By Eamonn Ryan | All photos by Eamonn Ryan
Gallagher Estate has installed a supplementary water tank with the capacity of a million litres in order to avoid any water woes if the city is experiencing challenges. Project manager Lutalo Construction Projects called in Goldmark Plumbing for what is one of the largest tank installations in the country.
Gallagher’s water engineers calculated the required water supply to Gallagher Estate, and Graham Solomon, owner of plumbing contractor Goldmark Plumbing, explains that this is a fairly straightforward process: “It’s a factor of the number of toilets and basins inside Gallagher.” The convention centre’s existing 300 000ℓ water system had been battling to provide sufficient water supply to the centre during Johannesburg’s periodic water cuts. With the additional 1mℓ the venue will have a total of 1.3 million litres.
“In 22 years of being in the business it’s the first time we’re doing a water storage system of this scale,” says Solomon. At the time of Plumbing Africa’s site visit, Goldmark had just installed temporary pipes to cater for one of Gallagher’s major events over the weekend, the iconic Comic Con Africa, due to concerns that its water supply would be insufficient, says Solomon. He explains that the new 1 million litres will not simply provide emergency reserves but will be integrated to the main water supply, with its water constantly circulating. “The mains supplies the main water tank, and from there joins the main line and on to the pre-existing tank. We will be installing a water valve on the 160mm galvanised water supply, whereby should there be a water leak it will automatically switch itself off.” This component of the job has not yet been done and will first pass through the project engineers.
The tank was manufactured by a company in Pinetown, SBS, where it was prefabricated and shipped up to Midrand to be assembled on site. “It consisted of sheets of galvanised steel with a plastic curtain on the inside. It’s very thick plastic – and that’s what holds the water in. The steel sheeting is to stop the plastic from stretching out.
SBS’s website describes its tanks as follows: “The wall panels and roof sheets of all SBS Tanks are made of steel that is hot dipped and coated with a molten alloy of 55% aluminium, 43.5% zinc and 1.5% silicon, commonly referred to by its trade name Zincalume , thus rendering SBS Tanks highly resistant to corrosion.
“In some extreme cases, sacrificial magnesium anodes are applied, further inhibiting potential corrosion. All SBS Tanks are fitted with an approved liner which prevents water coming into contact with the wall panels. This liner complies with the Australian Water Quality Centre standard AS/NZS 4020‐2005: Testing of Products for use in Contact with Drinking Water.”
On a project of this calibre, says Solomon, all products have to be SABS and Jaswic approved with a manufacturer’s warranty on it; and be industrial strength so as to handle the considerable pressure, traffic and harsh outdoor conditions with regard to both pipes and valves, so as to never restrict flow. “The actual SANS standards are specified by the engineers on their drawings. While on smaller jobs the plumber is often the wet services expert and will advise on plans, Solomon says for a job of this magnitude you have to have the professional wet services engineers on board for peace of mind to work out quantities, sizes of materials, system layout on a drawings and provide a comprehensive report. This spells out how they arrive at calculations and why it is the way it is.
The drawings will specify the pipe and valve sizes but leave the actual purchase and transport of them to site to the plumber.
Scope of work
Solomon says: “Our job as plumbers was the pipework connections into the tank and the pipework out of the tank, as well as to and from the pumphouse – the booster pumps and the pressure vessel – and everything leading from the pumphouse towards Gallagher Estate, connecting to a water line which was installed by the civils company.
“It’s actually a fairly straightforward process – the major difference is in the industrial size of the water tank.” The tank itself is located at the far end of the open-grounds parking field, several hundred metres from the entrance to Gallagher, which Solomon describes as the closest piece of available ground.
“One of the main construction challenges was that the foundation for the tank had to be robust enough to carry the considerable weight of the water tank at about
1 000t with all the rebar involved. It’s daunting.” That was constructed by Lutalo Construction Projects, as was the pumphouse.
“Once the installation is done, we will be presenting water saving options to Gallagher, hoping to ensure the mixers come with water-saving aerators and the toilets have half-flush – once the water reservoir is up and running.”
Scheduling woes
Goldmark has both a maintenance (commercial, residential and industrial) and construction divisions, and has been in existence over 15 years. “We do everything from a leaking tap washer in a house, up to urban upgrade of a 144-unit apartment block.” The combination of maintenance and construction assists in scheduling and flexibility in moving teams between small and large jobs.
The tank, water vessel and pump were all supplied by the client rather than Goldmark. The plumbing works was anticipated to be complete by November. The project has taken a year, but Solomon explains there were substantial periods of inaction in between, as primarily the tank was prefabricated. One of the challenges was consequently to manage a fitful workflow with other projects.
“Each sub-contractor gets called in by the project manager according to its schedule. For instance, the schedule provided that the water tank was to be full for the Comic Con. We fell behind schedule when we had to drill under the road to avoid damaging utility services – such as stormwater and fibre, Eskom and Telkom cables – which introduced a complication. The client did radar mapping to determine what was below the road, and contractors had to drill 2.4m below the road surface to miss all the services.
“The delay is the reason we had to do a temporary connection to at least survive Comic Con. That was done, and the coming months will be focused on setting the system up on a permanent basis,” says Solomon.
