Directional drilling

Suundpuurimine var.2The method can be used to construct pressured pipes, self-flowing short sections of pipes and sleeve pipes. The equipment consists of the following: drill press, mixer or compressor, location devices.

The first stage is pilot drilling. The suitable drill head is selected according to soil conditions. In pilot drilling, the location of the drill head is verified with a location device. This allows the operator to direct the drill head on the desired trajectory. During drilling, drill rods are connected to guide the drill head and direct special drill mix into the drill head. The composition of drill mix depends on the type of soil. When the drill head has reached the desired destination, it is replaced by an extender, behind which a retractable pipe is connected – usually a polyethylene pipe. Then the pipe is pulled into the pilot channel, where the extender in front enlarges the channel and directs drilling liquid into the channel. This decreases friction on the pipe and removes soil from the channel.

For pipes with larger diameters, so-called pre-extension is used before inserting the pipe to decrease tensile force and enlarge the channel “step by step”.

Directional drilling can be done from ground to ground (e.g. installing cable sleeves) or from pit to pit.

Pros (+) Cons (-)
Can be used in all types of soil, incl. limestone and granite Prior investigation of soil necessary
Minimal trace of diggings and cost of restoration (lower cost in many ways compared to open diggings)
Long stretches of installation
Installation reports for the location of the pipe

Pipe crushing

Pipe crushing and constructing new pipelines can also be carried out from well to well or from well to pit with this method in the case of smaller pipes. In this case, the existing well must be made of reinforced concrete and the well must have the minimum diameter of 1,000 mm.

Pros (+) Cons (-)
Increasing the diameter of the old pipe Relatively large digging track for larger pipe diameters
Low vibration Locations of joints must be dug up
The depth of the pipe does not significantly affect the cost of installing Follows the descent of the old pipe
 Length of installation Overpumping and/or temporary water supply required

Retracting pipes

The method can be used to renovate piping systems if the diameter of the existing piping system is permitted to decrease. The set of equipment consists of the following: winch, power station – can also be performed with directional drilling and bursting device.

Depending on the diameter of the new pipe, starting and finishing pits are constructed. In the case of a DN 110 pipe, pits are generally not necessary, as the flexing radius of the pipe enables to work via existing wells. A new pipe is pulled into the existing pipe. After pulling in the pipe, the gap between the new and old pipe is filled with foam concrete or special centering rings are installed around the new pipe before pulling it in. Filling with foam concrete is not necessary if the gap between the walls of the new and old pipe is less than 1/10 of the diameter of the old pipe.

Pros (+) Cons (-)
Quick installation Diameter of the old pipe is decreased
Large extent of installing Locations of joints must be dug up
The depth of the pipe does not significantly affect the cost of installing Follows the descent of the old pipe
 Does not require special skills Overpumping and/or temporary water supply required

Cementing wells

auguprits2The method is used for making existing observation wells and reservoirs watertight. Also known as torcreting. The equipment used is a mixing device with an injector and a compressor.

In the first stage, the well to be reconstructed is cleaned (with pressure washing) from dirt and sediments. In the second stage, leaks in the well are eliminated (holes, cracks where water seeps into the well) with a special plasticine-like substance and if necessary, the bottom of the well is profiled with a flow trench. In the third stage, the entire inner surface of the well is coated with an even layer and in the final stage, the final layer is applied, finishing the water-tightness of the well.

This method is not intended to increase the strength of the wall of the well, but only to stop infiltration, which is why it always pays for the contracting party to evaluate the actual condition of the wells beforehand.

Pros (+) Cons (-)
No complicated digging works Does not give better endurance to the walls of the well for external pressure, only stops infiltration
A quick and effective method of reconstruction

 

Hammer drilling

ImageThe method can be used to construct self-flowing pipe or sleeve pipe systems.

The equipment consists of a drilling device, power station and air compressor or mixer.

The pipes are usually installed from pit to pit.

After the pits have been prepared, the drilling device is installed in the starting pit, the angle of pipes is determined with a digital level and the drilling is carried out. The angle of pipes is verified during drilling.

The borehole is drilled with a compressed air hammer, using sleeve pipes with a screw conveyor which carries out the soil. The pipes are regular iron pipes. The method also allows to drill plastic pipes without metal sleeve.

Pros (+) Cons (-)
Can be used in all types of soil, incl. limestone and granite Requires prepared starting and finishing pits
Enables to drill sleeves with a predetermined angle and self-flowing pipes Instalment depth and level of surface water affect installation costs
Does not require additional anchoring or supporting walls to receive the working pressure of the device  Prior investigation of soil necessary
Minimal soil displacement
Minimal disturbance of traffic