City engineers have been given approval to look at plans and costs for a 2.5 metre diameter tunnel under 10th Avenue from Memorial Park to Graham Park.

The tunnel is expected to cost $5.9 million more than anticipated in the current 10 year plan. This cost is additional to the $16 million pipeline project.
It will provide wastewater storage for both the Judea and Memorial Park sewer pumping stations when they are linked into the southern pipeline project.
Engineers argue that while it is an additional short term cost, the longer term benefits make it viable. The tunnel will remove the need to install storage at Judea, costing an estimated $6.6 million, and for the eventual construction of a rising main from Judea to Memorial Park costing an estimated $3.5 million.
Until now, the Memorial Park costs were expected to be $16 million for a pump station and tank. The pump station and tunnel option costs an estimated $21.9 million.
When looked at from the 2012-20 perspective, the total costs for the Memorial pump station and tank, plus separate Judea storage, amount to $22.6 million.
The tunnel option would be $24.4 million. It is the $3.5 million Judea rising main to be added in 2051 that tips the financial balance in favour of the tunnel.
Tauranga City Council engineering and projects manager Chris Olivier told the Tauranga City Council Projects and Services Committee there are other issues. Existing estimates for the work in Memorial Park can easily blow out because it is a former swamp and problems are anticipated during digging and building the 2000 cubic metre storage tank.
The request to further explore the tunnel option came about because an independent review of the Southern Pipeline project recommended the council engineers plan further ahead than 50 years.
The full council expects to have another look at the options in about two months' time.