Pond 7

Increased residential development and a new school for Tauriko, Tauranga, led to the need for a large stormwater retention pond and discharge pipeline. Although building the pond was relatively straight forward, constructing a pipeline down a steep embankment with 30m of drop was not so straight forward.

A directional drilled pipeline was considered as a good solution and early contractor involvement with UUL set the project up for best chance of success. A loose soft sub-soil layer was the biggest concern for tunnel stability. To mitigate this risk the alignment remained deep with minimal grade for the majority 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. The tunnel fluid was re-cycled, processed and re-used making for an environmentally friendly pipe installation.

The pipe was installed and then the pipe/soil anulus cement grouted. A dissipation chamber was then built at the downstream outlet.

Another difficult and large project completer by Universal Underground.