PROJECT OVERVIEW
Phoenix Project #2228
Renovations to the interior of an existing building located at 33-41 Farnsworth Street in Boston required the installation of 18 drilled micropiles (“DMPs”), with all piles located inside the existing structure. The piles had compression capacities ranging from 60 to 110 kips each, and included permanent drill casing through the fill soils along with uncased bond lengths within the underlying sand/marine clay layers. With pile depths ranging from 65 to 110 feet deep, this project was not without its challenges!
Limited headroom and tight access made maneuvering the drill rig a continuous challenge. Phoenix selected the nimble Klemm 702 for this project given its slender width, short mast height, and detachable power pack. Our mobilization entailed hoisting the drill rig through a narrow opening in the side of the building and into the existing building. Once inside, a handful of piles were located down a narrow hallway that was just wide enough for the machine to fit on location. Many other piles required navigating around existing walls and columns in order to position the drill rig into the necessary orientation.
Making matters worse, the site was riddled with subsurface obstructions. Some pile locations were pre-excavated where practical, but many obstructions had to be drilled through as part of the micropile installation. Remnant foundations including thick granite sections were penetrated one by one, putting the equipment, tooling, and crew to the test…
As is the case with most projects, spoils management was critical here. Given its small footprint, this site had the potential to flood quickly once drilling began. In order to maintain control of these spoils, an open-top water tank was utilized. As drilling proceeded, liquid spoils were pumped away from the drill rig and into the tank, after which Phoenix would recirculate “clean” water out of the tank and back to the drill rig. This process significantly reduced the amount of fresh water that had to be introduced to the site.
The Klemm 702 specializes in limited access projects, while at the same time being versatile and powerful enough to tackle many outdoor drilling applications as well. With a detachable power pack that can be left up to 100ft away from the rig itself, this machine is ideal for tight access and low headroom drilling. Additionally, having the power pack remain outside while drilling inside helps to mitigate noise and exhaust issues that would otherwise result from running a diesel drill rig inside a building.
