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 into 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:
- 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;
- Remove the failed section of pipe from the flow path of the wastewater;
- Install bypass piping and pumping equipment and divert flow from the failed pipeline section;
- Install new segments of pipe to restore the pipeline to serviceable conditions;
- Restore bypass flow back to the interceptor and remove bypass pumps and piping; and
- 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:
- Inspection Supervisor – The owner representative that provides direction to the contractor and coordinates construction plans with in-house engineers;
- 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;
- 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 into service in less than 3 weeks. This was through communication, cooperation, and coordination from the contractor, engineers, and inspection staff. Additionally, the riverbank was stabilized and armored to prevent future erosion of the pipeline alignment.