May 2009 Vol. 64 No. 5
Features
Clay Hill Boring Thrives On A Good Challenge
Don Rea loves a challenge. In fact, he goes looking for them everyday; some just show up on his doorstep – but for good reason. Rea is the president and owner of Clay Hill Boring located in Lake Park, GA.
His company has developed a national reputation for tackling difficult pipe jacking and boring projects most companies would never consider.
It all began in 1956 when Rea completed his first bore under a road. “The project involved installing a 24 inch corrugated steel tube,” says Rea. “We dug it with a claw hammer and pushed in the pipe. To tell you the truth, I hurt in places I never even knew existed.”
But Rea caught the bug and formed his own utility installation company in 1963, then in 1985 began specializing in pipe jacking and boring. The rest is history, and thus began a reputation for taking on tough, even sometimes impossible projects.
Imagine taking a piece of 36 inch steel casing and having to shove it 400 feet through the ground under a divided highway at a .18 percent grade. That’s a 2 inch rise or fall for every 100 feet of casing. Now envision doing this without being able to see what is happening in the ground and trying to hit your target 400 feet away.
This is what sets Don Rea and his 10 employees apart from others in the industry. Today, the company works on projects ranging from 8 to 96 inches in diameter all over the country.
Bunch of bores (subhed)
Putnam County is located 40 miles south of Jacksonville, FL, and recently completed the construction of a new water treatment plant, water towers and groundwater wells in an effort to upgrade the regional water supply and delivery systems. The project also involved the installation of 30,000 feet of new water transmission lines.
The project called for the installation of 16 to 30 inch casings that would house the water transmission lines under 23 divided highways and county roads. The bores ranged from 60 to 220 feet in length with half requiring a .18 to 2 percent grade.
With 23 bores there was a lot of planning involved. But toss in a high water table, sandy soil conditions, significant underground utilities and a hurricane, and you have a potential mess on your hands.
Brian Metzger, operations manager for Clay Hill Boring worked with the general contractor, Florida Department of Transportation and the project engineer to design each bore.
“Each bore was unique, and once we arrived on site and identified the exact location of the existing utilities, most of the bore plans had to be modified,” says Metzger. “We were in close coordination with everyone involved to change the length and depth of the bores to work around the existing utilities.”
The underground infrastructure was a significant challenge. The neighborhoods were established in the 1950s and the county didn’t have adequate records documenting the location of the underground infrastructure. Add in new fiber and telecommunications lines and you have a recipe for disaster.
Extra care was taken to locate and verify the existing utilities. One Call was contacted to sweep each location and the Clay Hill Boring team potholed the marks using a vacuum excavator to visually identify the location and shoot the depth of each line. If the lines interfered with the bore, it was back to the drawing board.
“It involved a lot of field engineering to make this project work,” says Metzger.
Water everywhere (subhed)
No matter where Rea and his team turned, they were faced with water during the four month project.
“We were pretty close to the St. John River and the water table in this area is only 6 feet below ground level and the casings were to be installed at a depth of up to 15 feet to avoid the existing storm sewers and utilities,” says Rea.
To overcome the high water table, the team developed an intricate dewatering plan that included massive portable pumps and well points. Three days before a bore was scheduled to commence, well points were placed in the ground where the bore and receiving pits were to be dug. The well points were installed at a depth of 3 feet below the maximum pit depth, which varied from 11 to 15 feet. Once installed, they were connected to a 6 or 8 inch Thompson pump that ran around the clock to lower the water table in that area.
Now add in the effects of Hurricane Fay, and you have a real challenge on your hands.
“The hurricane was a mild annoyance, since we were only working two blocks from the river,” says Metzger. “The water levels rose quite a bit and that affected our dewatering plans, but we never had to abandon the project.”
Once the water table had been reduced, excavators were used to create a 20 foot by 10 foot bore pit, and the pits were shored for safety.
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.
Dealing in specialized and difficult work is what keeps Rea and his team going day after day. And no matter what he does or where he goes, difficult projects always seem to find him. But that’s what he loves about his job.
FOR MORE INFORMATION:
McLaughlin, (800) 435-9340, www.mightymole.com
Clay Hill Boring, (229) 245-9303
Comments