- ENGINEERING INFO
- CASE STUDIES
Tideland EMC is an electric membership corporation formed in 1971 through the merger of four electric utilities. Headquartered in Pantego, NC, Tideland EMC currently serves more than 22,000 customers in six counties in northeastern North Carolina.
Part of Tideland EMC’s recent system improvement initiative included replacing electric power cables originally laid under Pantego Creek in 1989. At the time, power cables were installed from a barge directly into a shallow trench excavated in the bed of the waterway. In 1994, lightning struck the underground cables, damaging one cable such that it had to be replaced immediately. The only power cable available for emergency replacement at the time was smaller than the other two existing cables, and could not handle the full capacity of the circuit. As the electrical power load on the system increased over time it eventually became necessary to replace all of the power cables.
In 2011, bids were requested for a directional bore project to install four 4-inch conduits to house new power cables under the Creek. Due to the 3,800-foot length of the project only a few contractors chose to bid. Bid prices were deemed unacceptably high compared to the available project budget. The concern with the project as originally designed was that standard conduit materials (HDPE pipe and solvent welded PVC pipe) were determined by HDD contractors to be unsuitable for an uncased, 3,800-foot bore. Another option to install a 12-inch steel casing to house the conduits was considered, but this approach proved even more costly.
Tideland EMC’s engineering consultant, Utility Electrical Consultants, evaluated another option to install the new power cables in conduits suspended from a nearby bridge which was under construction at the time. Further investigation revealed that construction of the bridge had progressed to the point where adding a suspended cable installation would have required significant engineering modifications to the structure.
Finally, Lee Electrical Construction, Inc. suggested value engineering the project by using 4-inch Fusible PVC® conduits in a “slick bore” to be pulled uncased directly through the borehole. Ultimately, Tideland EMC accepted the proposal which produced a total project savings of over $300,000.
Ben Beagle, Tideland’s Manager of Operations, summarized the project approach: “Tideland EMC had a very specific requirement for conduit sizing and length to cross under Pantego Creek. Lee Electrical Construction brought Underground Solutions into the project and the two of them, along with Tideland’s construction team, were able to take the project from concept to successful completion in a year’s time. We commend all the parties for their efforts and recommend other utilities consider this approach for similar projects.”
|Pipeline Details and Project Summary|
|Project:||Pantego Creek Crossing|
|Location:||Belhaven, North Carolina|
|Length:||3,800 LF HDD; 4,400 LF total fused length|
|Conduit Size:||4” DR14 x 4 Fusible PVC® conduit bundle|
|Installation:||Horizontal Directional Drilling|
|Contractor:||Lee Electrical Construction, Inc.|