Project Highlights
- New 2.25 mile aluminum conductor composite reinforced (ACCR) transmission line.
- Eight new transmission poles: five erected in the Patapsco River and equipped with vessel collision protection structures to provide protection from potential marine traffic collisions, and three land-based towers – one on the Hawkins Point side of the river and two on the Sollers Point side. Two existing structures required modification.
- A 2,200-foot single-center span crosses the shipping channel with a maximum ship height of 215 feet above the water supported by monopole towers three and four at a height of 397 feet – the tallest in the Americas.
- Solar-panel-powered Federal Aviation Administration lights with battery backup.
- High pressure fluid-filled (HPFF) underground cable decommissioning.
- Decommissioning and demolition of Hawkins Point and Sollers Point substations.
Project Description
Sargent & Lundy provided detailed transmission engineering services including partnering with Moffatt & Nichol (M&N) for the foundation designs. Engineering began with the conceptual design and permit process in 2018 and continued with detailed engineering into 2022. Sargent & Lundy and M&N supported BGE throughout construction in 2021 and 2022, including conducting in-water inspections of the pile foundations. Sargent & Lundy also partnered with McKissack & McKissack to provide project architectural renderings and production videos to support public outreach and vector corrosion services for cathodic protection and grounding design.
Project Scope
BGE engaged Sargent & Lundy to provide an extensive array of project deliverables.
- Sargent & Lundy designed and engineered the overhead lines to minimize environmental impact and incorporated avian mitigation features.
- The double circuit line utilized a double-bundled ACCR conductor and dual 96-fiber optical ground wires (OPGW) with marker balls.
- The poles incorporated FAA lights powered by solar panels with battery backup, a permanent ladder with a rail fall protection system, temporary ladder clips, OPGW downleads and splice boxes, pile-cap integrated grounding, and cathodic protection.
- The construction specification developed for the project included provisions for contractor submittals and owner and engineer reviews, pole erection requirements, helicopter stringing over the active harbor, and dynamic stringing methods to manage structure deflections.
- A detailed outage sequence and cutover plan was developed to minimize service impact to customers.
The deep foundation design incorporated collision structures to protect the monopoles from impact by marine traffic. A heavily reinforced combination of cast-in-place concrete and pre-cast concrete elements make up the decks of each foundation. The design features elements that assist BGE in overall maintenance by incorporating a davit crane to lift materials, personnel safety features, protection to prevent public access on decks, and avian mitigation.
Awards
- 2023 Precast/Prestressed Concrete Institute Design Award
- 2023 American Council of Engineering Companies/Maryland Engineering Excellence Award
- 2023 American Council of Engineering Companies National Recognition Award
- 2023 Engineering News Record Mid-Atlantic Best Project Energy/Industrial
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