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.