The solution seemed quite simple: cover the field and keep it warm until game time. But how do you effectively keep a 420-ft by 75-ft field warm in subfreezing temperatures? That task fell to Robert Roof, senior vice president of construction for Elliott-Lewis.

Since Roof knew he would need some form of portable heat for this project, he contacted TOPP Portable Air of Aston, PA, to help design a temporary heating system that would warm the frozen turf and make for optimum playing conditions during the game.

“Logistics of manpower before, during, and after the game would have been a scheduling nightmare,” Roof said. “The ability to man the machines around the clock was extremely important to the overall success of the job.”

He noted that city officials also aided in providing adequate staffing support.

“We had to act fast,” said TOPP regional manager John Rinck. “And we brought it all together in less than 48 hours, plus provided constant on-site monitoring.”

So Elliott-Lewis — working in conjunction with the National Football League, the city of Philadelphia, and TOPP — planned a similar approach as that used by the Pittsburgh Steelers to heat their turf at Three Rivers Stadium under comparable conditions. The city of Pittsburgh has often employed two large tarps to cover the Three Rivers football field, utilizing heaters to then inflate the tarps with warm air. This warm air creates an effective thermal barrier to protect the ground from freezing conditions, as well as snow and ice.

Working with the Steelers, the NFL flew in Three Rivers Stadium’s head groundskeeper, Brian Opasic, prior to the game so he could oversee the installation process. Meanwhile, work crews for Elliott-Lewis installed two large vinyl tarps, measuring 100-ft wide by 210-ft long and weighing a cumulative 2,500 lbs, that were brought by truck from Pittsburgh to Philadelphia.

Blanketing the Field

Upon arrival that Friday before the game, crews began the slow operation of unloading the tarps and laying them in place. The two sections were joined together at the 50-yard line using double-reinforced Velcro strips, then secured with concrete jersey barriers to hold the tarps down, as wind gusts leading up to and during the snowstorm were expected to be in the 30- to 40-mph range.

Once the tarps were in place, the next task was to provide forced hot air for inflating the tarps, thawing the frozen ground, and melting any snow that might fall if the impending storm hit. Elliott-Lewis and Opasic worked closely with TOPP engineers to calculate the heating load required and made recommendations for placement of several heaters in several key locations surrounding the football field at Veterans Stadium.

Ten SH-500 vapor propane heaters, each with a 500,000 Btu capacity, were positioned around the perimeter of the field. Two heaters were placed in each end zone blowing toward the center of the field, and three heaters were placed on each sideline (located on the 25-, 50- and 25-yard lines), also blowing toward the center of the field. Two SH-1000 units, each with a 1,000,000 Btu capacity, were later added for additional heating support along the sidelines.

Units were positioned inside the tarp with the back end of each heater drawing in 100% outside air to pressurize and inflate the tarps. The heaters were fueled by two 100-lb propane tanks and powered by a 120 V/20 A service.

With all the propane heaters working in unison, a total of 46,000 cfm of warm, pressurized air was produced to keep the tarps inflated. The propane heaters generated a total of five million Btus of heat, enough to maintain the air temperature inside the 31,500-sq-ft enclosure at a constant 85°F. The heaters maintained this temperature despite the fact that outside wind chill temperatures hovered around -10°F.

The heaters were designed to operate continually through early Sunday morning, just prior to kickoff. TOPP individuals took part in a six-hour rotation schedule (over a 42-hour period) to ensure the heaters ran at maximum efficiency.

According to Rinck, “As propane levels decrease in the tanks, and outside temperatures drop to freezing or below, the vaporization rate inside the tank also lowers. This reduces the capability of the heating units to provide maximum Btu, or heat, output.

“So the on-site technician was responsible for monitoring overall operation of the heaters, but also had to ensure that each unit contained adequate fuel and was not freezing up.”

Philadelphia did receive nine inches of snow as game time neared, leaving crews the additional challenge of keeping the tarps from giving way under the snow’s weight. Roof said the grounds crew utilized fencing to create a “tunnel effect” under the tarps to prevent them from touching any heaters and melting. He said the fencing provided additional protection from the devastating winds.

At the special request of the NFL, two of the units stayed on the sidelines during the big game so players could keep warm despite the bitter temperatures. Standby units were also on hand in the event of a breakdown.

Rinck, who volunteered for the first shift on Friday night, oversaw the monitoring process and received hourly status reports from those at the stadium throughout the weekend.

In the end, the heaters did their job to keep snow off the field. And the Eagles? They captured the playoff victory.

“If there is such a thing as 120%, then that’s exactly what everyone involved gave,” said John Hatfield, equipment manager for the Eagles. “You know, at the time, you wonder how everything will come together. But now I look back on it as a fun experience, in great part because of the cooperative spirit.”

For more information on TOPP products, visit www.etopp.com (website).

Publication date: 07/16/2001

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