New Braunfels Utilities (NBU; New Braunfels, Texas, U.S.) recently took delivery of the first of two Easi-Set precast concrete buildings purchased from Lonestar Prestress Mfg. Inc. (LPMI; Houston, Texas). Both buildings, which are engineered to withstand 140-mph (225-kmp) winds, will house relay and control panels, standby batteries, and supervisory control and data acquisition (SCADA) equipment. The integrity of the Easi-Set buildings is expected to provide enhanced stability for the substation controls, while giving NBU additional 138-kV exits.

NBU was first introduced to Easi-Set buildings in 2003 when it was evaluating possible replacement structures for an existing metal substation building. The deteriorating structure was in need of replacement, according to Jim Williams, NBU substation supervisor.

After extensive study, NBU selected a 24- by 40- by 12-ft (7- by 12- by 4-m)Easi-Set precast concrete building for that initial project. The buildings are constructed from 6000-psi steel-reinforced concrete and provide customers with a maintenance-free, water-tight enclosure. They have an expected life span of more than 50 years and can be erected in less than a week, not to mention the fact that they are UL level-four bullet tested. “We were attracted to the fact that the buildings are maintenance free, provide a fortified setting for our vital infrastructure and are affordable,” Williams said.

NBU chose Lonestar buildings again in 2008 as part of the renovations of two separate substations. The first building, measuring 24 ft by 40 ft by 10 ft (7 m by 10 m by 3 m), was delivered in March to a substation located near Wald Road in New Braunfels. The second building, measuring 24 ft by 20 ft by 10 ft (7 m by 6 m by 3 m), is scheduled for delivery in June to a location on the outskirts of town.

Both buildings will rest upon precast floor slabs, which are laid flat on an engineered gravel bed and post-tensioned together, thus providing a monolithic foundation for the walls and roof panels. LPMI erected and completed the first building in about five days, which was critical to the timing of the project due to the scheduled power shutdown.

“When we go off-line with a 138-kV transmission line, we can't afford any delays on equipment, materials or contractors,” Williams explained. “We have a set construction window that has to be met.”