Dickey Stephens Ball Park in Little Rock, Ark., is home to the AA minor league Arkansas Travelers, an Anaheim Angels farm team. A combination of recent flooding in the area and the park's unprotected drainage system led to the creation of multiple sinkholes around the field. The sinkhole in the outfield was of significant size, measuring 35 ft. in diameter. The ballpark is located in close proximity to the Arkansas River and positioned below street level, a factor that contributed to the collection of an abnormal amount of ground water underneath.
The French drainage system installed underneath the field was designed to drain and redirect water out from beneath the field. However, soil, silt and sand were also being washed into the drainage system and removed from underneath the field, leaving large voids that ultimately created the sinkholes. This recurring problem over a seven-year timeframe finally necessitated repair.
The city tapped into allocated funds to begin restoration of the drain system and repair of the sinkholes. The project involved installing new pipes, new aggregate, and a high strength geotextile fabric wrapped around the pipes that would keep soil out of the new drain system and eliminate problems of the past.
To protect the ballfield and minimize post-construction restoration of the grounds, portable construction mats were employed to support necessary vehicle and equipment traffic during many weeks of repair. Presto’s Geoterra HDPE mats were chosen for the project as their lightweight design allowed them to be deployed and installed without heavy equipment. Due to the length of time the mats would be required on site, the low cost compared to heavier mats was also a factor in the decision making.
The soils on site were very soft due to the recent heavy rains. To provide extra soil bridging and strength, a high strength HP270 geotextile fabric was placed between the subgrade and Geoterra mats. The individual mat sections connect with a locking device that allowed work crews to configure the access road and work platforms to the exact size and shape required. According to the project engineer, the portable mats worked well for this project. Track hoes, front end loaders, concrete trucks, and haul trucks all operated on the mat surface continuously for over a month’s time. Over 250 haul trucks carrying 16 to 18 cu yards of material per truck accessed the mats.
After the repair, nearly half of the mat sections were removed and moved to storage for reuse on later projects. The mats also work well for turf, protecting ground from concentrated rutting and minimizing need for post-construction restoration work.