Distribution Pipeline Design Project

GTS has engineered and designed several distribution pipeline replacement projects in Arizona to replace degrading plastic and steel pipe. The pipe replacements were primarily driven by potential integrity threats, including degrading PVC and Drisco M8000 plastic pipe, and CP issues on vintage steel pipe. Many of the pipe replacement projects were designed and constructed in a “grid” replacement format, requiring that pipeline main and services serving a large distribution system or community is replaced at one time.

For one such project, GTS provided engineering design for a main replacement in Phoenix, Arizona, to remove and replace approximately 6.5 miles of 2” PVC main installed in 1973. The operator identified the known location and general vicinity of the PVC pipe but turned to GTS to refine the project scope. Through extensive records research and coordination with operator technicians, GTS identified all piping, main, and services within the area that was PVC, or other problematic plastic pipe in need of replacement.

The original 2” main, serving a subdivision community of more than 800 customers, was installed within public utility easements in back alleyways and between residential property lines resulting in overbuild conflicts and access issues. The new 2” PE main was designed to be installed within the public right-of-way to reduce third-party conflicts and decrease the customer impact of routine survey assessments/maintenance. Because the new main needed to be relocated, approximately 700 customer service lines also needed to be replaced to tie to the newly installed main. Engineering design included careful review and assessment of existing utilities and landscape to effectively place the new distribution main, strategically route the main to more efficiently serve the distribution system, and route service lines and meters to reduce customer impact.

The design included selection of new pipe and fitting materials, selection of appropriately sized excess flow valves, and tie-in fittings to existing main. GTS completed a full project cost estimate including permitting needs and associated costs, all construction activities and associated costs, and material costs. This project was successfully constructed in the spring of 2018 and cost approximately $4.3 million.

Project Highlights: