Natural gas transmission and distribution companies continue to utilize compact directional drilling and numerous other forms of trenchless technology for large and small-scale projects. On the transmission side, numerous high profile large diameter directional drilling projects have taken place. While these projects command attention and publicity, it’s the smaller scale projects, the day-to-day installations that tend to be overlooked, however are no less important.
Peoples Energy, Chicago, Ill. has a 150-year history in the Chicago area and boasts the title of the city’s first gas utility when its gas lamps first lit the city back in 1850. Back then, the company was made up of a group of prominent citizens that formed the small company. Today Peoples Energy is a highly diversified company with businesses ranging from its core in gas distribution to power generation and oil and gas production. With over a million customers, 5,000 miles of gas main and a territory that covers over 50 Chicago area communities, efficiency is key to the everyday operations. One area where efficiency thrives is in system maintenance and repair. New Main Installation Coordinator Tom Sandonato oversees these efforts in his territory called “South Shop” that covers over 100 square miles in the southern reaches of greater Chicago. According to Sandonato, trenchless technology, specifically horizontal directional drilling (HDD) helps keep schedules moving ahead and customers happy. He said, “Since the late 1990s we’ve been directional drilling a majority of our main installations, probably around 75 to 80 percent. Directional drilling has proved to be very effective. It allows us to satisfy our customers’ needs without creating a lot of disruption. And it helps reduce our restoration costs.” Much of the directional drilling done by Sandonato’s crews is accomplished with mini or compact directional drill equipment like the Grundodrill 4X from trenchless equipment manufacturer TT Technologies, Aurora, Ill.
Directional Drilling Capabilities
According to TT Technologies Directional Drilling Specialist Bryan Bachmann, the development of smaller drills is something that has occurred gradually over the last several years. He said, “With a lot of the long range, medium diameter drill work dissipating, it seemed natural for the industry to shift toward shorter, smaller diameter installations. The technology put into today’s smaller drills has given them greater capability and made them easier to use.” With some “mini” drills offering as much as 9,800 lbs. of thrust and pullback, the machines are able to accomplish a wide range of installation tasks. At Peoples Energy the Grundodrill 4X is being used to install mains and services up to 4 inches in diameter and lengths up to 400 feet in soil conditions that range from sandy loam to clay and slag. According to Sandonato, the unit’s size makes it ideal for his territory. He said, “Picture the city of Chicago and its crowded, congested city streets. The footprint of the 4X makes it very versatile to get in and out of situations where there are cars parked and pedestrians and we’re not cluttering up the street with the machine or taking up a whole lot of room. So after we do the main installation, we come back and do the services. And the unit is small, mobile and compact enough where we can get in and out of tight working conditions and shoot the services. It’s been a really great addition to our fleet.” Bachmann said, “These mini-drills work well in residential or commercial areas. They’re lightweight. They can be transported on a trailer pulled by a pick-up truck and require minimal crews to operate. The 4X’s special steel track with bonded rubber pads offers excellent traction and durability while minimizing potential damage to concrete and turf, which is important in residential settings. “Plus the units are very easy to operate. The computerized Smart Vice system simplifies the drilling process by automating the drill’s vice cycling operations. The operator has single push button control of the function. That helps improve efficiency and speeds up drill times. The vice is also self-centering, reducing wear and tear. The operator can return to manual control with the flip of a switch. The whole system is very user friendly.”
Peoples Energy crews primarily utilize compact directional drills for residential main and service installations. With some cast iron mains dating back to the late 1800s, Peoples Energy is committed to updating its system. Sandonato said, “We’re required under federal guidelines to replace our antiquated mains. In addition to that we utilize what we call a main ranking index. Through that system we’re able to track what mains have given us problems in the past in terms of leaks. That gets entered into a database. So, if we go in and work on a main we know if we’ve done work there before. And after a certain point we just end up replacing the main. It’s the company’s goal to replace all of the existing cast iron mains over the next 50 years and we’re well into that.” A majority of the pipe that is being used to replace existing systems is medium density polyethylene pipe (MDPE). Sandonato continued, “When we install new mains it’s primarily for what we call, LP-MP conversion, low pressure system to medium pressure system conversion. Basically we’re abandoning our old low pressure main and installing a new medium pressure main and transferring all the existing services to the new main, running a whole new pipe to the house.” Existing mains in Sandonato’s territory are usually cast or ductile iron, ranging in diameter from four to six inches. Sandonato’s crews also coordinate with the city of Chicago’s construction schedule. Once a road or sewer construction project is scheduled, the city will alert Peoples Energy and tell them the locations of various projects. Peoples Energy crews then try to coordinate their gas main and service upgrades at the same time. Despite the potential to open cut such a project, crews still utilize directional drilling because it’s more efficient. Sandonato said, “We have become big proponents of double decking our mains. In a typical situation we would have one main running down the street feeding services on both sides. But now that we’ve become adept at directional drilling, we place mains on both sides of the street. Once those mains are installed, we’ll drill services to each house. Now we don’t have to worry about any future work the city is going to do. Our mains and services are out of the street.”
On The Job
All directional drilling is done in-house at Peoples Energy and has been that way since the company started using the technology. A recent project on the Southwest side of Chicago serves as a good example of a typical project for Peoples Energy. The project took place in Mount Greenwood, an established community, where the city of Chicago was planning a complete street restructuring and new sewer installation. According to Sandonato, his crews were notified and went out to evaluate the project. He said, “We took a look at the job and determined we had about 3,600 feet on main to install. We knew it was going to be a difficult situation because the neighborhood was very established, with immaculate and extensive landscaping. We did not want to go in there and start tearing things up.” Crews set to work locating existing utilities, then determining the location of launch and exit pits. According to Sandonato, the launch and exit pits were small and created little disruption. Crews were able to install on average 400 feet on new 2-inch MDPE per day to replace the old 6-inch ductile iron. After the mains were installed crews proceeded to directional drill the service, over 90 of them on this particular project. Sandonato said, “What’s nice about directional drilling those services is we’ve got the hole down at the main line down to about two feet by three feet, really small. Now at the house, all of our regulators are placed outside. So all we need there is a small one-foot by one-foot hole that can be dug with a posthole digger. You drill up to that hole, hook up your product and pull it back with very, very minimal disruption.” Currently, Sandonato estimates that crews within all three Peoples Energy regions (North Shop, West Shop and South Shop) are replacing between 30 and 40 miles of mains per year.
Keeping It Clear: Ground Water Pumps
Keeping excavation pits or trenches free from water is an essential part of underground construction projects. While certainly not the glamorous part of the project it is necessary for safety and to ensure the best quality workmanship. A recently introduced pumping tool is helping People’s Energy crews keep pits in tip-top condition. The newest version of the Grundex water and slurry pump from trenchless equipment manufacturer TT Technologies, Aurora, Ill. serves as a quick way to keep trenches and manholes free of ground water and slurry, improving the efficiency of any underground project. The unit weighs 8 pounds and can move up to 6 gallons of water per minute. Bachman said, “It’s really a cost-effective pump. It operates off a standard air compressor and requires about 38 cubic feet per minute of air. This is ideal for gas work, eliminating the need for a generator. The air hose is securely connected to the universal claw coupling of the pump.” People’s Energy crews have been utilizes the new pump with a great deal of success. Sandanato said, “We use it quite frequently for many of our excavations. In those situations we’re dealing with a good deal of surface water, as well as rainwater from time to time. The things I think everyone likes about the pump are its portability, the fact that it is lightweight and it can really throw some water around.” The fact that the unit is powered by compressed air also makes it effective for People’s Energey gas related projects. Sandanato said, “In the gas industry, any tool we have going into an excavation cannot be electric. So it has to be driven by some other source, primarily air.” The unit also features a 10-foot, spiral-wound discharge hose that connects to the pump with a cam and groove coupling. The pump’s main body narrows at the top, enabling the flexible hose to be led directly out of the trench or manhole. With rugged construction and no moving parts, it is fully resistant to wear. The Grundex is portable and durable, making it an ideal solution for many below ground dewatering problems. Sandanato said, “We certainly have big diaphragm pumps that we use as well. It all depends upon the situation. The whole objective is to keep the hole dry.”
Utility Product Showcase, September 2007