Tenders to build the pile and panel wave wall at Tauranga Bridge Marina are expected to be called as soon as the results from the geo technical survey are compiled.

Taupo company Geotech Drilling began the drilling programme to test the seabed soils this week.

Bridge Marina manager Tony Arnold with the Geotech drilling rig. Photo: Bruce Barnard.

The drilling and CPT testing programme results will tell them how long the piles need to be, says marina manager Tony Arnold.

The entire panel and pile breakwater project is expected to cost about $4.7 million, which will be paid for by berth holders.

It closes out a four year struggle to obtain a consent to try and improve marina safety and reduce vulnerability to damage from severe northerly storms.

It became apparent soon after the marina opened for business in 1997 that the northern floating wave attenuator wasn't performing to expectations.

After storms repeatedly damaged finger pontoons and boats, the bridge marina sought consent to build a 245-metre rockwall across the north end of the marina.

The Port of Tauranga objected, due to the effect the rockwall would have on the speed of the outgoing tide across the face of the container terminal.

While the rockwall would neutralise tidal currents within the marina, creating a safer marina environment and reducing the need for maintenance dredging, it accelerated the outgoing tide going from 6-7 metres per second to 9 meters per second - almost a 33 per cent increase.

The objection proved unsurmountable and the bridge marina went to plan B, a panel and pile breakwater.

Consent was obtained in March 2014, but the Ngati Ranginui iwi objected. A mediator was appointed, an agreement reached, and the consent was finally issued in August.

A line of piles are driven round the northern breakwater and 5.5m tall concrete panels are hung from them. The breakwater will be only 1.75 metres out of the water – the same height as the waves that break in northerly storms.

The bottom of the panels are clear of the harbour floor.

'We are working with local iwi to find a suitable motif to put on the front of the panels that symbolises the three iwi and Mauao's association with Te Awanui,” says Tony.

The berth holders approved the payment regime in December with 77 percent voting in favour.

It will be a design and build project, with Tauranga bridge marina director Brian Cardiff the project director.