Pipe relining at Castle of Good Hope

By Darren Goodman, director at Water Damage Services

Cape Town’s oldest building has been given a new lease on life thanks to groundbreaking pipe relining technology.

the castle of good hope cape town MM

Built between 1666 and 1679, the Castle of Good Hope is the oldest surviving building in South Africa and has been the centre of civilian, political, and military life at the Cape for more than three centuries. Over the past two years, the City of Cape Town has been restoring the Castle to its former glory through a complete and unprecedented restoration project.

In need of desperate attention

One of the problems the city faced was that the inaccessible copper and steel pipes of this important heritage building had become drastically corroded. The resultant leaks were not only causing structural damage to the Castle, they were also responsible for significant water wastage — a very real priority given the city’s current drought and water restrictions.

Both the water and fire systems were built into the building’s walls and ceilings, making them inaccessible to maintenance crews. Upon further investigation, the management team found that the cast-in down pipes situated on all the blocks were also in need of repair. These corroded rainwater pipes were causing internal damage whenever it rained. What’s more, the below-ground sewerage system (made from original earthenware pipes) was showing signs of severe cracking and displacement, and its location beneath 350 years’ worth of compacted earth and stones made access a real issue.

The resultant leaks were not only causing structural damage to the Castle, they were also responsible for significant water wastage.

The project managers had a big problem. Time was not on their side and they now had to assess and repair unreachable pipework throughout the site without affecting the facades of the oldest building in the country.

An innovative and elegant solution

The management team commissioned Water Damage Services (a specialized potable and structural trenchless relining contractor) to deal with these sensitive problems, due to the company’s proven track record in relining both the Cape Agulhas II research vessel and the Good Hope Centre.

Relying on cutting-edge technology that uses compressed air to blow potable epoxy into the reticulation system, Water Damage Services was able to reline all of the Castle’s pipes (ranging in diameter from 15mm to 300mm) in record time. The technology completely coats the insides of the pipelines, filling all the pin hole leaks within the system and prolonging the pipes’ lifespan by at least 50 years — all without having to chop a single floor, wall, or ceiling.

An inflated bladder installed into pipe while it cures. 
Image credit: Water Damage ServicesThe structural liner terminating into the manhole before trimming. 
Image credit: Water Damage ServicesThe top view of the liner within a 50-year-old cast iron sewerage line.
Image credit: Water Damage ServicesThe top view of the liner within a 50-year-old cast iron sewerage line
Image credit

Keyhole surgery for buildings

The storm water and drainage lines were relined using a different technique, which entailed installing (via the Castle’s manholes and full bores) structural felt liners impregnated with epoxy. Once these liners are in place an internal bladder inflates and pushes the epoxy-filled liner to the inside diameter of the pipe until it cures. After some time, the bladder is extracted, leaving a new pipe within the old one. The procedure has rightly been likened to putting a stent into an artery.

Both the city and the restoration team were blown away by the impact of the technology. This complex project was finished on time and saved the city millions in traditional replacements, resultant damage costs, and potential water losses.

The city, the engineers, and project management team are now turning to trenchless technologies, as they are safer, faster, and more cost-effective than traditional replacement. Water Damage Services installs these systems on residential, industrial, commercial, and marine applications nationwide.

Finding the leaks and technology used

On pressurised piping — that is, all copper pipes / fire suppression / general water reticulation — tracer gas and acoustic technology were used, as well as thermal imaging to determine the leaks within the walls, floors, and ceilings.

On non-pressurised piping — that is, storm water and drainage — CCTV inspection units were used to visually inspect all inaccessible piping in the walls and underground for any defects.

Impregnating the structural liner.
Image credit: Water Damage ServicesJetting the line through the maze of underground pipework.
Image credit: Water Damage ServicesA corroded steel pipe with new liner showing the new pipe within the old one. 
Image credit: Water Damage Servicesthe_castle_of_good_hope_cape_town2.jpgImpregnating the structural liner.
Image credit: Water Damage Services

Relining and the timeline

The entire project took a total of six months on site to complete all the pipe relining. Approximately 1 200m of square galvanised down pipes, which were built into the walls of the castle, were relined and about 100m of below ground drainage and storm water pipes were also relined. The sizes ranged from 80mm to 160mm.

Ensuring no weak links in the pipe system for the future

The galvanised down pipes were corroded and rusted, and the earthenware drainage was cracked. Due the trenchless technologies being structural, it makes no real difference on the condition of the original host pipe, as long as the product could be pulled through the line once it is inflated and cured. The new pipe within the host pipe is now structurally sound with a lifespan of at least 50 years.

No diagrams or drawings

The city had no idea where the pipes ran or had any indication of the network; pipe location equipment was used to track and map all the pipework.

The finished manhole post lining. 
Image credit: Water Damage ServicesAn inflated liner terminating in the downstream of one of the down pipes. 
Image credit: Water Damage ServicesInstalling the bladder through the impregnated liner.
Image credit: Water Damage Services
Installing the bladder through the impregnated liner.
Image credit: Water Damage ServicesThe high-pressure water line post potable epoxy coating. 
Image credit: Water Damage Services

Trenchless technologies’ traction in the market

This product has already been around for an extended period, and educating the market is key, as the take-up has been relatively slow. The Western Cape in particular has been using trenchless technologies more than any other province on municipal applications to rehabilitate underground bulk services. There is technology available to rehabilitate any size pipe within the infrastructure of a building or compound where the bulk technology cannot be applied due to the multiple bends and small workspaces often found within a building or complex. Pipe relining inside old body corporates, hotels and heritage buildings is a lot quicker, safer, and more cost-effective in most cases than traditional pipe replacement.

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