..,.;=---- sportsT'Sf T The Invisible Sun: The electrical heating system underneath the field has survived since the Lombardi era in Green Bay. Photo courtesy: Green Bay Packers. Heating Soil From Below By Mike Augsdorfer team rises from the head of a the roots of the turfgrass bask at a com- Electrical Heating Systems defensive tackle as he takes off his fortable, if not balmy, temperature. How When the Minnesota Vikings moved Shelmet and trots to the sideline. can the roots be toasty warm when the to the climate-controlled Metrodome, Nearby, the punter shivers beneath the surface temperature is below freezing? Lambeau Field in Green Bay, WI, inher- coat thrown over his shoulder. The ref- The answer is simple: the soil is heated ited the reputation of coldest field in eree dodges another snowball thrown from from below by a system designed to the NFL. While the fans and players in the stands. In the offensive huddle, the keep the roots warm, even when the Green Bay brave sub-zero temperatures quarterback's face is shrouded by the surface temperature is better suited for for their late-season games, the turf at frozen cloud formed by his breath as ice hockey than football. Lambeau benefits from an underground he barks out the snap count. Mean- Several high-profile athletic facili- heating system that keeps the roots at while, the barefoot placekicker con- ties in the U.S. utilize soil heating sys- a comfortable temperature. The elec- templates the relative merits of frostbite tems to maintain consistent soil tem- tric heating system underneath the field and his high salary. The team lines up peratures regardless of the weather. At has survived since the Lombardi era in for the potential game-winning field least five NFL teams play home games Green Bay. "It's 27 years old," says sta- goal, gratefully acknowledging that - on fields that feature below-ground soil dium turf manager Todd Edelbeck. "The win or lose - they will soon be back in heating systems. Coors Field in Denver, last few years we've been to 20-below, but the locker room taking hot showers to home of the Colorado Rockies baseball our winters haven't been too bad." Edel- stimulate the circulation in their frozen team, also has an underground heating beck admits that the team is exploring bodies. The kicker winces, knowing that system, and several major colleges uti- the possibility of installing a new hot- the football will be rock hard when he lize underground heating for their foot- water system at the stadium. The cur- kicks it. The ball is snapped, and frozen ball game fields. Some field heating rent electric system features cables foot meets frozen ball ... systems operate by pumping hot water planted approximately six and a half The grass beneath the players' frozen through underground pipes to main- inches below the surface. They run 12 feet is green - a particularly nice shade tain a constant soil temperature. Other inches apart at the center of the field. ''Up of green, considering the frigid conditions. systems utilize underground electric until last year we turned it on a week or Just a few inches below the frosty scene, wires or cables to heat the soil. two before the last game," says Edelbeck. 10 sporfsTURF FOR PRODUCT INFO FAXED TO YOU NOW! DIAL: 1(800) 817·1889 tance copper wire in the center and a PVC Hot-Water Systems around it, then a braided wire and a PVC Razum's NFL counterpart in Denver coating," explains Razum. He also must is Thomas Lujan, who manages turf be careful about taking heavy equip- maintenance operations at Mile High Sta- ment on the field because the electric dium for the Denver Broncos. "We used heating system is sensitive to the weight to have electric heat, but now we've placed on the field. "It's pretty fragile - installed a water system," says Lujan. "I any extra weight on the surface can haven't used it yet," he admits, but with break the wire," says Razum. the constantly changing weather con- Indiana-based Easy Heat, Inc., ditions in Denver, he can expect to use designed the heating system for the system often during the season. Coors Field. While electric heating systems using "What we installed was about seven wires or cables have been in use for watts per square foot of heating cable six many years, hot-water systems have inches below the surface," explains John become popular in recent years. The Zollman, national sales manager for Chicago Bears do not have a heating Easy Heat. The company has also worked system at Soldier Field, but they have The football field at Arizona State on heating systems for Busch Stadium experimented with a heating system University, which is also used by the in St. Louis, MO, Sullivan Stadium in on one of their practice fields. "We've used Arizona Cardinals, utilizes an Foxboro, MA, the Air Force Academy in it for two years just on the side of the prac- underground heating system to Colorado Springs and Mile High Stadium tice field," says Ken Mrock, who main- extend the season for the tains the practice fields for the Bears. The bermudagrass. hot-water radiant-heat system was "Last year we turned it on when it installed at eight-, ten- and twelve-inch started getting cold in October, and we depths. "We found the ten-inch depth is were able to keep the frost out until we best because it doesn't affect your cultural were done, so it worked much better." practices." The Bears are planning to Mark Razum, who supervises the install a hot-water system at the new 37- grounds crew at Coors Field in Denver acre practice facility they are building in for the Rockies, operates an electric Lake Forest, IL. heating system for the baseball field Heating systems have been in use right out of his office. "There are three for years at cold-weather venues such as zones that control the entire field, and Denver, Green Bay and New England, I have the control right in my office,"says but they can also be used to extend the Razum. "Each zone has it's own ther- season for bermudagrass fields at warm- mostat set eight inches below the surface." weather venues. Don Follett, manager Razum keeps the controls set at 58 of stadium grounds at Arizona State degrees, but he can override the system University, has developed a unique with a flip of a switch if he feels the field application for the hot-water heating is getting too much heat or not enough. system at Sun Devil Stadium, which is "I can turn it to manual and go out with shared by the Arizona State football a temperature probe if I felt that 58 team and the Arizona Cardinals of the degrees wasn't enough." NFL. ''I take steam heat from the campus Coors Field in Denver, home of the Razum will maintain the soil tem- boilers and store it in a 500-gallon tank Colorado Rockies, has 45 miles of perature at 58 degrees for the remainder underground heating cables installed in the end zone," he explains. Follett uses of the baseball season and through any in the rootzone. Photo courtesy: heat sensors to determine the temper- playoff games the Rockies might play. Randall & Blake, Inc. ature of the soil, and when that tem- "After the season I'll set it to 48 or 50, then perature drops to a certain, predetermined work the temperature up gradually," in Denver. "It is something that has level, the heating system is automatically he relates. Razum expects to use the been proven to work," says Zollman. "It activated. "I usually keep it right around system for initial greenup in the spring. is really designed to fool the grass into 72 degrees," says Follett. The German- Last year he started warming up the field believing that it's the growing season." designed system was installed approx- in mid-February to around 50-52 degrees, In many cases, sports turf managers imately seven inches below the surface and with mild temperatures for the pre- can keep turf green and growing even of the field at Sun Devil Stadium. season replacement games, he was able when air temperatures dip to freezing or BioTherm Hydronic Inc. of Petaluma, to back the system off gradually until it below by keeping the roots at a con- CA, has developed a soil-temperature con- was turned off entirely in late March. stant temperature. "The daylight is a trol system called TurITemp that has been The electric heating system at Coors factor," admits Zollman, "but in many installed at several golf courses, including Field features roughly 45 miles of cable cases there is enough daylight to buried beneath the surface. ''It has a resis- sustain growth." continued on page 12 October 1995 11 ---- r FOR PRODUCT INFO FAXED TO YOU NOW! DIAL: 1(800) 817-1889 Heating Soil ''It's done in Europe all the time." Rearden with heating systems and says he's seen continued from page 11 admits that the company markets his share of problems. "I haven't seen one Palos Verdes Country Club near Los heavily toward golf courses, but he sees that really worked well," he notes. Toma Angeles and Pebble Beach Golf Links, to plenty of room for expansion into the specifically recalls problems with the combat problems with soil tempera- sports- turf market. underground heating system at RFK tures on sensitive greens. Jim Rearden, Drawbacks of Heating Systems Stadium in Washington, DC, when he was president ofBioTherm Hydronic, Inc., says Not all soil-temperature control sys- preparing that field for an NFL playoff the trend is spreading toward athletic tems are unqualified success stories.