One of Galvac’s vacuum excavation units has been working on the new Heysham bypass in support of GPL Group’s Special Projects division.
The scaffold structure which can be seen in the photograph above (with the new A6 diversion and bridge abutment visible in the background) is supporting a bank of services 3.0m wide. These included a 225mm water main, a 450mm water main, 6no HV electric ducts, 9 no BT ducts and 2no Cable TV (fibre optic ducts). GPL’s task was to carry out temporary works to allow the installation of a 750mm diameter drain 5.0m deep to cross below the existing services.
Our vacuum excavation unit was used to excavate locally around the services to expose a 1.0m clear zone all round prior to mechanical excavation. This is an excellent example of how vacuum excavation can be used in conjunction with conventional excavation methods to carry out more delicate operations before utilising traditional plant.
The Galvac team have been busy in Manchester city centre recently, using one of our Dino 3 units to assist with pipe replacement works on behalf of a main contractor.
The construction of high rise blocks occasionally causes problems with existing utilities as these can easily be disturbed or damaged during the process of piling – the creation of deep concrete piles within the ground which are needed to support tall structures.
Existing sewers or drains which are damaged as the contractor digs during the boring process then become filled with concrete which in turn can cause a back up of sewage / surface water which may go undetected for a period of time.
The Galvac team were employed to use vacuum excavation in order to remove ground around existing services to a depth of around 5 metres so that a pipe which had become blocked in this way could be exposed and safely replaced without further damage to pipework.
With an excavation area of approximately 5 metres long by 1 metre wide, the use of a vacuum excavator allowed the excavation zone to be kept to a minimum and meant that the contractor could literally just replace the section of blocked pipe with limited disruption to the area.
Within 2 shifts we had vacuum excavated through a series of services, cleared around the blocked pipe and the contractor had replaced the earth and reinstated the pipe.
Galvac has taken delivery of two 39 tonne chassis vacuum excavators (or VacEx). Manufactured in Germany by MTS and priced at £390k, they will be the only two of their kind currently in the North West.
Both units, which are Dino 5 models, were purchased by Galvac, GPL Group’s specialist vacuum excavation division. They have a skip capacity of 12.9m3 with the ability to be powered by remote control to excavate subsoil and soft rock during construction work.
Galvac provide vacuum excavation to some of the UK’s leading construction and utility companies as a safe, cost effective alternative to conventional excavation methods. Vacuum excavation is regularly used during the removal and replacement of utility pipework to ensure no damage.
The first of the new units delivered to Galvac is a high tip and is the only one of its kind in the North West. The second unit is what is known as a triple fan. There are currently only a few other triple fan units in the country.
The ‘high tip’ will enable the unit to tip material to go straight into an accompanying truck, removing the need for double handling of waste on site and allowing the excavator to continue its task of removal.
The triple fan 39 tonne unit is highly powerful and will reduce time on projects significantly due to its ability to excavate at up to 250m away.
Mick Thomas of Galvac, GPL said: “This is a significant investment for us and will truly position us as a major player in this area. The two new units will join our existing fleet of five 26 tonne units which means we can offer clients flexibility on projects to suit their needs.
“With the significant work on our highways and utility networks, not only here in the North West, this equipment will be in high demand and we already have a healthy pipeline for our new additions.”
Galvac has delivered intensive training for the operators of the new equipment. The dedicated team at Galvac will all receive 120 hours of training by a qualified operator before they are put in control of any of the units. In line with GPL’s commitment to the highest standards of health and safety, there will always be a two-man fully trained team working with the units on sites.
Vacuum excavation is typically used to expose live utilities under highways or footpaths safely and efficiently.
There are several benefits of vacuum excavation over more traditional excavation methods (such as a mini digger or shovel.)
Firstly and crucially, vacuum excavation presents a much lower chance of damage being caused to utilities as there is no mechanical interference to the ground.
It is also beneficial from a safety point of view, particularly when compared to a hand dig where there is a significantly increased risk of injury to operatives.
Vacuum excavation is also faster than more traditional methods. In normal conditions with buried pipes and cables, a manual dig would typically remove less than 1 cubic metre of material per 6 hours. Using vac-ex, up to 24 cubic metres of moderately heavy soil could be removed in the same time period. For this reason, vacuum excavation tends to be more cost effective than a hand dig.
Excavation site size can be reduced by up to a third compared to the use of a mini-digger, which makes vacuum excavation ideal for areas where space or access is an issue. Because the earth is collected in the vehicle (with up to 12 cubic metres of spoil tipped in a designated on site area), site cleanliness is also improved, which is particularly beneficial in public or heavy traffic areas.