Protecting Our Global Environment

Case Studies
Wetlands

In the 1996 Olympics, there was plenty of records and gold medals. In Savannah, Georgia, the Olympic sailing venue, a record was set for a directionally drilled crossing in June. Environmental Crossing, Inc. (ECI) deserved a medal for their efforts.

ECI drilled 5,328 ft. with 5 in. pilot string and left it in place using an American Directional Drill DD-140. Bruce Brasher, Vice President of Operations at Environmental Crossings, Inc., was the project manager for the installation for Bell South. Neil Swope of ECI, was the rig superintendent. He directed the details of this operation and was assisted Russ Randoll and Bobby Staggs, both drillers. Bell South was represented by Buddy Waller, Senior Engineer and the project engineer, Nalria Gaddy. Ms. Gaddy claimed, "That the effort was a perfect drill."

The crossing was on the Gold Coast of Savannah, under the Wilmington River and ran from Skidaway Island to Wilmington Island. This area is environmentally sensitive one on both shores. It includes a wild life refuge with extensive marshlands, as well as resting grounds for the endangered wood stork on the entry side. Sound barriers were erected around the job site to prevent the noise of the 24 hour operation from disturbing the rare birds.

In spite of being on the ocean coast, crossing under rivers and marshes, the great majority of the 70 ft. deep crossing was in marl clays. This required us to use a mud motor for accurate steering. ECI used a 4-3/4 in. Black Max mud motor with a 7-7/8. bit.

ECI used their own steering tools and TruTracker on this job.  Steel spiders were used to keep pressure off the probe wire. Only one wireline short occurred and that was at the 3,300-3,400 foot mark. The short was due to a pinched wire.

Bruce Brasher stated, "Good mud was critical to the success of the job." Luther Finley of Parchem kept an eye on the mud operation. Bentonite was mixed at 40 to 50 second thickness. A viscosifier, INVIS, was used to make the drilling fluid act like 70 to 80 second thickness. In addition a polymer, MUDUP, was used to slick up the hole in the soft ground.

ECI used a mixture of white and yellow bands 5 in. pipe from RK Pipe out of Lafayette, Louisiana. Prior to the job's beginning, the pipe was rattled along with the scale and debris cleaned out with bottle brushes.

The first 2,400 ft. of yellow band pipe was drilled on the pilot, then followed with 3,000 ft. of white band pipe. This sequence put the stronger and better quality white band pipe at the end of the drill string, where greater torque forces are present.

On Wilmington Island, the pilot hole was originally 8 ft. to the right of and 18 ft. under the desired exit point. It was difficult to build the proper angle due to the very soft ground. Also the 4 to 5 foot water table made it impractical to dig down to the Bottom Hold Assembly for its removal and installation of the fiber optic line.

ECI then backed up the pilot string several times and slowly tried to build angle. The crew was successful, and the final exit was 4 ft. long off the exit point. The exit angle was flat at 94.6 degrees. 300 ft. of TruTracker was used at the entry side, and 360 ft. was used on the exit side.

Once the pilot was through and the Bottom Hole Assembly was removed, ECI had two tasks ahead of them. One was to remove all the steel spiders in the drill string. The second was to recover the more expensive and reusable white band pilot string.

The extra yellow band pipe was trucked over to the exit side. Then installed piece by piece as the entire pilot string was tripped out and cleared of the steel spiders on the entry side. The only route to the exit side was a 30 mile, 45 minute drive through downtown Savannah. After all the cleared yellow band pipe was installed, the 96 fiber cable was put into the pipe.

Brasher, Swope, Gaddy, Finley, and senior officials from Bell South and Environmental Crossings, Inc. all celebrated the successful crossing at its conclusion and all were quite proud of the effort. And well they should be. This was the longest crossing ever done with an American Directional Drill DD-140.

For those of you with good memory, you might remember another Environmental Crossing, Inc. job from a couple of years ago. The job involved a crossing with 130 degree lateral angle. If an Olympic event was held for directional drilling, Environmental Crossings, Inc. would have received several medals for its challenging crossings.

Underground/Trenchless Technologies • Environmental Crossings

Questions or Comments? info@ecihdd.com

ECI Home   /   Fiber Optics /   /   Contact Us

Environmental Crossings Inc. ©2000 All Rights Reserved, S.I. MI 49686