Communities around the world depend on transmission to power their economy and provide the reliability needed to keep residents safe. Electrical transmission projects can run overhead, underground or undersea — whatever is necessary to meet the demand.

Underground transmission line design is a highly specialized service used to meet unique siting and capacity challenges. Underground transmission lines are often used when more transmission capacity is needed in challenging environments, such as dense urban areas. When bringing additional transmission power into highly developed areas, there is typically not enough physical space for an overhead line.

There are also permitting constraints that tend to favor an underground approach. For example, if a transmission line needs to pass through an avian sanctuary, an underground transmission line could minimize impact to migrating birds. There are also resilience benefits to considering an underground transmission line. While it is often a more expensive option, it can be solution to harden the grid for storms.

Navigating a line through urban areas requires stakeholder management to find the most appropriate route and to acquire easements and rights-of-way. During underground transmission construction, projects often encounter something unexpected in the subsurface. These variables can be managed by an engineer-procure-construct (EPC) project delivery method — an all-in project approach that offers one point of accountability, cost certainty and timely delivery.

With EPC, the necessary experience and knowledge exist in a one-stop shop. When all major disciplines that support underground transmission construction — siting and routing, environmental permitting, stakeholder management, civil design, electrical design, construction management and construction of underground systems — are led by an integrated team, turnkey project solutions are readily available. That’s essential when projects are schedule-driven, to avoid lengthy disruptions to urban communities. The EPC project delivery method also encourages early and ongoing collaboration between the owner and qualified design and construction team, which is critical to see that the transmission line meets the siting and capacity requirements.

An integrated team can strike the right balance between tight project completion and schedule flexibility. If an unexpected project variable crops up when construction begins, the entire team can adjust and overcome together. The EPC method also helps streamline communication and manage challenges seamlessly.

When an EPC contractor has experience with underground transmission projects, it knows how to mitigate risk, quickly resolve unforeseen challenges and keep everyone on track. There is often no hesitation when an EPC team of capable field supervisors and engineers approach a next step. They know what it takes to overcome a challenge and who to partner with to get it done. Experienced EPC partners know who the major players are for producing equipment or supporting installations. These factors all contribute to innovative EPC solutions that keep an underground transmission project on schedule without any major stakeholder challenges.

 

A customer service-focused strategic undergrounding program for electrical distribution systems provides improved system reliability and increased resiliency.

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Tyler McArthur is a professional engineer with the Burns & McDonnell underground transmission group. His project background includes EPC delivery with projects, to include substations, industrial and public rights-of-way across the U.S.