Photo:Lanman Aerial

When Topaz commissioned Zachry, the general contractor, to re-power these plants on brownfield sites, Zachry faced challenges ranging from aged existing infrastructure, and the need for demolition, to nearby waterlines and a lack of laydown space.

Nueces Bay held five existing gas-fired plants built in the 1940s. The plants were on reclaimed dirt from the bay in the 1920s. The site is located adjacent to the ship canal and required massive structure modifications. Reclaimed earth typically causes geo-technical challenges, and the soil was unsuitable for building Three of the five units had to be completely demolished. A tight schedule required the completion of demolition and the start of construction at the same time.

Zachry mitigated the challenges with tight planning. By using a subcontractor for demolition, Zachry was able to focus its efforts on the repowering project and navigate through the difficulties in the existing infrastructure. When two units remained, including unit 6 (left intact) and unit 7 (re-powered), Unit 7 used the latest in steam turbine technology, replacing a 1960s turbine and decreasing emissions by 80%.

The site was quite small at only 4.5 acres. A typical project of such size and scope would require at least 20 acres for laydown space, equipment maneuvering and similar construction efforts. Zachry had to coordinate with the Port of Corpus Christi to allow for laydown space for large supplies such as the steam turbines. The massive pieces of equipment were then transported to the site via heavy-haul vehicles. Timing was coordinated precisely, based on the previously arranged schedule. The size of the site was further restricted because the existing infrastructure was bound on three sides by water. Due to tight management, Zachry was able to complete the project with zero cost change orders.

Nueces Bay was completed 26 days ahead of schedule.

Key Players

Submitted by: Zachry
Developer/owner: Topaz Power Group LLC, Austin, Texas
General contractor: Zachry, San Antonio, Texas
Architect: Skidmore, Owings & Merrill, San Francisco, Calif.
Civil, structural and MEP engineer: Zachry Engineering Corp., Amarillo, Texas