Infrastructure project to improve quality of life

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Murray & Dickson (M&D) Construction is on track to complete the first phase of their Moretele South Water pipeline project for Magalies Water — the operations and maintenance of water supply at Moretele Local Municipality. By Tarren Bolton | All photos by Tarren Bolton

The all-steel pipeline is supplied by spiral-welded steel pipe manufacturer Hall Longmore and is delivered in sections of 80-metre lengths.
The all-steel pipeline is supplied by spiral-welded steel pipe manufacturer Hall Longmore and is delivered in sections of 80-metre lengths.

M&D offers a wide range of construction services such as general building construction; civil engineering construction; pipe laying (in the water as well as oil and gas industries); earthworks and road construction; as well as construction plant hire. M&D offers a wide range of construction services such as general building construction; civil engineering construction; pipe laying (in the water as well as oil and gas industries); earthworks and road construction; as well as construction plant hire.

With the company CIDB grading of 9CE PE, the pipe laying division is able to tender on contracts for the public sector, clients including mining companies, water utility boards, fuel and gas suppliers, municipalities and the like. Water, Sewage & Effluent met with the M&D team on site at their current project: the Magalies Water project — the construction of the Moretele South Water Supply Scheme, consisting of 30km of bulk steel pipelines and cross-connections to existing infrastructure to augment water supply to towns in the Moretele South region of the North West Province.

“It’s a new pipeline and we are adding to its capacity,” says Dirk Steyn, M&D Construction site manager. “We have started from an existing line, then will bring it all along the N1, go underneath the N1, up to the R101, underneath the R101, through to Moretele. On the way, we will tie into various existing pipelines in order to increase the supply.”

Steyn says that the project started in October 2018; M&D has estimated approximately 18 months as the duration of the project. “Four months into the project, we have around 2km of pipe in the ground,” says Steyn. “We are running two heads — what we call the fast head and the slow head. The fast head runs parallel to the N1, in Kekana at the moment. It’s a bit slower than we’d like because there are obstacles such as traffic and pedestrians to overcome.” Steyn adds that the slow head is from the N1, coming back to the R101, which falls in the middle of an existing road. “This means we have to work through the road, with houses on both sides, as well as existing water and sewerage systems. Once we’ve crossed the railway line and move towards the Apies River, there are two wetlands, and the project will progress faster from there.” 

Excavation

Rowan Barnard, head of plant at M&D Construction, explains that the size of the trenches for the pipe diameter, and the design metreage per day quota, necessitates the use of excavators. M&D has built up a plant division that caters to all construction divisions within the group. The company considered it strategically necessary to own sufficient plant to both increase the competitiveness of the various divisions and to ensure an accessible pool of plant to satisfy site needs and requirements.

Certain plant items such as large side booms are specific to the pipe laying industry, but most of the plant owned can be used in general building, earth moving, as well as civil engineering projects. The company constantly upgrades and renews its plant fleet to increase its production output.

Project specs

The all-steel pipeline is supplied by spiral-welded steel pipe manufacturer Hall Longmore. The steel pipes are pre-coated with a three-layer coating process called 3-LPE. The first layer is the corrosion protective layer consisting of fusion-bonded epoxy, which offers very good corrosion protection and bonds well with the blasted steel surface. The second layer is the copolymer adhesive, which has good chemical bonding to the fusion-bonded epoxy, and layer three is polyethylene, which also bonds well and seals the layers.

“The pipeline is delivered in sections of 18-metre lengths, so every 18 metres there is a weld to join them on a spigot and socket joint,” says Steyn. “Our welding team are all API qualified, which is an American standard. Every welder is certified with a number. On this project, we do a dye-pen (dye penetrant) test on the joints, using a penetrant and a developer to check if there are any cracks in the welding. There is a cement-mortar lining inside the pipe, which we repair at every joint. In addition, at each welder-joint, we use a coating on the outside of the pipe for corrosion prevention and sealing. Quality plays a big role, and we have our quality-control officer on site,” he adds.

Steyn explains that every pipe will have a block with the chainage (linear pipe length), the joint number, the welder number, and the date the pipe was welded, and every joint is recorded. All this information is captured and submitted to the client.

Barnard adds, “We have an in-house fittings factory which manufactures the elbows and joints — we’ll get the parts and join them. It then gets sent to our pipe supplier who 3-LPE coats it.” 

Processes

Access under roads or railway lines is made possible through pipe jacking. Steyn explains the process: “A trench is dug, and we start excavating under the road or railway line, by hand usually, using air breakers. Then, using huge jacks, a concrete sleeve is pushed through the excavation site until they get to the other side. The resulting ‘tunnel’ is then secured with grout in order to ensure that it doesn’t collapse, and we slide our pipe through the concrete sleeve.

“Another part of our pipe laying process is the installation of air valves and scour valves,” says Steyn. “The air valves are always at the highest point. When you pump water, air tends to get trapped, and if you don’t get rid of the air, the water won’t flow — it forms an air pocket. Then, at the lowest points, there are scours. If there is a problem along the pipeline that needs to be fixed, then the scours are used to drain the pipeline so you can work on the affected section. In addition to this there are isolation points, which require chambers to be built — which is civils work,” he says.

Steyn says that pressure is at nine bar for the 700mm pipes, and this pipeline project will include surge tanks in case of a shutdown on the pumps. “When pumps shut down, a water surge occurs — where water continues along the pipeline for a certain distance, but then backwashes and causes a surge. The pressure when this occurs is so high that it can remove the water lining and even cause the pipe to break in some instances. For this reason, there will be surge protection, where the water comes up into a surge tank, returns at a slower rate, thereby reducing the flow pressure,” explains Steyn.

Challenges

A project of this scope and magnitude is not without its challenges. Barnard says, “Typically on site, you will find some M&D plant, and some plant from local suppliers. Although we have all the plant available in-house, first option is to use a portion of local plant. If the locals do not have the kit we’re looking for, then we’ll use our plant available.”

Steyn says, “Whenever we need plant equipment, we speak to the project steering committee (PSC) — made up of councillors appointed by the council, and the local community liaison officer (CLO) — made up of community spokespeople. What makes this project interesting is that it starts in Tshwane and crosses into Moretele in the north-west — which means that not one, but two local communities are involved. Each community has their own appointed CLO. Each CLO represents the individual community’s needs and requirements and therefore each needs to give approval in all matters individually. This means whenever we hire labour, plant equipment, or any other items, it has to go through the individual CLOs, the PSC, and then out to the community. Then only does it come back to us, once all parties have agreed and approved the way forward,” says Steyn.

Barnard says, “Aside from this being a time-consuming exercise — having to get permission every step of the way through the CLOs, the PSC, and the locals — it can also get quite complicated in that there is not one external supplier who will supply five different plant units, but five different suppliers each supplying one piece of equipment. The logistics itself is time-consuming, but it’s also understandably not very economical since you end up paying five suppliers, and not just one.

“Stoppages do hamper production, but we have found that the best and quickest course of action is to involve the CLOs immediately and the local municipalities, who assist in solving the problem. A stoppage can be anything from between two to three hours at a time, but we keep record of it,” adds Barnard.

Despite the challenges, M&D is on track to complete the project by mid-2020, which will increase capacity to ensure the delivery of services across the water value-chain and support the ‘source-to-tap’ vision. Working closely with the municipalities, M&D will bring efficient water service delivery to the end consumer, communities, and industries served by Magalies Water.