Emergency Replacement of the Brennan WTP Discharge Header

Like many utilities in the U.S., the City of Daytona Beach supplies water to their approximately 70,000 residents through a single regional water treatment facility, the Brennan Water Treatment Plant (WTP). Constructed in 1972, this facility discharges water through one 36-inch pipe, which manifolds seven high-service pumps (HSPs) that deliver all finished water to customers. Despite serving as the critical link between the City and its only source of water, this 45-year-old header pipe’s condition was rapidly deteriorating, posing the serious risk of a single point of failure.

To bolster the reliability of the discharge header pipe and the Brennan WTP’s supply delivery, the City contracted Carollo to investigate the integrity of this ductile iron pipe (DIP) and to design all necessary improvements on a highly accelerated schedule that reflected the criticality of keeping the City’s the high-service pump station (HSPS) and its pipe in uninterrupted service.

Though the City had initially only planned for rehabilitation activities such as blasting and recoating, Carollo quickly determined that the existing pipe rested in a tunnel whose design acted as a humidity trap that created an exceedingly “sweaty” and corrosive environment. As a result, the pipe’s exterior, flange bolts, line taps, and other components were all highly corroded, raising considerable safety concerns and high risks of failure, especially during the rehabilitation effort.

To secure a long-term solution that holistically lowers risk and enhances safety, the City decided to replace the 36-inch pipe with a new discharge header pipe that rests “overhead” of the HPSs and the existing pipe. By locating the new pipe outside and over the humid tunnel, the project team could isolate its construction and sequence its tie-ins to the old pipe, all while maintaining the City’s water supply. Along with this major improvement, Carollo prepared the deigns of all structural, mechanical/piping, electrical, and civil modifications required to protect the old pipe and prepare the site for new construction.

Carollo designed the new replacement header in two months, simultaneously preparing a detailed construction approach to maintain continual operation of the HSPS. To support the aggressive emergency schedule, Carollo investigated lead times for the project’s main components and guided the City to directly pre-purchase the longest-lead equipment, which reduced the overall construction duration. Carollo also worked closely with the City to develop a best-value procurement process for selecting a contractor according to their qualifications, ability to meet the expedited schedule, and price.

In approximately eight months, construction at the Brennan WTP’s HSPS was completed in five phases:

• Phase 1: Prepare for the new header pipe by filling the existing tunnel with lightweight concrete and safely encasing the old pipe.
• Phase 2: Receive equipment deliveries and, using special rigging equipment, fabricate and install new piping overhead of the HSPs, which were in active operation.
• Phase 3: Install a line stop in the old discharge header pipe outside of the building, connect the new header pipe to the west discharge main, and transition the pumps, all while keeping both header pipes in service.
• Phase 4: Connect the new header pipe to the east discharge main.
• Phase 5: Complete the restoration including painting, paving, and safety features.

The project achieved substantial completion in February 2020 during Phase 4 and final completion in March 2020, just one year after the design phase kicked off. Today, the City is served by new assets that are installed in a safe, less corrosive, and more maintenance-friendly environment and ensure the reliable delivery of water to communities that depend on them.