It could take State College borough and area school district crews up to a week to fix a sinkhole found Thursday morning at Memorial Field.
According to a State College Area School District news release, a district physical plant supervisor discovered the “subsidence” on the sidelines near the home bleachers.
District physical plant employees, a State College borough crew and a representative from State College engineering firm CMT Laboratories were called to investigate the hole, which measured about 4 feet wide and 4 feet deep — after cutting through the turf.
Borough spokeswoman Courtney Hayden said the borough will repair the sinkhole, while field closures are in the hands of the school district.
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“Just like we have in past, we’ve maintained that sinkhole,” she said. “It was in 2013 that we did a special capital project to do reverse filter on Memorial Field.”
In October 2012, geotechnical studies revealed instability under part of the home bleachers, which were then stabilized.
The district has since completed nearly $3 million in improvements to the field, including new bleachers and turf and a drainage system.
District spokesman Chris Rosenblum said the goal is to have the field open to the public next week.
He said an underground stormwater pipe joint separated and allowed water to erode the soil. The damaged pipe runs from Nittany Avenue to the sinkhole.
“There are problems with underground drainage,” Rosenblum said. “It’s not a naturally occurring sinkhole.”
The bleachers were unaffected, said district Director of Physical Plant Ed Poprik.
Borough engineer Amy Kerner said sinkholes in the area have been a recurring problem.
“Basically there is a sinkhole; they’re dynamic structures, and it’s just the fact that they take in storm water,” Kerner said. “We do repairs to keep it as stable as possible, but they can continue to grow with or without stormwater. In this case, it’s probably directed to the fact that stormwater is going down there.”
The sinkhole found Thursday is in the vicinity of the prior sinkhole, but not in the same spot, and is smaller than the one previously at Memorial Field, according to borough officials.
“There is no way to prevent sinkholes because we have direct stormwater there,” Kerner said. “There is no way to not take stormwater to that. There is a rock formation, but it keeps washing up. The best way is to get to the throat and fix it.”
A throat is part of the sinkhole that acts as a funnel. A sinkhole usually has one main throat, Kerner said.
“It’s hard because when we’re working the area, it keeps subsiding around it,” Kerner said.
To fix the hole, oversized rock is used to bridge the gap, Kerner said.
“It could take several days to complete,” Kerner said. “This is nothing new. All (of the) Centre Region is sinkhole prone.”
No cost has been determined.