Guide to O'Brien Field

PEORIA - As a teenager in the 1980s, Mark Vonachen portrayed the now politically incorrect mascot Chief Rainout during Peoria Chiefs games at Meinen Field.

Now, as the club's assistant general manager in charge of stadium operations at state-of-the-art O'Brien Field, Vonachen will vouch that rainouts at the ballpark should become as outdated as, well, his old Chief Rainout costume.

"The field will hold up to five inches of rain an hour," Vonachen said. "About the only way we'll have a rainout is if it's pouring during the game."

Anyone who's sat through a rain delay at a new major-league park and has seen how quickly the grounds crew can get a soggy field ready to play understands the concept. But most of us don't know the science behind it.

The O'Brien Field sod has an eight-inch deep root zone of 90 percent sand and 10 percent Dakota peat for nutrition. The high concentration of sand naturally relieves soil compaction.

Beneath the sand and peat mix are six inches of gravel. Running through the gravel are drainage tiles that run from home plate to center field. A huge sump pump beyond center field then drains into the city sewer system.

The makeup of the pitcher's mound and batter's boxes are almost 100 percent clay because it packs better and holds moisture well. The rest of the infield skin area is 80 percent clay and 20 percent sand.

The infield mix was bought from Stark Excavating in Bloomington.

"Seventy-five percent of the game is not played on the turf, but on the red dirt," said new Chiefs head groundskeeper Perry McCoy. "So you put more priority on the red dirt (keeping it watered and smooth)."

Throughout the stadium construction, the weather has smiled on the Chiefs. A mild winter allowed River City Construction workers to virtually continue non-stop. A cool, wet spring has provided excellent conditions for the 90,000 square feet of sod to take root well.

The sod, purchased from a sod farm near Gary, Ind., is a special sports turf mix of bluegrass seed.

The Meinen Field sod was bought locally at D.A. Hoerr & Sons.

"This is a different blend of bluegrass that's more tolerant to the traffic and sports usage," said Vonachen. "It's a stronger and hardier blend and a lot more expensive."

Indeed, the price tag just for the field was around $450,000.

"For today's technology, this is a state-of-the-art field," said McCoy, a Delavan native who has worked around the world on golf, soccer, polo, baseball and football fields. "The main difference people will notice compared to Meinen is the finished grade of the field.

"The outfield is flat and the infield has been laser-graded on a one percent slope draining away from the pitcher's mound. And you don't have that big dropoff from the infield to the outfield."

Even fertilizing is a high-tech undertaking. For the first two months, McCoy must collect four samples of soil and grass from different areas of the park and send them to a lab in Texas. He then receives a detailed list of how much fertilizer and what kind of nitrogen/potassium/phosphorus mixture to use.

It's applied every week to 10 days during the early two-month period. Later, the frequency of the testing and application can be scaled back.

"The first year is definitely a more aggressive fertilizer program," McCoy said. "It's a real spoon-feeding process at first.

"Next year, it'll still be a pretty heavy fertilizer application, and by the third year, we'll have more organic matter from decaying roots and grass clippings built up and can cut back."

The field is mowed every day during homestands, trimmed to 1-1¼ inches high. It takes less than an hour to cut the outfield grass with the Chiefs' new 72-inch cut mower. A walk-behind mower is used for the infield.

So far, the field's only problem has been a small proliferation of weeds, also aided by the weather but unseen from a distance. Because the sod is so young, a weed control couldn't be applied until last week.

"There are a few dandelion plants and some pretty good patches of clover," said McCoy. "But you can't see them until you get right on top of them."

A few weeds haven't dampened his enthusiasm.

"I get excited about this field every time I come down here, every time I see a picture of it in the paper or on TV," he said. "The grounds crew is definitely excited about moving down here. This is going to be our baby to nurture to fruition."