Cranes hoisted five tonne poles into the air on Monday morning, signalling the start of an operation to lay a new water main across Tauranga Harbour.

Two of the five tonne poles on the back of a truck, waiting to be lifted into place.

The 'spud' poles are placed on the four corners of a large barge that was towed to a site near the Matapihi Rail Bridge on Saturday.

Once the spuds are lifted in place by two large cranes, the barge is lifted up out of the water.

McLeod Cranes supervisor, Ian Monk, says drilling equipment will be placed on the barge when it is stabilised.

The drill will bore holes in the soil in Tauranga Harbour and test the water main foundations.

'We've been having a few problems because the soil down here is so soft.”

When the drilling is complete, work will begin on laying the new water main.

The spuds are expected to be placed on the barge by midday.