Trenchless Technologies and Infrastructure Renewal

Many regions of the United States are facing a painful and daunting task to keep up with the need to restore their aging and increasingly inadequate pipeline infrastructures, particularly when it comes to meeting present and future needs of water, wastewater and natural gas pipeline systems.

The Mid-Atlantic region is a microcosm of a nationwide need to replace and expand all of these infrastructure systems. Even those states that may profit greatly from the tapping of Marcellus shale gas reserves will also face the need for installing a safe and efficient distribution pipeline system.

One of the keys to replacing and expanding the pipeline infrastructure in an efficient, cost-effective manner will be horizontal directional drilling, auger boring or pipe jacking. ?This capability not only saves time and money, but can also save on disrupting the environment and exposure to potential hazards,? says Vince Rice, president and CEO of Aaron Enterprises, based in York, Pa. Rice adds that advanced horizontal ?trenchless technology? can allow pipeline construction at a very fast pace.

?There is a need for thousands of miles of pipeline to replace or expand the water, wastewater and natural gas infrastructures in Pennsylvania alone,? says Brian Funkhouser, P.E., president and CEO of full-service architectural and engineering firm Buchart Horn Inc., also based in York. This firm provides services in the transportation, water?and wastewater systems, facilities/architecture, and construction anagement sectors.

A Challenging Report Card

According to the American Society of Civil Engineers? 2010 Report Card on Pennsylvania?s Infrastructure, aging wastewater management systems discharge billions of gallons of untreated sewage into Pennsylvania?s surface waters each year. Further, it is estimated that the state must invest $28.3 billion over the next 20 years to repair and upgrade existing systems to meet regulatory requirements. In May of this year, Pennsylvania?s Commonwealth Financing Authority approved $172 million through the H2O PA program to fund 160 water and sewage infrastructure projects in 51 counties.

Funkhouser says that most of the pipeline work will include subsurface, horizontal pipeline construction, including crossings under roadways, rivers and streambeds and environmentally sensitive areas such as wetlands and parklands.

This type of pipeline construction is a sort of niche, requiring special equipment and capabilities. Funkhouser cites, for example, a major project in which Buchart Horn was a consulting engineer, a crossing of the Susquehanna River in Williamsport, Pa.

?Directional boring technology was needed to make this crossing,? he explains. ?We consider this a more cost-effective approach than using a cofferdam (watertight enclosures across the bottom), which can be compromised if you get heavy rains, for example, and then you have to start over from scratch.?
Funkhouser describes directional boring and other types of horizontal drilling to be a specialty that is provided by experts such as Aaron Enterprises. Aaron has worked with Buchart Horn on water and wastewater projects requiring tunneling and directional boring.

?Even though horizontal drilling and boring are frequently the best approach to handling crossings, for example, this is actually a niche capability,? Rice explains. ?We are essentially a horizontal drilling specialist, and the majority of our work is done through some type of trenchless technology.?

Because most states will not permit pipeline construction contractors to open cut highways, the pipes must be sent under the highways in order to avoid problems such as traffic congestion and safety issues.
Horizontal auger boring or directional drilling is also a solution to pipeline crossings of environmentally or historically sensitive areas where temporary trenching or running aboveground pipeline would be undesirable.
Rice explains that there are a number of ?trenchless technologies? that are a form of work performed by specialists such as his firm. Pipe jacking, for example, allows the contractor to push pipe through a horizontally excavated hole. Pipe jacking is usually done for installation of concrete pipes.

?Pilot drill microtunneling is another horizontal technique for jobs that requiring precise line and grade control,? he adds. ?That requires installing a small pilot opening using hollow steel rods. As you install them you monitor their horizontal and vertical positions by means of a theodolite survey instrument with a digital camera. Once the small-diameter rod reaches target location, and then you attach to it a larger diameter pipe and as you thrust that larger diameter pipe, the smaller one acts as a guide, making that go exactly where you want it to go. It gives you the ability to jack piping 400 feet, for example, and stay within a one-inch tolerance.?

One of the forms of horizontal drilling that will play an important role in replacing or expanding the pipeline infrastructures is direction drilling. As opposed to simple straight-line drilling, the directional approach is accomplished by locating the drill on the surface and penetrating the ground at a predefined angle. Directional drilling uses electronic steering to track the borepath. According to the HDD Good Practices Guidelines, published by the North American Society for Trenchless Technology (NASTT), existing utilities should be located and exposed before drilling to ensure that there are no inadvertent and utility strikes.
Aaron Enterprises also has extensive experience using directional drilling for gravity sewer installations.

Believed to be a world record, the firm used a specially modified, pit-mounted directional drill to complete a 900 lf gravity sewer bore through sandstone and red rock, maintaining a 0.0097 percent slope, then pulling back a 10-inch diameter HDPE sewer pipe. The use of directional drilling on this project eliminated the necessity of drilling-and-blasting a 35-foot deep open trench installation alongside existing water and gas mains. This saved the owner substantial dollars by eliminating the need for an additional sewer pump station, which will also save operational costs far into the future.

?Using this method we can?t make 90 degree turns,? says Rice, ?but instead make a gradual, arcing turn over the length of the bore.?

A Marcellus Miracle?

Directional drilling will likely facilitate the installation of pipeline collection points and distribution crossings for the Marcellus gas industry that is now getting started in the Mid-Atlantic region. Exploration is already well under way in areas of Pennsylvania and West Virginia.

Property owners, as well as state and local governments, are very positive about the jobs and revenues that will result from mining Marcellus gas, and consider the installation of a distribution network an urgent matter.
?You can?t always anticipate what you are going to run into,? says Rice, whose firm has over 25 years experience in dealing with the terrain in Pennsylvania, West Virginia, Virginia and Maryland. ?In some instances, you are dealing with a combination of geological formations that will require the use of multiple technologies. Even pipeline construction contractors who have the necessary equipment may not have the experience in our Marcellus regions or don?t want to get bogged down with this kind of work.?

He adds that unforeseen construction difficulties or inadequate handling of documentation required by local agencies can hamper pipeline construction progress of any type. Whether it concerns infrastructure repair, replacement or new construction, delays over documentation or other compliance requirements will be costly and time consuming. Yet, experienced horizontal drilling and boring specialists who know the ropes and have the necessary equipment will likely enable pipeline contractors and engineers to save significant time and money.

Ed Sullivan is a Hermosa Beach, Calif.-based writer. He has researched and written about high technologies, healthcare, finance, and real estate for over 25 years.

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