Maintenance Hole Slip Lining – Echuca

Project Summary Sheet

Customer: Coliban Water

Location: Echuca, VIC

Delivered: 2015

The Challenge

Inspection showed that while the lower half of the maintenance hole was in reasonable condition, the top half was severely deteriorated, with the acid attacked concrete being in a “crumbling” condition due to raw sewage from a deteriorated internal dropper 1.5 metres from the top.

The Solution

Interflow proposed to slip line the maintenance hole with a length of steelreinforced polyethylene liner grouted in position. Though this type of pipe is typically used to structurally line large diameter sewers, its properties meant that the same benefits could be provided for this application.

Benefits offered included:

  • The steel reinforcement encased in the ribbed polyethylene provided sufficient strength for the liner to offer structural renewal.
  • Polyethylene is inert in sewer conditions and has high abrasion resistance.
  • Polyethylene has the strain capability to handle ground movement.
  • The liner could be installed with minimal man-entry.
  • The liner could be installed in a single length, without joints.

The Project

Installation of the liner meant minimal surface preparation. Man entry was only required to take measurements to confirm the diameter of liner that could suitably fit.

Measurements showed a liner with an internal diameter of DN1500 allowed sufficient annulus around the outside.

Preparation required removal of the top slab and lid and the severely corroded top section of the maintenance hole.

The steel reinforced polyethylene liner was manufactured off-site in a one-piece 11 metre length. Once the site was prepared, the liner was delivered to site and craned straight from the truck to be installed in the maintenance hole.

The base of the liner was sealed with expanding foam and the liner was propped at the top and bottom of the shaft to centre it and ensure it remained vertical. Following positioning, filling of the annulus with stabilised sand commenced.

Following an initial 200mm pour to secure the bottom of the liner, complete filling was carried out in two lifts. The top of the maintenance hole was then replaced, with the top slab poured and the lid re-fitted.

Conclusion

A strong, corrosion and abrasion resistant maintenance hole, with the flexibility to handle ground movement had been provided by a quick, safe, minimally disruptive process.

Interflow is committed to offering its customers optimum solutions of the highest value for pipeline rehabilitation.