Shapiro & Duncan

Owner:

U.S. Army Corps of Engineers

Architect:

URS Corporation

General Contractor:

Whiting-Turner Contracting Company and Summer Consultants

Scope Of Work

Challenge

The Intelligence Community Campus – Bethesda (ICC-B) Centrum project involved renovation of a campus of federal buildings once used by the National Geospatial Agency. The redeveloped facility, operated by the Defense Intelligence Agency, is a modern, state-of-the-art facility that will serve a coalition of 17 intelligence-gathering agencies and organizations within the Executive Branch.

The Centrum phase was the first big block of work, reconstructing a building within another structure to provide new office and meeting space for 356 occupants, computer room facilities and campus amenities such as an auditorium, cafeteria and an outdoor plaza. The Centrum, which houses the new central heating and cooling plant for the entire campus, is designed to improve overall building circulation by serving as the central circulation spine that ties together existing buildings on the site. Featuring green roofs and energy efficient systems, the Centrum is a LEED Silver-rated project.

Meanwhile, the Washington Gas Energy Services – Central Mechanical Plant (WGES-CMP) project was built concurrently with the Centrum; the systems were installed in the same physical spaces. The plant, which is the source of heating and cooling for the campus, includes a large and complex mechanical equipment package designed by Washington Gas.  It includes:

• Three 1,100 ton chillers
• One 340 ton chiller
• Emergency Refrigerant Exhaust Fans / Controls
• Three 4 million  BTU High Efficiency Boilers
• Cooling towers sized to handle a flow rate of up to 2,200 gallons per minute.
• Heating, Chilled, and Condenser Water Pumping Systems equipped with Variable Frequency Drives (pump speed controllers)
• Fuel Pump System supplying the Emergency Generator

 

An interesting aspect of this combined project is that it has all the different facets of construction including new core-and-shell construction, renovation and design/assist.

Centrum Challenges

For the Centrum phase, our biggest challenge as a design/assist partner was working with general contractor Whiting-Turner and architect/engineer URS Corporation to provide systems that would comply with the government’s requirement for “N+1 redundancy” which is a prerequisite of the national intelligence agency’s mission of this facility.  All systems must have a dedicated backup system (+1) in the event of a primary system failure.  

 

Another huge design/assist challenge was coordinating with Whiting-Turner and the trades to address space requirements and constraints of various building operational systems so that mechanical systems could be efficiently located in conjunction with other utilities as well as architectural elements such as structural beams, clearances and ceiling space constraints. Specifically, these challenges involved fitting duct work, plumbing piping on grade for proper drainage, sprinkler piping, electrical wiring, cabling for phone and data communications and more in very limited ceiling spaces throughout the Centrum office and corridor areas, while maintaining the minimum required architecture clearances of the interior spaces.  

 

Additional challenges posed by the Centrum phase of the project included:

• Installing pipe anchor inserts throughout the building structure during concrete construction, in order to streamline the pipe hanger installation process by eliminating the need to drill slabs after construction.

 

• Coordinating and designing a structural support system for 42 4’ x 10’ rooftop solar panels which constituted six separate solar arrays. Challenges included design of custom supports that integrated with the roofing system and varying roof slopes, so that the panel support system met the specification requirement to withstand a wind load requirement of 90 mph.
   
• Working through site logistical issues that hindered rigging activities and site utility connections.
   
• Designing and installing a method of rerouting existing underground high pressure steam piping serving an adjacent building occupied by approximately 400 full-time employees. To accommodate new utilities, piping had to be relocated over a distance of approximately 200 feet (two-thirds the length of a football field) and could not be removed from service due to continuing occupancy of the building.

 

• Assisting design engineers with recommendations during construction while working through logistical and space constraints when installing specified systems.
   
• Facilitating owner requirements to expedite specialized HVAC equipment delivery and installation due to re-designation of system requirements.
   
• In the Centrum phase of the project, the re-routing of an existing underground steam pipe required a heroic effort over a single winter weekend in mid-February. Working in a driving rain, our people ran new piping up and out of the ground, positioned them on concrete piers beyond the point where they were interfering with other utilities, and then ran them back into the ground and re-connected them to the existing pipes, tested the new and old steam piping, and had it back in service in time so as not to interrupt normal business operations on the following Monday morning.

 

 

WGEs-CMP Challenges

The complementary WGES-CMP phase of project included installation of the WGES-provided large mechanical equipment designed to supply heating and cooling for the entire campus. The biggest challenge was locating the 150,000 lb. cooling tower that rests on the roof of the adjacent building, supported by custom-made 21-inch steel I-beams oriented with the building structure. The support structure rests on custom vibration isolators that are one third the size of a car. The cooling tower assembly, meanwhile, is as big as a small house. All of this had to be placed on the rooftop, and tied into the 18-inch condenser water piping that runs across the roof resting on a framework of custom steel supports.

In addition to the mechanical systems on the rooftop, the condenser water piping had to be routed from the central plant in the basement of the Centrum building, up three stories, and out onto the roof of the adjacent building.  An especially challenging  part of this job was taking piping through the adjacent occupied building, which required an additional level of security requirements. This meant our people had to be accompanied by security escorts the entire time.

Solution

Shapiro & Duncan’s Building Information Modeling (BIM) system, operated by our CAD department, powered our collaboration efforts with the general contractor, architect/engineer and other trades to resolve space constraints. Once all systems were properly fitted within available space using the BIM system, our CAD team verified their constructability. Then the needed material was pre-fabricated at our 51,000 square foot prefabrication shop in Landover, Md. Ninety-nine percent of the piping, valves and fittings that were installed on this combined project were pre-fabricated at the Landover shop.

Since the Centrum was new construction, we were dealing with a cast-in-place concrete structure. Our CAD team also utilized 3-D BIM drawings to lay out all pipe anchor and sleeve locations. Then our field personnel coordinated with the concrete contractor so that all pipe hanger imbeds could be delivered before concrete was poured.

After pre-planning and placement of the support elements, the prefabricated materials were installed, tested and put into service in time to reach the general contractor’s milestone for conditioned air. All mechanical systems were up and running in time to meet those milestone dates. 

Ultimately, our Centrum solution included an eye-opening array of mechanical and plumbing systems and equipment including:

• Two 300-ton centrifugal chillers;
• Two 300-ton roof-mounted cooling towers;
• Three custom manufactured rooftop air handling units;
• 11 indoor air handling units;
• Four energy recovery units;
• 244 variable air volume boxes;
• One packaged fuel oil pump system with direct-buried double containment piping supplying the remote emergency generator;
• One kitchen make-up air unit;
• Multiple types of fans, heat exchangers, fan coil units, air filtration devices, HVAC pumps, plumbing sump pumps, domestic water booster pumps, split system A/C units, backflow prevention devices and steam pressure control devices;
• High pressure steam piping, heating water piping, natural gas piping and plumbing/storm piping;
• Certification requirements for welded piping;
• Commercial plumbing fixtures;
• 18,500 gallon Rain Water Harvesting system with dedicated non-potable water piping supplying toilet/urinal fixtures;
• Custom solar water heating system designed to supplement steam powered domestic hot water generator;
• Specialized chilled water system supplying 73 computer room air conditioning units;
• Custom sheet metal ductwork air distribution and exhaust systems including welded grease ducts for commercial kitchen exhaust hoods; and
• Integrated automatic temperature / humidity control systems interconnected with fire alarms and emergency power.

Results

Everything came together on the Centrum/WGES-CMP project as planned and on time. In a design/assist project such as this, making sure everything fits is the primary objective. The end result was a tremendous accomplishment for our entire team including our subcontractors, a testament to our combined expertise and dedicated team spirit. Keys to success included pre-planning, collaboration with design engineers and subcontractors, and effective use of pre-fabricated materials.

Shapiro & Duncan enjoys a good relationship with the general contractor, Whiting-Turner, Washington Gas Energy Services, and the owner, the U.S. Army Corps of Engineers. All indications are that the customer is very happy with the finished product. Says Shapiro & Duncan’s Senior Project Manager, John Hoke, “In my 32 years in this business, I haven’t seen a project where so many levels of management, field, and subcontracting groups cooperated with each other and worked so well together to overcome the inevitable challenges of such a complex design/assist project.”

 

For complete case study, please visit http://www.shapiroandduncan.com/government/icc-b-centrumcentral-mechanical-plant/