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Southern Maryland Reliability Project
Project Name
Southern Maryland Electric Cooperative
Client
Hughesville, Maryland
Location

Southern Maryland's ring of power reliability delivered by Black & Veatch

Southern Maryland Reliability Project

Client: Southern Maryland Electric Cooperative
Location: Hughesville, Maryland

Regulators and environmentalists praise Southern Maryland's ring of power reliability

What Black & Veatch does isn’t always visible to people and communities where we work. But today and in the future, families and businesses in Southern Maryland enjoy the highest standard of reliable electric service without having to think about it. 

The region served by Southern Maryland Electric Cooperative (SMECO) has a rapidly growing population and a high demand for electricity. In order to enhance system reliability, Black & Veatch was chosen to complete the 230,000-volt loop through the SMECO service area. The final 30-mile segment consisted of 28 miles of overhead transmission and 2 miles of underground transmission. The challenge was the 4,500-foot crossing under the Patuxent River at a depth of 160 feet at the deepest point. 

Black & Veatch’s innovative solution to this problem was to use fusible polyvinyl chloride (FPVC) conduits installed with horizontal directional drilling (HDD) techniques. To date, this is the longest FPVC bundle installed successfully. 

Throughout the project, there was rigorous protection of the sensitive environment of the river and the wetlands traversed by the overhead transmission lines.

Communities in Southern Maryland will benefit from significant improvement in electric reliability and enhanced emergency preparedness thanks to the partnership of SMECO and Black & Veatch.

Black & Veatch is building more than just the infrastructure that brings reliable energy to people everywhere. We are committed to a clean, safe and healthy environment. We are Building a World of Difference. 

MORE ABOUT THE PROJECT

Black & Veatch provided permitting support to prepare the

documentation required to obtain a Certificate of Public Convenience

and Necessity (CPCN) from the Maryland Public Service Commission.

Services for Southern Maryland Electric Cooperative’s (SMECO’s)

Southern Maryland Reliability Project included the following:

  • A threatened and endangered species study, wetland

    delineations, and socioeconomic and environmental justice studies

  • A cultural resources study
  • Permit application preparation
    • Multiple agency contacts were required for project permits
    • Environmental permit applications and technical studies
  • Engineering design
  • Program management
  • Conceptual and detailed designs for the substations,

    transmission lines and river crossing

  • Bidding drawings and specifications for the substation,

    overhead transmission line, underground cable, and submarine cable,

    equipment and construction contracts

  • An outage and construction sequencing plan
  • Drawings and documents to obtain construction permits
  • An Environmental Assessment (EA) to develop a Rural Utility

    Services (RUS) Borrower’s Environmental Report (BER)

  • Documents to obtain Maryland Department of the

    Environment/Army Corps of Engineers (MDE/USACE) permit

The Southern Maryland Reliability Project involved the following:

  1. Two new 230/69-kilovolt (kV) substations
    • The first new 230/69-kV substation (Holland Cliff) is

      configured in a six-position 230-kV ring bus arrangement on the high

      side with four transmission line circuit positions and two transformer

      positions. The low side is configured in a two-bay breaker and one-half

      arrangement with four transmission line circuit positions with the

      230/69-kV transformers separately feeding each main bus.

    • The second new 230/69-kV substation (Sollers Wharf) is

      configured similar to Holland Cliff and is located 18 circuit miles

      away. A new 230-kV circuit position is also being installed 10 circuit

      miles away at the existing Hewitt Road substation to interconnect with

      the new Sollers Wharf substation.

    The substation work includes the following modifications:

    • New two-line position 230-kV switching station to tap

      two existing overhead 230-kV transmission lines.

    • Four-position 69-kV box structure switching station

      replaced by  a 230/69-kV substation configured in a

      six-position 230-kV ring bus and a six-position 69-kV breaker and

      one-half arrangement.

    • New 230/69-kV substation configured in a six-position

      230-kV ring bus and a four-position 69-kV breaker and one-half

      arrangement

    • Relocation of existing 230-kV 225-MVA transformers and

      addition of one new line position at an existing 230-kV substation.

  2. Twenty-eight miles of 230/69-kV overhead transmission line
    • The Holland Cliff, Sollers Wharf and Hewitt Road

      substations are all interconnected by 28 miles of new 230-kV

      double-circuit overhead transmission line to complete SMECO’s 230-kV

      system loop. The work consisted of replacing 28 miles of existing 69-kV

      single-circuit transmission line on wood poles on the same right-of-way

      with quad-circuit steel poles designed to accommodate two new 230-kV

      circuits in the upper deck. The existing 69-kV single-circuit

      transmission line was transferred to the first position in the lower

      deck with a new 69-kV circuit installed in the second position in the

      lower deck.

    • 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 helicopter flights were used to install the pull

      lines for installation of 181 miles of the 197 miles of conductor for

      28 miles of overhead spans.

  3. Two miles of 230-kV underground transmission line
    • The overhead transmission line makes a transition to a

      2-mile 230-kV XLPE solid dielectric underground transmission line at

      the Patuxent River.

    • Approximately 4,600 feet of the underground

      transmission cable crosses under the Patuxent River at an approximate

      depth of 160 feet below mean sea level at the deepest crossing point by

      means of horizontal directional drilling. 

    • 25.5 miles of PVC conduit and 6.9 miles of cable were

      used to complete the river crossing.

    • Because of anticipated environmental concerns

      associated with the jet plow method, SMECO chose to use HDD, a more

      technically challenging method, but one that was more likely to receive

      permit approvals. 

    • The HDD method caused no environmental disturbance to

      the aquatic life in the river.

    • The length of this crossing required Black &

      Veatch to use a new type of plastic pipe called fusible polyvinyl

      chloride (FPVC), which has the strength characteristics for a

      successful pipe pull-back through the HDD. This was a first-of-its-kind

      use of the new FPVC pipe in a bundled slick-bore application.

 

“Black & Veatch was absolutely essential to completing this project. It was a very challenging engineering project, and we wanted a world-class engineering firm helping us.”

Joe Slater, President and CEO, Southern Maryland Electric Cooperative
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