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Fast repair limits down time of critical water supply

A simple, permanent repair has been carried out to a leaking concrete reservoir in Queenstown, New Zealand, using specialist hydrophobic grout Hyperflex, supplied by Source One Environmental (S1E) in the UK.

“The repair was essential as the leakage was causing erosion to the hillside on which it is situated,” explained Ian Fraser, S1E’s New Zealand representative. “It forms part of Queenstown’s drinking water supply system, so it was critical that the repair was carried out without delay and was successful and permanent, with no need to return. The town has an urban population of more than 14,000 residents, so any issues could have caused a major headache.”

Infrastructure managers had discovered leakage from the joints between the walls and base of Arrowtown reservoir, as the original silicon sealant had broken down. The problem was worsened by tree root ingress.

Hyperflex was selected to permanently seal the gaps that had appeared as, once installed, this closed-cell hydrophobic grout will not allow the passage of any water and does not shrink over time. It was safe for this application as it has US approval NSF 61-2007, for contact with potable water. Hyperflex was designed to combat widespread, low flow rate infiltration and flows to fill any void, even down to the finest cracks during installation, with an expansion rate of 20:1.

The installation process was straightforward and took only three days:

Day 1: Thorough power wash of the walls and the channel at the intersection of the wall and base, followed by treatment for tree root ingress

Day 2: Chlorine spray and wash and installation of Hyperflex, mostly using the standard caulking gun

Day 3: Removal of the excess Hyperflex, addition of a fillet of waterstop and cement around the entire base/wall intersection, then final power wash and chlorine wash before refilling with water

“The gap around the base varied in width, but the Hyperflex flowed to fill the entire void. Good penetration between the walls and the base became apparent when the foam appeared underneath the reservoir where excavation had taken place to repair valves,” explained Ian.

Hyperflex is ideal for the repair of tunnels, manholes and bunds and can be used for ground stabilisation purposes. It is a complementary product to SealGuard II, a faster-acting polyurethane product designed to stop rapid water flow. Both products are available exclusively from Source One Environmental.

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