Contractors Concor in partnership with OptiPower, have been awarded the R202 million infrastructure project for the structural foundations and associated infrastructure for of 24 dishes to the sixty-four dish MeerKAT radio telescope.
Located in a remote area of the Northern Cape, MeerKAT was launched in 2018 and is a precursor facility to the next-generation radio telescope, the Square Kilometre Array (SKA).
According to Concor’s contracts director Joe Nell, the scope of Concor’s work will include a construction camp for about 250 people, 40 km of gravel access roads to the dish positions where the antenna platforms will be constructed, and the structural concrete foundations for the 24 telescope dishes.
The camp will include facilities for wastewater and sewage treatment, settling ponds, water storage and security fencing.
Concor will also be building four guardhouses, which will be powered by solar energy. OptiPower will carry out the electrification of the works and the provision of fibre connectivity to the new installation with approximately 60 km of trenching, electrical power cables, fibre ducting and fibre cables required. The Concor-OptiPower venture (COP) will also design a further 109 satellite foundations, with the associated roads, power and fibre installation.
“A key constraint of this current project is the need to limit any radio frequency interference (RFI) in the vicinity of the MeerKAT telescope array,” says Nell.
“This is due to the highly sensitive nature of the radio telescope equipment, which is designed to detect extremely weak radio signals from astrophysical sources.”
He highlights that RFI from manmade radio signals emanating from commonly used equipment like cellular phones, vehicle electronics, microwave ovens and many more can easily distort or corrupt weaker signals, and even damage the telescopes themselves.
“This means that we have set up our office in the town of Carnarvon, some 100 km from the site,” he says. “We are in the design stage of the project, and will begin work on site in June this year.”
Nearer the time of site establishment, a specialised RFI container will be established on site from which the team can communicate and operate certain electronic equipment. The container will be insulated to prevent any signal reaching the telescopes. Dealing with the RFI means that every vehicle and item of equipment required on site will need to be tested and certified, says Concor site agent Roy van Leeve.
“We have employed an RFI expert to test our equipment and submit the necessary data to the client,” says van Leeve. “After careful analysis of this data, we will be granted a permit for that particular item of machinery or advised what steps need to be taken before machinery can be passed for use on site.”
He notes that just about every model of construction vehicle built within the last decade is likely to include telematics, which presents a potential RFI risk in this project. The construction camp itself also needs to be located a suitable distance from the MeerKAT site to avoid RFI, so it is planned to be about 15 km away.
For the roadwork, Concor will be operating in a geological environment of mainly sandstone and calcrete, overlying mudstone and shale, where 20 tonne hydraulic excavators will be put to work.
“It is vital that the roads be well designed and constructed, especially in terms of their vertical and horizontal alignment,” he says. “This will ensure that the low-beds and other heavy trucks delivering construction material and large componentry can navigate the route safely.”
For the radio telescopes’ concrete foundations, Concor will be using two methods depending on conditions. Where bedrock founding conditions are deeper than three to four metres, eight piles will be cast for each foundation’s seven metre diameter cap; most of the foundations will be done this way. In those cases where bedrock is shallower, a pad foundation will be cast with an 11 metre cap.
The limited number of foundations has meant that Concor’s common practice of establishing its own on-site batch plant is not feasible. Instead, the concrete will be sourced commercially – presenting another logistical challenge.
“We will require about 5,000 t of concrete aggregates, which will have to be delivered some distance in trucks with capacity of 34 t each,” says Van Leeve. “Added to this, the trucks will need to undergo RFI testing well in advance, so that they have the necessary RFI permit to enter the site and discharge their load.”
The same restrictions apply, of course, to all suppliers that must deliver to site. Where the testing and permitting of vehicles is not possible or viable, he says that a certain amount of double-handling of equipment and materials is likely to be inevitable.
Broadly speaking, however, Concor’s proven track record on constructing similar projects has positioned it well for the work at MeerKAT, Nell says. The infrastructure aspects are quite similar to the eight wind farms that the company has constructed to date. It is also in the process of completing another two of these wind farms.
“Contractually, we have been very successful in carrying out these projects efficiently and on time, in a spirit of collaboration that has overcome various challenges and earned us considerable repeat business from clients,” he says. “Our experienced management team and staff ensures that planning is detailed, and implementation is professional.”
Concor will also be making use of SMME suppliers from the local Kareeberg municipal area, which includes the towns of Carnarvon, Brandvlei, Williston, Loxton and Vanwyksvlei.