Records of pollution permanent

Contaminated sites remain permanently on Environment Canterbury's (ECan) database, no matter how thoroughly they are cleaned up.

However, sites can be reclassified on the listed land use register (LLUR) if soil sampling proves that remedial work has made a difference.

As well as the 42 known contaminated sites that were listed in The Press last week, the region has another:

* 28 sites with significant contamination that has been controlled to isolate it from ground or surface water, or from people;

* 52 sites with traces of contamination above background levels but below environmental guidelines for the current land use;

* 16 sites with concentrations of contaminants at, or below, background levels found naturally in the area.

ECan director of investigations and monitoring Ken Taylor said there was no "remediated" category.

"Land is either contaminated in the context of its current land use or not.

"Sites are never taken off the LLUR database.

"A land owner can always provide additional information for ECan to review that may lead to our recategorising a site.

"However, we continue to hold the site on the register, so we can communicate the history of the land to future interested parties."

Many of the 68 sites with traces of contamination were likely to have been remediated, he said.

Of the remaining sites on the register, 165 had been verified as never having had a hazardous activity or industrial operation on them, and 3114 had not yet been investigated to determine any contamination.

A site's degree of contamination depended on what contaminant had been released, how much of it there was, and the work undertaken to address that, Taylor said.

Soil testing was nearly always at the owner's expense.

"Many land owners choose to address contaminated land that is not in contact with groundwater by capping it with an impervious layer, like asphalt or concrete, then prepare a site-management plan that communicates the hazards that still remain on site to anyone that may come into contact with them."

The owner-operator of the Tuam St, Christchurch, Challenge service station, Gordon Lewis, told The Press contamination on his site was minimal and questioned its inclusion on the list of 42 known contaminated locations in Canterbury.

He said any contamination was over a period of many years and no testing had been done for 10 years. There would be hardly any service stations where petrol had not dripped from pump nozzles on to the forecourt.

The file for his site shows five petrol, diesel and waste-oil underground tanks were removed in October 1999. Nine soil samples were analysed for total petroleum hydrocarbons and one was tested for other compounds. One exceeded the Ministry for the Environment's guidelines for xylenes.

Taylor said the onus was on owners to get testing done, but agreed it was "fair to say" service station owners were "among the most environmentally knowledgeable landowners ECan deals with".

"For liability reasons, petroleum companies require that service station owners operate their businesses in ways that reduce the potential for spills, and address spills promptly when they do occur.

"However, as with all types of sites and all types of site owners, there is substantial variation in the way service station owners respond to land-contamination issues."

- © Fairfax NZ News