Installing transmission cable underneath the Patuxent River

230-kV Project

The Southern Maryland Reliability Project is a 230,000-volt transmission loop through SMECO’s service area. The new line came into service in November 2014 when SMECO energized the portion underneath the Patuxent River from Solomons to Town Creek.

The line had been part of SMECO’s vision since the early 1970s to meet the electricity demands of a growing population. We built the first section in 1990 from Ryceville to Lexington Park. Calvert and St. Mary’s counties had been connected by a 69,000-volt line, and when the submarine portion failed on a very cold day in January 2005, the importance of upgrading the line became obvious.

 After holding a series of open houses for the public and receiving customer-member comments about the project, the cooperative applied to the Maryland Public Service Commission for a Certificate of Public Convenience and Necessity (CPCN) on November 21, 2008, and the Commission granted the CPCN on September 9, 2009.

The seven-year, $108 million project included new switching stations in Aquasco and Sollars Wharf, an expanded switching station in Holland Cliff. The Hawkins Gate and Hewitt Road switching stations received upgraded transformers to increase capacity where it was needed most. The new line completes the transmission loop by linking Aquasco in Prince George’s County with Hewitt Road in St. Mary’s County.

Electric utilities are obligated to maintain the highest standard of reliable service and provide the most up-to-date technology to improve economic and operational efficiency. By completing this 230,000-volt loop through our service area, customer-members are assured of improved reliability, particularly in Calvert and lower St. Mary’s counties, including Naval Air Station Patuxent River. SMECO expects the new line to provide enough capacity for the next 50 years.

To run the new line between the two counties, SMECO used a horizontal directional drilling technique to bore under the riverbed, and then pulled two bundles of five fusible PVC pipes through the bored holes. This was a first for the industry; no previous installations using fusible PVC come close to the length and complexity of this project.

  • 25.5 miles of PVC conduit and 6.9 miles of cable were used to complete the river crossing.
  • 19,543 cubic yards of concrete were used for the foundations of 291 steel poles, replacing 430 poles used for the previous 69-kV line.
  • 15.5 miles of roads were graded along the right-of-way and for construction access.
  • 15 helicopter flights were used to install 181 of the 197 miles of conductor for 28 miles of overhead spans.

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