Crossing the Fourth Largest City in the U.S. with a 96-Inch/84-Inch Pipeline: A Case Study

This paper will focus on the challenges, best practices, and lessons learned from the design of a segment of a major water supply project crossing the 4th largest city in the country. This project includes more than 9 mi of 84-in. steel pipeline as well as some parallel distribution lines ranging in diameter from 36- to 84-in. The first half of the paper will discuss the challenges and approaches to challenges in preliminary design. These challenges and the approach to address them will cover routing of large pipelines in narrow corridors, pipe material selection for several pipe diameters, embedment material selection, preliminary utility coordination, and other stakeholder outreach. The second part of the paper will focus on the critical final design considerations that were evaluated; such as isolation valve placement, transient analysis, testing/disinfection planning, final utility coordination, tunnel design, and agency coordination. This case study will give other engineers and owners a roadmap for accomplishing the design of a project of this size successfully and minimizing the impact to the community without increasing costs to the Owner.