What are Vac Ex’s or Vacuum Excavators most commonly used for
27th May 2020
Vacuum excavators can be used in almost any terrain or location but are found most often in cities excavating around live services which is where they really excel. Most of the ground in cities has already been dug when the city was originally built and the ground is perfect to excavate with a suction excavator. The cost of not using a vacuum excavator to dig around live services in city centres can be astronomical. Hitting one cable with a traditional excavator could cost millions of pounds worth of damages or cause death or critical injury.
For the above reasons vacuum excavators are most commonly used by utility contractors including Gas, Water, Electric and Telecommunications contractors laying new or repairing old utility pipes. Within the utilities gas is the largest market for vacuum excavators followed by water. The higher the health and safety, efficiency and environmental standards demanded by the client the more they will use vacuum excavators.
Many utility companies within the UK now insist on the use of vacuum excavation rather than the more invasive methods. This is because of the minimised disruption, reduced reinstatement and superior safety performance that suction excavation has over other methods.
Using a vacuum excavator to construct Trail holes
Vacuum excavators can be used to construct trial holes. Digging a trail hole allows the contractor to check what soil the ground is composed of. This can be essential in deciding the correct excavation technique for completing the excavation. It also helps identify if there are any existing services or utilities in the ground and whether the utility drawings are correct.
Trail holes tend to be excavated up to 4.5metres in depth. If they are deeper than 1.2metres and a person is going to go into the excavation then they need to have trench support to contain the walls of the trench and prevent them from collapsing on a person.
Using a suction excavator for airport construction and civil engineering works
Most airports in the UK will not allow excavation without the use of a vacuum excavator.
Airports have many existing utilities including water, gas, electric and telecommunications cables. Damaging any one of these utilities would likely result in the immediate closure of the airport which would cost millions of pounds worth of losses per hour. It could also endanger the air traffic control systems causing a fatal accident. Airports in the UK spend hundreds of millions of pounds every year upgrading existing facilities to improve the infrastructure both inside and outside the airport boundary.
Major airport schemes currently taking place in the UK include Manchester airport which is owned by the Manchester Airports Group which has a one billion pound airfield transformation programme taking place which includes the building of new aircraft landing piers and runway works at terminal two of Manchester airport.
Birmingham airport also has a 500million pound improvement plan being project managed by Mace and set to run to 2029 including a connection to HS2. Other airports with major transportation projects include Edinburgh and Leeds Bradford. Airport expansion projects have been thrown into question now especially in the short term in the wake of the coronavirus outbreak with a sharp reduction in business and other forms of travel and an increase in home working. This has thrown the largest proposed airport scheme in the country into doubt the 14billion pound expansion of Heathrow airport.
Vacuum excavators are used extensively on motorway construction and maintenance projects throughout the UK. Often they are used when installing new infrastructure and also repairing old utilities including service pipes for motorway signs and motorway lights. Highways England oversees all the projects on the motorways in the UK. The civil engineering contractors they use to carry out the public works on the highways use vacuum excavators as they are the safest way to excavate when there is a danger of hitting existing utilities. An added benefit of using a vacuum excavator on the motorway is that the excavated waste can be recycled on-site. The vacuum excavator can suck up the soil and tip and store it in a safe onsite location where it can later be used as backfill to fill another trench. This is more environmentally friendly as it reduces the overall carbon footprint of the highways civil engineering works as the muck away lorries do not need to transport the waste to the landfill. The excavated material can be reused on-site which saves costs both to the public purse and also to the environment.
VAC UK can supply left-hand tipping vac exs and these are popular on the highways as they allow the vacuum excavator operator to tip the contents of the wagon unto the verge keeping it safe from the vehicles which may be using the motorway or the hard shoulder. Vacuum excavators can also be used for litter picking on the motorways as they are perfect for sucking up waste in hazardous locations. Road sweeping units can also be attached to the bottom of the vacuum excavator trucks. Road sweepers mounted to a suction excavator are able to clean the roads more effectively than a traditional road sweeper as they have the additional advantage of the suction power from the vacuum excavator. Roads need to be swept on the highways whilst construction and maintenance works take place and also periodically to give the roads a deep clean so that the roads last longer in a better condition, free from dust and debris, and have a less slippery surface.
In the 2020 budget, Highways England were given a 27billion investment fund to complete their smart motorways programme to improve congestion across the network. The fund will also set aside 2 billion for the tunnel under Stonehenge and more funds to finally start the lower Thames crossing which will be the longest road tunnel in the UK. The whole 27billion scheme is currently under review as there is a challenge been put to it by the climate change lobby. The department of transport are expecting some changes to the programme to take account of climate change concerns and also the concerns over the safety of the smart motorway schemes. Nevertheless there is expected to be a big push over the next 10 years to invest in the road network in the UK and there will need to be a continued investment in vacuum excavator technology to meet the demands of this programme.
Building contractors and developers
Vacuum excavators are increasingly being used in the construction of new housing. Many of the major national housebuilders of the UK have started to insist that their construction contractors use vacuum excavators whilst completing the groundwork contracts for their new housing projects. Using a vacuum excavator for new housing groundwork projects is more efficient and also reduces the chances of a cable strike.
Rather than excavating one trench at a time the housebuilders build their houses in a factory assembly line type process. Using a vacuum excavator it is possible to construct up to twenty utility services catchment pits in one day.
There is currently a shortage of housing in the UK and a housing crisis where young people are finding it difficult to buy houses. Vacuum excavators are a useful technology to help solve the housing crisis as they enable houses to be built safer and quicker and more cost-effectively. There is also a skills crisis within the housing industry. Younger people today are less interested in a career involving manual and physical labour. This makes it important for the construction industry to embrace the latest technological innovations. A vacuum excavator with a skilled operator can complete the works faster and safer than a whole gang of workers with a range of heavy plant equipment including dumpers and 360 excavators.
Tunnelling, shaftsinking and specialist underground engineering works
Vacuum excavators can be used to dig tunnels and shafts and are particularly useful at excavating in difficult to access confined areas.
It is possible to attach the end of the hose of a vacuum excavator to a robotic device and move the hose into position using a remote control. This enables the vacuum excavator to reach far into confined areas which may be hazardous for people to enter if there are toxic or harmful materials. VAC UK can supply up to 200metres of hosing which enables the vacuum excavators to reach into the hardest to access locations, helping to keep the workers safe whilst the excavation works are completed.
Examples of confined areas where vac exs are often used include:
• Deep Drainage Pipelaying
• Repairs of faulty and burst mains
• Timber headings
• Digging out of culverts and embankments
• And many other specialist civil engineering and tunnelling works
In addition to tunnelling contractors Horizontal Directional Drilling (HDD) contractors often use vacuum exs to unearth existing utility services before they launch their rigs so that they do not hit existing services.
Vacuum excavators can also be used to dewater tunnels and shafts and reception pits on deep drainage and civil engineering projects. Having a vacuum excavator on-site enables confined spaces to be dewatered quickly and safely compared to using manual workers and excavators. This allows workers to regain access into confined areas that have filled with contaminated material or mud, flood and rainwater due to rainfall or flooding.
Vacuum excavators are often used for refurbishing existing buildings. They can be used for sucking up the floors of buildings without damaging buried pipework and also removing waste debris from buildings. Using a vacuum excavator saves operatives having to carry out potentially hazardous and toxic material by hand during building refurbishment and also demolition works. Using the hose of a vacuum excavator the building refurbishment contractor can reach directly into the building or unto the roof from the street and suck the material into the wagon where it can immediately be transported to the local waste transfer station.
VAC UK had a number of jobs recently on English Heritage sites. Last week we were called out to Lincoln Castle as the embankment walls had started to loosen endangering the houses below and risking the castle walls collapsing.
Using manual labour the access would have been too difficult, the job would have taken too long, been too expensive and riskier from a health and safety perspective. The castle walls are in the middle of the city surrounded by houses. Carrying the muck out in buckets whilst in keeping with the way the castle was originally built, using manual labour, would not be taking advantage of the latest technology available.
Archaeologists are often employed before major infrastructure projects such as HS2 to export archaeological remains which may be disturbed as the enabling works commence. The archaeologists need to expose and record the remains without damaging them and this is a time-consuming process involving hundreds of skilled staff trained in archaeological fieldwork.
Interestingly during the1800s gold rush in California the gold miners invented a specialised digging practice to quickly reveal the gold without disturbing and hiding it. This involved steam pump-pressurized water to dissolve the land around the gold deposits and then a screen slurry to finally capture the gold. This was an unsafe practice and lead to many fatalities. It is also not ideal from an environmental or waste disposal perspective as the slurry produced could be hazardous to humans and dangerous to the environment. Dry suction excavators are a perfect invention that can be used by archaeologists to reveal their archaeological findings without damaging them. Vac exs are the most sensitive and least invasive means of mechanical excavation. VAC UK has the most modern fleet of vacuum excavators in the UK with the most advanced technological features. Using an airspade, VAC UK’s skilled operators can dig in controlled layers which allows us to ensure we can excavate the earth of archaeological sites without risking damage to any of the archaeological remains.
Suction excavators are also used on railway civil engineering projects. The vac exs are particularly useful for sucking up and relaying ballast which is laid underneath the railway lines.
Vac exs can also be particularly useful in the construction and maintenance of:
• level crossings
• Drainage and catchment pits
• Other excavations and trail holes.
• Foundations for signal and pylons etc
• Precise exposure of points or railway sleepers.
• Reliable removal of litter and dust near stations and in tunnels.
• Removing leaves from the track system and points boxes – particularly in the autumn.
• Cleaning the drainage and discharge system in tunnels and bridges.
• Removing residues after smoothing of the rails.
• Sucking up sand between the rails and points – for example after a storm.
• Removing contaminated material after a hazardous or environmentally hazardous substance leak.
Vacuum excavators can access the rail line by running a hose down the railway embankment and parking the vacuum excavator on the nearest road, bridge or car park. They can also be mounted on a specialist road-rail vehicle and driven unto the railway track.
Tree root excavation
Vacuum excavators can be used to expose the roots of a tree so that it can be replanted without damaging the tree roots. VAC UK can suck up all the earth around the tree without damaging the roots and pick up the tree and transport it by lorry to another location to be replanted. The skilled vacuum excavator operator uses a specialist airspade to disperse the soil around the tree without causing damage to any of the roots. This can also be used for rejuvenating the trees. Exposing the soil around the roots allows for more air and sunlight to access the roots. This oxygenates and hydrates the roots enabling optimum tree growth and health.
Vac exs are often used after environmental disasters. They can be used to pick up waste and hazardous material without endangering the workers. Vacuum excavators can be used to clean up after oil spills or aid in reconstruction works after earthquakes.
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