Snacking on an apple and dismissing health fears, Pete Gellerson explained asphalt production Thursday at a Scarborough asphalt plant in full operation.
Shaw Brothers Construction Inc. of Gorham is proposing a similar, though bigger, asphalt plant along with a quarry in Gorham. The Gorham Town Council will consider amendments to town ordinances Tuesday that could pave the way for approval of the company’s controversial plans in Gorham.
Shaw Brothers bought the Commercial Paving asphalt plant earlier this year, and allowed the American Journal to tour that plant last week to view the operation first hand. Besides Commercial Paving, other southern Maine asphalt plants are in Limerick, Portland and Westbrook.
Gellerson said the ingredients of pavement include crushed stone mined from quarries, sand and recycled pavement. The ingredients are mixed with a dark, liquid asphalt cement and stored at 300 degrees temporarily in a silo where trucks are loaded for transport to job sites.
He said asphalt production doesn’t present health risks, though many in Gorham disagree. The process from quarries to the finished product is regulated under federal and state laws and several licenses are required from by the Maine Department of Environmental Protection. Gorham resident Dave Babino and other critics of locating a plant in Gorham worry that emissions from the manufacturing of pavement could lead to health problems like cancer. But Rick Perkins, the head of compliance for air emissions at the Maine Department of Environmental Protection last week called public exposure to asphalt plant emissions minimal.
Here’s how asphalt pavement is produced, according to Gellerson, the plant manager at Commercial Paving, which is located in an industrial area on Gibson Road, off Pleasant Hill Road.
A ton of hot mix typically includes 20 percent recycled asphalt pavement, which is crushed before re-using. Besides a stockpile of recycled pavement, Commercial Paving also had stocks of two stone sizes trucked in from Gorham, one from an existing Shaw Brothers’ quarry and the other from Grondin’s; and stone dust, which Gellerson called “man-made sand,” trucked from a Shaw Brothers’ operation in Dayton.
A front-end loader fills the cold, raw material from the stockpiles into six separate bins. Utilizing computer control, the material is then fed by conveyors to a shaker screen, which kicks out big rocks, before the material goes into a rotating, cylindrical drum.
A flame shoots into the drum, drying and heating the mix of aggregates. The plant is fired by a burner fueled by home heating oil. When producing pavement, the plant burns about 150 gallons of oil an hour. Two gallons of heating oil is required to produce a ton of asphalt.
Gellerson said a bag house, which is located above the plant, captures all the dust in the plant’s manufacturing process. The bag house is a separate compartment containing 364 cloth bags. Acting like a vacuum cleaner, the bags pulse, sucking in air. Collected dust is recycled back into the drum. “Those fine particles are an important part to the finished product,” Gellerson said.
A secondary drum at the Commercial Paving Company is where the liquid asphalt cement is added to the mix. The liquid is stored in a 30,000-gallon tank. The product, which is 300 degrees, is trucked hot from the Portland waterfrontwhere it arrives by barge. Commercial Paving maintains the temperature of the liquid.
The liquid asphalt costs $350 a ton now and about one ton is needed to produce 20 tons of finished product.
The finished product, which is 300-325 degrees, rides up a slat conveyor to two 75-ton silos. Trucks drive onto weigh scales under the silos to load. Driver Ron LaChance of Old Orchard Beach, who has worked for Shaw Brothers for eight years, pulled up a big dump truck Thursday for a 5-ton load destined for a utility job site in Portland.
“I know there’s no health danger to it or I wouldn’t be sitting here,” LaChance said.
Gellerson said a driveway mix sells for $49 a ton, which is up from $36 two years ago. The liquid asphalt cement needed for one ton of pavement costs $17.50. “The price is petroleum driven,” Gellerson said.
The 1988 model asphalt plant at Commercial Paving is similar but smaller than the one Shaw Brothers is proposing for Gorham. Pavement produced at the Scarborough plant can’t meet the specifications to produce “superpave,” required in federal projects.
“This plant isn’t sophisticated enough to make superpave,” Gellerson said.
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