To laypeople, a quarry may seem like just a big hole in the ground. But the professionals who plan, design, build and operate a quarry know that it requires a deep understanding of economics, production, the demands of the regions it will serve, and the equipment that will make it all happen. Such was the case recently with a quarry in Maine.
Economic Growth Invades New England
In the 1990s, New England saw strong economic growth. The Boston area alone experienced a population boom that eventually pushed northward through New Hampshire and into southern Maine. Because of this growth, there would soon be a huge demand for aggregate materials. In the early 1990s, Barletta Construction, based in Roslindale, MA, realized this and purchased some property in Eliot, ME, with the intent of building “Rocky Hill Quarry.” Immediately after that, the intensive — if not unwieldy — permit process had begun.
The Permit Process: A Slew of Studies
In 1999, Barletta Construction contacted Terry Oliver, president of T.W. Oliver Inc., a consultant company. Oliver’s mission was to expedite and complete the permitting process to get the quarry up and running.
Environmental impact and economic studies were done. After all, the quarry needed to be economically feasible: There needed to be enough aggregate demand to justify the quarry’s existence.
During the course of the studies, however, an important factor was unearthed. The site contained fine-grained granite, which is ideal for construction aggregate, particularly for the production of asphalt and ready-mix and road-base materials.
What’s more, this product would meet Department of Transportation (DOT) requirements for Maine, Massachusetts and New Hampshire, the regions that the quarry would serve. The quarry’s location also was near to I-95, which further enhanced the desirability of this site.
As soon as the permit process concluded, Barletta Construction and T.W. Oliver Inc. aggressively moved forward to get the quarry properly equipped to begin production.
While the plant layout was being designed, computer programs were used to give Barletta an idea of what equipment would be needed.
The quarry is 301 acres (121.8 ha). Of this, 125 acres (50.5 ha) had been permitted for the extraction of stone and 7 acres (2.8 ha) had been permitted for the processing of materials. It also was determined that a total of 50 million tons (45 million t) of aggregate could be removed from the site.
Many regional equipment suppliers submitted proposals to Barletta Construction and T.W. Oliver Inc. After all proposals were evaluated, Whitney & Son, based in Fitchburg, MA, was selected.
Oliver explained how the decision to go with Whitney was made. “Part of this decision involved the fact that we wanted to use a mobile primary crusher, which would eliminate the need for haul trucks to carry materials around the quarry, ultimately making production as economical as possible.”
Haul trucks can cost as much as $250,000 and Oliver believed that if they could design this quarry to eliminate haul truck usage, there would be substantial cost savings. Whitney & Sons filled this need, he explained, because it could provide a Nordberg/Metso LT125 37 by 49 in. tracked crusher, which is the only track-mounted primary crusher that could meet Rocky Hill Quarry’s production needs.
“Nordberg/Metso had the best reputation of overall quality of portable tracked crushers,” said Oliver. “They also brought to the table a tremendous engineering background. Nordberg/Metso has been in the portable tracked crushing business longer than anyone.”
Oliver also praised Whitney & Son. “We’ve known them [Whitney & Sons] for nearly 30 years and that gave us a very good sense of security. They’re a full-service company that provides wire cloth, crushers and support manganese. But in addition, we shopped for price and they were very competitive,” he said.
Up and Running
Production started at Rocky Hill Quarry in mid-May 2001, and so far, 250,000 tons (225,000 t) of aggregate have been produced and removed from the site.
Oliver is pleased that the quarry and the equipment were specifically designed to handle the tremendous amount of growth that is expected in the future. The quarry can produce 500 tons (450 t) of aggregate per hour, if necessary, at 1.5 in. minus. It can produce 300 tons (270 t) per hour, if necessary, at 3/4 in. minus.
The entire plant can operate with just six employees. Production operation is computer controlled, yet the entire operation can run manually or in an automated mode. Once the dust suppression system is up and operational, there will be no visible dust emissions from the quarry.
Nearby residents were given special consideration. The entire quarry is surrounded by a berm and there is an 8-ft. high (2.4 m) fence over that area that is designed to keep noise levels at an acceptable level. All blasting is done in remote parts of the quarry so that neighbors are not affected by the blasting.
The Town of Eliot has stringent noise restrictions at its property line — much higher than the state’s requirements. To significantly reduce noise during the screening process, special scalping screens were installed and discharge shoots were lined with rubber.
Rocky Hill Quarry has a very limited processing area, so it must have the ability to process stone at a very high capacity but with a limited space to stockpile the product.
“Today, everyone is using the new generation of cone crushers,” Oliver said. “They are a higher speed crusher with a larger stroke. Nordberg/Metso was the company that pioneered that particular field.”
“Because Nordberg/Metso was the pioneer in this field and had developed a large percentage of the machines in our marketplace, we selected the Nordberg/Metso HP400 cone crusher as our secondary and tertiary crushing machines,” said Oliver. “That combination of machines exceeded our criteria that we were requiring for the site. Two machines that were purchased were identical, and one is set up for secondary crushing and the other is set up for tertiary crushing. The secondary machine is a standard course configuration.”
The screens on the site are all Deisters and were purchased from Whitney & Son. Oliver said that when going into this project, it was Barletta’s intent to purchase all machines from one supplier and Whitney was able to bring the right mix of products to make that possible.
“We also felt very comfortable with Whitney & Son,” said Oliver. “Whitney is a stocking parts supplier and its headquarters is only two hours away from our plant. They have a very strong reputation in the local market and that gave our decision a tremendous comfort level.”
Oliver said that Whitney was critical in providing direction and startup assistance, adding that equipment was being placed in the quarry by mid-December and on May 1, the quarry was up and running.
“We are particularly happy with the Nordberg/Metso LT125 portable primary crusher. It is a very high capacity crusher with the same capabilities as a stationary primary crusher, yet it’s very portable,” said Oliver. “In fact, the tunnel and the tunnel feed conveyors that take the product from the primary crusher to the staging area for the secondary crushers is the only part of our operation that is not portable. The Nordberg/Metso equipment from Whitney & Sons has exceeded all production criteria that we set forth for them.”