UniSource recently completed a relatively rare and complex effort to increase the operating pressure of one of its natural gas distribution systems to better serve the Town of Chino Valley.
The work, known as “uprating,” was completed in October in preparation for a new Justice Center that will open this year. The expansion also will help support residential growth in the area while maintaining safe and reliable service to existing customers, particularly during times of high demand.
The project, which increased the maximum allowable operating pressure from 100 pounds per square inch (psi) to 175 psi over about 18,800 feet of main line, demands a methodical, measured effort to comply with federal guidelines, safety standards and company procedures. “This project was months in the planning,” said District Manager Teresa Inman. “It may sound simple but increasing pressure is actually very involved.”
Long before the extensive field work took place, a written procedure was prepared to document compliance with our own plans and federal code.
Workers then had to identify the locations of all system components, from underground mainlines to service lines, regulator stations, meters and valves. Valves were examined to verify pressure capacity. Some gas meter components had to be changed to absorb the increased pressure.
Planners, leak surveyors, service and measurement technicians and construction crews were on hand as the pressure was slowly increased in multiple increments. After each pressure increase, leak surveyors and construction crews performed a survey of the entire system to ensure there were no leaks in the system. Personnel staged at each regulator station monitored and adjusted set points to accommodate each increase. Once the higher pressure was established, the meters on the system needed to be inspected.
Inman said the project was completed on deadline and without any issues, thanks to skilled and effective teamwork across the departments.
“I think it really illustrates our collaboration with our customers,” Inman said. “Our customers took proactive steps to let us know about their needs so we could be prepared. On our side, we worked hard to meet their operational timelines,” she said. “I am really proud of how smoothly everyone worked together to ensure that the system has the capacity it needs to grow.”