Micropiles Support South Carolina Manufacturing Expansion
Goose Creek, South Carolina
UMA worked two shifts to install 304 micropiles to support a fabrication facility addition for a manufacturer in Goose Creek, South Carolina. In November 2019, including an addition to the fabrication building (Building F) and an expansion to accommodate the massive turntables used by the manufacturing facility (Building J).
Team UMA hit the site during Christmas of 2019. The first test pile was installed in late December and load tested in January. Two load tests were conducted at 480 kips. UMA designed piles to achieve loads of 240 kips for Building J, and 200 and 240 kips in Building F.
UMA started production shortly thereafter, installing (or drilling) 20-plus piles per day and working two shifts. The job was finished before the February deadline. Once the micropiles in Building F were completed, UMA left for a month before returning to finish up the 14 piles in Building J.
UMA was initially supplied with a geotechnical report from Charleston, S.C.-based Terracon, which determined the suggested micropile spacing. Although it was thorough, geotechnical borings are only guaranteed accurate at the boring. The distance between borings can vary and so can the soil characteristics. UMA determined the diameter, depth, and means and methods used to install the piles.
UMA worked with general contractor Fessler & Bowman, Inc. and the owner’s engineer to select a design-build deep foundation system that would meet their needs. The selection was a 7-inch Outside Diameter (O.D.) casing. The casing was installed the full length of the micropile for structural capacity, and the bond zone was pressure grouted through the casing. A 14″ x 14″ x 2″ plate was attached to the top of each pile with a non-structural bar and nut and embedded in the structural concrete slab.
UMA’s design-build skills were unexpectedly tested when its work was more than half-way completed. The contractor was informed that an additional four columns in the middle of the building would require support by 16 additional micropiles. UMA continued construction, did a design and got it approved, and then implemented the new design while on-site without delay.
UMA used one if its specialty Casagrande C7 XP-2 Crawler Drilling Rigs for all micropile drilling. The rig’s 30-foot stroke allowed the team to install piles up to 30 feet deep. UMA used a custom drill bit and its experience with unique soil formations to drill the piles through a wet sandy overburden layer and down into the Cooper Marl bond zone.
When all was said and done, UMA had completed 304 micropiles by the February 2019 deadline. It took Team UMA working a double shift, deploying its fleet of specialty foundation equipment, and its past success working with the unique Cooper Marl Formation.
