Trenchless construction has changed the way the world's utility infrastructure is constructed and rehabilitated. While trenchless methods are perceived as a "new" development, a small number of trenchless pioneers have been using them for decades.

Back in 1982, Sweden's Styrud Ingenjörsfirma AB recognized the need for alternatives to conventional construction methods. The company adapted well-drilling equipment to drive pipe through the ground and designed and developed bits to use in the pipe-ramming process. In 1987, the company began investigating the then-new technology of horizontal directional drilling, and three years later invested in its first HDD machine.

The company now has its headquarters in Gothenburg, with regional offices in Malmö, Stockholm, Sundsvall and Karlstad.

Joint owner and Business Development Manager Rolf Borras says Styrud AB currently has 15 HDD units working in Sweden installing water and sewer lines, electric power and telecommunications cable, natural gas pipe, and piping for district heating and cooling systems.

Directional drilling is used in urban areas where excavation is difficult or impossible, on projects where surface improvements would require extensive and costly restoration, to install pipe and cable under highways and railroad tracks, and to bore beneath rivers, streams, and other bodies of water.

Styrud AB operates a wide range of Ditch Witch® directional drills, including the JT1720, JT2020, and JT8020 Mach 1, and the JT2720 and JT4020 All Terrain. The All Terrain models are designed to drill through rock and other difficult conditions without the need to use a mud motor. Styrud was the first organization to use All Terrain technology in Sweden.

All Terrain technology employs a dual-drive drilling system featuring an inner rod that drives a rock bit. The outer pipe steers the downhole tool while drilling pilot holes, and provides rotary torque for the hole opener during backreaming. The mechanical drilling system delivers maximum downhole horsepower and operates on low volumes of drilling fluid. In addition to rock drilling, an All Terrain unit is productive in nearly all types of soils.

Styrud AB recently employed directional drilling to upgrade the district cooling network for Göteborg Energi, one of the largest energy suppliers in Sweden. Owned by the municipality of Göthenburg, Göteborg Energi provides electricity and gas for district heating and cooling for air conditioning. The purpose of the project was to enlarge cooling capacity and connect smaller systems that had in the past provided different parts of the city with cooling.

Styrud AB initially became involved on the project as a subcontractor providing drawings of plans and installing pipes. The company eventually assumed the position of general contractor, working closely with Göteborg personnel. Styrud AB now is involved in planning future segments of the improvement program.

"Because the entire extent of the ring main was located in the downtown area, trenchless technology was a natural first choice," said Borras.

The final part of the job was an 880-meter long section, consisting of two parallel pipelines 630 mm in diameter, from Pusterviksplatsen to Bältesspännarparken. The pipeline runs from there via Allén, Drottningtorget and St Eriksgatan to its end point at Lilla Bommen. Plans also call for the district cooling network to cross the river Göta älv on its way back to Rosenlund, as well as connecting the Lindholmen district to the ring main.

"Göteborg Energi is one of the organizations in Sweden that has invested the most in trenchless technology," said Görgen Johansson, Styrud AB project manager. "The presence of favorable geotechnical conditions is, of course, one of the explanations, but attention is also paid to finances, keeping in mind that trenchless technology is often more cost effective. The minimal level of environmental impact and the minimal disruption to traffic are also factors that carry a lot of weight."

During the project, Styrud AB used its Ditch Witch JT4020 All Terrain and JT8020 Mach 1 equipment. The company's crews completed 20 HDD installations ranging from 100 to 800 meters in length and two to 20 meters deep. The diameter of the installed HDPE pipe is 110 to 800 millimeters.

Johansson said Göteborg Energi is recognized as a progressive provider of energy and is on the leading edge for developing ways to use renewable energy. The company owns and operates several wind farms.

Styrud Ingenjörsfirma AB was founded in Herrljunga in western Sweden in 1978, and during its first years of business the company focused on the drilling of water wells. After adding its first trenchless capabilities four years later, the company's capabilities have steadily expanded. In 1989, Styrud AB completed its first project outside Sweden—a hammer drilling contract in the United Kingdom.

In 1996, the company added its first 40,000-pound drilling unit and the following year completed a difficult and challenging assignment in Romania to install a segment of a broadband cable just over 500 meters long under the Danube River.

Regional offices are located in Gothenburg and Sundsvall and to better serve Northern Sweden, the company purchased Järvsö Borr AB, a firm specializing in energy and water wells.

At the turn of the millennium, broadband expansion in Sweden was in full swing, and the company doubled in size in one year.

"In 2005 Styrud Ingenjörsfirma AB published its first manual on trenchless pipe installation," said Borras. "We also acquired Finnish Borealstar OY, with whom we had collaborated for several years, and which opened the door to the Finnish market, and an office was established in Helsingfors."

In 2007, TGB Borrteknik was acquired, making Styrud AB one of the major drilling companies in northern Europe. The main office, the western regional office, and StyrudTGB consolidated their premises in Sävedalen east of Gothenburg, while local offices in collaboration with StyrudTGB opened for business in Järfälla and Sundsvall.

To meet the needs of its clients, Styrud AB, operates drilling equipment in several size categories.

The JT1720 develops 17,000 pounds of pullback, 1,800 foot pounds of spindle torque, and spindle rotation speeds to 200 rpm; the JT2020 produces 20,000 pounds pullback, 2,200 foot pounds of torque, and spindle speeds of 150 rpm; JT2720 equipment has 27,000 pounds of pullback, 3,200 foot pounds of spindle torque, and spindle speeds to 225 rpm. These compact models are well suited for construction sites with limited space for setup.

The two larger models are capable of installing larger-diameter pipes at longer distances. The JT4020 has 40,000 pounds of pullback, 5,000 foot pounds spindle torque, and spindle speeds to 250 rpm; the powerful JT8020 can produce 80,000 pounds of pullback, 10,000 foot pounds of torque, and spindle speeds to 210 rpm.

Each of the self-contained models is mounted on tracks.

Ditch Witch equipment is manufactured by The Charles Machine Works, Inc., Perry, Oklahoma, a leading manufacturer of underground utility construction equipment. The Ditch Witch product line includes trenchers, horizontal directional drilling systems, vibratory plows, vacuum excavators, compact skid-steer loaders, electrical utility locators, and related products.

Sales, parts, service, and product support for Styrud AB is provided by JLM Ditch Witch Scandinavia, Malmö, Sweden.