Putting Resiliency to the Test—How the SAWS ASR Pipeline Has Stood the Test of Time

In the early 2000s, the San Antonio Water System (SAWS) developed the Aquifer Storage and Recovery (ASR) Project. This project was significant in the evolution of SAWS as it was the first potable water source outside of San Antonio, as the city had been supplied by the Edwards Aquifer below its surface since 1877. The capacity of the transmission system, comprising pump stations and a 27-mi (43.5-km) long, 60-in. (152.4-cm), and 42-in. (106.7-cm) diameter main, was designed to transfer 60 MGD (227,125 m3/d) in both directions (storage and recovery). SAWS had limited experience installing large-diameter pipelines prior to the ASR Program. Several factors went into choosing the pipeline material, joint type, and methods for protecting the pipe from pressure transients and corrosion. SAWS made several programmatic decisions to incorporate this critical attribute for the pipeline and pump stations. These decisions guided SAWS into implementing a modified C200 steel pipe within their distribution system, which was previously utilized by SAWS only within their pump stations. All these design decisions established at the beginning of the program resulted in a robust and resilient pipeline that has been operating flawlessly for over 20 years. ASCE MOP 151 Sustainability Design of Pipeline (2022) defines resiliency as "the ability of a system to withstand or rebound from a natural or man-made disruption and return to an acceptable level of functionality in a shorter time and at less additional cost than if it had not been considered in the planning and design of the system." This paper will review how decisions made by SAWS early in the planning stages of the project helped meet these objectives and how the system has continued to operate following several disruptive events.