Channel Segment C Sanitary Sewer Relocations

Fort Worth, Texas, sits where the Clear Fork Trinity River, the West Fork Trinity River, and several streams meet, making it prone to flash flooding, especially during heavy spring and fall rainfalls. Since the levee system was put in place in the 1960s, the city’s population has tripled from 350,000 to over 920,000 residents. This considerable population growth, coupled with extensive construction of water impervious, runoff-generating developments, created significant drainage problems, further contributing to flood risk.

In the early 2000s, The United States Army Corps of Engineers estimated that 86% of Fort Worth’s levees could no longer adequately protect against expected events. The aging infrastructure left over 2,400 acres of neighborhoods vulnerable to flooding.

The Central City Flood Project is a bypass flood protection initiative created to help reduce flood risk. It is a partnership between several federal, state, and local entities, including the Tarrant Regional Water District, City of Fort Worth, Tarrant County, Texas Department of Transportation, U.S. Army Corps of Engineers, and Streams & Valleys. Once completed, the project will also create 200 acres suitable for development and assist in meeting the city’s goals for sustainable expansion.

Before these initiatives could begin, existing infrastructure had to be moved to make way for the proposed bypass channel near downtown Fort Worth. This included relocating sanitary sewer lines to prevent them from interfering with the new construction.

One of the critical steps in this process was the construction of watertight access shafts. This site development and ground improvement project would prepare for the extensive tunneling operations required to relocate the sewer lines beneath both railroad tracks and the West Fork Trinity River. The watertight nature of these shafts ensured that tunneling could proceed without the risk of water ingress, which could compromise the integrity of the tunnels and the safety of the workers.

The City of Fort Worth prequalified our team to install watertight access shafts essential for relocating sanitary sewer lines beneath the West Fork Trinity River. Our scope of work on this project included geotechnical construction, site development, and specialty civil construction of four watertight drop shafts consisting of secant pile walls that would act as a retainer for equipment and facilitate tunnel construction.

Using a cased continuous flight auger (CFA) technique, we installed 750 mm unreinforced piles in a circular arrangement, forming a compression ring at each of the 4 locations. The access shafts, measuring 30 to 40 ft in diameter and 55 to 60 ft in depth, allowed tunneling operations to cross beneath railroad tracks and the West Fork Trinity River, facilitating the relocation of potable water transmission lines.

With the secant pile access shafts completed, the existing sanitary sewer lines were abandoned-in-place and relocated to North Henderson Street. Our team’s successful completion of this preparatory project laid the groundwork for subsequent phases of the bypass channel construction, ultimately contributing to the city’s enhanced flood management and infrastructure resilience.

Upon completion, this channel will play a vital role in flood management, redirecting floodwaters and enabling water from both the West and Clear Forks of the Trinity River to flow through the current levee system at a faster rate and lower volume. This improved flow will provide enhanced flood protection to at-risk neighborhoods during heavy rainfall events.

Additionally, the channel will help maintain the functionality and integrity of the existing levee system, preventing potential overflows and breaches. By efficiently managing water flow, the bypass channel will contribute to the overall resilience and sustainability of the city’s flood control infrastructure.