15 Apr 2019/in Latest News and Information, Power Generation and Transmission, Uncategorized /by Jeanne Sapon
In August, 2018, the Phoenix area experienced some of the
State’s worst monsoon winds in recorded history. Many locations within the metropolitan area
experienced serious damage caused by high winds and lightning strikes. One such location, in the west valley near
Tonopah, Salt River Project’s (SRP) 500 kV lattice power transmission poles (Hassayampa-Jojoba
Line section) were twisted at their concrete foundations and bent over. This created a situation where many local
businesses and residents lost power.
Once the emergency response was executed and temporary power
was restored, SRP could get on with the business of repairing the foundations
and replacing the towers.
In February, 2019, DBA was contracted by SRP to construct
the ultimate replacement of the foundations so that SRP personnel could replace
the 500 kV towers “walking giants”. This
included very precise templates for drilling core holes in the newly poured
foundations that would fit-up with SRP’s anchor bolt assemblies.
Project management staff, structural superintendents and DBA
mechanics reviewed the damage, drove to the site and took photos of the
existing conditions and met with the SRP Principal Engineer, Jim Adams. SRP’s original plans included a template for
the fit-up that did not take into consideration the added grout to the core
drill holes and rebar that would need to be in place as part of the
remediation. DBA developed a unique
template that took all of the new conditions into consideration and created a
mock-up in the DBA maintenance yard to demonstrate its use to SRP engineering
management.
Once the solution was approved, the remediation project was
able to proceed. DBA’s scope of work
included: removal of the existing
concrete foundations (8 each) down to 1’ below grade (removals varied from
1’-9” to 3’-0” depending on location); holes were drilled in each foundation to
accommodate rebar dowels and the forming of a rebar cage to pour new concrete
atop the existing foundation for structural strength. Once the concrete was set, DBA subcontractors
cored holes in the new foundation (using the new template layout). DBA placed the anchor bolts (3.5” diameter 3
per foundation placed 15’-3” deep) into the holes and grouted around them,
lining up precisely with SRP’s anchor bolt assemblies and preparing the new
foundations for the steel towers.
DBA crews had to coordinate our construction work with the
SRP crews who were bringing in the new steel towers for fit-up in the field.
The project was a great success and DBA was praised for our
innovative approach to the challenge.
“Everyone is very
pleased with the work you guys did for us.
Grout is good, tower legs fit-up nicely, and finished ahead of
schedule. As always, very innovative on
your part to a non-standard project.”
Jim Adams, Principal Engineer, Salt River Project
