The River and The Highway: How an Interceptor Failure Produced Solutions

The objective of emergency repairs for TRA is to put critical infrastructure that has failed back in to service immediately to prevent or reduce environmental impacts and to restore wastewater collection and transmission service for our customers. After significant rainfall event in March 2020, the Collection Systems Group for the Trinity River Authority of Texas inspected the external conditions of all of the major interceptor lines in the Central Regional Wastewater System for possible line breaks. On March 26, CSG staff identified a major pipeline failure on the 102-inch pipeline for the West Fork interceptor. The pipeline failed in a section immediately adjacent to the West Fork of the Trinity River while the river was in flood stage from the latest significant rain event. The interceptor was passing over 150 MGD of wastewater meant for the CRWS treatment facility, but a portion of the wastewater flow was escaping from the collapsed pipeline in to the river. Once CSG notified the Construction Services group, of the on-call construction contractor, Flow Line Construction, was contacted and immediately mobilized to stop wastewater leakage and to begin pipeline repairs on the collapsed portion of the pipeline. The solution for the emergency repair was multi-faceted: 1)Construction a massive sandbag wall between the failed pipe and the Trinity River to stop wastewater leaking in to the river and to keep the river from washing out the pipeline work are;2) Build a working surface for excavators to access the pipeline site and to setup of bypass pumps;3) Remove the failed section of pipe from the flow path of the wastewater;4) Install bypass piping and pumping equipment and divert flow from the failed pipeline section;5) Install new segments of pipe to restore the pipeline to serviceable conditions;6) Restore bypass flow back to the interceptor and remove bypass pumps and piping;and 7) Perform all of the work listed above while adhering to rapidly changing conditions due to COVID-19 pandemic without having losing one member of the work force to COVID-19. The Roles and Responsibilities of the project team were: 1) Inspection Supervisor – The owner representative that provides direction to the contractor and coordinates construction plans with in-house engineers;2) Engineer – Provided flow ranges for bypass pumping design, collaborated with the contractor to size and layout the bypass pumps, and oversaw the re-installation of the collapsed pipeline;3) Contractor – The contractor staff includes a professional engineer who collaborated with TRA staff to rapidly develop and implement a plan for demolition and reconstruction. In conclusion, while the work took place in a difficult to access area during a period of greater than normal rain and a pandemic, the pipeline was put back in to service in less than 3 weeks. This was through communication, cooperation, and coordination from the contractor, engineers, and inspection staff. Additionally, the river bank was stabilized and armored to prevent future erosion of the pipeline alignment. Copyright © 2021 Water Environment Federation

Keeping Construction Going during the COVID-19 Pandemic

The Trinity River Authority (TRA) Construction Services group oversees $550 million in active construction projects. These projects are needed for a variety of critical reasons that include increase treatment capacity, improve energy efficiency, replace aging infrastructure, and increase pipeline capacity. None of these projects can be delayed by any significant length of time, as they are all needed to be in service to prevent future failures and minimize down time to TRA customers. Failure of service is not an option, 100% service and 100% of the time is essential. TRA, like the rest of the world, had to learn of the threats that the COVID-19 pandemic presented to TRA staff and the potential impacts the threats posed to completing construction projects. TRA had to react to the threats based on information that was available early on in March 2020 and prepare plans for staff and construction contractors based on the best available information. Plans are only as good as the people who execute them, and fortunately TRA staff along with the support of the engineering consulting and construction contractor communities worked together to adhere to the plans that TRA developed for our projects. The response plans were put in place early in the pandemic and updated frequently as more information was made available. Key takeaways from this experience are TRA continued to move forward with all construction projects using a modified routine for additional safety requirements;communicate frequently, with everyone on the project team both internal to the organization and with external contractors and consultants;be prepared to evolve work plans with changing national and local guidelines;and above all, do not panic, do not shutdown, do not hide in the office or at home;instead, get out in front of the unknowns and create a safe environment with a clear set of guidelines for staff to follow. Getting through a major event whether it is extreme flooding or a global pandemic requires leading from the front and relying on input from the team. Dealing with adversity is in every way possible, a team effort, and it takes constant feedback from the team in the field as well independent research of the latest recommendations for safety for the leader to make the best decision in the moment. © 2021 ASCE.

Essential Infrastructure Emergency Repair of the West Fork Interceptor

After significant rainfall and subsequent surcharge event of March 15-19, 2020, the Collection Systems Group (CSG) for the Trinity River Authority of Texas inspected the external conditions of all of the major interceptor lines in the Central Regional Wastewater System for possible catastrophic line failures. On March 26, CSG staff identified a major pipeline failure on the 104-in. (2,650 mm) diameter pipeline for the West Fork interceptor. The pipeline failed in a section immediately adjacent to and between Interstate Highway 30 (IH-30) and the West Fork of the Trinity River, while the river was in flood stage from the latest significant rain event. The interceptor was conveying over 150 MGD (570,000 cubic meters per second) of wastewater meant for the Central Regional Wastewater System (CRWS) treatment facility, but a portion of the wastewater flow was escaping from the collapsed pipeline in to the river. Once CSG notified the Planning, Design, and Construction Administration (PDCA) team, our on-call emergency construction contractor was contacted and immediately mobilized to begin the process of stopping wastewater leakage and to begin pipeline repairs on the collapsed portion of the pipeline. The solution for the emergency repair was multifaceted beginning with the contractor constructing a massive sandbag wall between the failed pipe and the Trinity River at flood stage to stop wastewater leaking into the river and to keep the river from washing out the pipeline work area. Next, the contractor built a dry, elevated, working surface for excavators to access the pipeline site and to setup of bypass pumps. This work area was cut into the constructed slope of the Texas Department of Transportation (TXDOT) Right-of-Way (ROW). Several attempts were made to quickly repair the pipeline using oversized pipe (110in.) to replace the collapsed and broken pieces of existing pipe. With the still high flows from the recent rain event, this was not possible and that effort was abandoned. It was now obvious that we had to take the next step in elevating the effort, bypass pumping. Immediately bypass pumping operations were initiated. After 20 days of setup and stringing 20-in. HDPE bypass pipe along the Access Road for IH-30, we began pumping. The work concluded with the conclusion of bypass pumping, restoration of normal pipe flow, and streambank restoration along the river. All of the emergency work was performed while adhering to rapidly evolving conditions due to the pandemic without losing one member of the work-force to COVID-19. While the work took place in a difficult to access area during a period of greater than normal rain and a pandemic, the pipeline was put back in to service in less than 3 weeks. This was through communication, cooperation, and coordination from the contractor, engineers, and inspection staff. © 2021 ASCE.