Time, the elements — and a heck of a lot of foul balls — have damaged the roof at Joseph P. Riley Jr. Park.

Joseph Riley Jr. Park

About: Opened in time for Charleston Riverdogs 1997 season. The Citadel plays there, as well.Cost: $19.5 million.Nickname: The Joe.Seating capacity: 6,000. Attendance records regularly surpassed.Designer: Designed by HOK Sports, known primarily for their work at Oriole Park at Camden Yards in Baltimore and other major league fields.

How many errant baseballs?

Workers last year found more than 150 elusive strays tucked into crevasses, nooks and other hard-to-reach places out of public view.

Sixteen years after it opened, the city of Charleston is moving to replace part of the building’s roofing and gutters.

And while foul balls aren’t the only cause of the damage, officials say the repetitive banging of strays coming down under extremely high velocity has weakened some of the spots up top.

The two areas to be addressed include the rain gutter situated high behind home plate, and a maintenance/walking area on the rear rooftop. It does not include any part of the green sloping roof known to give off that familiar thud when fouls rain down.

Still, a visit to the roof shows evidence that many of the wayward hits’ return to earth under heavy force. Spots around the green metallic roof reveal various circular dents that resemble hail dents on car hoods.

Meanwhile, the gutter to be replaced — which faces the interior playing field — has been a particularly effective grabber of foul-tips over the years, witnesses report. Among them is David Moon, maintenance manager at the park, who has collected many of the errant hits, giving the leftovers to neighborhood kids or to the children of co-workers.

Some of the balls recovered were frayed and decayed, he said, indicating they’d probably been lost up top for several seasons.

“The cover was completely gone,” Moon said of one particularly bad specimen.

The hits came from the home team Charleston Riverdogs and their South Atlantic League opponents; The Citadel plays its games there, too.

Moon guessed that the balls he’s recovered reflect only a very small portion of the actual number of fouls that have landed on the roof, since most roll back into the crowd, the parking lot or the adjacent Ashley River marsh.

“You probably have a lot more fouls (hit) than singles or doubles,” he said.

The roof work, which is being bid out this month, follows a major $850,000 fix last year to add new irrigation and drainage to the playing field.

A cost estimate for the new roof wasn’t released by the city because the project is going out to a bidding competition.

About 2,500 square-feet of space will be replaced up top, going from the current “single-ply” covering to a more durable “two-ply” shield, city documents say.

Reach Schuyler Kropf at 937-5551.