During a winter’s day on Chicago’s north side when the high temperature never reached 20°F, a CZMEK250 Drill Rig pulled reams of steaming blue clay from a five-foot diameter hole. In Chicago’s Old Town neighborhood, two city blocks were cleared for construction of a mixed-use, 21-story high rise, an eight-story parking ramp, and a three-story shopping center. To support the structures, Case Foundation Company was drilling 335 caissons ranging from 30 inches to eight feet in diameter.
Founded in Chicago more than 75 years ago to help usher in the age of skyscrapers, Case Foundation Company specializes in deep foundations. “We work all over the country, installing foundations for high rises,” says Jim Minyard, equipment superintendent.
At the Old Town site, the EK250 primarily drilled four- to five-foot diameter shafts. Three to four shafts, approximately 80-feet deep, were drilled per day. Bell foundations at the bottoms of the shafts are as large as 16 feet in diameter. “The ground conditions here are perfect for bell foundations,” Minyard says. “Chicago has a lot of blue clay, then it goes to hardpan before hitting bedrock.”
The CZM EK250 Drill Rig that Minyard relies on is mounted on a Cat® 336 Hydraulic Excavator. A 350-hp Cat C9 ACERT™ Diesel Engine provides plenty of hydraulic muscle to handle deep-hole drilling.
The EK250’s rotary head features robust design and the industry’s largest inner passage (31½ inches) for high drilling torque. The forward torque is a great help installing protective casings.
“We typically drill pilot shafts, then put the casings in and twist them down,” Minyard says. “The EK250 has a lot of forward torque that does a great job twisting them into place.”
Headquartered in Pembroke, Georgia, CZM provides a broad range of machines for a variety of foundation applications. Like many manufacturers, the company relies on Caterpillar OEM Solutions for partial machines and components to create specialty machines for niche applications.