Can Transmission Pipelines and Interstate Highways Coexist? Formulating the Flagstaff Red Gap Pipeline Route within the I-40 Corridor

The City of Flagstaff began a process in 2008 to develop a pipeline route from a new water source (Red Gap Ranch) to its city limits. The route is approximately 40 miles in length with 2000 feet of elevation gain. This paper explains the alignment issues considered, including environmental factors, property owners, capital cost drivers, and public input. The analysis model includes weighting and sliding scales for each factor considered. After unexpected property issues occurred with newly designated Native American Tribal lands, 20 miles of the alignment necessitated utilization of the I-40 highway right of way, requiring extensive coordination with Arizona DOT officials. Technical issues include pipeline rupture risks, potential impacts to highway facilities, and mitigations; legal issues include historical public right of way and use of the property. The paper concludes with the recommendation of a final alignment for technical evaluation and cost estimation, providing a basis for project funding. The project proved that solutions are possible, although significant technical and legal issues needed to be resolved, which required several years to accomplish and involved an intergovernmental agreement between city and state.