AWARD OF EXCELLENCE: Water Structures Category

RESTORATION OF LARGE DIAMETER PRESTRESSED CONCRETE PIPELINES

Water Flow, New Mexico

Submitted by QuakeWrap, Inc.

The San Juan Generating Station, located near Farmington, NM, went on line in 1973. It consists of 4 coal-fired units that generate about 1800 megawatts and provides electricity to most of New Mexico and parts of Utah, Arizona, and California. It is the seventh largest coal-fired power station in the West and therefore, an essential part of the electrical grid that services one of the fastest growing regions of the U.S.

Thousands of feet of underground 10 ft (3 m) diameter PCCP are used to transport hot water from the units to cooling towers. These 35-year old pipelines have already shown signs of significant corrosion damage to the steel reinforcement, compromising their structural integrity.

Recently, 840 ft (256 m) of PCCP segments were targeted for urgent corrosion repair. As a result, 30,000 ft2 (2787 m2) of CFRP structural liner was installed to replace the corroded steel and reestablish the design internal pressure capacity of the PCCP. A specially-designed carbon fabric was manufactured for this project to avoid multiple layer arrangements (minimizing installation time). Also, a moving scaffolding system was designed to allow single 50 in. (127 cm) wide strip installation, spanning the circumference of the pipe with a single overlap at the bottom (maximizing water tightness). The liner received a final layer of epoxy paint to improve abrasion resistance and minimize friction losses.

This project showcases the versatility of CFRP use in PCCP pipeline retrofit, allowing for the repair of long pipeline segments in the time allocated for maintenance shutdowns, with minimum loss of flow capacity.

Owner
Power Services of New Mexico
Water Flow, New Mexico

Project Engineer/
Designer
Quakewrap, Inc.
Tucson, Arizona

Repair Contractor
FRP Construction, LLC
Tucson, Arizona

Material Suppliers/
Manufacturers
QuakeWrap, Inc.
Tucson, Arizona