River Crossings
Numerous river crossings have been performed to install utilities under environmentally sensitive waterways. This crossing under the St. Joseph's River features installing multiple conduit for communications utilities.
Feature • Multiple Conduit Pullbacks in Drilling Extremes•
It was a record-setting month for Environmental Crossings, Inc. (ECI) of Traverse City, Michigan. July 1993 was the month ECI completed two monumental horizontal directionally drilled crossings. Deeper and longer directionally drilled crossings had been completed, but never before have multiple conduit formations been placed as on these two crossings.
These projects, the St. Joseph River crossing in Mishawaka, Indiana (which you can read about under our Fiber Optics case study), and the crossing of the shipping channel at Port Canaveral, Florida had a number of similarities. Both involved crossing traffic ways and installing numerous critical communications circuits. Both also utilized conduit formations without external casing, using a method of placement developed by Douglas Allman.
The second of these two multiple conduit jobs took ECI and their equipment to Florida. There they had to cross the shipping channel at Port Canaveral. This crossing, 1175 ft. in length and 101 ft. in depth, would use seven 4 in. ID HDPE conduits placed in a 24 in. borehole drilled in the sandy soil.
Once again, these conduits would be encased in grout during the pullback. Security of the communications circuits for the U.S. Air Force Command was the reason. The number of U.S. Air Force circuits was not specified (classified information), only that they were Cape Canaveral Command Control Links. Personnel with M-16 emphasized the importance of whatever number of circuits existed!
This project surpassed all previous multiple duct placements by 56% in length (425 ft.). While becoming the longest, it also became the deepest placement of this type of formation.
The Port Canaveral conditions of sandy clay with some shell fragments provided a much shorter interval to completing this crossing. Nine days were all that were required to drill the pilot hole.
Coordination at Cape Canaveral became very interesting and complex. The Space Shuttle, Atlas, Titan, and Delta rocket programs were presently active at the cape.
Scheduling of all work activities was done around these flight periods. All personnel were required to obtain clearance and passes to enter the military base. Seventy-two hours prior to flight, restrictions classified as F3, F2, and F1 (three, two and one day prior to flight, respectively) began on construction operations. With each twenty-four hour period before launch, increasingly rigid restrictions on construction were implemented. Twenty-four hours prior to flight, F1 restrictions took effect and all digging ceased. A shovel was not permitted to enter the ground during the F1 interval. Such restrictions were to prevent any disturbance to below ground communications and control circuits.
The crossing was completed on July 21st; the total time from drill-in of the pilot hole to completion of the crossing (including several days of imposed delays and varying restrictions) was 14 days.
Both these projects required innovative approaches. Completion of these types of crossings required more than a knowledge of one area. The integration of several systems, materials, applications, designs, and most importantly the customers' needs, made these accomplishments stand out as more than records for Environmental Crossings, Inc. Not always is it the challenge of the task, but the vision that is brought to it.
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