Case Study:- Rockhampton Manholes Refurbishment



Client: Fitzroy River Water
Year Completed: 2015
Project Scope: 130 Manholes
Time To Complete: 5 months
Material Applied: MIR-970 Concrete Coating and MIR-960 Concrete Primer
Application System: Spray Liner

Summary:

After considering the network issues, material options and application considerations Fitzroy River Water chose to use MIR-970 to rehabilitate their network because:

  • it addresses all of the issues that arise with an aging manhole sewer network;
  • it does not matter that the manholes had differing dimensions;
  • the sprayable option is low risk, low shrink, fast and efficient;
  • Unlike other concrete coating systems the material bonds with the concrete substrate;
  • the material can reinforce and/or rebuild the substrate, as required, and with minimal surface disruption;
  • the material has excellent chemical resistance and creates a homogenous bond with the substrate, which protects the substrate and steel reinforcing;
  • being a polymer the coating material is much thinner than cementitious alternatives, which is advantageous within confined spaces;
  • most structures will be cleaned, reinforced and/or sealed within 24 hours; and
  • the material presents a compelling value proposition.

Client Considerations:

Rockhampton on Queensland’s eastern coast has a population of 72,000. Its 14,000 concrete manholes have been installed at various times over the last 100 years.

In the past, whenever a concrete manhole failed it was simply dug up and replaced. Very little preventative maintenance had been carried out on the network.

Fitzroy River Water management, who are responsible for the water network in the region, were introduced to Mirteq’s concrete coating system and liked what they saw because it was economical, solved a whole range of issues that every council is faced with and it also had a simple and efficient application system.

Manhole Issues:

  • a) There was no standardization across the network and relatively few standard precast products were used, so every manhole cavity was a different size and/or shape and therefore presented a range of different problems.
  • b) Depending on their location every manhole was in a different stage of disrepair, due to either its age or the severity of the chemicals flowing in the sewer.
  • c) Manhole wall thicknesses from the concrete corrosion were uncertain. The slime accumulation in the manhole made it difficult to ascertain the precise state of disrepair. After cleaning and inspection the council chose to structurally reinforce several of the manholes by applying a 20mm thick MIR-970 coating.
  • d) Inflow and infiltration (I&I) in areas of the network were abnormal. It was impossible to determine with any certainty whether the I&I was attributable to the pipes, manhole walls or manhole junctions.

Cr Greg Belz, chairman of Rockhampton Regional Council’s water committee said, “Access chambers are an integral part of our sewer network and it is of utmost importance we maintain these assets. The new liners have restored the manholes to near-new condition.”

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