PDC worked with Allegheny Power
Service to design, prepare specifications and assist construction
inspection on a 138kV cable circuit for a small commercial airport in
Claridge, Pennsylvania. The cable project, "Harrison City
Substation 138kV Loop", was under construction in July 1999 and will
be commissioned later this summer.
The figure at left shows the
cable trench after one of the phases has been installed. The soil
and trench conditions were such that shoring was not required for this
particular section. The entire section was open trenched prior to
A loop of spare cable was
placed at the base of the riser structure to allow for a repair if a
termination needs to be reconstructed. An advantage to this approach
is faster restoration times because a spare cable section does not have to
be located and spliced between the underground section and riser.
Fluidized Thermal Backfill
was placed around the cable to reduce the effective soil thermal
resistivity and optimize the circuit's rating. The photo to the left
shows the trench shortly after the FTB was poured. This material
provides optimal compaction around the cables. Geotherm, Inc. developed
the FTB "recipe" for the project.
If you would like to know more, please contact
John Cooper at PDC.