Report shows arsenic contamination at Whanganui site patchy

A planned subdivision at this Whanganui site was scrapped because high levels of arsenic were found in the soil. Photo / Bevan Conley

The soil found to have a high level of arsenic on a central Whanganui site was likely trucked in to level playing fields, contractor Ben Keet says.

His report to Whanganui District Council says the level of arsenic in soil at 185 London St reached 100mg/kilogram in some places. The limit for New Zealand subdivisions is 20mg/kg, and for parks and recreation 80mg/kg.

Because of that high level, a proposed eco-subdivision on the site was scrapped.

Soil pulled off the site was to have been used to top up Wanganui Collegiate School playing fields. The school couldn't take it at short notice, London St landowner Harvey Green said.

Instead the soil was taken to 146 Seafield Rd.

The London St land was grazed until 1962 and was school playing fields for the next 50 years, the report said. Soil high in arsenic was only found in patches, which may indicate it was trucked in and dumped in some places but not others.

No other contaminants were found in the soil tests.

Green has other plans for the site, but said he was not willing to share them. He was disappointed to see negative news on the front page of the Whanganui paper.

Arsenic is an element many animals need in small amounts for their health. In large amounts over a short time it can be fatal.

Humans exposed to moderate quantities over a long time can develop skin changes,
damage to the heart and other organs and cancers of the skin, lung, bladder and other organs.

In the past arsenic has been used to kill bugs, especially in sheep dips, and with lead in orchard sprays and with copper and chrome in timber treatments.

There are other towns in New Zealand with high arsenic levels in suburban soil. Hamilton has suburbs built on old orchards, where the level is 80mg/kg, four times the current maximum.

Thames has a suburb where the soil has 670mg of arsenic per kilo, as well as other metals. It may be based on tailings from a former gold mine.