Gladstone Regional Council 1800mm Steel Culvert Rehabilitation by Russell Groth

Abstract

Scope: Gladstone Reginal Council approached Mainmark to inspect and advise a solution to repair the 1800mm x 230m steel culvert in Callemondah, Gladstone QLD. Upon inspection, we found the steel culvert to be situated in a populated industrial area running through several properties. The stormwater drain was in poor condition after the 2011 flood event. The drain was failing in two significant ways: 1. The steel pipe culvert had been badly damaged and had no structural integrity. 2. The steel pipe culvert had been dislodged within its foundation and was badly out of shape throughout most of its length.

Primary Objective: To rehabilitate or reroute the stormwater drain. The decision to rehabilitate was based around the OH&S, environmental impact, public disruption and Council’s budget. The rehabilitation method also had to consider hydraulic loads. With the aid of computer modelling at the university of Newcastle, Mainmark was able to demonstrate with two technologies, ENCAP6™ and Uretek resin injection, a repair equivalent to a class 2 concrete pipe load rating. With Uretek resin injection, the entire foundation of the pipe was encased with Uretek resin to stabilise and realign the pipes original shape, and improve correct inclination. This also helped with ground water and infiltration. The second step was to reline the entire internal surface of the pipe with the ENCAP6™ structural relining resin. ENCAP6™ has a flexural strength of 135MPa. The total thickness of ENCAP6™ was 18mm, which was a hydraulic advantage over other repairs such as concrete.

Outcome: The major hurdle in the project was that the stormwater trunk main could not be shut down or diverted. The job was completed on time and on budget, taking in the entire rehabilitation process of approx. 6 months.