Commercial Construction & Renovation

JAN-FEB 2014

Commercial Construction & Renovation helps our subscribers design, build and maintain better commercial facilities by delivering content to meet the information needs of today's high-level executives.

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102 CommerCial ConstruCtion & renovation — January : February 2014 federal construction • AlAskA goose creek correctionAl fAcility facilities, but Goose Creek was our frst new construction prison project," says Mark Erickson, GM at Superior. In true Alaskan spirit, the new facility is equipped with a no-nonsense hydronic system to heat the three largest buildings on the campus. The general housing, support and visitation, and vehicle maintenance buildings account for 435,000 square feet of conditioned space. Two smaller buildings – located more than 300 feet from the central plant – have stand-alone systems. The outside administration building and warehouse each have two, one-million BTU boilers. The mechanical systems in the complex are designed around a -23 degrees F design temperature. The system's central plant – as formidable a creation as the prison itself – occupies two stories in the Support and Visitation building. From there, 3- and 6-inch pipes run underground to general housing and under the concertina wire to the vehicle maintenance building. Heavily-insulated pipes are trenched 10 feet below grade – well below the 5-foot deep frost line. "It was a major coordination effort," says Erickson, "especially being 75 miles from the shop." Seven foremen were on-site for the duration of the project. When things were in full swing, there were 50 plumbers and pipeftters, 20 sheet metal workers, and fve offce staff at Goose Creek every day. That's in addition to the other trades. The general contractor for the project was Anchorage-based Neeser Construction. Alaska Sheet Metal, one of Superior's sis- ter companies, handled all the ductwork at the site, while Alcan Electrical, Alaska Industrial Insulation and Fireproofng, and Alaska Air Balancing were among the host of Anchorage-based companies that worked their trade at Goose Creek. Controls, refrigeration and security subcontractors were co-joined in the effort as well. Challenges in the sub-arctic One of the biggest challenges was designing and building the system consecutively. The initial concept design was a collaborated effort of two mechanical and electrical engineering frms with one of the frms, Coffman Engineers, taking over the full design responsibilities at the midpoint of the design. Coffman, located in Anchorage for more than 30 years, has extensive experience in designing facilities in the harsh sub-arctic climate. "We took over at the 65 percent completion mark," says Bill McNeal, PE, principal mechanical engineer for Coffman. "Our job was to 'Alaskanize' the system. It took a better building envelope and more robust mechanical system than what had originally been envisioned. Much of Alaska is challenged not only with frigid winter tem- peratures, but several other issues as well. Frequent and signifcant earthquakes are a harsh reality. Ash fallout from several nearby active volcanoes offers additional challenges. As if that's not enough silt is generated by glaciers, including the nearby Matanuska Glacier. Rocks and boulders grinding against bedrock create a fne dust that easily goes airborne in high winds. The silt and ash re- quire the ventilation systems to be equipped with good air fltration. "The central boiler plant and pumping systems are confgured with redundant or reserve units in order to ensure that heat is always available," McNeal says. "The natural gas-fred equipment also has an on-site propane reserve system good for two weeks of winter operation. The reserve fuel is a necessity in the event that an earthquake interrupts the natural gas pipeline to the site. The reserve power generation system also has redundancy and a two week fuel supply." Hefty hydronics Due to the project's fast pace, and Alaska's short construction season, they already were trenching pipe while we were completing the design of the plumbing and other under- ground systems. Appearing more like a master plan for a futuristic a superhighway, the piping layout for Goose Creek shows the branching network from 12 natural gas-fred Aerco Benchmark boilers. The main boiler room took roughly a year to pipe. The best way to get the boilers to serve the numerous buildings and loads was to use an extensive primary-secondary system. An 8-inch primary loop connects all the condensing boilers, each equipped with a Taco KV3009 pump and two-horsepower motor. Two 6-inch secondary loops tee off; one goes to the support and visitation building, and the other goes to general housing. Inside the buildings, the large secondary loops feed heat exchangers for in-foor radiant loops, VAV boxes and air handlers. In addition, several fat-plate heat exchangers tap the glycol loop to heat large, indirect water heaters. A Superior Plumbing and Heating technician checks pressure drop across the suction diffuser on a Taco KV Vertical In-line pump. Along with the suction diffuser, the VFD-powered pump uses a multi-purpose valve to help eliminate straight pipe runs and save foor space. CCR-JanFeb.14_XX-CVR4.indd 102 2/7/14 1:57 PM

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