The repair process for the sinkholes at Dickey-Stephens Park required a replacement of the drainage system.
After three months of replacement and repairs, the Arkansas Travelers are hoping the only thing sinking on the baseball field come April 7 is a pitch or two.
The outfield of Dickey-Stephens Park on the Arkansas Riverfront in North Little Rock is flat now, thanks to $425,000 worth of work and materials. But in December, sinkholes filled the warning track, making the field unusable for gameplay. While the sinkholes didn’t appear until late fall and winter, the problem began during the 2015 season.
What followed was a dash by the Travelers and the city of North Little Rock, which owns the ballpark, to make necessary — and permanent — repairs to the field and its underground drainage system before the Double-A minor league baseball team begins its 10th season at the stadium.
While the team worked with engineering consultants Terracon to identify key problems, the time crunch didn’t permit the city to hire outside contractors, so the city was on its own when it came to repairs.
“We didn’t have time to contract out to a contractor, didn’t have time to contract out the engineering,” Chris Wilbourn, the North Little Rock city engineer, said. “It was done in-house.”
Warning Signs
According to General Manager Paul Allen, small dips developed in the field last spring and summer. One at a time between games, the grounds crew would pack them full and flatten out the surface of the field.
“At times, that would take from sun-up until the gates opening for a game, and that would be consecutive days during the peak time when it was happening,” Allen said.
But those temporary repairs were not enough. In December and January, rainstorms and flooding on the Arkansas River caused the field to deteriorate further, creating more sinkholes. One, on the center field warning track, was about 35 feet wide and six to seven feet deep, according to press reports at the time.
Wilbourn said the sinkholes were caused by a series of events.
High waters on the river caused the groundwater to rise. Although the field had a drainage system in place to divert the groundwater, the sheer volume of water allowed sediment into the system, which caused parts of the field to sink.
Wilbourn said the resulting sinkholes weren’t what many people might imagine: the ground collapsing and swallowing whatever is above in a matter of minutes.
“If you sat there for 24 hours you would see, in the worst case, minute movement,” Wilbourn said. “So what was happening was, a little bit of sediment was getting into the water that was coming into the pipe. Well, a little bit of sediment over a long period of time becomes a lot of sediment. So it was very slow moving — no danger of anybody ever getting hurt or anything … It was over a large amount of time an amount of sediment slowly moved into our drainage system that we didn’t want.”
The volume of sediment in the pipe compromised the drainage system, calling for a full replacement. So in mid-January, Wilbourn and the North Little Rock mayor’s office decided to undertake a complete repair. They began by digging into the warning track and replacing the drainage system.
“We have the luxury of hindsight because we believe we know what caused the problem — it was definitely a groundwater pressure issue,” Wilbourn said. “So when I looked at it, I made adjustments to the original design … I believe it’s a permanent fix.”
The Final Step
After replacing the drainage system with sediment-free lines, workers used layers of filter fabric, industrial sand and C-ballast gravel, a type of crushed rock that is used for drainage and gravel roads.
On March 17, workers laid the turf, the final step in the repair process. That gives a couple of weeks before the season begins for everything to settle, Wilbourn said.
Allen said planners were aware of the possibility of sinkholes when they selected the park’s riverfront site about 10 years ago. The original drainage system was in place because of that risk; it just didn’t work perfectly, he said.
“You can always be a Monday morning quarterback and say you would do something different,” Allen said. “Another idea would have been to build the stands up instead of building down. It’s hard to say. But this is absolutely an outstanding facility, second-class to no one — and perfect location.”
The Arkansas Travelers’ home opener is at 7:10 p.m. on April 7 against the Midland Rockhounds.
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