Valley Terrace Stormwater Upgrade
Hamilton West, Waikato

Brief

Civtec was engaged by the Hamilton City Council to complete a stormwater culvert line upgrade at Valley Terrace, in Hamilton West. The culvert, which contained old concrete pipes, had cracked and degraded over time and was not performing as designed. Flow existed but not at a rate sufficient to handle heavy downpours which created up stream flooding during periods of high rainfall.

Solution

Access to the worksite was restricted to a driveway used by the Hamilton West Kindergarten which presented an obvious risk to the safety of kindergarten children, parents and teachers. Clear communication and access guidelines were established to minimise the risk of harm and a close working relationship was formed with the Kindergarten.

When completing the install, the decision was made to install a new pipe alongside the old pipe, and leave the obsolete pipework in place. The existing stream flow was then blocked upstream and pumped away as a means of diversion while a new trench was excavated next to the old culvert to allow the installation of the new pipework. Because of the depth of the excavation, trench shields were used to ensure the safety of staff working at depth. A manhole with a scruffy dome at the top was installed to prevent flooding permit occasional servicing of the line.

Challenges

Site access was constrained by the property locked location, with access only available through the Hamilton West Kindergarten. This presented challenges with H&S around children, restraints on moving material and machinery, and minimising noise for surrounding property in the area.

Extremely difficult ground conditions. Supervisor Lindsey Lambrinoudakis said it was the worst he had ever encountered in more than a decade of working in civil. Weather conditions at that time of the year made it even harder, with near constant rainfall throughout the duration of the project.

Working at depth, being at 3m deep at the bottom of the excavation, which was then at the bottom of the gulley.

Highlights

By far the biggest highlight was completing a tricky job in trying circumstances, and ensuring we kept everyone safe in the process. By the end of the project, we had also established a very positive relationship with the Kindergarten.

During the work, the school kids were making a scarecrow for the Hamilton Gardens Scarecrow competition and we helped them out with some gear for their entry so he could be clearly spotted amongst the other applicants. Jim, as he was named by the Civtec team, has since retired to keep an eye on the gardens at the Kindy.