Fort Belvoir, VA
Task Order Contract
As part of the Joint Venture Firm, AKHI Construction, TMG was the Prime Contractor for a design-build project that installed the primary electric system along North and South Loop Road at this new agency campus. The project consisted of the installation of approximately two miles of underground electrical duct bank and cable, the installation of five SF6 SCADA-capable switchgear units, multiple pad-mounted transformers, and the removal of a temporary overhead line previously installed to serve the construction trailers on base.
The project began with the design team preparing a preliminary design that was capable of serving both the proposed buildings and security gates and having provisions for the future facilities intended to be built in the coming years. Since the campus has an electrical system that has been privatized by Dominion Virginia Power, the electrical system was designed to comply with both the military UFC specifications and the Dominion Virginia Power design and construction standards so that future turnover of the facilities would be simplified. A series of five SCADA-capable SF6 switchgear units with provisions for motor operators were designed to serve this system, with provisions for a second loop feed from Dominion to be installed in the future for a self-healing network. Individual circuit branches were designed off of the SF6 switchgear to serve buildings and traffic control / security checkpoints around the facility.
A complete coordination study was performed to coordinate the SF6 switchgear, equipment fusing, and the Dominion delivery point. An arc-flash analysis was also performed for the entire system, and arc-flash hazard stickers were created for all pertinent equipment and manholes on the system. For equipment where the arc-flash hazard was too great to allow for safe energized work, alternate protection schemes were implemented for worker safety during construction.
The electrical contractor performed the installation of all electrical equipment. Their work was coordinated around the numerous other construction activities on the campus to ensure that completion schedules were met without causing delays to other contractors there. Additional manholes were added at locations where future buildings and services were anticipated. Due to the critical nature of the existing buildings being fed by the temporary line, the conversion to underground and removal of the existing facilities had to be performed under energized conditions. The electrical contractor utilized live-line techniques to perform all operations under energized conditions so that no momentary outages occurred.