Clay Hill Boring Thrives On A Good Challenge

Florida Boring Project Delivered Challenges Beyond This Company’s Dreams
May 2009 Vol. 64 No. 5

Now that the pits were dug and shored, the team began prepping them for the McLaughlin auger boring equipment. Since some of the water lines were gravity fed, the floor of the bore pit had to be graded using lasers to meet the desired grade, which ranged from .18 to 2 percent.

“Boring on grade is difficult enough, but we were also dealing with wet sandy soil, and maintaining the grade in shifting ground conditions can be a tough challenge,” says Rea. “Trying to attain a two inch fall or rise every 100 feet is a challenge no matter the ground conditions.”

Rea and Metzger decided to use a 3 inch hex auger and steering head from McLaughlin. This allowed them to monitor the bore and know exactly where the lead pipe was at all times. It paid off well as they hit the target to within a couple hundredths of an inch of where they needed to be. To keep the bore on grade, every section of pipe was aligned using a water level.

“The biggest concern during the bore was potentially hitting a water pocket under a two lane road or divided highway that could result in a collapse,” says Metzger. “We definitely didn’t want to create a void under the road. Our planning and dewatering plan paid off and we didn’t experience any unusual problems throughout the 23 bores.”

Production varied for each bore due to the water levels. At times, the crew needed to back up and reset the well points before they could continue moving forward. But on average, they would complete a 220 foot bore in less than three days.

History of tough jobs (subhed)

Rea has seen his share of unique projects during the past 20 years and he has worked closely with McLaughlin to design and engineer auger boring equipment to handle these challenges.

“I worked with McLaughlin to develop a boring machine with 2 million pounds of thrust that we used to push 400 feet of 48 inch concrete pipe a few years ago,” says Rea. “The total weight of the concrete pipe was around 400,000 pounds and we didn’t use a steel casing on this project. We’re one of the few companies in the country that can do that.”

On another project located in Manassas, VA, Rea and his team pushed 130 feet of 72 inch steel casing through solid rock (shale) with 15/16 of an inch fall. He worked with the McLaughlin engineers to design a machine specifically for this project as well.

“McLaughlin has been a great partner since we started this business,” says Rea.