United States Naval Academy: Central Chilled Water Plants Restoration and Expansion

Hurricane Isabel inundated a large portion of the Mid-Atlantic seaboard with a storm surge of 15’ that pushed up the Chesapeake Bay and into the Severn River, home of the US Naval Academy in Annapolis, MD. As a result of the flooding, the primary yard chiller plant located in the basement of one of the primary buildings was destroyed. A temporary plant was put in place and in 2004 a Design-Build RFP was advertised for a new primary plant and the replacement of the flooded plant which would become a winter/backup plant. The team of The Haskell Co, Green Contracting, RMF Engineering, CPF Utilities and Native Sons, Ltd. submitted a superior technical proposal and won the award over 4 other competitors.

The project consists of a new plant with a capacity of 7500 tons (10,000 tons total future) and the replacement plant with 5000 tons of capacity. The new plant is housed in a new addition to one of the existing buildings. The system is designed to provide chilled water to all of the buildings on the campus and is flexible enough to provide for the cooling needs of the yard in all seasons.

The electrical system is derived from the existing yard 13.6kV bus which feeds double ended 10mva substations in both plants that contain new 13kV switchgear, 4160v chiller substations and dual ended 480v substations. Pump power is through either VFC or Soft Start controllers. Dual MCC’s were provided for supplemental motor loads. A substantial portion of the feeds in the new plant were installed underground to allow space for the extensive amount of piping required for the multi-selective system.

One of the more challenging aspects of the project was the relocation of the primary substation at the replacement plant. This sub was moved from the basement to the roof with the feeds for the replacement chiller plant running vertically through the existing facility. To further complicate this installation, the existing building services were also fed from this basement sub. All of the buildings distribution was changed from bottom up to top down, all while the facility was in operation. Over 35 outages were required to convert the existing loads to the new feeds, all of which were accomplished either on or ahead of schedule. During the design phase it was also found that emergency services needed improvement and these additions and modifications were included without extending the project schedule.

The original RFP called for standard ductbank and cable 13kV feeders from the existing main substation, however to avoid substantial conflicts and disruptions to the yard and its operations, Native Sons proposed installing submarine cable around the water bound campus. The installation of the two 7500’ long 500mcm 13kV submarine feeders was carefully designed and planned both to avoid damage to sensitive marine life in the area, but also to achieve security for boaters and the cable. The main cable reel was 35’l by 12’ high and weighed 107,000lbs. Each cable’s carefully choreographed installation took only 3 days.

The $8.8 million (electrical) project was completed four months ahead of schedule. The general contractor was The The Haskell Co, Jacksonville, FL, John Brendel, Project Executive, Tom Sais, project manager; the owner is The United States Navy, NAVFAC, Washington, DC, Tom Trulli, ROICC; Michael T. Oles, general manger of Native Sons, Ltd. oversaw the design and construction of the electrical, low-voltage and life safety systems for the project.