One of the main trends in the modern world is to improve the quality of life. This process inevitably leads to the development of technologies and the appearance of technical innovations in the market. Hydro excavation, also known as ‘vacuum excavator’ or ‘vacuum excavation’, can be considered one of these technologies. While some of the first prototypes were tested in the ‘50s, hydro excavation technology was primarily developed in the 21st century.
The hydro excavation process is a system of washing away the soil using pressurized water, and the use of a vacuum to pump the waste soil and soil deposits into a special reservoir. This method allows for an order of magnitude achieving a more accurate excavation process.
By Jurij Artiukhov, General Manager, PipeTime, LLC
The principle of hydro excavation originated in countries with cold climates and significant deposits of oil and gas. As the laying (or repair) of pipelines often occurs during the cold season, traditional excavation processes can be difficult due to ground freezing. The supply of heated water under pressure therefore greatly facilitates the task.
The main application of modern hydro excavation is, however, found in urban conditions. Namely the laying or repair of urban communications when the traditional process of dredging the soil with an excavator bucket is fraught with damage to existing pipeline or cable lines.
In the Russian Federation, for example, more than ten million utilities have been laid. If the units need to be identified underground, opened for repair, or new ones are laid, conventional methods of approaching this task can be very difficult, while hydro excavation technology can cope with this task with minimal risks. The soil near the cable or pipeline is washed away with pressurized water and then removed (sucked) by a hose.
Taking into account the fact that the hydro excavation machine can be of different configuration, a hole with an area of 90 cm2 and a depth of 1.6 m can be dug in 20-30 minutes. While hydro excavation machines are capable of excavating soil up to 50m deep and 200m long, urban communications are rarely laid to a depth of more than 2 meters.
Of course, this depends on the type of soil, so it is appropriate to give some speed and time parameters for the excavation process, see Figure 1.
Types of Hydro Excavation Applications
At the moment, the following types of hydro excavation machines are available on the market:
Hydrodynamic type – Water of different temperatures is used for soil erosion and further absorption (depending on the ambient temperature). This method is perfect for clay, dense soils. The efficiency of this method is higher than that of the air type, since water transports the blurred material much faster.
As mentioned above, depending on the environmental conditions, you can vary the temperature of the supplied liquid, which is important for Northern latitudes. The water can either be heated in the tank of the hydro excavation machine, or fed to the tank in the already heated form.
This type of soil washing can also be considered more environmentally friendly, since there is no dust in the process of washing which is why this method is the most common in urban settings.
Air type – Despite the obvious advantages of washing the soil with water, air type excavation has found its application in construction work. In particular, it is excellent for large excavation projects with dry sandy soils.
The main advantage of the air type is that the operation does not require the presence of water. The installation of applications can therefore be used in arid regions, where finding a water source is a difficult task. As the extracted soil is not exposed to water and remains dry, it can be used for filling trenches or ditches. The period of operation for this type of machine is almost unlimited, since no water is required. With no saturation of the soil with moisture, which can lead to the collapse of the soil, this method is also safer for personnel.
The primary disadvantage of air type excavation is that it is not applicable for solid soil; it will not be able to provide the necessary pressure for erosion. The sandy soil in conjunction with the air is another disadvantage as the two elements together work as a sandblasting mixture and increase the wear on parts, such as: pressure-suction hoses, fasteners, and device components.
The combined type – Is a device that combines hydrodynamic and air technology to erode the soil. The scheme of switching from water to air provides additional safety for the operator during work (it eliminates the possibility of a ground collapse by an order of magnitude). Switching between types is performed using the switch.
Depending on the type of terrain, the hydro excavation vehicle can be wheeled, tracked, or trailed.
Components of the Excavation Machine
Depending on the manufacturer, the location or presence of additional nodes in a unit may change, but the principle of operation remains unchanged. The container contains one of the most important components of a hydro excavation machine – a pump that provides water supply and suction operation. The pump creates a suction flow of up to 44,000 cubic meters per hour with a maximum vacuum force of up to 55,000 Pascals. As a rule, the pump compartment is equipped with a special window for air inflow and circulation. This capacity allows the vacuum excavator to suck up items up to 25 cm in size and up to 30 kg in weight.
The machine is also typically equipped with a filter compartment that prevents dust and other particles from entering the pump (especially important for air-type soil erosion) ND a container for storing waste sludge. As previously mentioned, the containers can be of different sizes, depending on the amount of sludge to be processed.
Behind the device is a mounting system and the suction hose.
The suction hose must meet the following requirements:
- Made of wear-resistant material (usually rubber with the addition of polymers).
- Ability to withstand cyclic decompression (achieved by having a steel spiral that strengthens the frame).
- Have a light weight for easy operation.
- The diameter of the hose, depending on the model of the hydro excavator, can reach up to 300 mm (12 inches).
A section of steel pipe with a smooth wall will often be installed at the end of the rubber sleeve. This is attached using a sleeve attachment device that is reinforced stainless steel clamps or a lock-type connection. This is necessary to ensure that there is even vertical suction in all required areas.
If the hydro excavator is located far enough from the nearest water intake point, it is possible to use flexible mobile pipelines made of polyurethane or PVC to obtain the water. The length of this type of pipeline is generally unlimited.
Looking to the Future
It is safe to say that the hydro excavation method will spread to most countries of the world in a matter of time. Hydro excavation technology has too many advantages to bypass it and use traditional methods of excavation for laying/repairing underground utilities and other tasks.
As hydro excavation is less impactful on the environment and the repair processes are acute, it will continue to thrive as a distinguished alternate from classical methods.