Sports to the Max

Make the Most of Your Sports Fields

By Rick Dandes

Many municipalities and school districts are having to consider upgrades to their current recreation facilities, or building new sports complexes altogether, given the increasing popularity of youth outdoor sports, especially soccer, field hockey, softball and Little League baseball. Each of these sports are best played on slightly different sports surfaces, mostly natural grass, but tight budgets and the need to maximize programming also might mean that a switch to a multi-use synthetic field is in order, and that's OK, said several experts.

It's all about maximizing the safety and playability of an athletic field, said designer David Nardone, principal, Stantec, Boston. And that's accomplished with better, safer playing surfaces resulting from the development of improved construction and maintenance techniques.

"If you are considering putting in a new surface," Nardone said, "before you approach a vendor, start by asking yourself about the user groups: What is the sport? What are the ages of those who will be using the field? The best vendors will really try to tailor the turf to the user group. And yes, there are preferred turfs for certain sports."

Take an artificial turf baseball field. There are certain infill mixes that affect a ball coming off the bat. [By definition, infill is usually an acrylic coated, green-colored sand with antimicrobial properties or black crumb rubber particles. Either infill product is put in between the blades of the artificial grass lawn products to deliver a complete solution.] The infield might have a different infill mix than the outfield. In the infield, it is more the ball bouncing off the surface, while in the outfield a player might be diving to catch a ball and you can provide a more resilient surface to make it safer for the ballplayer to stretch out and dive on.

When it comes to the rectangular field sports and synthetic turf, Nardone said, "if we're talking about soccer or field hockey, the ball is constantly in contact with the turf, so the surface is a critical part of the game, versus lacrosse or football."

You want to consider the type of fiber a vendor offers, because different fibers are more appropriate for a soccer field versus a lacrosse field. You don't want the ball to roll too slow or too fast in soccer. Field hockey is almost the opposite. You want the ball to roll as fast as possible and there are some synthetic turf products that specifically are geared to that kind of surface. "But most smaller municipalities could not install such sports-specific surfaces because of the cost of a dedicated facility. In those cases, a multipurpose surface is called for, given monetary restraints," Nardone said.

Meanwhile, there are now hybrid surfaces being developed that are appropriate for both lacrosse and field hockey, and those hybrid surfaces are trending among buyers.

If your fields are natural grass, the sports turf needs to be maintained and cared for rigorously to preserve its durability and responsiveness to players. Like any material, it should be regularly evaluated for performance and replaced when necessary. But the proper selection process will help ensure that you get the most out of your grass, Nardone explained.

Natural grass management is a constant task, he stressed. Football fields, golf courses, even some grass tennis courts, all require regular evaluation and attention to counteract wear and tear. Depending on the intensity of traffic, some natural grass is more suited to certain sports than others. Golf course grass, for instance, can't sustain the heavy traction of football sprints, tackles and team movement.

Besides players and game action, weather elements must also be considered. If you are in the mid-Atlantic or up in the Northeast, where weather is a concern, said Darren Gill, vice president, global marketing, of a Montreal, Canada-based synthetic turf manufacturer, the playing season needs to be shortened. During winter months, fields aren't being used and as the snow melts and the weather turns better, grass fields need time to rebound from the cold weather. They need to thaw and maintenance work needs to be done. As a result, the playing season gets even shorter. That's a major reason why universities and pro teams in those parts of the country have turned to artificial turf. But in other more moderate climates, Kentucky bluegrass and perennial rye grass are popular choices for general multipurpose recreation areas.

If, however, the traditional maintenance methods are not restoring grass in your recreational area to an acceptable standard, you may need to invest in synthetic turf, meant to be long-term.

You should make a decision based on climate, use, weather and location, suggested Noel Brusius, Certified Sports Field Manager, Waukegan Park District, Ill.

The district has 13 natural grass soccer fields, four softball fields and one synthetic field, added Mike Trigg, Waukegan's manager of risk management. The grass fields are bluegrass-rye grass. "We do monthly and annual safety inspections of field conditions," Trigg said, "testing both our synthetic turf field and natural grass fields."

Testing Field Hardness

A major trend in sports surface management is a movement toward becoming more aware of field hardness, explained Andy McNitt, director of Penn State's Center for Sports Surface Research. "Surface hardness is affected by many things. Certainly, wear is one of them. The more foot traffic you have on a native soil, especially on native soil fields, the more compact it gets. You will want to relieve that compaction."

What most affects the surface hardness of native soil is moisture content, said McNitt, who also serves as a technical advisor to the NFL groundskeeper association. "We know a native soil field is high in silt and clay and when it dries out it is very hard. When it's wet it is very soft. So, moisture management becomes critical and at a park and recreation level, sometimes that's very difficult to control."

One thing to do is set some kind of a use parameter or use discipline. Don't use the field if it's too wet, and don't use it if it's too dry. But how do you know if it's too wet or too dry? Something every park manager can do, "and I think it's smart to do from a liability standpoint, is go out and buy an impact tester," McNitt suggested. For example, a Clegg tester. "You can get them now calibrated to the NFL standard for about $4,000. In the past, when I've talked to park and recreation people and high school people they were like ostriches with their head in the sand. They said, well, if we don't test, we don't know, then we can't be liable. And I think that is a pretty shortsighted response that they don't want to know whether their fields are too hard or too soft. Primarily too hard."

Keeping Players Safe

The priority when maintaining sports fields at any level is to provide safe, playable fields for athletes. Turf safety is measured by what's called a G-max test, which measures the shock attenuation of a surface by dropping the impact tester's "missile" onto the turf and measuring the resistance and absorption rate. The resulting G-max value, Nardone explained, represents the ratio of deceleration upon impact to acceleration due to gravity. In other words, it measures how well the turf absorbs and slows the impact.

Right now the American Society for Testing and Materials (ASTM) and Synthetic Turf Council recommend keeping the G-max level below 200 (although there is talk of lowering it to 165). The NFL is testing requiring teams to maintain their fields below 165 as well. These lower numbers stem from growing research on concussions showing that any safety enhancements can help. So, the lower the turf's G-max value, the greater safety buffer the surface can help provide.

When well-maintained, typical natural grass turf systems inherently have a lower G-max value—usually in the range of 80 to 110. So, synthetic turf manufacturers are trying to create systems that get closer to those naturally lower levels, which involves designing a field with a padded turf. But, it is also important to remember that the variety of soil profiles in a field area, and the maintenance practices used (or not used) on the field, can make the safety level of natural grass fields harder to predict. While the NFL now tests its fields before every game—whether synthetic or natural—lower levels of competition don't have the resources to maintain that same kind of rigorous program to ensure the turf is at safe levels.

"Because of the publicity surrounding safety, and preventing concussions at every level of sport, there is increasing awareness that we need to monitor field quality," McNitt said. "So for the cost of a Clegg Impact Soil Tester and very little time, I think it would be very impressive if you're called into court because someone got injured on the field and you were able to produce documents that prove you test regularly, were way ahead of the curve and have use parameters."

Park maintenance staff should understand that a field has to be aerated if it gets too hard or irrigated, if that's available. "Just have some ongoing record," McNitt said.

Artificial turf is under the same scrutiny as grass—maybe even greater scrutiny now. "The thing about artificial turf is it needs to be maintained just as a natural grass field needs maintenance, but in a different way," McNitt said. "People are under a false assumption that synthetic fields get hard over time because of compaction, and that is really not true. Assuming that you are working with a quality vendor and they give you quality infill material, that infill material is going to be fairly uniformly sized and difficult to compact to any great degree."

What McNitt and his team of researchers learned is that fields get harder over time due to walk-off rubber. The infill crumb rubber gets in people's shoes or on clothing, and it slowly, almost imperceptibly, leaves the field. What you then need to do is buy a depth gauge, walk around and monitor the infill depth.

"In the NFL," McNitt noted, "they have to do it at a minimum of 40 locations before every game. The manufacturer will give you a target value and a range, and when the infill depth falls below that number, it is time to begin topdressing the crumb rubber. That is very easy to do. You need a topdresser and a broom, which you should have anyway, to drag behind it."

Put it down in small quantities and drag it back in. In the past what has happened is rather than do this routinely, people wait until it reaches the critical level, and there was too much crumb rubber lost and the fibers were too matted. Then, instead of a simple in-house correction, you'd have to hire a company to come in and renovate the field, add the crumb rubber and get the fibers to stand up straight.

McNitt suggests that it is much cheaper to go out once or twice a year and put on small amounts yourself. Monitor it with a gauge, put on small amounts of crumb rubber, broom it in and make sure you're buying the crumb rubber from the manufacturer you bought the product from so that the infill matches. That's important. If you do all this, you'll find it is more cost-effective than bringing in an outside company once every five years and spending tens of thousands of dollars to get the field back in shape.

With artificial turf, moisture content is not as important as long as the field isn't completely frozen with water in the infill. The worst-case scenario with a synthetic field, McNitt said, is you get some snow, snow partially melts and then it re-freezes. That is when those fields will get exceptionally hard. But, they don't hold much water, so usually freezing doesn't have a major effect on surface hardness. And, a properly designed drainage system can also help prevent problems.

"You don't have to guess if you have an impact tester," McNitt said. "You walk out, bounce it around, bounce it on the seams, bounce it on the inlays and make sure the field is in good shape, and I believe it really lowers your risk of injuries."

Another way to prevent injury is to install a safety pad underneath the infill. "More pads are going in than ever before—it's a trend," said Nardone. "Concussion prevention is a big part of the reason for the trend. Understand, though: Your infill depth is part of your safety system whether you have a pad or not. And depth of rubber."

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