management team quickly decided against
the ice TES system, citing that it would
require a change in the existing refrigeration system to produce the ice, either
through a chiller replacement or addition.
The team also preferred the simplicity
of a stratified chilled-water system’s
operation, which would require very little
maintenance. While ice storage systems
need less space than chilled-water storage
systems, both would raise concerns about
tank location; however, since USC was
not limited by space – given that the
tank would be buried – priority was
placed on ease of operation.
In November 2002, Retrofit Originality
Incorporated (ROI) and RBF Consulting
were named the project mechanical
engineer and project civil engineer,
respectively. Design began in December
2002. With a chilled-water district energy
system, no changes were necessary to
the existing system to make it compatible
with a TES tank. Simply speaking, the
tank stores chilled water generated by
the existing chillers at night, and then
uses the existing chilled-water loop to
distribute this chilled water during the
day. ROI’s Scot Duncan analyzed the
existing system for sizing purposes only
briefly, as optimizations were not necessary
to make the existing system mesh with
the new tank.
Another primary concern during the
project planning phase was tank location.
Given the university’s urban setting, there
was little available above-grade space, and
none allocated for a TES system. However,
Welsh offered a creative solution that
allowed the facilities management team
to greatly expand their siting options:
place the tank completely below grade.
Several sites had been analyzed
during the predesign process. These were
narrowed down to the Cromwell Field
track facility and the Brian Kennedy and
Howard Jones Fields football practice
facility – the only available sites located
near a cooling plant. Being near a cooling
plant reduced the amount of piping to
the tank and provided a location for the
additional pumps and valves necessary
for TES tank operation. In the end, after
much debate, the Cromwell Field track
facility was selected because it was the
closest to the chiller plant. Given the
anticipated fall and winter construction
window, construction there would also
have less of an impact on the track team
than it would on the football team, minimizing the need to relocate practices
and competitions for USC’s sports teams.
Throughout project design and construction, the facilities management team
kept all project stakeholders well-informed
about its progress, which eased any potential challenges to approval and construction.
During construction, facilities management
also directly addressed the needs of the
track team, which stood to benefit from
the project by receiving new field turf.
A 30,000-ton-hr TES tank was
selected based on campus cooling capacity
and the amount of space available within
the track facility. The 3 million-gal tank
was the largest one that could be constructed within the selected site and could
be recharged nightly with the existing
chiller system. An AWWA D110 Type I
prestressed concrete tank was chosen
because it provided a maintenance-free,
watertight tank. This cast-in-place concrete
tank has performed well in seismic events,
a key concern in the Los Angeles region.
The tank was designed with a 123-ft
Courtesy DYK Incorporated. Photo Warren Aerial Photography.
In May 2004, construction began on the University of Southern California’s 30,000-ton-hr TES tank
(above). On completion of the project, the tank, buried beneath the Cromwell Field track facility, was no
longer visible (below).
Courtesy D YK Incorporated. Photo Warren Aerial Photography.