Hitting A Home Run
When a new professional sports stadium opens, you can bet your last dollar it will be teeming with the latest and greatest technology.
Target Field, the new $520 million home of the Minnesota Twins that opened to rave reviews in early April, certainly falls into that category - especially in the plumbing, turf-conditioning and green technology departments.
“Money was spent on quality,” says Kip Olson, the piping coordinator/food service project manager on the stadium project for Eden Prairie, Minn.-based Metro Mechanical Contractors.
“Plumbing-wise, it’s not nearly utilitarian. It’s quite fancy.”
Aesthetic, Yet PracticalFixtures in the 39,504-seat facility - such as the 407 lavs (sinks by Kohler, Elkay and Lacava; faucets by Kohler, Zurn and Mirabelle) - were designed with the end user in mind.
“The finishes are pretty upscale for a building that is going to be utilized by the public as much as it will be,” Olson says. “Fixtures go up in scale quite dramatically when you get into the suites and the private areas. But, for example, we didn’t use anything in the presidential suite that the public couldn’t buy. This stuff is very nice. They wanted high quality but a lot of quantity.”
The practical part comes into play with how the fixtures were laid out (Colorado-based M-E Engineering was the design engineer, while Kansas City-based Populous was the stadium architect). Public restrooms are loaded with water closets, urinals and, in many cases, back-to-back walls of lavs (one bathroom on the terrace level has 19 toilets in a row with back-to-back walls of eight lavs each). Waiting in lines snaking out of bathroom entrances will likely be an uncommon occurrence.
“Somebody really thought it out and got it right,” Olson says. “They definitely have the fan in mind. The layout is fabulous. If I’m there with my family, I know where I’m going to the bathroom.”
Green MovementGreat thought was also given to water conservation at Target Field. Of the 610 water closets (by Kohler and Sloan), 306 feature Sloan’s dual-flush Flushometer toilet - complete with green handle. Low-flow faucets and showerheads also were chosen for the restrooms and locker rooms.
But the biggest green advancement comes in the stadium’s elaborate, custom-designed water filtration system.
The Twins were approached about the filtration system - tabbed the Rain Water Recycle System - by Pentair, a Minneapolis-based water solutions company that supplied the engineering and the equipment for the system.
“To my knowledge, this is the only system where the water is reversed right back to the ballpark,” says Paul Johnson, the stadium project manager for the Twins. “If you look at the big picture, it’s a cost savings and it’s the right thing to do environmentally.”
Rainwater and water washed down from the main bowl of the facility (which typically includes sundry beverage and food waste) are collected in a 12-foot diameter cistern buried beneath the field’s warning track.
The water then goes through a filtration and disinfection process before entering a holding tank. When there is no demand for water, the treated water will accumulate in the holding tank and overflow back to the cistern. When there is demand to irrigate the field or wash down the lower bowl, water-booster pumps draw water from the holding tank and supply the water.
“We have the ability to pump the water to the filtration system and then put it right back on the field (for irrigation) or make that bowl wash-down water clean,” Johnson says. “We’re taking the burden off by not putting the water back into the storm sewer system and by not taking from the city’s water supply.”
According to Pentair, the system is designed to reduce the demand on the city’s municipal water supply by approximately 2 million gallons per year.
The U.S. Green Building Council in early April awarded the stadium silver-level certification in its Leadership in Energy and Environmental Design program.
More CreativityThe number of boilers, water heaters and tankless water heaters is not overwhelming at the stadium (a total of 88 water heaters were installed). That’s because the team is able to tap into the city’s district steam supply in order to generate most of its hot water. Certain areas - smaller restrooms, food-service facilities and mop closets - still have some form of traditional water heaters. Tankless water heaters (by Eemax) are mainly found in family toilet and more private restroom settings.
“The district steam comes in at high pressure and is converted down (100-120 psi); then it runs through convertors and produces hot water that is stored in a large tank and that water is circulated through the building,” Olson explains.
Thinking About The WeatherWhen plans were announced for an open-air baseball stadium in Minneapolis, early-season weather was a common topic of discussion.
But the Twins have a definitive answer to that dilemma in the form of an elaborate turf hydronic heating system beneath the playing field - similar to one installed at Lambeau Field (home of the NFL’s Green Bay Packers). Designed by Zurn and Green Bay, Wis.-based mechanical contractor Tweet/Garot, the system utilizes 3/4-inch PEX tubing (by Zurn) at 6-inch o.c. throughout the playing field (total linear footage of approximately 40 miles). The tubing is located 10 inches below the finished turf elevation.
A water-glycol mix is circulated throughout the system to prevent water from freezing during winter months if the controls system is not calling for heat.
The system is separated into six heating zones (the right field area had to be broken into two zones based on sun-shade studies) that allow new Twins groundskeeper Larry Divito (former groundskeeper for the Washington Nationals) to fine-tune temperature adjustments throughout a portion of the field based on sun-shade variations. A total of 20 sensors are buried 5 inches below the turf elevation. Those sensors provide continuous data to a controls system Divito can view and evaluate from remote locations.
“It allows earlier baseball to be played because the grass is further along in its growth cycle than it normally would be in early spring in Minneapolis,” says Brendan Moore, the playing field construction project manager for Mortenson Construction, the stadium’s general contractor. “The heating system is state-of-the-art.”
Like the water filtration system, cost-savings will be realized with the hydronic heating system, which also taps into the city’s district steam supply.
“It will give the Twins a tremendous amount of savings,” says Kipp Sturdivant, former senior project manager at Tweet/Garot (now a project manager for Fields). “Being able to utilize the central steam is definitely an advantage long-term. There is less maintenance on a heat exchanger compared to boilers - it’s not even comparable.”
The field also has a 13-zone irrigation system with 80 irrigation heads (by Toro).
With the wide discrepancy in the weather conditions in Minneapolis, extra caution had to be used in making sure pipes do not freeze - especially ones located outside the park. A portion of the stadium sits over both Interstate 394 and two railroad systems.
“The use of heat trace is quite substantial,” Olson says. “There’s miles and miles of it. Both the storm and the sanitary systems are located over 394 and the railroad. Those pipes have heat trace and are insulated and metal-jacketed because of weather and the pigeons. They love the fiberglass insulation.”
A Helping HandOlson said the use of building information modeling software was a key component in the success of the plumbing installation.
“BIM was used on all the mains, corridors and all of the sleeving,” Olson notes. “It’s an invaluable tool for doing that. It’s the only way to build a job as far as I’m concerned.”
Olson, whose primary function for the last several years at Metro Mechanical has been working with BIM technology, used England-based MAP software on the stadium project.
“Everything is drawn in 3D,” Olson says. “We can order right off the program. If you can draw it, you can order it. When you are drawing steel W-beams, every W-beam manufacturer in the world comes up.”
The accuracy of the software boggles Olson’s mind.
“It gets it down to 3/8 nuts on a 3/8 rod,” Olson notes. “The accuracy goes down to 256th of an inch. When you are drawing, it’s like you have your hands in a bag of fittings.”
ChallengesThe plumbing portion of the construction did include a few hurdles - which Olson and his crew cleared. Olson says varying soil types made things tricky in terms of laying the 18,500 feet of underground sewers.
“They call it the city of lakes for a reason,” Olson jokes. “The soil conditions for bedding pipe were challenging. You could dig through decent soil and 10 feet away there could be water. It made it interesting.”
And because of the portion of the stadium that hangs over the interstate and railroads, Olson and his crew had to contend with not only cars whizzing by, but also the trains on the nearby Burlington Northern-Santa Fe line and the city’s Light Rail system operating in the vicinity while elevated plumbing work was ongoing.
“There is overhead plumbing that was installed, so you had cars whizzing over the top and the railway was live. We were working on aerial lifts and had to get out of the right-of-way when a train would pass by,” Olson says. “We made it work.”
The Big MomentWhile the first official ballgame in the stadium was held in late March (the University of Minnesota played Louisiana Tech in front of more than 36,000 fans), Metro Mechanical (led by MMC Plumbing Superintendent Mark Burch) held its own exhibition game last fall to test out its handiwork via a “Super Flush.”
“It was 2,000 gallons per minute,” Olson notes. “We got about 100 people together and we timed the flushing and used the stadium public address system to coordinate. We started flushing very slowly (with 20 percent of the tested fixtures) and then we increased. We ramped it up and ramped it back down again. It was like a seventh-inning stretch, but it lasted three times longer. How else do you certify that everything is working? You have to give it a test. It was a little unnerving at first. With that much water flowing throughout the systems, one error could be catastrophic. It came off without a hitch.”
And after spending 26 months on the project, Olson feels multiple home runs were hit when it comes to the plumbing components of the stadium.
“It’s a win-win situation for the fans, the Twins and the environment,” Olson says.