Episcopal High School is located at 1200 N. Quaker Lane in Alexandria, VA. Spread out over a 130-acre campus, EHS is approximately 10-minutes from downtown Washington, DC. The site for the Centennial Gymnasium Addition is located between two existing structures. The Flippin’ Field House, located north of the proposed site, is the indoor track facility for the EHS athletic department. Existing Centennial Gymnasium, located south of the proposed site, currently houses all of the athletic department offices, basketball, volleyball and wrestling facilities.
The main issue with the new addition site is the amount of existing utilities that cross the area. Gas, water, electric, storm and sanitary lines run through the site connecting several other campus buildings. Several of these utility lines will need to be re-routed prior to excavation of the new addition building pad.
A detailed 3-phase construction sequence has been developed for the Centennial Gymnasium project to ensure that EHS has access to certain areas throughout the entire schedule. Demolition, renovation and new construction will take place simultaneously throughout the duration of the project. There are four distinct turnover dates that allow the athletic department to relocate equipment, personnel and athletes without losing functionality of the facility.
The new gymnasium addition and renovation work is slated to achieve a LEED Certification. A major component of achieving this rating will be thorough construction waste management and recycling of materials. DAVIS will coordinate and oversee the recycling efforts on site. In order to reduce the heat-island effect from the new addition, a high performance two-coat fluoropolymer “cool roof” finish system will be applied to the 18” wide standing-seam metal panels on the roof.
The power distribution system is an existing 480Y/277, 3-phase, 5-wire, 60 hertz feed supplied by an exterior Dominion Virginia Power Company transformer. The elevator equipment requires a 480V + 5%, 3-phase service. There is no back-up generator specified for the project, however battery back-ups are to be provided for the emergency fire alarm system.
The lighting for the Centennial Gymnasium project includes several types of fixtures to accommodate the many different areas throughout the facility. All fluorescent fixtures have high-powered electronic ballasts unless otherwise noted. The main area lighting fixtures are as follows:
Locker Rooms: 4’-0” 277V fluorescent pendants
Team Rooms: 2’x2’ 277V recessed fluorescent fixtures in the center surrounded by 6” 277V recessed, wet location downlight fixtures at the perimeter
Lounge: 277V compact fluorescent flex linear cove system in the center surrounded by 8” 277V recessed downlight fixtures at the perimeter
Gymnasiums/Wrestling Cage: 400W pulse-start hi-bay pendants with electronic ballast
Fitness/Weight Area: 8” 277V recessed downlights
Corridors: 2’x2’ direct/indirect 277V recessed fluorescent fixtures
There are two mechanical rooms located on the lower level of the existing Centennial Gymnasium in the current fitness room area, and a third mechanical room located on the upper level of the new addition adjacent to the gymnasium. The overall system is an air-water AC system with the primary air supplied by air-handling-units and secondary air circulated by terminal/fan coil units. There are two AHU’s and one cooling tower located on the roof above the lower level mechanical room, and five AHU’s located inside the building. AHU 1 is a glycol run-around heat recovery system with 100% outside air. The rest of the AHU’s operate with a VAV mixed air system. One 572 GPM centrifugal chiller is located in the lower level mechanical room and provides the chilled water for the AC system. Two 3000 MBH condensing boilers supply the hot water for the reheat/radiation system. Single line ductwork distributes the treated air to the individual spaces, while hydronic piping transports water to the terminal units.
The subsurface foundation for the new gymnasium addition is to be an aggregate pier soil reinforcement system. The piers are 2 ½’ in diameter and filled with compacted #57 stone. 297 piers are to be installed to an average depth of 14 feet in order to support the building loads on the concrete footings that have a 5000 PSF net allowable bearing pressure. Concrete grade beams ranging in size from 12-27” wide by 25-81” deep will support a 5” slab-on-grade with 23 lbs./CY of blended fiber reinforcing. All foundation walls are designed to be retaining walls and have heights ranging from 3’-0” to 15’-0”. All pier caps, footings and SOG are to be 3000 psi normal-weight concrete, while the foundation walls and grade beams are to be 4000 psi normal-weight concrete.
Reinforced cast-in-place concrete is the main structural system for the new addition. The majority of the columns are 18”x18” with 4000 psi normal-weight concrete. The floor slabs are 9 ¼” thick one-way slabs supported by concrete spandrel beams with an average depth of 1’-6” and average width of 1’-0”. Both the slabs and beams are to be 4000 psi normal-weight concrete. A unique feature of the CIP concrete system are sixteen 12” round, exposed columns that run along the South side of the new gym addition. Special type ‘A’ formwork and placement strategies must be used to achieve the specified finish for these elements.
While the majority of the structural system is cast-in-place concrete, there are several structural steel elements in the Centennial Gymnasium project. The six large white columns at the West entrance to the new addition house two-story tall HSS8x8x.25” steel columns with W12x14 beams spanning 13’-0” from the columns to the bearing wall. At the expanded mechanical room area, four HSS6x6x.25” columns support W18x35 beams for the rooftop AHU’s and cooling towers. Inside the Wrestling Cage area, a two story mat-lift hoist will be supported by 4’-0” HSS5x5x.25” beams connected to three HSS6x5x3/8” columns.
The largest structural steel element on the project is the 107’ roof trusses spanning the two story gymnasium, shown below in Figure 4. Between each truss will be W8x18 braces spaced to allow for all MEP lines to pass through the structure above the bottom chord of the truss. The roof of the new Centennial Gymnasium will be ER3.5A 18 gage G90 galvanized metal decking supported by the trusses above the open gymnasium portion, and 1 ½” x 18 gage G90 galvanized metal decking supported by W14x22 beams over the remainder of the addition. On top of the metal decking will be 18” wide standing-seam metal panels
The main building enclosure system for the exterior wall of the new Centennial Gymnasium is a modular “Delmarva” face brick backed by structural reinforced masonry bearing walls with 8” CMU’s and air cavities. Structural steel lintels are to be utilized at interfaces with the existing structures to support the brick façade. Cast stone masonry sills are to be installed at all exterior windows with cast stone masonry clad units between the entry and upper level windows on the new gym addition. Connecting the new Centennial Gymnasium to the existing gymnasium is a two story glass atrium constructed of aluminum curtain wall framing with Solarban 70XL glazing. There is approximately 1500 SF of curtain wall designed by the Architect, Cannon Design. The stick-built system is to be erected by the installer with a 1/8 inch in 10 feet plumb tolerance and a 1/8 inch in 20 feet level tolerance.
