Falling Springs Quarry

Rock Around the Clock

It’s dawn. A tandem axel dump truck rumbles in to Falling Springs Quarry in Dupo, Illinois, and stops at what resembles an ATM machine. Following the instructions on the interactive touch screen, the driver enters his company name and his order for 10 tons of custom blend aggregate. After the driver completes the transaction, aggregate falls from a large bin into the truck bed. The driver pockets his receipt, and in a matter of minutes, he’s on his way to the job site.

Before Wissehr completely and totally replaced its electrical systems, the quarry relied on 1930s technology, producing 600 tons of aggregate an hour. Now, the plant produces 1100 tons an hour. The number of operational staff needed has been significantly reduced, and its loading and hauling operations also have been reduced.

Installing electrical equipment in a limestone quarry poses inherent problems. The proposed wiring was buried in underground duct banks, which were located beneath 50- to 70-year-old roadways made of aggregate but hard as concrete. To speed the trenching operation, Wissehr innovated and instead of a backhoe used a large carbide-tipped trencher. Wissehr’s electricians cut relief slots in the “concrete” and then pulled it out with an excavator, creating space for the new systems. They installed in concrete-encased duct banks approximately two miles of 5 KV underground distribution.

During the project, Wissehr also installed the following:

• a 5 MVA, 34 KV to a 4160-volt substation
• four 5 KV to 480-volt unit substations
• 5 KV for each of the four crushers
• all the control, power and logic for 52 conveyors, totaling more than a mile of belt length
• 14 screens and more than 100 total motors

The limestone quarry, which opened at the turn of the 20th century, is fully automated with state-of-the-art technology. Now it operates unattended, controlled from a laptop computer in the home office. As a result, productivity has increased, and overhead costs have decreased.

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