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www.rockproducts.com ROCK products • March 2018 • 35 FIGURE 2: Entry road in early days. Charleston Stone employs 20 people and is an important part of the local econ- omy. 6 The industry requires highly skilled workers to operate heavy equipment that extracts and processes stone into a variety of products. Compensation and benefit levels are attractive and job retention is high. Many of the employees have worked at Charleston Stone for more than 20 years. The Tarble family has been in the quarry business in Illinois since the mid-1930s. Charleston Stone Co. was formed in 1958 by Van Tarble, who is the grandfather of the current owners. The original plant was on the west side of the Embarras River near Charleston, Ill. The company expanded in 1963, by purchasing the quarry directly across the river. The two quarries were operated independently until 1999 when a new plant was built. 7 John Tarble, co-owner of Charleston Stone, said the core process in this business has not changed since his grandfather's time, "we crush big rocks into smaller rocks." 8 Mined materials are conveyed into a series of crushers. The rock-crushing process begins with a primary crusher that breaks down large, 2- to 3-ft. diameter rock into rocks 6- to 8-in. in diameter. A secondary crusher can then break it up into pieces about one-quarter as large. Charleston Stone also has tertiary crushers that turn smaller rock into gravel, sand or lime. This rock crushing process enables the company to offer consum- ers a wide variety of aggregate products, from agricultural lime to the largest of landscaping boulders. Charleston Stone utilizes both quarries. They mine one side of the river at a time and use a mobile primary crusher that they can move back and forth as needed. When they are mining on the west side of the river, the rock coming out of the primary crusher is conveyed to the east side, where the remainder of the crushing and screening takes place. Charleston Stone's primary crusher was installed in 1999 and had become less reliable. In addition to needing frequent repairs, it also limited the kind of prod- ucts Charleston Stone was able to produce. Because it was diesel fired, it was expensive to operate when diesel prices were high. The 18-year-old crusher needed to be replaced. Management at Charleston Stone was familiar with electric rock crushing, because several of the company's secondary and tertiary crushers are electric. The Tarble family owns another rock-crushing operation elsewhere in Illinois that was con- verted to electricity many years ago. RESIZE www.kpijci.com