When sprinklers water the grass at City Hall North, runoff leaks into the underground parking structure below, so city officials said Monday they're making the switch to artificial turf.

Water seeping through concrete planters on the building's southern and eastern edges has stained the southern area of the parking structure ceiling and broken two fluorescent light fixtures, but the city's Assistant Public Works Director Nick Fidler said it has not structurally damaged the five-story 1990 building.

"During the watering of it, concrete cracks, that's what it does. Water has found its way through the cracks and is dripping into our basement facility," Fidler said. "It was just an isolated spot, but we want to make sure we don't have an ongoing problem."

Park Superintendent Ken Trone said hiring Courts and Greens to replace the grass with "fescue" green-colored artificial American Turf Products will cost $19,000, but the project will pay for itself in about four years by saving the city $5,000 in annual maintenance costs.

The turf is expected to last anywhere from seven to 20 years. Once it's in, Fidler said, the light fixtures will be replaced.

City crews removed the real grass and its sprinkler system from the planters over the weekend. Shrubbery nearer the building, and lantana plants flanking its entrance, require less water and will remain.

After the soil is compacted, and sprayed to kill any remaining grass, the artificial turf will go in, some time during the next 10 days to two weeks. If you'd like to get a sneak preview of the new "sod," a patch is currently in place, on the west side of Eye Street, just north of Truxtun Avenue.

Tight on space at City Hall, the city was able to purchase the building in 2006 from the Borton Petrini law firm for $9.5 million, $2 million under appraisal.

A former managing partner said he had been unaware of the problem during the 16 years his law firm occupied the building, which it had built.

"I don't remember that. There could have been some (leakage), but I don't think so," said George F. Martin, counsel at Borton Petrini. "That's always a worry when you try to beautify an area over a parking structure."