Heavily populated and dense with pre-existing sewer, water, electricity and telecommunications infrastructure, urban areas present a range of challenges to pipeline construction. Pipelines International examines the construction techniques being deployed in projects around the world.
For pipeline construction contractors operating in urban areas, problem solving is key to ensuring pipeline projects are completed on time, minimising disturbance to local residents and businesses. Limited space to manoeuvre equipment, noise constraints, and avoiding interrupting service to existing utilities are just some of the challenges which must be overcome.
Minimising impact in bustling Bangkok
When Thailand’s PTT Public Company needed a construction contractor for its Sai Noi North Pipeline, which traversed the congested streets of Bangkok, it turned to Nacap Asia Pacific.
The Sai Noi North Pipeline runs from the Tarchaburi-Wang Noi Gas Pipeline to the South Bangkok Power Plant and while the pipeline route first traverses 30 km of swamp and rural terrain, the 36 km of pipeline that follows were laid in increasingly urban terrain as the route followed major highways approaching the centre of Bangkok.
According to Nacap one of themost significant challenges of pipeline construction in urban terrain is the limited space. Space restrictions impact on pipeline spreads and impede the positioning of pre-welded pipestrings on rollers.
To overcome the challenges caused by limited space, Nacap implemented a system using supports on containers in which the pipe strings were actually prepared on the containers.
The completed pipestring ran overhead through densely populated streets and thus required a comprehensive design profile to ensure its safe behaviour during preparation and pullback.
Nacap carried out risk assessmentsto establish the weight loading of the containers and added rubber curtaining to protect against the uninsulated power lines which ran parallel to the working area.
Specialised construction techniques in South Africa’s urban jungle
Transnet is currently constructing the New Multi Product Pipeline (NMPP) from Durban to the Jameson Park terminal in Gauteng, South Africa. Two sections of the 720 km pipeline pass through urban terrain; the Jameson – Alrode spread and the Alrode – Langlaagte spread.
Group Five has partnered with Spiecapag to construct the pipeline and has found crossing urban terrain a challenge on this project.
Construction crews were limited to working between regular working hours to prevent noise pollution and traffic congestion for local residents.
A range of different crossings were used to avoid existing infrastructure which has meant slow progress in some areas of the project.
According to Group Five “In built-up areas where the line goes under canals, railway lines and municipal services, progress can be a tortuous 100 m a day.”
South African companies Esor Franki and Jacked Pipelines completed pipe jacking along the project. Esor completed eight pipe jackings while Jacked Pipelines completed pipe jacking of some 18 road and rail crossings with 48 inch diameter and 100D concrete sleeves with a total length of 1,049m. Under the contract the company also completed grouting on all the crossings using a 6:1 bentonite/cement mix.
France’s Horizontal Drilling International completed a 1,050 m crossing under the Uncle Charlies Interchange, located in the city of Johannesburg. The route of the pipeline was designed to ensure a straight approach to this crossings and also a length of open ground on which to prepare the pipe that was pulled through by HDD.
HDD is the ideal method for urban areas
Horizontal directional drilling (HDD) equipment has become the installation method of choice in urban areas, according to Vermeer Corporation’s Jon Heinen.
“Municipalities and residents around the world realise the benefits of the technology – reduced disruption to our daily lives and less restoration to the existing landscape.”
Vermeer supplies HDD rigs to the pipeline industry and has recently supplied the HDD rigs used to install an intricate pipeline system beneath the Dallas/Fort Worth Airport to transport natural gas extracted from the Barnett Shale natural gas field.
“The project involved installing a 24 inch diameter pipeline around the perimeter of the airport and a gathering line consisting of 8 inch to 24 inch lateral lines that serve to channel the extracted natural gas from more than 100 wells.
“There were numerous logistical challenges involved with installing such an intricate pipeline system under one of the world’s busiest airports. The only way this project could be completed was by using HDD, as what lies on the surface is a network of runways, terminals and cargo facilities. Disrupting that flow of air traffic was not an option.”
Another supplier of trenchless technology Herrenknecht also sees an increasing need for trenchless technology in delivering pipeline projects in urban areas. “Large cities are growing in size, almost everywhere in the world. And along with them, the demands placed on urban infrastructure is also increasing,” the company says.
To address this growing need, Herrenknect is providing innovative technologies such as its Pipe Thruster for pipelaying. The thrusters provide, for example, additional push and pull forces for particularly long drills and large pipe diameters. In combination with microtunnelling technology and using the Direct Pipe method, the Pipe Thruster allows the trenchless installation of a prefabricated pipeline together with the simultaneous construction of the required drill hole in one single, continuous working operation.
