Sheeting + Pile Driving
“What is that racket and when will it stop!” – Construction in Boston.
It’s rarely a pretty affair, but as the saying goes, “You’ve got to crack a few eggs in order to make an omelet.” The biggest “egg cracker” is often right in the beginning of a project when you must pound sheeting and wood piles into the ground to support the foundation, and eventually, the building.
Much of the glorious city of Boston was built over marsh area. Or, in the case of the Back Bay, trucks delivered fill to create a landmass where there was once only water. Seriously, study your Boston history; an entire hill in Milton was cut down and used to infill the area to create the Back Bay. And now you know why they call it “Back Bay”.
Enough with the history lesson! When you are trying to build over unstable soil, your options are few and pricy. We decided to go with sheeting and wood piles. Allow me to explain the process.
First, the sheeting is driven into the perimeter of the building’s foundation. It then becomes the soil stabilizer around the foundation and is often incorporated into the foundation as the “backside” of the formwork for the foundation. The foundation is further stabilized by driving piles through the interior footprint of the building. This provides underground stability for the foundation and interior load-bearing walls. This is where the problem arises: the most affordable method is to use pressure treated wood. In our case, we are working with 60-foot tall timbers that resemble telephone poles. This project requires 240 piles. At an anticipated rate of 14 piles driven per day, you have 17 working days of brain numbing pounding…and pounding…and pounding. Sorry folks, but this is what it takes to build over much of Boston. The additional problem is that these timbers are driving through obstructions like stone, granite, urban fill, etc. When the timbers meet these obstructions, they will split, or simply “refuse”, meaning that it won’t drive any further no matter how you pound on it. You then have to re-design and pound additional piles to compensate for the refused timbers.
And that is just one reason why construction in Boston is so noisy.