Utilities across the U.S. are rolling out large-scale investment programs to address aging distribution pipeline infrastructure. For nearly a decade, utilities have been working in response to a call to action from the Pipeline and Hazardous Materials Safety Administration to accelerate the repair, rehabilitation and replacement of high-risk pipeline infrastructure — often distribution pipelines made of bare steel and iron that are reaching the ends of their useful lives. With the right project planning, these system upgrades can increase reliability, improve safety and meet resiliency requirements.
Distribution pipelines often travel through dense urban areas and suburban neighborhoods to deliver natural gas to individual homes and businesses. That forces the construction of these pipeline mains and services lines to often disrupt the community, from its streets and sidewalks to residences and businesses. Poor design and project planning can lead to unsafe conditions for construction crews and residents. Project teams that design natural gas distribution pipelines without construction in mind risk messy construction sites, potential schedule delays, increased project cost and unhappy stakeholders.
To avoid these shortcomings and challenges, design teams must carefully consider the various aspects of distribution pipeline projects — each stage of work is linked to the next, from design to construction. A distribution pipeline design that accounts for the back-end construction work will set a project up for smooth execution.
The pipeline design should start with a site visit, so that the team is informed by the needs of the community. The design should consider how to avoid construction on sidewalks that might impact heavy pedestrian traffic or block an entrance to a business or home. The design should also seek to avoid impacting streets to minimize traffic delays and mitigate any safety challenges that could arise when traffic control reroutes people to detours.
With a few methods of installation available, design teams should strategically select a method that will be conducive to distribution pipeline construction. Horizontal directional drilling (HDD) often results in minimal impact to the project site. It utilizes a boring machine to drill the pipe underground, reducing the disruption and restoration required, especially when compared to the open cut trench method that excavates a hole for the pipe to be placed in. HDD also allows for a quicker pipeline installation process in dense, residential areas. No matter the methods of installation, the pipeline must be designed to deliver the required pressure and should be tested appropriately.
Utilities should also be mindful of what season the construction will occur in. In cold weather climates, utilities often complete construction in the summer to limit outages to when residents would be using their gas less. Similarly, outages during summer months in hot weather climates could be detrimental to residents. Regardless of when the construction happens, utilities should conduct thorough analyses of the distribution system to minimize outage periods for customers.
With these considerations in mind from the start of the design phase, a distribution pipeline project can be executed safely and efficiently — for both the utility and the community it’s impacting. With the end in mind, utilities can implement a successful gas distribution main replacement program that increases reliability and safety while reducing outage frequency and decreasing construction disruption.
Natural gas pipelines require uncompromising reliability and safety. When a midstream energy company sought to develop its first major cross-country pipeline, it chose an integrated project delivery to meet its needs.