Award of Excellence: How a Precision Locating Device Confirms Accuracy of Pile Placement
In another elegant solution to a controls-and-management problem on the surge-barrier project, Jones turned to an instrument-laden, 50-ft-long, bullet-pointed pipe to provide accuracy validation for pile placement 35 ft under an active navigation channel.
As it built the wall of the Inner Harbor Navigation Channel Surge Barrier, TMW installed, under a separate contract, hundreds of foundation piles for the barrier's 150-ft-wide sector gate on the Gulf Intracoastal Waterway.
The gate requires a strong foundation and pad to stand up to the enormous load of a 26-ft hurricane surge. The accurate installation of several hundred 42-in.-dia, 140-ft-long foundation piles, spaced 10 ft apart—required to be at -35 ft elevation, plus or minus 3 in.—had to be continuously verified.
"We drove them at night with GPS during navigation shutdown," says Jones. To authenticate accurate placement, Jones used the 24-in.-dia probe, which had GPS units on each extended arm and an inclinometer to establish verticality. When nested into an unseen pile top and plumbed, the instruments confirmed the pile's X, Y, Z location. "We had one pile wander out of tolerance vertically because we had to do a redrive due to some external factor. It came out really well. I was particularly pleased to do that at night," Jones says.
"I built one similar on the Braddock Dam," he adds, bringing up a legendary 1999 project that involved floating large dam modules over foundation studs on the river bottom and sinking the modules into place. On the first module, operators tweaked settings for many hours to ensure a perfect set. Finally, an exasperated Jones seized control, sited the marks and quickly dropped the module neatly on its pins, much to the crew's delight.
