NFL Field Certification

To ensure this, NFL Football Operations leaves little to chance when preparing fields for game day. Even the color of the tarp is prescribed.

Because a white tarp reflects the sun’s rays and is less likely to burn the grass, the NFL mandates its use on natural grass fields in warm-weather locations and on those in cool-weather sites from August through October. From November through January, those cold-weather sites are instructed to flip their tarps to the dark-colored side; since darker colors absorb the sun’s rays, that helps to warm the grass and melt snow and ice.

That’s just one example of how NFL Football Operations makes sure its venues are ready for each week’s contests. Home teams are responsible for ensuring that their fields live up to NFL standards and comply with the league’s recommended practices.

ENSURING A LEVEL PLAYING FIELD — LITERALLY

If a field fails to meet the NFL’s standards on any of the tests, the club shall initiate remedial measures and take all reasonable measures to remedy the problem. To make sure test results are accurate, the league may send a third-party company to do spot checks on a day’s notice.

Field managers test all fields — synthetic turf and natural grass — for hardness within 72 hours before a game. A Clegg Impact Tester drops a weight at several designated points on a field to measure its hardness. Spots that are too hard must be fixed and retested — and must be in compliance before gameday.

The NFL requires a visual inspection of all fields to check for defects or foreign objects. Field managers often drag the field with a magnet to look for items such as loose screws, bolts or nuts left behind by a concert, spikes that may have fallen out of player cleats, or other debris.

The NFL’s synthetic fields are tested for the depth and evenness of the infill — the substance that absorbs impact and creates the field’s foundation, allowing it to play like a natural surface. The league measures infill depth at 40 designated areas around the field to make sure that it isn’t too soft or too hard and that the infill is distributed evenly. In spots that are uneven, crews can add, remove, or smooth the infill.

Synthetic fields must be certified for infill before every game. The league requires certifying a synthetic field within 72 hours before a game, which allows for an evaluation and leaves time for any needed repairs. If a concert or other event is held on the field, the infill must be tested between the event and the next NFL game.

Natural surfaces are tested for moisture content at the same time they are tested for hardness. Within 48 hours after a game, the field is also subject to a stability test, which measures how well it held up.

There is no single way to define exactly when a field is stable or when it should be resurfaced, so the league relies on an expert’s opinion. Field experts use the online Gameday Field Surface Reporting System to grade fields in three areas:

• Surface shear (how easily grass separates from the soil), measured in nine locations
• Percentage of the field covered by grass, measured in nine locations
• Overall rating on a scale from 1 to 10

These criteria determine whether a surface is fine or needs to be repaired or replaced.

The league recommends that all NFL venues consider the dates of scheduled games when planning other events to allow enough time for repairs, irrigation or replacement of a playing surface before the next game.

NFL Football Operations prescribes when clubs must cover fields and which safety-tested chemicals they can use for treating ice. There are also requirements that clubs have enough snow removal equipment on hand and that they have enough bright-colored paint in case snowfall makes the field markings “indistinguishable from the body of the playing field.”

All clubs with natural grass fields submit a resodding plan to the league; nearly all grass fields require re-sodding at least once during the season.

A lot of preparation — and a little luck

Despite all of the planning and hard work, sometimes NFL officials and field managers in open-air stadiums still need help from Mother Nature.

Winter weather created terrible conditions on the synthetic field at New Jersey’s MetLife Stadium before Super Bowl XLVIII in February 2014. There had been so much snow and rain that moisture had gotten into the field and had frozen after overnight temperatures dipped into the single digits. The field’s hardness measurements were “staggeringly high.”

Two nights before the Super Bowl, the NFL brought in vibrating steamrollers to break up the ice, and temperatures in the 30s the day before the game helped warm the field up and dry it out. Workers covered the field and blew heat under the tarp all night, then groomed the field the morning of the game. At kickoff, the temperature on the field was 49 degrees.

“The field is great for the Super Bowl and we look like heroes, but it was a really lucky break with the weather,” said Mike Kensil, the vice president of game operations at the time. “And the next day, we get nine inches of snow — it starts snowing like a madman. So I’ve even thought, ‘Man, even Mother Nature won’t mess with the Super Bowl.’”