BELL ACRES - October morning crawls over the ridge, where most of Bell Acre's 450 residents nest, and spills brilliantly into the Big Sewickley Creek basin, illuminating the borough's commercial corridor.

The concrete plant hums with industry as cement mixers are filled from a 40-foot tower. An auto-body shop, a bolt plant and a construction-products firm accelerate into the work day.

Sunlight glistens off the Eiffel-like electrical towers that stand sentry on the ridges.

Utility poles, more than 30 feet high and planted at 30-yard intervals along Big Sewickley Creek Road, carry heavy black wire from the Ohio River north toward Economy and Franklin Park. Two communication towers rise in the south end of the basin.

Civilization long ago began leaving footprints on the floodplain.

Bell Acres Council will soon decide whether one more footprint will disturb the great blue herons and other residents.

An alternative-energy demonstration site - involving a single 66-foot-high wind turbine, a 15-foot-high turbine, some solar panels and a trailer - has been proposed by a collaboration of Metal Foundations (Ambridge), Vox Energy (Allison Park) and Jet Industries (Ellwood City) for a site near the intersection of Big Sewickley Creek Road, also designated as the Red Belt, and Turkeyfoot Road.

In hearings in July and August, Bell Acres residents voiced concerns over the proposed site's impact on the area's great blue herons, and the noise the turbine could create.

A third hearing will take place at 6:30 p.m. Monday at the Big Sewickley Creek fire hall. Council members could then vote to approve or reject the proposal, although they have a 45-day window to render a decision.

"There's been a big misconception," said Don Williams, chief executive officer for Jet Industries. "People hear about our proposal and think of Somerset, but nothing could be further from the truth."

The Somerset Wind Farm includes six wind turbines, each standing more than 200 feet tall, which are visible from the Pennsylvania Turnpike.

The electricity created by the wind and sun at the Bell Acres site would serve the trailer, where prospective customers will visit. The compound, 42 by 100 feet, will be fenced. The property has been vacant since government housing, built for people who came north to work in steel plants in Ambridge and Aliquippa during World War II, was demolished.

The proposed alternative-energy site would be built less than a mile from a great blue heron rookery, which has thrived high in sycamore trees along the creek as it forms the border between Economy and Bell Acres.

Charles Kulbacki, borough manager for Bell Acres, estimates the great blue herons have inhabited the area, mostly on the Economy side of the water, for more than 10 years.

Matt Kramer, Pennsylvania wildlife conservation officer in Beaver County, says the great blue heron population in the area has been "stable" since the waterways have been cleansed of acid-mine drainage.

"With the return of the watershed ... (the herons) have been expanding their range, probably in the last 10 years," he said.

Gary Fujak, wildlife conservation officer in western Allegheny County, has studied the Bell Acres rookery, watching it grow to include between 24 and 36 nests.

"It's a pretty significant rookery," Fujak said.

Some fishermen in the area have complained, said Fujak, that the great blue herons are eating all the fish.

Herons nest in colonies, said Jim Bonner, director of the Audubon Society of Western Pennsylvania, but hunt alone. They wade in such shallow water sources as creeks and marshes, spearing fish and small amphibians, such as salamanders, with their beaks.

Bonner said it is not surprising to see the herons persisting despite commotion created by concrete plants, auto body shops, power lines and traffic.

"They're a hardy bird," he said.

Kramer said he knows of great blue herons in Washington County that have maintained a rookery for 20 years despite nearby logging operations.

"As long as they have a food source, they'll return," he said.

The prospect of a great blue heron flying into the 66-foot-high wind turbine also seems unlikely.

"Great blue herons fly during the daytime, so visibility wouldn't be a problem." Bonner said.

The Pennsylvania Bureau of State Parks installed a 120-foot-high wind turbine at Presque Isle State Park in 2006 and employed a team from Gannon University to study the effects of the tower on the bird population in the vicinity. In 14 months, they reported one death, a grackle. Results, released in February, said that "the probability of bird and bat mortalities ... is low."

Wind turbines stand in five Pennsylvania state parks.

Vox Energy showed its proposal to the Pennsylvania Game Commission and received two requests:

* "Maintain a 100-foot buffer along Big Sewickley Creek to protect the quality of water in stream in order to maintain the wetlands and the foraging areas for herons.

* "Avoid construction during the nesting season (Feb. 15 to Aug. 15)."

Williams said the project will comply with the game commission's suggestions.

The alternative-energy center will also have to comply with Bell Acres noise ordinances, council President Larry Pryor said. There are no residences within 500 feet of the proposed alternative-energy center.

Economy has a 36-foot-high wind tower behind its offices on Conway-Wallrose Road and has experienced no problems with noise. The borough received a grant through a Pennsylvania Department of Energy program designed to promote alternative-energy sources.

"On very windy days, you might hear a noise, but it is very muted; it is not annoying, and it is not a problem," Borough Manager Randy Kunkle said. "If you were standing in the yard, you might hear something, but you wouldn't know where it was coming from."

The noise, on the windiest days, cannot be heard inside the building, Kunkle said.

Williams said any expansion plans at the site would include solar panel arrays but no additional wind turbines. He said the nation's green mentality, its search for new and cleaner energy technology, makes his proposal an asset to the community.

"This could bring a lot of recognition and a lot of positive light to the state of Pennsylvania and the Bell Acres community."

Monday meeting: A third hearing on a plan to create an alternative-energy demonstration site is scheduled for 6:30 p.m. Monday at the Big Sewickley Creek fire hall. Borough council has 45 days to make a decision.

About the great blue heron: Herons nest in colonies but hunt alone. They wade in shallow water and spear fish and small amphibians, such as salamanders, with their beaks. (Source: Jim Bonner, Audubon Society of Western Pennsylvania)