Feature Article - February 2012
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Greener Grass Awaits

Environmental & Fiscal Responsibility Team Up in Synthetic Turf

By Tammy York

What Lies Beneath

When you are replacing your field, it is a good time to test the field for proper drainage. To see if water is percolating through the stone as it should, you should have your consultant do a dual-ring as well as a flood test.

stone base. The center ring is filled with water and allowed to drain into the stone below. This gives you information on only the vertical drainage of water from the inner ring and gives you a good indication if you have problem with your stone base.

The flood test is exactly how it sounds. An area of the field is flooded. The flood line is marked and then you record how much time it takes for the water to dissipate. Then you repeat this process again. And it gives you an indication of how quickly the stone is draining. If you have problems with the drainage, these will need to be addressed before you proceed with the field replacement.

Whether you are starting with a new field or replacing an old one, the right underlayment can have an impact on long-term costs. You can find products made from recycled materials that are capable of lasting through two or three turf replacement systems. Be sure to ask your synthetic turf supplier about the underlayment and its lifecycle.

Keeping G-Max Values Low

One of the safety concerns with playing fields is the g-max value. The g-max value is a measurement of the shock-attenuation performance of the field, or how hard it is. The g-max value is a ratio of the maximum acceleration experienced during impact to the normal rate of acceleration due to gravity, or in simpler terms: Is the force of the impact absorbed by the field or the player's body?

The higher the g-max value, the poorer the shock-attenuation performance of the surface. This will affect the playability of the field and the safety of the players. A typical synthetic turf field when built has g-max values around 100, which is equal to perfect natural grass. As synthetic turf fields age and if they are not well maintained, the g-max values can climb to 160 and higher. At 200 g-max value you can fracture your skull.

"We are seeing a prevalence of 160 g-max values on fields," Sawyer said. "Parks and schools don't have the maintenance budgets anymore and think that they don't have to maintain it since it is artificial turf. But when you have the field that has band, track, football, soccer and lacrosse on it and the infill is being packed down—if it isn't properly maintained, the g-max goes up."

"You never want to see your g-max value reaching 200. You want to be in the 90 to 160 g-max value range to ensure that the field is safe and playable," Novak said. "When you replace the field, the amount of work and costs involved isn't as much as installing a new field. You can make the field better by adding a pad underneath the field to mitigate the shock-attenuation and protect the laser-graded base."

This pad below the carpet layer will also protect the stone underneath, Novak added. "When you do a future field replacement, it will cost less money because you won't have to fine-tune the stone," Novak said. "There are different pads on the market, including poured in place pads that are expensive but last a long time. Shock pads are another alternative and are created from polypropylene panels or rubber. These can vary in height from 10 to 13 to 25 mm. There are claims that the pad can extend the life of the field, but this hasn't been proven in any studies."