June 2016, Vol. 243, No. 6
Features
Side-by-Side HDDs Effective On Gas Line Replacement
PG&E began work in September 2014 to replace two aging natural gas pipelines that cross Cache Creek near the town of Capay, CA. In September 2015, the HDD Company completed two directional drills on the project, replacing the pipeline that had been exposed on the bottom of Cache Creek.
PG&E’s Line 400 was permitted in 1960 and constructed in 1961-62. It is a 36-inch pipeline that carries gas from Canada south through the Central Valley. The other pipeline, Line 401 was permitted in 1991 and constructed in 1992. It is a 42-inch natural gas pipeline that runs parallel to Line 400. Both pipelines cross Cache Creek and PG&E decided to replace these pipes with two new pipes that would be laid roughly 80-feet below Cache Creek using directional drilling.
The HDD Company’s Operation’s Manager Jeremy King noted that construction on the project was under the direction of two contractors, prime contractor Barnard Pipeline and drilling subcontractor The HDD Company.
Early activities included truck delivery of more than 5,000 feet of pipe for the project and the stringing and welding of the pipe by Barnard Pipeline crews.
The pipe selected for the project was 36-inch 750”X65 and 42-inch 750”X70 Longitudinally submerged arc welded (SAWL) steel pipe. While Barnard Pipeline’s crews were stringing and welding the pipe, HDD arrived to begin the directional drills.
King noted that the HDD contract covered two water crossings and the installation of two parallel directionally drilled crossings, each 2,560 feet long to accommodate the installation of the 36-inch and 42-inch steel pipe 80 feet below the creek bed.
Initially, King said PG&E had requested the work be performed using one HDD rig and for crews to work around the clock to expedite project completion. Instead, King said The HDD Company recommended to use two rigs: An American Augers 440 to install the 36-inch pipe; and the company’s self-built Rig 3 (a 900,000-pound rig) to install the 42-inch pipe. After PG&E agreed to the new plan, the two rigs were mobilized to the site in early May 2015 and set up side-by-side, 70 feet apart.
According to King, the entry location on the south side of the creek was in an open area 1,200 feet from the creek bank. The entry location offered ample space to set up both HDD spreads and support equipment, while the exit location, on the north side, offered sufficient space for Barnard’s crews to string and weld the pipe.
Since plans called for the two crossings to be drilled simultaneously, the initial pilot bores were started by both rigs on June 3. In describing the crossing, King said the12¼-inch pilot bores carried out by both rigs went smoothly. Each pilot bore was completed in a little over two weeks. The drill for the 36-inch pipe was back reamed to a final diameter of 48 inches and the drill for the 42-inch pipe was enlarged to 54 inches.
He described the soil conditions encountered as clay and mudstone and the weather as ideal over the entire course of the project. King said 8-inch mud motors were used for both pilot bores. For locating they relied on magnetic high resolution guidance systems. They used high yield Wyoming bentonite drilling fluid furnished by Drilling Mud Direct LLD of Colorado. All excess fluids and cuttings were dried and hauled to a landfill site.
Working with eight people per shift, the final pipe pull of the 36-inch pipe was completed in early September and took only 12 hours to complete. King said, “Despite being set back by a pipe failure on the 42-inch line, crews were able to fish the tooling out and continue the drill. Work progressed and the 42-inch pipe was pulled in two weeks later.”
As to the punch-through locations, he said the 36-inch drill was within .44 feet of the proposed exit location and the 42-inch drill was within 1.2 feet of the designated exit point. Final line tie-ins were carried out by Barnard’s crews.
Noting that HDD began the two crossings in early May 2015, King said when the drilling was officially completed HDD was off site by mid-September.
He credits the team work of PG&E, Barnard Pipeline and The HDD Company with the project’s success. “We had good communication, good planning and good execution throughout,” he said.
The HDD Company was founded in 1999 by Neil Swope and then a portion of the company was sold to The Crossing Company in 2009. Today, both companies own just under 30 HDD rigs, making them one of the largest drilling contractors in North America. The combined companies specialize in challenging HDD projects that include major shore approaches and pipeline projects throughout North America.
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