Winstone's plan to refill quarry site upsets locals

Three Kings Quarry. Photo / Steven McNicholl

Residents near the Three Kings Quarry fear a plan to fill it with soil from building sites will lead to the quarry leaching toxic heavy metals into the environment.

Winstone Aggregates has been mining volcanic rock from the 14ha quarry for 80 years and now wants to begin re-filling the hole by letting developers dump soil, clay and other debris left over from construction projects.

The plan is stalled in the Environment Court after challenges by local residents and a trade competitor, Envirowaste Services.

In February, Winstone added a second prong to its application - this time to discharge contaminants to the site - in case it loses its legal argument that it does not need a discharge permit.

Critics of the plan say the maximum contamination levels Winstone wants to allow on the site are many times higher than the volcanic scoria that is already there.

Some residents are worried that heavy metals, hydrocarbons and pesticides could leak into neighbouring areas and into the groundwater under the quarry, which is clean enough to drink.

Winstone Aggregates, which is owned by Fletcher Building, says the site will be filled with mostly natural soils and clay.

General manager Bernie Chote said experts hired to assess the plan found the effects on the environment would be minor. He said the site would be monitored as it was filled to make sure that was true.

Auckland City and Auckland Regional Councils agreed and gave permission to the plan.

But a competitor for some of the more contaminated waste that may end up at the quarry, Envirowaste Services, has appealed against the councils' decisions.

Groups representing about 75 local residents have joined in the court hearings as interested parties to oppose the plan.

Envirowaste managing director Gary Saunders said the maximum contamination levels set by the councils were much too high.

He did not see why such high maximum toxin levels were needed when 95 per cent of the material it would take would be clean dirt, concrete, bricks and tiles.

Envirowaste wants Winstone to give up the most contaminated 5 per cent of soils it plans to put in the quarry - such as dirt from old timber treatment yards - because it has not spent millions lining the quarry, as Envirowaste has with its landfills.

"There are risks of migrating heavy metals off that site," said Mr Saunders.

Diane Hill, of residents group Three Kings United, said neighbours were concerned about leaching toxins and about the number of truck trips in and out of the site.

If the proposal went ahead, up to 750 trucks could go in or out of the quarry every day for up to 20 years, she said, compared with 20 or 30 trucks now.

The application documents say the fill material will be similar to what ends up in Winstone's existing landfill on Puketutu Island.

Winstone has not said what it plans to do with the land when the filling is completed, but wants to make sure the land meets health guidelines to have houses on top.