Project Pond 7 at Tauranga New Zealand

An increased demand for residential development and a new school in Tauriko, Tauranga New Zealand, meant that a large stormwater retention pond and discharge pipeline needed to be built. Despite the seemingly straightforward task of building a small pond, constructing a pipe to carry water, to control water levels, and to ensure an adequate water flow was much more complicated. Early contractor involvement helped the designer to suggest a directional drilled pipeline as the best solution, setting the project up for success.

To mitigate risk of tunnel stability and maintain a favorable subgrade, the alignment remained deep with minimal grade for most of the line before turning up steeply to intersect the pond. The 900mm diameter HDPE pipe required a 1m diameter tunnel and at 300m long, a large volume of soil was removed. This innovative installation was made environmentally friendly by recycling the tunnel fluid and re-using it to reduce groundwater contamination through dewatering and disposal.

The job site itself was particularly difficult due to the working conditions, but Universal Underground managed to complete the project.