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Tough Rock Not a Problem

Riff Wright

tough

As far as jobsites go, it doesn’t get much more beautiful than drilling on the coastal bluffs of northern California. But regardless of how spectacular the views may be, there were no shortage of challenges along this seven-mile Verizon fiber project that required an impressive 21,100 ft of horizontal drilling.

Besides a meticulous drilling plan, additional consideration had to be given to issues such as traffic control and lane closures along the narrow and winding coastal Highway 1, as well as a fluid management plan to deal with water delivery and drilling in delicate areas of the ocean front.

Weldon and Wayne McCurley of Westech Industries in Galt, Calif., possess years of experience in drilling throughout northern California and were familiar with the challenges involved in such a project. They approached the job only after developing a comprehensive plan.

The narrow road conditions and lack of adequate shoulders and medians on the popular highway meant that locations for drills and support equipment were planned in advance. “Lane closures were necessary but with careful planning we were able to keep traffic problems to a minimum.” Weldon explained. “The City of Sea Ranch was also very cooperative.”

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California’s coastal bluffs are composed mainly of sedimentary rocks such as sandstones and shale that are particularly prone to erosion. Grains of quartz, feldspar and mica are compressed into layers of sandstone.
Coastal bluffs, however, are less evident along the northern California coast where the mountains plunge abruptly into the ocean. Rocky headlands are more prevalent along the Northern and Central California coast, but may occur anywhere erosion-resistant rocks are found along the shore. Rocky headlands are composed of igneous rocks — granites and basalts — that are resistant to wave erosion.

The project consisted of numerous bores averaging 550 ft with a few longer 800-ft shots. Armed with a Ditch Witch JT3020 Mach1 and a JT4020 Mach1 the McCurleys employed a “three-strike” approach to the project. To prevent delays from troublesome bores, each crew would only make two attempts at the hole. “Obviously most were successful on their first attempt, but as difficulties arose, we simply considered a possible third attempt before moving to the next bore.”

By limiting the amount of time their rigs were dedicated to tough bores, the timetable was much easier to maintain. Toward the end of the project Westech employed a Ditch Witch All Terrain HDD unit to complete the difficult bores they had skipped over.

Since the fiber project consisted of pulling two 1-1/4-in. poly lines, no reaming was required after the pilot hole was achieved. Since both rigs were outfitted with Radius rock bits and rock housings, Westech was able to use the unique “pullback” adapter to speed up the pulling process.

The Radius rock bit is designed with an adapter that simply bolts to the front of the bit once the pilot is
complete. Other similar rock bits require the bit and sonde housing be completely removed and some form of pulling device be attached, which in some cases can be  difficult.
“With the Radius pullback adapter, my crew was ready to pull the poly less than five minutes after the pilot was complete,” McCurley said. Along with offering a speedy connection and quick turnaround, the Radius “pullback” adapter keeps the sonde housing in place to provide the option of tracking the pullback as well. Once the pull-back is complete, one bolt removes the adapter and the bit is ready to drill the next hole.

With sensitive environmental controls and few nearby locations to dump spoils, Westech kept a fleet of vacuum excavation trucks and reclaimers moving throughout the job to prevent delays and cost overruns from unplanned clean-up cost such as spills and frac-outs.

With the sun setting boldly in the Pacific, the drills were loaded and the trucks pointed toward home. Weldon is quick to credit the talent of his entire crew for their accomplishment, and indeed it was an impressive team effort. There is still no question that thorough planning, good project management and years of experience contribute greatly to a job well done.

Riff Wright is owner of Radius Professional HDD Tools, Weatherford, Texas.
Courtesy trenchless technology

 
 
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