On top of impeccable geotechnical performance, VelociFoam changes the parameters of the civil works of a pipeline project. Removing the need for thousands of truck journeys along the pipeline path means lower requirements for access roads, both in terms of construction robustness and size.
The VelociFoam method saves construction resources in 3 ways:
- Backfilling with native, extracted soils means that no backfill needs to be imported.
- Replacing excavated masses means that they don’t need to be transported for disposal elsewhere.
- The reduced logistical requirements mean the construction row can be reduced by 40%.
The diagram shows the difference between a standard project (upper) and a VelociFoam project (lower):
Pipeline construction is a always a major logistical exercise. The inherent linear nature of pipelines, combined with the probably that the pipeline is located in terrain with no prior access roads, means that logistics have a major impact on project timelines and finance, as well as the environment.
Some types of pipeline have further complicating factors; for example, hydropower projects will often have a requirement for the same access roads to service construction of the inlet / dam system, or the turbine system. This means that a single lane access road may not be sufficient. Where the area closest to the pipeline trench is occupied for longer periods by the installation team, this normally requires the construction of a second lane.
Additional to the access road, there is a requirement for storage of excavated spoil and imported backfill. When this is laid along the length of the pipeline path, it represents a major use of terrain that exceeds the actual pipeline path by a factor of 5 or more.
The ecological impact of the project is massive. Pipelines often remain open for a year or more. No matter what rehabilitation requirements are imposed, the impact on fauna and flora is immense. This impact often leads to justifiable resistance from environmental groups.
The Effect of VelociFoam
It is impossible to remove all access or spoil storage requirements for a pipeline project, or negate all the environmental impacts.
Allowing use of native backfill (subject to removal of biological material), means that aggregate transport journeys are massively reduced. Under some conditions, (for example, in wet soil conditions in Norway), drainage may still be required, but the use of PU foam normally removes this requirement.
In typical conditions, 1.5km / 1 mile of 500mm / 20-inch pipeline will require between 10,000 and 15,000 tonnes of aggregate, or 250-375 40-tonne truck loads.
With VelociFoam, this is reduced to 40-60 tonnes of PU foam component, that can be transported in 1-tonne IBC bulk containers, if necessary by 6-wheel ATV.
This means that the access road can be constructed to a far lower grade.
Use of Trench As Road
Where pipe diameters are sufficient, we can use a ‘pipehead laying strategy’. This means laying and installing in series, ‘as you go’, instead of the more usual ‘lay and fill’ methods used when installing with aggregate.
We have designed our in-line robotic spray platform to be able to utilise a narrow track width of 180cm / 72-inch, meaning that a typical 2 metre / 80-inch trench bottom is well-suited to this strategy. In practice, this means that any pipeline from 1200mm / 48-inch and above lends itself; even with smaller diameters, increasing the trench width, instead of both digging a trench and building a construction row / access road, may well be more economical, particularly as the backfill is native soil and not imported aggregate.