Rewarding Patriotism

New England Patriots fans are known for their loyalty. For years they braved the elements in Foxboro Stadium, where aluminum bleacher seating was the norm and "conveniences" were defined as rows of portable toilets in the concourses. That loyalty was finally rewarded last fall, when team owner Robert Kraft opened the doors of Gillette Stadium.

By Glenn M. Bernard, Associate Engineer, Vanderweil Engineers, Boston October 1, 2003

New England Patriots fans are known for their loyalty. For years they braved the elements in Foxboro Stadium, where aluminum bleacher seating was the norm and “conveniences” were defined as rows of portable toilets in the concourses. That loyalty was finally rewarded last fall, when team owner Robert Kraft opened the doors of Gillette Stadium. The open-air facility seats 68,000 guests—in actual seats. Luckier fans can even manage to stay out of the cold in premium club rooms that can accommodate up to 6,000. And for those fans with more discretionary income, about 2,000 are able to enjoy some of the largest luxury suites of any NFL facility. Even the grass stays warm, with a radiant-heating system that helps extend the natural turf’s growing season.

But to make all fans happy in time for the ’02 kickoff meant no overtime could be afforded by the design and construction team. Complicating matters was the fact that the opening kickoff would take place in June, not September, and by soccer players at that, as the 1.9-million-sq.-ft. stadium would also host the New England Revolution. Further hammering those deadlines home were non-negotiable television contracts that established substantial owner penalties for any delays. As a result, a design-build delivery approach was taken with the team consisting of R. G. Vanderweil Engineers as the M/E/P designer, Bliss & Nyitray as the structural consultant, HOK Sport + Venue + Event as architect, and Beacon Skanska and Barton Malow Co. as the contractor. This, of course, meant the team had to work closely to ensure complicated systems came together as planned.

Plumbing becomes a hot issue

The design-build scheme would help ensure faster project delivery, but it also allowed little tolerance for revision once design was underway. This especially affected the mechanical systems, requiring significant cross-discipline planning. For example, piping was routed through pre-engineered openings in the structural steel. Because structural steel needed to be ordered very early in the process, those openings—down to degrees of angles for pitched piping—had to be specified before design was complete on other systems.

To ensure that design and schedule were maintained, Vanderweil engineers worked closely with Bliss & Nyitray personnel as early as May of 1999. In fact, because of the tight timeline for design and construction, the owner opted for taking a section-by-section approach to the stadium’s design. Bid packages for the steel were then submitted for each section as designs were approved. In some cases, schedules required bid packages to be submitted before all designs were complete. However, other than field-cut openings, the plans matched finished installation requirements perfectly.

Piping systems, in general, posed a number of other significant engineering challenges. Case in point: The stadium’s hot water, cold water and sanitary systems serve more than 1,500 plumbing fixtures throughout the facility, including public toilets, food-service equipment, concession areas, locker rooms and training rooms. The facility also incorporates an environmentally friendly gray water system to limit demand on both water supply and community sewer systems (see “Gray Water for Green Design,” p.50). And, of course, additional piping was required for fire-safety systems.

As much of good stadium design is about improving the experience of the fan, including great sight lines from the concourses themselves, such an approach meant many of the spaces being served by all this piping had to be located along the building’s exterior, raising a number of hurdles. First, doing so subjects piping to sub-freezing temperatures. Therefore a mix of heated chases, along with heat-trace systems and related controls, had to be specified to help ensure pipes stay thawed.

The team also took an alternative approach to dealing with the interior sanitary-waste systems. These lines are connected by gravity to the exterior sewer in 14 locations to minimize the amount of underground sanitary piping within the building. All floor drains located in the service tunnel and loading docks are connected to two exterior gas/oil interceptors. Interior roof-drainage systems convey rainwater from flat roof areas and the seating bowl by gravity into an exterior storm sewer.

As far as the water supply itself, potable, domestic water is supplied by a separate onsite, above-ground storage tank, via a 6-in. service line. Paralleling the gray-water system, potable supplies enter their own booster-pump system, also in the main mechanical room. In this case, four constant-speed pumps maintain the required water pressure within the stadium at all times. Distribution within the stadium is again split into low and high zones, to supply all lavatories, showers, hydro tubs in the locker rooms, and food-service equipment in kitchens and concessions.

Domestic water mains on site serve other on-site buildings, including the ticket building, team store, boiler plant and maintenance building.

Keeping cool during heated games

Although Gillette is an open-air field, the stadium still includes some 750,000 sq. ft. of conditioned space. This includes the luxury clubs and private suites, along with the training facilities, food service and concession facilities as well as maintenance and support spaces. Executive office space for the Patriots and Revolution consume almost another 100,000 sq. ft. within the stadium structure.

To serve these varied needs, a central chiller and boiler plant were incorporated. The plant houses equipment producing more than 1,600 tons of cooling and nearly 40-million BTUs of heating.

A combination of primary and secondary pumping systems is connected to the glycol piping distribution system serving the four 416-ton, air-cooled screw chillers to cool the conditioned spaces. More than 11 indoor central-station air-handling units, totaling more than 190,000 cfm, provide conditioned air to the field level, administration level and the press area on the upper and lower suite levels within the stadium. Ten outdoor air handling units totaling over 235,000 cfm serve the two main luxury clubs, and kitchen and pantry spaces on the club and suite levels. More than 100 high-capacity fan-coil units, averaging between 700 and 1,400 cfm each, serve the 80 luxury suites. Each concourse concession and adjacent public restroom is served by direct gas-fired AHUs that provide a combined total of over 290,000 cfm of make-up air for cooking hoods and toilet exhaust.

Heating, however, is more complicated. Three gas-fired water-tube boilers, along with primary and secondary pumping systems and accompanying piping distribution, provide heating hot water for domestic water production, the playing field heating system and the stadium heating system for the field level and administration level. Direct buried, pre-insulated piping systems deliver the primary chilled water and hot water from the boiler plant to the secondary pumping stations within the stadium.

Hot water for pre-heating and re-heating is distributed primarily to the service level and office level of the stadium. The remainder of the stadium is primarily pre-heated with gas furnace sections within each AHU. Space re-heating is via electric resistance coils within the ducts, VAV boxes or VAV-fan powered boxes.

Electrifying performance

As far as electrical systems, flexibility and redundancy were the key elements. The owner wanted assurance that a simple outage wouldn’t force an end to a game. Not only would such a result leave fans unsatisfied, it could also result in a substantial loss of television revenue.

To meet this demand, the electrical design provides 15 MW of electrical service available to serve the stadium’s 10 MW load, delivered via two independent utility service stations designed and coordinated by the Vanderweil team. The primary, 10-MW feed generally carries the full load on its own. A secondary, 5-MW line is available for outage situations. The design allows non-critical loads, including air conditioning and some lighting, to be shed, so games can continue without interruption.

The utility company provided local automatic switching between the preferred and alternate lines, based on commands from the stadium’s DDC control system. Should the preferred line fail, a complex system of controls and timed events would occur to initiate load shedding to meet the standby line’s capacity limits.

Utility demarcation occurs outside the stadium, with a lineup of 15-kV double-ended switchgear. These units, in turn, feed 10 unit substations located throughout the stadium and on other outbuilding pad-mounted transformers. A 2,000-kW, diesel-fired emergency generator, located adjacent to the central plant, provides emergency power for life-safety functions and standby power for controls and dedicated M/E/P systems.

Electric distribution within the stadium was developed to support programming needs by system type. Each substation, typically 2,500 kVA, serves mechanical, lighting and power, concessions and life-safety risers.

Because broadcast capabilities are especially important to this facility, there was a need to provide specialty services for television production and other critical audio-visual (AV) systems, including the stadium’s scoreboards. To meet this end, Vanderweil’s design provided both power and communication pathways to service a complex network of AV and telecommunications systems.

Speaking of TV…

A full network-level broadcast studio is housed within the stadium, requiring more than 250 performance lighting circuits and associated controls. The stadium’s AV systems include more than 700 televisions, numerous matrix and LCD display boards, and multiple camera positions, as well as two main amplifier rooms and a central control room. Mobile TV production trucks account for an additional 300-kVA load, and—to ensure fans at the stadium can enjoy super slow-mo, too—each scoreboard receives a 500-kVA power service.

Lighting is obviously critical for television cameras, and 600 individual 1,500-watt fixtures were installed along with a control system that provides automated programming for numerous event scenarios. Such flexibility was important considering the multiple audiences the field serves. Low-voltage controls provide facility-wide oversight, including event lighting, club and suite lighting, various public areas and parking-lot lighting. Instant-restrike lamps provide egress lighting during power failures.

Test of time

With state-of-the-art design wrapped up in a fan-friendly package, Gillette Stadium brings Patriots fans a new level of comfort, with an open-air plan that maintains a compelling closeness to the field. However, only time will tell if Gillette Stadium joins the ranks of legendary sports palaces; that level of recognition can have more to do with the idiosyncrasies of a team’s fan base than with any particular design or construction qualities.

But Patriots managers are certainly making the most of their new home, moving the team’s training camp to Gillette’s playing field after more than 30 years at Bryant College. And if team enthusiasts are missing the aluminum benches and portable toilets, their game attendance isn’t showing it. Their preseason opener against the New York Giants kicked off on the same night Boston’s maligned-but-loved Red Sox were scheduled to take on the Anaheim Angels—only two and a half games behind age-old rivals, the New York Yankees. A near-capacity Pats crowd, in the face of such competition, proved to many that Gillette Stadium is here to stay.

Gray Water for Green Design

The capacity crowds Gillette Stadium is designed to attract can go through a lot of water—from 600,000 to 1,000,000 gallons per event. Supplying and treating that water could force a strain on any municipality’s bud-get. To address sustainable-design goals, as well as concerns raised by authorities in the facility’s hometown of Foxboro, Mass., Vanderweil Engineers developed an extensive gray-water system that successfully recirculates up to 80% of the wastewater generated by the facility.

Gray water, used in all water closets and urinals within the stadium, is supplied by the separately designed on-site waste-treatment plant and 500,000-gal. storage tank, via a 14-in. service line. A booster-pump station in the stadium’s main mechanical room incorporates two constant-speed pumps and four variable-speed pumps that distribute gray water throughout the stadium. The two small pumps operate during non-event, low-flow conditions, while the larger pumps maintain water pressure within the distribution system during events.

The gray water distribution system itself is split into two zones. The low zone serves the field level, administrative level and main concourse, while the high zone serves toilets at the club level, suite levels and upper concourse level.