Harrisburg has allocated nearly a half-million dollars to support a green-roof initiative in Lancaster County.

"We got everything we asked for," Mary Gattis-Schell, a senior planner with the Land Recycling Program of the county planning commission, said Wednesday. "We're thrilled."

The project will foliate the roofs of seven buildings in the county. Designers hope this will reduce electricity consumption, stormwater runoff and the ambient temperature of those sites.

However, one grant participant — Columbia Borough Hall — may withdraw from the program because of structural issues related to weight.

"They're not out, but they might have some problems," Gattis said.

If Columbia does withdraw, she said, the county will seek another municipal building to take the borough's place in the program.

The grant from Gov. Ed Rendell's Energy Harvest program totals $479,333 and will cover an estimated 79,000 square feet of rooftop in seven locations.

Green roofs are not rooftop gardens. They are layers of soil and densely packed plants. In this case, the project will use a blend of fine gravel and organic material and a variety of sedums, or low, scrubby succulents, that require no irrigation and little maintenance.

According to the proposal, the project will reduce stormwater runoff by as much as 90 percent, preventing  that water from pouring into the county's storm and sanitary sewer systems.

Also, the project is expected to reduce electricity use by about 20 percent by providing insulation that both cools the building in summer and warms it in winter. It will improve air quality and provide a habitat for birds and bees.

Millersville University's earth sciences department has been engaged to measure the environmental benefits of each roof.

Gattis said the project has been a successful collaboration between the city and county, both of which stand to benefit if the green-roof initiative is successful and spreads in the area.

"It's a good partnership and a common direction between the city and county," she said.

In fact, Gattis added, city Mayor Rick Gray on Tuesday signed the Sierra Club's Cool Cities initiative to cut greenhouse gas emissions. That initiative falls right in line with the green roof plan, she said.

Gattis said she hopes to see rooftop planting begin as soon as April, "but that may be optimistic."

The county planning staff expects to spend a few months dealing with paperwork from the state Department of Environmental Protection to finalize the details of the grant, she said. The county also will begin a series of educational programs with participants to give them a greater understanding of the process.

"We're right on schedule," Gattis said.

News from Columbia is disappointing but will not derail the project, she added.

"We're afraid they're going to have some structural issues with their building," she said. "And that's one of the first steps (for all participants), making sure the buildings can support the additional weight."

Besides the Columbia building at 308 Locust St., Lancaster city participants in the program are the Bare Building at 39 E. Chestnut St., Box Company Flats at 225 E. Grant St., Penn Stone at 190 W. Ross St., National Novelty Brush Co. at 505 E. Fulton St., Two Dudes Painting at 750 Poplar St. and the YMCA at 265 Harrisburg Ave.

E-mail: tknapp@lnpnews.com