Providing Vermont granite to a worldwide market
Based in the quaint New England city of Barre, VT, Rock of Ages Corp. is tightly linked to the history of its surroundings. While Barre has a population only slightly under 10,000, the city is certainly not one to be overlooked. Rich in granite, the first-known quarry began operating on a farm around 1814. Soon, Barre granite became a standard building material for memorials, mausoleums and architecture. Through the years, Rock of Ages has capitalized on this growing market, and many years ago became the exclusive quarrier of Barre granite. Currently, it owns over a dozen of quarries in the U.S., Canada and Ukraine - one of them being its Bethel White granite quarry in Bethel, VT.
The company first came about when three gentlemen - James M. Boutwell, George B. Milne and Harvey W. Varnum - pooled their resources and formed the Boutwell, Milne & Varnum Co., which was only involved in the quarrying of granite. The company soon ran a national marketing campaign to promote the quality of its product. It then adopted the logo â€œRock of Ages,â€ which it registered with the federal government in 1914. In 1925, it was decided that this slogan would be the company's new name, due to the positive response it had received.
Despite the Stock Market Crash of 1929 and other uncertain times, Rock of Ages pressed on and has continually expanded its business. Today, Rock of Ages Corp. is a publicly held company traded on the NASDAQ Exchange (ROAC), and is considered to be among the largest memorial manufacturers. â€œRock of Ages is the largest quarrier of dimension stone in North America - quarrying over 1 million cubic feet of saleable material annually,â€ said Robert Campo, Vice President of Sales and Marketing, adding that the Bethel quarry produces 225,000 cubic feet of blocks per year.
Surrounded by rolling green mountains in Bethel, which was the first town chartered in Vermont in 1779, the site encompasses approximately 50 acres and sits in the middle of more than 250 acres owned by Rock of Ages. With 20 workers, the company runs one shift from 7 a.m .to 3:30 p.m. with a half hour for lunch and overtime as required, according to Campo. â€œOur quarry operations worldwide employ 250, and company-wide about 1,000 people,â€ he said.
At the Bethel quarry, drilling is performed with Tamrock equipment, and Pellegrini diamond wire saws are used to make cuts. Additionally, waterjets from Ned-Jet are employed, and Caterpillar 992 loaders move the granite blocks around the site.
Channeling methodsRock of Ages employs three different methods of channeling in its quarry operations. Each method has specific advantages and disadvantages that determine under what conditions it is best utilized, according to the company. Water is used in conjunction with each cutting method to suppress dust, control heat and wash detritus from the cut.
In one method, a slot drill is used to drill a series of vertical holes 2 1â„4 inches in diameter approximately 4 1â„2 inches apart. Once these holes are drilled, a 3-inch-diameter bit is then used to drill or core the â€œwebâ€ - the small amount of granite that remains between the previously drilled holes. According to the company, this â€œcoringâ€ process removes all of the granite between the holes, creating a channel between the mass being quarried and the quarry walls. As a result of this method, the channel has a corrugated appearance.
A second method of channeling used by the company is done with a diamond wire saw. â€œWe have been utilizing the wire saws more to cut channels and speed up production,â€ said Campo.
Channeling is also done with a waterjet - a process involving oscillating nozzles shooting water at a pressure of 40,000 pounds per square inch. The pressure of the water is the sole cutting agent, and the automated wand containing the nozzles moves vertically, cutting at speeds of up to 40 square feet per hour, according to Rock of Ages.
After the vertical channeling process is completed with one of the three methods, a horizontal cut - called the â€œliftâ€ - is completed with pneumatic drilling. The work is conducted from a ledge below the work site if one exists or from a staging platform that is suspended against the face at the point where the cut is to be made. Next, a pneumatically powered drill, called a â€œlift holeâ€ drill, is placed so that it is perpendicular to the quarry wall. A series of holes that are about 6 inches on center are then cut, and the resulting row of holes extends completely beneath the block being cut. It stretches from the face of the quarry to the channel line at the back of the block, meeting the channel line at approximately a 90-degree angle. Once this series of holes has been completed, every other hole or every third hole is filled with primer cord - a type of explosive. The controlled detonation is set off electrically, causing the granite to crack along the drill lines, separating the large block from the quarry wall, reports the company.
DrillingOn average, a bench at the Bethel White quarry measures 40 feet long, 30 feet wide and 15 to 17 feet high. To divide up the large block into smaller pieces so it can be lifted from the quarry, a double deep-hole drill is used to cut the block along the â€œhardway,â€ the direction in which it is hardest to cut the granite. A series of vertical holes - 15 to 17 feet deep - are drilled approximately 4 inches apart. The resulting row of holes forms a â€œhardway line.â€ A series of hardway lines are cut, with the rows being spaced about 5 feet apart, according to Rock of Ages. Once these rows of holes have been completed, long, tapered metal wedges - known as â€œglutsâ€ - are driven into the holes with a jackhammer. The stress causes the granite to split along the hardway lines, which divides the bench into more manageable pieces.
According to the company, after the hardway lines break free, the resulting pieces are drilled one more time along the â€œriftâ€ or â€œgrain.â€ Small, pneumatically powered plug drills sink holes of about 3â„4 inch in diameter and 6 inches in depth about every 3 inches to form a row of holes or â€œrift line.â€ Wedges and shims are inserted into these holes and driven with an 8-pound sledgehammer to split the block along its rift.
A standard block removed from the Bethel site is about 10 x 5 x 5 feet and weighs more than 20 tons. Blocks are then carried on trucks and fork loaders to storage areas, where each one is meticulously graded and then inventoried.
Bethel White granite is widely recognized for its even grain and purity of color, reports Rock of Ages. The material has an average absorption of 0.256%, compressive strength (CL70) of 34,027, average modulus of rupture (psi) of 1,937, and average flexural strength (psi) of 1,687.
The material produced by the Bethel White granite quarry has been used for many high-profile projects around the world. The Grand America Hotel in Salt Lake City, UT, which was built to serve as a conference center for the 2002 Winter Olympics, features an exterior clad with over 300,000 square feet of Bethel White. Rock of Ages quarried about 5,000 tons of the material for this project, which recently was awarded a 2003 Marble Institute of America Pinnacle Award. Additionally, Bethel White was supplied for the Mormon Bountiful Temple, also in Salt Lake City.
When looking to the future, Rock of Ages plans to continue increasing its production at its existing quarries as well as searching out new sites. â€œWe are actively looking for additional quarry properties around the world that will fit into our product line of exclusive high-quality granites,â€ said Campo. â€œRock of Ages is also committed to building its retail monument distribution, which currently boasts 100 company-owned stores throughout America.â€