Burwood Wastewater Earthquake Repair

Scope

• 916 m of wastewater gravity pipe replacement, 400m installed in excess of 4m deep
• 2 No. dig down repairs, 28 lateral repairs
• 5 No. new wastewater manholes, with 9 No. drop structures

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Project Description 

This project was for the repair and renewal of wastewater assets damaged as a result of the Canterbury earthquakes. Works undertaken included grouting of lines and ducting flows after the new pump station was commissioned.

With a worksite close to the river, ground conditions were challenging and required extensive dewatering. Works were further complicated by overhead power lines which prevented sheet piling in a number of locations. However, with our expertise and access to specialised equipment, we devised an approach which enabled the project to be completed safely and efficiently.

Our methodology utilised adjustable whaling frames, leaving gaps where overhead hazards precluded sheet piling. These sections were then shored with sheet plates and propping to keep the trench section open.

Given the site-specific hazards, we worked to a comprehensive safety plan. However, we enhanced this with an innovative measure, designed specifically for the site.

This comprised 1.5m x 1.5m banners emblazoned with High Voltage warnings and were fixed to the site fencing directly underneath powerlines. This placement ensured the banners were highly visible, in the digger operator’s line of sight, and provided a continuous reminder of overhead line hazards.

The warning banners proved to be extremely effective. Constructed from permanent materials, they have been retained and redeployed on subsequent projects to enhance site safety.