Taking Water Pipe HDD To Extremes

By Jeff Griffin, Senior Editor | June 2011 Vol. 66 No. 6

Bell said the drill rig was then turned about 45 degrees for the start of the second crossing which proceeded to bore upward to the storage tank, following the path of the main park road part of the way. The second bore was 4,394 feet long with a 600-foot upward elevation changing to a 76-degree side bend throughout the entire crossing.

“We could not shoot straight to the tank because of sharp drop-offs on the sides of the old road,” Bell explained. “In addition to the sharp turn, there were multiple side and up-and-down changes. It was a very difficult installation.”

Soil conditions were similar to those on the first bore. Average depth was 70 feet. The same size mud motor, drill bit and hole opener were used as on the first bore.

“The waterline stringing and welding area was limited to less than 1,000 feet until a few days before pull back, so the pipe was welded in several sections then pulled out to its full length just prior to installation,” Bell said. “This layout area had multiple “S” curves and elevation changes of over 120 feet. It was extremely challenging.”

The bore was completed in three weeks. With logistical issues to deal with, pipe pullback took two days.

Limited excavation was required at exit points of the two bores to connect the two installations at the top of the mesa. Two large concrete thrust blocks were constructed at each end of both installations to stabilize the pipe, and the first 200 feet of each end of the pipes were grouted.

From start to finish, the project was completed in about three months, with winter snow falling near the end of construction.

Challenges met
In spite of the complexity of both installations, along with terrain conditions, and limits on disturbing the park land, Bell said the project essentially went as planned. He praised Laney personnel for their performance and Laney Project Superintendent Kyle Orum.

“We did have several frac outs -- something park service people never want to see,” Bell said. “Some we were able to access and address, on others, the fluid simply dissipated. The park service was very good to work with, but we had several levels of government administrators and environmentalists concerned about pollution and damage to the land and plant life, and naturalists who were looking out for the animals.”