Contractor Drives Micropile Production, Safety with KLEMM Equipment By Brian M. Fraley
Technical Foundations has been providing specialty foundation con- tracting services along the Eastern Seaboard for 27 years, with a heavy focus on Virginia and the Carolinas. The contractor’s reputation for taking on unique projects is evident in its selection of equipment, the most recent of which was the rental of a KLEMM drilling rig and rod handling attachment from Equipment Corporation of America (ECA). “Technical Foundations specializes in unique projects,” says Project Engineer Butch Stoneman. “We like to provide cost-efficient, innova - tive solutions, and sustainable ground improvements for challenging sites where conventional approaches won't quite work.” The contractor has done business with the ECA Washington branch for more than 10 years. Although the original connection was with Branch Manager Mike Brown – known by Stoneman and many other contractors for his intricate knowledge of the KLEMM line – it was Account Manager Greg Barta that arranged the rental of the drilling rig and rod handling attachment. Technical Foundations is no stranger to KLEMM drilling rigs, but ECA’s KLEMM specialist Burt Kerns was sent to conduct on-site operator training for the team at the beginning of the project since this was the contractor’s first time using the HBR 120 Rod Handling Attachment. Micropiles Chosen to Avoid Disruption Technical Foundations put the KLEMM drilling rig and handling system to work in January 2021 on a project near Roanoke, Vir - ginia. The contractor was hired to install 230 micropiles to support a sizeable commercial building addition and multi-story precast parking garage. The micropiles would be spread across the roughly two-acre site to support the proposed structures in unsuitable soils. The existing site was essentially a valley that had been backfilled with a variety of ma - terials to level it. Technical Foundations started off by test drilling to locate the bedrock. During that process, it discovered that unsuitable fill would make it im - possible to build the structures on conventional spread footers without settlement issues. Various deep foundation systems were considered. The existing business would remain fully operational, so avoiding disruption was
critical. Driven piles were ruled out primarily due to the vibration that would occur with pile driving and heavy equipment. After several load tests, it was determined that six-inch-diameter piles would achieve the right capacity. They were to be clustered in a pile cap configuration around the building columns and under some of the grade beams. Micropile Drilling with the KLEMM The KLEMM KR 806-3G was the primary workhorse for micropile drilling. Technical Foundations had several other rigs on standby. “It was more efficient to have one drill concentrating on drilling and the other focused on grouting the holes afterwards,” says Stoneman. “It was also a really tight schedule, so we had an extra machine out there to make sure our flow of work wasn't interrupted.” The KR 806-3G was drilling piles from 20 feet to 65 feet deep and seating them five feet into bedrock. The top layer of fill material was generally soft and moist, containing a mixture of concrete debris, tree roots, and various types of soil that had been in place for up to 40 years. The native soil below was a weathered rock, which was underlain by bedrock. “We chose the KLEMM because it was the most reliable machine we had available, and with the different features it has, it was going to be a little bit more versatile in difficult drilling conditions,” says Stoneman. Stoneman is referring to the rig’s electronic shifting capabilities, which allow for the changing of torque and speed. The KR 806-3G’s double- head drilling capability was also beneficial since it has separate drives for the outer casing and inner rod. This was especially helpful when drilling through different types of materials and formations. Technical Foundations drilled holes with a KLEMM KR 806-3G and fed rod and casing sections to the rig with an excavator-mounted HBR 120 Rod Handling Attachment on a micropile project near Roanoke, Virginia.
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csengineermag.com
july 2021
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