Summer flooding strains library's drainage system

Repairs began last week on a newly installed stormwater management system at the Chapel Hill Public Library — a system that is already giving residents headaches.

The system, which was installed during a $16 million library renovation that wrapped up in April, began to fail almost immediately after construction ended, according to a report from the project’s engineer Michael Hammersley.

This summer’s flooding further weakened the system, leaving residents to deal with crumbling sediment washing into nearby creeks and parks.

The stormwater management system is supposed to collect rainwater and pipe it off-site as quickly as possible. If such a system fails, it can cause structural damage to a facility and erode important vegetation and soil.

Eric Hyman, a Chapel Hill resident who lives adjacent to the library, said he immediately noticed when the library’s stormwater system began to fail. Sediment and silt became loose and started making its way into the creeks in Pritchard Park, the wooded area that sits between his property and the library.

“It was quite a failure,” he said. “All that silt went into the creek and, while it would be nice, I’m not sure how they’re going to clean it up.”

Hyman said Pritchard Park is known for the trails and creeks that wind through it.

“It hasn’t really affected the trails all that much,” he said.

The library’s bioretention cell, which is the part of the stormwater system designed to temporarily contain up to 12 inches of water during severe storms, began to fail in April, according to Hammersley’s report.

It took project managers nearly two months to come inspect the property, and initial repairs weren’t made until June 8, the report states. The contractor was waiting for a dry period to commence work on the cell, said town spokeswoman Catherine Lazorko.

Lazorko said the town — and taxpayers — won’t shoulder the cost of the repairs. Instead, she said, the contractor will be responsible for paying to restore the cells.

“The first phase of the work involves the removal of unsuitably wet fill materials and the temporary closure of the breach in the embankment to contain water in the basin while permanent repairs to the embankment are completed,” Lazorko said in an email.

The town will work with the State Division of Environment and Natural Resources to complete the repairs of the bioretention cell, said Public Works Director Lance Norris in an Aug. 9 email to Town Manager Roger Stancil. Hammersley, along with the site’s Construction Administrator Ken Smith, issued a directive to begin the repairs last week. In his report, Hammersley estimated the job would take about three weeks to complete.