New rocks for Hokitika seawall as mayor brushes off concerns

Larger rocks are to be placed on the Hokitika seawall after high seas washed over the top of the wall, throwing a chaos of debris and driftwood across the popular walkway.

A spokeswoman for the regional council told Local Democracy Reporting big seas last week had caused driftwood and stones to wash over the top of the floodwall.

Westland District Council contractors had cleaned up the walkway by dumping the driftwood on to the rockwall again, she said.

"Westland District Council cleared the walkway and put displaced material back on the revetment."

Regional council staff had inspected the site again on Monday and although they did not find any "obvious failures" with the rockwall, the structure can only reduce the sea's energy and not prevent it from going over the top, she said.

"Wave overtopping can occur at this type of structure during high seas as a revetment [barrier] reduces wave energy but doesn't prevent all water from passing over it."

The regional council has previously suggested replacing the smaller rocks on the seawall with larger ones, costing $140,000.

Independent contractors have also suggested replacing the rock, as well as an in-filling of gaps in the wall.

Westland Mayor Helen Lash objected to this, and yesterday [Tuesday] said the wall had not been compromised.

Mrs Lash said the sea can only overtop the rockwall during storms, and denied the walkway being inundated this time.

However, regional staff say they will now fortify the wall with larger rocks and remove the smaller pieces.

"WCRC is preparing a staged maintenance programme for the revetment. A key part of what is proposed is to replace smaller stones there now with larger, appropriately graded rock.

"The material will be removed off site as part of the planned works rather than returned to the revetment," a spokeswoman said.

Staff had proposed replacing the smaller rocks at a Hokitika Rating District Joint Committee meeting in April.

Catchment officer Oliver Rose had proposed stripping down the crest of the seawall by 600mm and placing larger rocks to form a more cohesive structure, at a cost of $140,000.

An assessment by independent contractors found some of the armour rocks had broken down on the seawall, creating gaps. The contractors recommended replacing the primary rock armour, as well as in-filling gaps.