Island Creek
Coal
Company
After assessing
a study of longwall mining adjacent to
Virginia Power and Electric Transmission Tower 300,
stating that subsidence was immenent should pillar
failure occur, Island Creek Coal Company retained Morgan
Mining and Environmental Consultants to develop plans and
specifications to stabilize the foundation of Tower 300.
On August 17, 1990 a contract was issued to The Judy
Company, Inc. to construct two low slump barriers and
backfill grout the mine cavity through drilled holes
penetrating the 300 feet of overburden.
SOLUTION
The project
began on August 27, 1990 and was
completed on September 28, 1990. The two low slump
barriers were built using 137 C.Y. of 1500 psi,
0-2.5" slump, type "A" grout with the
backfilling between the barriers using 3959 C.Y. of 600
psi, 8-12" slump, type "B" grout.
It can be estimated with the amount of grout, and the
achieved grout strength, (1000 psi in six months), the
four pillars under Tower 300 will not crush or be subject
to subsidence movement caused by pillar failure.
The successful and timely completion of this project
is another example of the capabilities of The Judy
Company.
Void Fill Grout Tremied Inside of
Barrier
On Site Grout Mixer
