Key Crossing Reliability Initiative

BGE Key Crossing 230-kV Transmission Reliability Project
Baltimore, Maryland
Client: Baltimore Gas and Electric Company

Project Highlights:

2.25 miles of new ACCR transmission conductor.
Eight new transmission poles: five poles 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 require 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 3 and 4 at a height of 397 feet – the tallest in the Americas.
Solar-panel-powered FAA lights with battery backup.
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 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 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.
With a main center span of 2,200 feet over a shipping channel requiring over 230 feet of water clearance, the 397-foot-tall monopoles are the largest in the Americas.
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.

Schedule Milestones:

Engineering Services: 2018-2022
Construction: 2019-2022
Commercial Operation: 2022

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