City of Little Rock, Arkansas Sewer Expansion Project
Contractor: FSI GEO-CON/Foundation Specialties, Inc.
Equipment: *TEI HEM350 Excavator Drill Attachment
Hollow Bar Solution
A TEI HEM350 excavator drilling attachment was successfully employed by FSI GEO-CON/Foundation Specialties, Inc. of Springdale, Arkansas to install 14 hollow bar micropiles as deep foundation for the City of Little Rock’s sewer expansion project. While excavating for the new sewage lift station it was discovered that native soils had been removed to a greater depth than anticipated during the construction of the original station.
Driven piles were initially considered for use to address this soil condition, but were later determined to be impractical for installation due to access limitations at the jobsite. The project’s geotechnical engineer recommended micropiles as a deep foundation application. Hollow bar micropiles provided the optimum solution for field-proven anchorage in the sandy, silty, alluvial soils at the confined site.
TEI’s innovative equipment design allowed the HEM350 drill to be bolted in different positions to the excavator. These various attachment configurations provided access to all micropiles from one setup point above the restricted area. “The ability to install the micropiles from the top of the excavation with a TEI 360º excavator mount and drill turned an otherwise challenging job into a routine one,” said Paul Gintonio, President FSI GEO-CON/Foundation Specialties, Inc. This unique positioning can also be accommodated with the use of a second TEI hydraulic positioner mounted to the drilling platform.
FSI GEO-CON added their own innovation to the hollow bar installation process with the addition of a grout box to capture and pump the excess grout out of the excavation area and into containers. “The Foundation Specialties team has a well-earned reputation for geotechnical innovation and professionalism. They rely on our drilling platforms to measure up to their high performance standards,” noted Joe Patterson, Vice President , TEI Rock Drills, Inc.
After installation, the hollow bar micropiles were successfully tested in tension to double their design load of 40 kips. The confined work area prevented the performance of a compression test.
*The TEI HEM350 drilling platform has been upgraded to the powerful TEI HEM360 Excavator Drill Attachment with an advanced ASA Percussion System