying an auxiliary
engine and a booster engine. These engines are connected to the rig by high pressure air
hoses.
Diamond core drilling utilizes an annular diamond-impregnated drill bit attached to the end of
hollow drill rods to cut a cylindrical core of solid rock. The diamonds used are fine to microfine
industrial grade diamonds set within a matrix of varying hardness, from brass to high-grade
steel. Holes within the bit allow water to be delivered to the cutting face. This provides three
essential functions: lubrication, cooling, and removal of drill cuttings from the hole. The drill hole
is approximately 3.5 inches in diameter.
Diamond drilling is much slower than RC drilling due to the hardness of the ground being drilled.
Diamond rigs need to drill slowly to lengthen the life of drill bits and rods, which are very
expensive. Core samples are retrieved via the use of a lifter tube, a hollow tube lowered inside
the rod string by a winch cable until it stops inside the core barrel. As the core is drilled, the core
lifter slides over the core as it is cut. An overshot attached to the end of the winch cable is
lowered inside the rod string and locks on to the backend, located on the top end of the lifter
tube. The winch is retracted, pulling the lifter tube to the surface. The core does not drop out the
inside of the lifter tube when lifted because a "core lifter spring," located at the bottom of the
tube allows the core to move inside the tube but not fall out.
Once a rod is removed from the hole, the core sample is then removed from the rod and
cataloged. The driller's assistant screws the rod apart using tube clamps, then each part of the
rod is taken apart and the core is deposited out into core trays. The core is washed, measured
and broken into smaller pieces using a hammer to make it fit into the sample trays. Once
catalogued, the core trays are retrieved by geologists who then analyze the core and determine
if additional work needs to be conducted in the same area.
Drill holes can be vertical or angled. All drill holes would be surveyed and plugged as an
operational procedure immediately after completion of drilling. All drilling activities would be
conducted in accordance with Wyoming Water Quality Rules and Regulations (WWQRR),
Chapter 11, Part G, Section 70 for plugging and abandoning drill holes. These requirements
include filling and sealing part, or all of the drill hole with impervious material, marking the
location of the drill hole (considered a well under WWQRR regulations), and filing a plugging
and abandonment report.
1.3.4 Water Use
The primary source of water for drilling will come from either the production well in Section 16 or
from the City of Sundance Cole Well Field via pipeline. Other supplemental water sources could
be the City of Sundance Well No. 6 or water transported from Hulett, Wyoming as done in prior
years. It is estimated that 4,000 gallons would be required for a rotary hole and 100,000 gallons
would be required for a core hole. Total water requirements for exploration over the 40+ year
project life is estimated to be 104 million gallons.
