Stormwater Management Upgrades Underway at Oak Hall Regional Park
Significant stormwater management upgrades are underway at Oak Hall Park Regional Park in Boalsburg, an area that has seen severe flooding in recent weeks during sudden, heavy rainstorms.
Ron Woodhead, director of Centre Region Parks and Recreation, says the Pennsylvania Department of Environmental Protection and Centre County Conservation District have approved various supplemental stormwater management measures in response to the recent storms.
College Township officials, contractors, engineers and COG began addressing stormwater issues after the June 25 storm that caused serious flooding. Then, the DEP and CCCD approved the detailed remediation plan Friday, July 11 – two days before Sunday's severe rainstorm, which resulted in 1.15 inches of rain.
"So we had more water, not nearly as much, but we had more water come down ... but at least the measures taken prior to that reduced the amount of water, but didn't eliminate it," says Woodhead. "Now, contractors are proceeding full speed ahead on the plan."
Engineering and maintenance crews are implementing the plan, which is expected to be complete within roughly 10 days.
"So the challenge in this interim time is to take any extra measures so that if you do get overwhelmed, you don't have these catastrophes that we face," he says.
The overall goal is to stabilize areas at the top of the hill at the park, before the water reaches the bottom of the hill at the park's driveway – which is where the severe flooding occurs. Work will include making sure each basin on the hill receives the amount of water it was designed to receive, which would help minimize the impact at the bottom of the hill.
"What happens is the rain is diverted around those basins, hits the bottom and there's nowhere for it to go," Woodhead says. There are 13 areas that have to be addressed to take care of that water while it's manageable. ... That amount of volume is far in excess of the approved erosion sedimentation plan is designed to accommodate, so it got overwhelmed."
Some of the specific upgrades include:
- Establishing seeding on open areas to include banks, diversion swales, infiltration swales and grass field areas. However, it may be a year until the turf is established to the point where it's fully functional, says Woodhead.
- Installing grade dips or culvert pipe in various areas of the outer loop hiking trail to mitigate trail damage and concentrated flow that is discharged at the park driveway.
- Provide positive drainage toward culvert pipes through the use of broad swales.
- At total of 11 grade dips or pipe installations are proposed.
- Remove sediment and scarify the surface from the rain gardens that are not yet vegetated, along with the primary detention basin.
- Repair swales and trail banks. Engineers say there are several areas where erosion has caused swales to function improperly and consequently directed runoff to undesired drainage areas.
- Adding, expanding and replacing piping in the area of the park driveway.
Engineers did consider the idea of moving the roadway, however, Woodhead says when looking at the topography it's possible a new roadway would disturb the neighboring wooded area and subsequently exacerbate the problem.
"We still think we're ahead by working with the road that is there instead of trying to bust in and stabilize a new entry or exit to that park," says Woodhead. "We're still working on it. We're still making progress. Not enough ... but everybody involved in this is doing their best to get it right. We're not there yet, but we're working on it."
The 68-acre park is still slated to open next year. The total park budget is $3.2 million. Stormwater management created between $50,000 to $70,000 in new expenses.