Pipe manufacturer AquaSpira is helping Scottish Water keep programme length and disruption down on two major projects in Glasgow.
The Lancashire-based firm is supplying in excess of 500m of composite steel reinforced (CSR) pipe to contractors working on the Shieldhall Strategic Tunnel project and the separate Clarence Gardens SR15 scheme.
In both cases AquaSpira says the pipework will require fewer deliveries to site, and will be easier to handle than concrete pipe. It says using the CSR pipes will also result in the removal of less spoil.
Flood risk mitigation
Shieldhall Strategic Tunnel will be 5km long and run from the existing sewer network at Queen’s Park to Craigton Industrial Estate. Expected to cost £100M, it is designed to reduce sewage flooding during storm events.
A Costain-Vinci joint venture is the main contractor, while consulting engineers Aecom specified the AquaSpira pipe, which will be installed by civils firm George Leslie.
The CSR pipe will primarily be used to create and link new storage pipes to the main machine-bored tunnel.
It is being put in at several locations across the overall scheme but is currently being delivered in bulk to two areas in particular.
“More than 150m of our 1800mm diameter pipes have just been installed up to 6m deep within, or adjacent to the highway at two areas – Prospecthill Road and Aitkenhead Road,” says AquaSpira director Mark Stanway “and several hundred metres of 1200mm diameter pipes, 900mm diameter pipes and innovative access bends are currently being installed in Curtis Avenue.”
The Clarence Gardens unidentified intermittent discharge and flooding improvement scheme is being led by Amey Black & Veatch through Scottish Water’s SR15 framework.
“Here we are supplying 130m of 1800mm diameter and 45m of 1200mm diameter pipe with factory fitted dry weather flow channels” says Stanway.
Useful under roads
He says the CSR pipework is particularly useful for installation beneath existing roads.
“If our pipes were not available for these two schemes, the contractors would have been forced to use conventional concrete pipes,” says Stanway.
AquaSpira believes its CSR pipes – which are designed to have better long-term structural strength than plastic equivalents – also have many advantages over concrete pipes or box culverts. “For these applications, the weight of our 2.6m long, 1800mm diameter pipe is 319kg,” says Stanway. “An equivalent concrete pipe would be over 7t.”
This huge weight difference can make an impact from the point of delivery.
“You only get three concrete pipes weighing 7t each on an articulated trailer, but you get seven of ours on,” says Stanway. “Ours are slightly longer too, so you can reduce site deliveries by 60%.”
Given that the two Glasgow projects involve working in tight residential areas, reducing delivery visits is a major boon.
Minimised truck movements
“You need to minimise articulated lorries arriving and manoeuvring in congested and constrained streets like these,” says Stanway.
There are also benefits at the next stage – handling and installation.
“The size and type of the site machinery needed to install our pipe is far more manageable on residential streets than the 50t machines or cranes that might be needed to handle concrete pipes.”
Narrower than concrete pipes
As well as weighing less, CSR pipes are much narrower than standard concrete equivalents.
“The outside diameter of our 1800mm pipe is 1886mm compared with 2160mm for a concrete pipe of the same usable inside space,” says Stanway. “So at Clarence Gardens, for example, where existing services go across the working trench, our pipework is much easier to manoeuvre around these.”
An excavation can be up to 500mm narrower for an 1800mm diameter CSR pipe than for a thicker concrete version with an outside diameter of almost 2400mm at the end where it connects to an adjoining pipe, according to Stanway.
25% excavation reduction
“The average reduction in excavation is 25%, which is a big number as it also reduces the amount of spoil to be carted away from a residential site.”
This cuts costs as well as again reducing the number of large trucks needed to visit site.
“On many residential utility projects, minimising disruption to residents is a key focus.
Looked at another way, a contractor can use a 1500mm diameter CSR pipe in the same physical space as a 1200mm diameter concrete pipe.
“This gives a large amount of extra storagefor the same space in the road, a core benefit when dealing with storm water,” says Stanway.
AquaSpira says there are other benefits to its pipes.
“We supply pipe in short lengths, designed to be fitted within the lateral trusses of temporary trench support systems used for health and safety reasons.”
Stanway adds that another important feature is the use of spigot and socket push-fit joints for easy connection in narrow trenches.
“The primary benefits of our pipe over concrete are programme reduction from reduced excavation; minimised disruption to the community through fewer deliveries and muck-away lorries; and the ability to install using standard site plant.
“All this is done without compromising the long-term performance of the asset due to the structural stability of steel, combined with the excellent durability of polyethylene.
Stiffer than plastic
Once installed, depending on the diameter, the long-term stiffness of a CSR pipe is up to 10 times greater than a plastic pipe,” says Stanway.
He says that when installed in accordance with company standard guidelines, AquaSpira pipes should have a minimum design life of 120 years.
“We have a hybrid that we have been producing in the UK for seven years with demand increasing more rapidly now than ever.”
The steel contains an average of 50% recycled material, meaning the pipe can be used to contribute to Breeam ratings and other environmental targets on a project.
The composite pipe material is also fully recyclable.
AquaSpira supplies its pipes in sizes from 750mm to 2250mm internal diameter. It has been consistently supplying Scottish Water for three years and other water companies including Anglian Water for over five years.
“We have worked with every major UK water company and we are also experiencing significant growth in adoptable storm water attenuation on new housing developments,” says Stanway.
In association with Aquaspira