The Alliance Pipeline is one of the most aggressive pipe construction projects in many years. The 1,857-mile pipeline, as many know, will run from Fort St. John, Canada, to Chicago, IL. The high-pressure gas line will operate at 1,740 psi, and will have an initial carrying capacity of 1.325 billion cubic feet of natural gas per day.
Contractors from around the United States and Canada are currently working on this massive undertaking. In 1999 over 7,000 people worked on the project, and by the end of the year 70% of the mainline construction was complete. With a target completion date of October 1, 2000, construction crews are employing all types of pipeline installation methods in order to bring the pipeline to fruition.
Trenchless installation methods are playing a role in the project as well. As to be expected directional drilling has been a prominent fixture along the pipeline with a number of spectacular river crossings. Pipe ramming has played a large part in the project as well. In addition to assisting directional drills on numerous bores, thousands of feet of pipe have been installed through pipe ramming.
Pipe installation contractor Murphy Bros., Inc. of East Moline, IL. is working on the final 124-mile stretch from the Illinois/Iowa border to the Aux Sable processing plant just west of Joliet, IL. According to Murphy Bros. Superintendent Jim Murphy, the addition of pipe ramming tools to the equipment list has been very rewarding. Murphy said, “The rammers have definitely added to our overall productivity. From safety to crew size the impact has been very positive.”
Murphy Bros., Inc. has been in the pipeline installation business since 1971. They specialize in the installation of gas, oil, mixed product and water mains. Their crews are highly skilled and well versed in numerous installation techniques including directional drilling, auger boring and conventional open cut.
According to Murphy, the company got its first real look at pipe ramming during the 1999 construction season on the Alliance job. Murphy said, “We were working in a very congested area of the Alliance project; probably the tightest working area of the entire line. We couldn’t use conventional augering so we turned to pipe ramming instead. The installation went well, but we still didn’t think of ramming as a primary installation tool.” That would change in the 2000 season.
At the end of the ’99 Alliance season, Murphy reviewed the performance of the Grundoram pipe rammer from TT Technologies, Aurora, IL. According to TT Technologies Pipe Ram Specialist Scott Kneip, the advantages of ramming became clear. Kneip said, “The soil conditions in the area where Jim was working were not very conducive to auger boring. The glacial till soil contains many rocks and boulders that can play havoc with a conventional auger bore system. Ramming is often a preferable choice.”
With the rest of the Alliance project on the horizon, Murphy needed to make a decision about what equipment his crews would use for the upcoming season. Murphy said, “We kind of pulled all the information together and did a ramming test in our yard. We wanted to see where the plusses were and where the minuses were. We also needed to decide whether we would run one auger crew and one rammer crew or two rammer crews. After the yard tests, we decided to add another Grundoram.”
Because of the nature of the job and soil conditions, Murphy figured he would get more productivity out of the rammers. He said, “Over a two week boring scenario, a standard cradle auger boring machine might be up and running eight out of 12 days and down for maintenance or set up the rest of the time. A rammer, on the other hand, will run for the whole 12. Plus, because the rammer is not thrown off by rocks or boulders, our bores come out more consistently on target.”
With a 38-mile stretch left on their Alliance Pipeline segment, Murphy Bros. added a second ramming crew and started the 2000 season in May. Within the 38-mile section from Hwy. 47 to Hwy. 251, the Murphy Bros. crew would have to complete over 40 pipe rams under roads and railroad crossings. When complete, footage totals will reach over 4,000 feet of ramming alone.
The crews each used 18-inch diameter Grundoram Goliaths to install the 36-inch casings, then installed the mainline through the “slick bore” process. According to Kneip, Murphy Bros. used a standard ramming tool configuration.
Kneip said, “A segmented ram cone and a soil removal cone are used to connect the tool to the casing. First the 36-inch segmented ram cone is connected to the casing and reduces the overall diameter from 36 inches to 21 inches. A soil removal cone is then added. The soil removal cone reduces the diameter from 21 inches to 18 inches. The Goliath is then put in place and the connection is complete.”
Murphy said actual ramming times averaged about one foot per minute depending on soil conditions. Once the ram is complete, the casing is sealed off with a cap and the spoil is cleaned out using compressed air and a polyurethane pig. After the spoil is cleaned out, the slick bore process begins.
During the slick bore process the actual product pipe is welded to the back end of the recently installed casing. A winch line is connected to the lead end of the casing and is used to pull the casing out. As the casing is removed the product pipe is pulled into place. According to Murphy, the process works very well and rammers are sometimes used for an extra push.
Murphy said, “We hook up the winch line and start pulling. Some move more easily than others. If we get one that is not moving very well, we’ll just attach the rammer to the back end of the product pipe and just tap it into place.”
Soon after implementing the two rammer crews Murphy saw what ramming had to offer. He said, “We identified several tremendous benefits to pipe ramming. First, pipe ramming has less crew requirements. We are able to complete the bores by ramming with fewer people. Second, we needed less space. Bore pits didn’t need to be as long or as deep as they do with conventional augering.
Third, pipe ramming made for a safer job site. Fewer people, less machinery and less pit work all contributed to a cleaner and safer work area. Finally, we improved our consistency in reaching our bore goals and basically eliminated undermining under the roadways.”
With plenty of boring still ahead, Murphy is looking forward to improving his crews’ efficiency and utilizing pipe ramming to its fullest potential.
by Jim Schill
NUCA, December 2000