Advantages of Trenchless technology
Technology
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The installation can be made at the shortest possible distance
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Less risk of ground settlement since no soil is moved in installation – the pipe is in its place
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No impact on groundwater
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No impact on drainage, e.g. in agricultural areas
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No need for sheet piling
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No impact on ground surfaces, and hence no need for restoring
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Trenchless installation can just as well be done during winter, below frozen soil
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Can be used where the ground’s bearing capacity is too low for trenching equipment to be used
Economy
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Easier permit-process; low or no compensation to landowners
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No need for pipe bedding, nor backfill
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Deep installations, e.g. for sewage, are less expensive with trenchless since sheet piling is not needed
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Lower costs for reinstating surfaces – asphalt, stone laying, plantations
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No need for compensation for disturbances to businesses and stores
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Lower societal costs due to streets not being closed, less traffic disturbances, less delays, less loss of income
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A project with trenchless technology offers opportunities to make complementary installations in the area at the same time, and thus at a lower cost.
Environment
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Using trenchless means taking sustainability seriously
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Less use of energy due to a faster process
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Less use of finite resources, e.g. fuels and filling
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Less transportation of material from trenching
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People and businesses are not disturbed
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No or decreased disturbance to traffic
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No impact on plants and trees
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Trenchless pipeline and cable construction is significantly faster. What disturbance that cannot be avoided is thus smaller, e.g. noise pollution and emissions from machinery
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Lines can be constructed also in protected natural areas, near historic landmarks etc. without damage
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No risk of collapses trenches
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Polluted ground material is left undisturbed
Time
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Trenchless projects are faster than trenching
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Preparations are in many cases faster and less complicated
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Restoring of asphalt, stone-laying and plantations is faster or unnecessary
Trenchless methods
Boring in soil
The soil consists of various soil materials – clay, sand, gravel etc. Often, the soil is a blend of rocks, boulders and even bedrock. Some drilling methods are especially developed for certain types of soil and may be less, or not at all, suitable for other materials. A project of pipeline and cable construction thus often means that drilling will be done through different soil materials.
All drilling jobs in soil have that in common that the drilled hole must be stabilized to avoid collapse. Therefore, the drilling process includes the installation of a casing. When drilling is completed, this casing can be used as a conduit. The line (water, power cable, fiber cable etc.) is placed within the conduit pipe. In some projects, and using certain methods, the media may be installed directly in the ground without a conduit pipe.
Basic information on the most common methods can be found here on our website. For more information, please visit our “WikiNoDig” at www.nodigplatform.se
The easiest and cheapest of drilling methods. Unmatched ease for short distance and small diameter holes.
Basic description: The impact mole’s pneumatic hammer functions as a broach. It presses the soil material to the side, creating a hole in the ground. A plastic pipe – carried by the tool – is inserted.
Used in: Gravel, sand and dry clay
Limitations: Large rocks, bedrock, loose clay, sub-groundwater levels
Launch pit: Small pits. No thrust support needed
Used for: Conduit pipes for power, fiber, water, gas
Excellent and reliable method for gravel, and soil with rocks and boulders. See also Rock drilling below.
Description: The pneumatic DTH-hammer allows the drill bit to crush the material in its way. The outer ring bit pulls a steel casing, which keeps the hole open and functions as a conduit pipe after competed drill. Cuttings are transported out through the casing.
Used in: All soil types, and bedrock
Limitations: None in terms of geotechnology
Launch pit: Provides room for drilling equipment, ranging from 3x7 m
Pipe length, diameter and material: 0-80 m, 100-1200 mm, steel
Used for: Conduit pipes for power, fiber, gas, district heating, pressurized wastewater, as well as gravity sewers for waste- and storm water.
Used for somewhat larger pipes under roads, railways and more. Primarily developed for clay and sand.
Description: The pneumatic hammer drives the pipe into the soil, “punching” out a hole. The pipe is emptied after the entire pipe is through.
Used in: Clay and sand
Limitations: Larger rocks, bedrock
Launch pit: Provides room for drilling equipment, ranging from 3x10 m. Thrust support not needed.
Pipe length, diameter and material: 0-50 m, 300-1500 mm, steel
Used for: Conduit pipes for power, fiber, gas, district heating, water, sewer force mains, and gravity sewers for waste- and storm water.
Used for conduit pipes under for example roads and railways. Primarily developed for clay and sand.
Description: The conduit pipe is pushed into the soil. The pipe is emptied parallel with the drilling process by a large screw placed inside the pipe.
Used in: Clay and sand
Limitations: Larger rocks, bedrock
Launch pit: Provides room for drilling equipment, ranging from 4x10 m. Thrust support needed.
Pipe length, diameter and material: 0-50 m, 300-1200 mm, steel
Used for: Conduit pipes for power, fiber, gas, district heating, water, sewer force mains, and gravity sewers for waste- and storm water.
Amazing technology that enables the drilling of long and curved holes. Primarily developed for clay and sand.
Description: The pilot rod is drilled through the ground according to a projected bore alignment. The direction of the drilling bit is controlled with the help of a radio transmitter in the bit itself, and steered by a steering tool ahead. As the rod is reversed, the hole is reamed out and the pipe is inserted into the hole.
Used in: Mainly clay and sand
Limitations: Gravel, rocks and bedrock
Launch pit: Only needs small launch- and receiving pits
Pipe length, diameter and material: 0-600 m, 40-1000 mm, plastic, steel, MG ductile iron
Used for: Conduit pipes for power, fiber, gas, district heating, water, sewer force mains, and gravity sewers for waste- and storm water.
Similar to HDD, the difference being that this method can be used in more challenging soil.
Description: The pilot rod is drilled through the ground according to a projected bore alignment. The rotary drill head is made to rotate by an internal shaft, grinding the material in its way. The drill head is steered by altering the angle of the outer drilling rod, and tracking is allowed through a built-in transmitter. The hole is reamed out and pipe inserted as the rod is reversed.
Used in: Frictional soils and clay, stony hard ground, including bedrock
Limitations: Larger dimensions in swiftly shifting soil materials
Launch pit: Needs only a smaller launch- and receiving pit
Pipe length, diameter and material: 0-300 m, 100-500 mm, plastic, steel
Used for: Conduit or service pipes for power, fiber, gas, district heating, water and sewer force mains.
Used for installing concrete pipes in clay material. Projects often concern gravity sewers for waste- and storm water, with a small incline.
Description: The concrete pipe is pushed into the clay by the force of hydraulic cylinders. A steering tool as placed at the front, correcting for deviations from the straight bore alignment. Clay material is extracted from the pipe as the drilling proceeds, using a conveyor, slusher or by flushing etc.
Used in: Clay
Limitations: Frictional soils
Launch pit: Provides room for drilling equipment, ranging from 2x2 m. Thrust support needed.
Pipe length, diameter and material: 0-200 m, 400-2500 mm, concrete
Used for: Gravity sewers for waste- and storm water.
Used for installing concrete pipes. The method is similar to pipe jacking, but can be applied in all kinds of material, even solid rock. Often used for gravity sewers with a small slope, but also for installing conduit pipes for water, cable culvert and more.
Description: The concrete pipe is pressed into the soil using hydraulic cylinders. Drilling and steering tools are placed at the front of the drill head. The drill head makes the soil penetrable, and a crusher cone grinds the fragments. Cuttings are extracted along with the drilling fluid in a closed system to a drill fluid separator placed above ground.
Used in: Clay, sand, gravel, block, boulder and solid rock
Limitations: None in terms of geotechnology
Launch pit: Provides room for drilling equipment, ranging from 2x2 m. Thrust support needed.
Pipe length, diameter and material: 0-1000 m, 250-4200 mm, concrete
Used for: Waste- and stormwater tunnels. Also as conduit for power, fiber, gas, district heating, and water and sewer force mains.
Rock drilling
The Scandinavian mining industry has provided many years’ experience of drilling in bedrock. Several methods have been developed, which often can be combined to ensure the best result.
Rock drilling includes two main steps: high precision pilot drilling, and reaming. Significant for rock drilling is that casings seldom are needed, since the full distance is completed in bedrock. The service pipe can be installed directly into the hole. In some projects, the hole is lined with a lining pipe and the spacing injected.
Basic information on the most common methods can be found here on our website. For more information, please visit “WikiNoDig” at www.nodigplatform.se
A fast and reliable method for moderate lengths and dimensions.
Description: The pneumatic drill bit crushes and pulverizes the rock. The method is similar to techniques used for drilling wells but offers much higher precision. When the pilot hole is completed, the hole is reamed out in one or several steps to achieve the wanted dimension. The reamer bit resembles a pilot bit connected to a steering rod.
Length, diameter: 0-150 m, 100-400 mm
Used for: Channels for power, fiber, gas, district heating, water, sewer force mains, as well as gravity sewers for waste- and storm water.
A very fast method for longer holes that require steering. Straight or curved.
Description: The pneumatic drill bit crushes and pulverizes the rock. The method is similar to regular HDD but is here especially adapted to drilling in solid rock. When the pilot drilling is completed, the hole is reamed out in one or several steps to achieve the wanted dimension. The reamer bit, equipped with hard-metal rolls, grinds the rock as it is pulled back through the pilot hole.
Length, diameter: 0-300 m, 100-400 mm
Used for: Channels for power, fiber, gas, water, sewer force mains
Method for large holes in solid rock.
Description: A pilot hole is created using for example a rotary drill bit (e.g. All Terrain, see soil drilling methods), hammer drilling or core drilling. When the pilot hole is completed, it is reamed out to the wanted dimension in one step. The reamer bit, equipped with hard-metal rolls, grinds the rock as it is pulled back through the pilot hole.
Length, diameter: 0-1000 m, 600-4000 mm
Used for: Channels for power, fiber, gas, district heating, water, storm- and wastewater. Connections to storm- and wastewater tunnels, mining shafts and power plant tunnels.
Precision drilling for pilot holes or for geological investigation.
Description: A hollow, rapidly rotating drill pipe is used, with a diamond drill bit, which cuts out a core through the rock.
Length, diameter: 0-2000 m, 40-100 mm
Used for: Pilot drilling for reaming with a complementary method, as well as geological investigation.
Microtunneling is commonly used for drilling concrete pipes, see also Microtunneling for boring in soil, but the method could also be suitable for boring in solid rock as an alternative to a tunnel blasting.
Description: Boring- and steering tools are placed at the front of the drill head. Hard metal cutters in the drill head breaks down the solid rock, and a crusher cone grinds the fragments. Cuttings are extracted along with the slurry fluid in a closed system to a slurry fluid separator placed above ground. Concrete pipes behind the drill head push the drilling equipment forward. New concrete pipes are installed at the hydraulic cylinders of the jacking station as the boring proceeds.
The drilling equipment may also be used without pipes, using grippers to press against the bedrock and advance the machine forward or pushing against segment lining installed behind the machine to advance forward.
Pipe length, diameter: Microtunneling 0-1000 m, 1200-4200 mm. TBM 0-10,000 m, 1200-14,000 mm
Used for: Waste- and stormwater tunnels. Also for conduit for power, fiber, gas, district heating, water and pressurized wastewater.
Pipeline rehabilitation
Today, there are several well developed and tested methods for pipeline rehabilitation. These methods are relevant for sealing pipelines, restoring lines to original function and strength, or even increasing the pipe dimension.
Basic information on the most common methods can be found here on our website. For more information, please visit “WikiNoDig” at www.nodigplatform.se
Fast and easy technique for rehabilitation of pressure pipelines by inserting a pipe of smaller dimension into the existing pipeline.
Description: A new “carrier” plastic pipe is welded together and pulled into the existing “host” pipe with a winch. The annular space between the carrier and host pipes can be filled out with concrete (grouted).
Existing pipe: All types
Space for installation: Insertion pit for the new pipe
Pipe length, diameter and material: 0-500 m, 100-1000 mm, plastic
Used for: Water and sewage, gas
Pipeline rehabilitation through inserting a pipe of smaller dimension into the existing pipeline. A continuous pipe with a momentarily reduced cross-sectional area is installed into the existing, while regaining normal dimension after installation. Annular space between old and new pipe is minimal.
Description: A new plastic pipe is reshaped at the worksite or folded already at the factory. After installation, the new pipe regains its original shape through added pressure and heat, normally water vapor.
Existing pipe: All types
Space for installation: Manhole or insertion pit for installing the new pipe
Pipe length, diameter and material: 0-1000 m, 100-1000 mm, plastic
Used for: Water and sewage, gas
Bursting carrier pipe for installing a new pipe. The new pipe may be of the same size as the host, or larger.
Description: A hydraulic pulling equipment allows the expander head to break down the existing pipe, while at the same time pulling with it a new pipe, replacing the existing. The equipment may carry a cutting tool to ensure easier bursting of the existing pipe.
Existing pipe: Concrete, ceramics, plastic, cast- or ductile iron, steel
Space for installation: Launch pit provides room for equipment, ranging from 2x2 m
Pipe length, diameter and material: 0-150 m, 50-600 mm
Used for: Water and sewage, gas
Method for bursting an old pipe and installing a new pipe. The new pipe could have the same dimension as the existing, or larger. This pneumatic method is the predecessor to the hydraulic bursting technique.
Description: The pneumatic hammer allows the expander head to crack and expand the existing pipe, while at the same time pulling in a new pipe. The equipment is pulled with a winch.
Existing pipe: Concrete, ceramics, plastic, cast iron
Limitations: Not suitable in surroundings that are sensitive to vibrations. Oil in the compressed air (used for lubrication) may contaminate the pipe.
Space for installation: Launch pit provides room for equipment, ranging from 2x2 m
Pipe length, diameter and material: 0-150 m, 50-600 m, plastic
Used for: Water and sewage, gas
A reinforced flexible liner, impregnated with thermosetting resins, is inflated and set in place in the existing pipeline.
Description: The flexible line is made up of felt or fiberglass, impregnated in polyester resins. The liner, which is coated in a protective foil on the in- and outside, is pulled into the existing pipe, or folded in by the force of water, compressed air or steam. Once in place, the liner is cured with UV-light, hot water or steam.
Existing pipe: All types
Space for installation: Manhole for installation of lining
Pipe length, diameter and material: 0-500 m, 100-3000 m, reinforced polyester
Used for: Water and sewage
Lateral pipes: Lateral pipes may be cured from inside the pipe using a so-called hat-profile made of flexible lining, installed by robot.
Pipe rehabilitation through installing a pipe of smaller dimension inside existing pipe. Pipe length ranging from 0,5-6 m.
Description: A new short pipe is placed in existing manhole or launch pit. Each short pipe is pushed into the host pipe in turn. The annular space between carrier and host pipe is filled with concrete (grouted).
Existing pipe: All types
Space for installation: Manhole or launch pit for installation of short pipes.
Pipe length, diameter and material: 0-500 m, 100-2000 m, plastic, reinforced plastic
Used for: Water and sewage
Rehabilitation of large pipes through the installation of a new pipe of smaller dimension into the host pipe. The new carrier pipe is assembled in halves or parts of a pipe segment.
Description: A new segment is installed via existing manhole or from a launch pit. Each segment is assembled in its place, successively building up the new pipe. The annular space between carrier and host pipe is filled with concrete (grouted).
Existing pipe: All types
Space for installation: Manhole or launch pit for installation segments.
Pipe length, diameter and material: 0-100 m, 800-2500 m, reinforced plastic, concrete
Used for: Water and sewage
Restoring a corrosion resistant barrier in pipes.
Description: Mortar is sprayed onto the inside surface of the pipe, using a rotary nozzle.
Existing pipe: Steel, cast- or ductile iron
Space for installation: Launch pits for equipment
Pipe length, diameter and material: 0-300 m, 200-1200 mm, concrete
Used for: Water and sewage
Restoring internal corrosion resistant barrier in pipes.
Brief description: Epoxy- or PU is sprayed onto the inside surface of the pipe, using a rotary nozzle.
Existing pipe: Steel, cast- or ductile iron
Space for installation: Launch pits for equipment
Pipe length, diameter and material: 0-150 m, 100-1000 mm, Epoxy, PU (polyurethane)
Used for: Water and sewage
Applying Trenchless
- Trenchless provides advantages, both in installation and rehabilitation
- Greatest savings in projects with deep and inaccessible pipelines
- Common in road- and railway crossing, as well as with pipeline and cable construction along streets
- Advantages also for transmission lines under agricultural lands and fields
- Trenchless meets standards for pipe slope
- Trenchless provides advantages in all contexts
- Advantages for installing pipelines and cable conduits under parks, city squares and streams
- Boring for, and inserting, multiple conduit pipes simultaneously, saves money and space
Multiple pipelines can be drilled in one step
- Pipelines can be laid straight or curved
- Curved pipelines e.g. under streams, can be drilled without causing the pipe to be deformed
- With beneficial geological conditions, pipelines for district heating can be installed without conduit pipes.
- Equal prerequisites as for district heating
- Plastic pipelines provide higher flexibility when drilling
- Fast installation
- Minimal costs for resetting surfaces
- Under and along roads, under streams, on the countryside as well as in urban areas
- Trenchless is an environmentally and economically viable alternative
- Used for installing new pipelines as well as renovating old pipelines.
- Time consuming legal processes of water management can be avoided
- A pipeline can easily be installed under a stream, for example by using HDD
- The line is securely installed under the stream sediment
- Polluted sediments are not disturbed, as in cases of trenching and dredging
Drilling means that the pipeline is securely installed under in the sediment, and the water is not clouded in the process of installation
- Trenching across a road or railway is impermissible
- Trenching is tedious, expensive and time consuming
- The Transport administration often requires trenchless solutions
- Trenchless is suitable for the rehabilitation for stormwater culverts
- Also suitable for stone culverts under railways
- The best solution may be to install a new pipeline and close off the existing
- Weather, wind, ships etc. can cause damage to the pipeline
- Concerns about seawalls and shorelines are avoided
- No or minimum impact on boardwalks, as well as flora and fauna
A trenchless installation of pipe landfalls keeps the pipeline safe from impact and erosion.
- A drilled culvert through the road eliminates risks for endangered species
- Safe crossings for all wildlife
Crossing for salamanders
- A church ruin interceding the projected alignment?
- With trenchless technology, the pipeline can be installed in the ground under the ruin
- Affected authorities will thank you
Cultural landmarks may hinder the installation of a new pipeline.
- Trenchless technology is perfect for protecting valuable environments, endangered plants and unique trees. In a national park - Natura 2000 area - trenching is practically impermissible, but drilling can be done.
- Drainage systems for agriculture are normally not affected
- No heavy machinery, no damage to surfaces. Construction machinery compressing the soil is not desirable.
The old maple tree could stay in its place, since the pipeline was installed through drilling.
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- When the ground is already crowded with multiple pipes, rendering conventional trenching impossible, trenchless technology provides opportunities.
Johan Lundberg AB is an independent consultant company within trenchless pipeline and cable construction and rehabilitation.
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Johan Lundberg AB
Johan Lundberg AB holds the AAA rating, i.e. the highest rating of creditworthiness.
Johan Lundberg AB is certified to the ISO 9001 and ISO14001 standards, which are the international standards for quality- and environmental management systems respectively.
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