BLOOMINGTON -- A noise expert told the McLean County Zoning Board of Appeals Wednesday night that a gravel pit operation should be at least 2,640 feet from a residential area or school.

But an engineer who works for Stark Excavating said the setback should not be more than 100 feet to allow full excavation of a site.

It was the second day of a hearing on proposed changes to McLean County's guidelines for gravel pits. The county is proposing changes after many questions arose during a public hearing on a request by Stringtown LLC for a special-use permit for a gravel pit operation near Fox Creek Elementary School.

The McLean County Board's Land Use and Development Committee suggested gravel pits be at least 1,000 feet from houses and schools and that gravel loading areas be at least 2,000 feet from developments.

Greg Zak, a former noise expert for the Illinois Environmental Protection Agency, said besides changing the required setback, the county should require gravel pit operators to have a noise control plan that includes ways they will mitigate noise.

Zak, who was testifying on behalf of a contingency that believes the proposed setbacks are too lenient, said stockpiled materials can help buffer noise but the piles have to be at least as high as the nearby houses to be effective.

"You have to break the line of sight," said Zak of Springfield.

But David Brown of Lewis Yockey and Brown engineers of Bloomington said unless there are health or safety concerns, the separation between a residential area and a gravel pit doesn't need to be more than 100 feet.

He also suggested the space between the screening, crushing and loading area and a residential area be 500 feet instead of the proposed 2,000 feet.

"Permit flexibility for everything that's needed in the operation," he said.

Brown said to determine health and safety standards, the county should consider scientific evidence. He also suggested the county consider a "resource overlay district" for known areas in the county that have gravel and other natural resources.

By designating the area, he said, anyone building near there would know there was a chance a gravel pit operation could occur someday.

Don Adams, an engineer with the Farnsworth Group, agreed.

"Gravel is a natural resource in the county," he said. "I feel strongly that it should be protected."

The hearing on the proposed changes was recessed until 6:30 p.m. Monday.

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Key details

Current McLean County zoning ordinance:

-- At least 1½ miles between residentially zoned property and mines and quarries with crushing, loading, hauling, storage or cutting of stone.

-- At least 1,000 feet between residentially zoned property and a landfill, mine or quarry with extraction operations only .

The proposed changes would require:

-- At least 1,000 feet between a residential district or school

and a gravel pit excavation area.

-- At least 2,000 feet between a residential district or school and

a gravel pit's storage piles, washing, screening, crushing, loading, hauling and other activity areas.