Clay Hill Boring Thrives On A Good Challenge

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

“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.