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Sites contaminated with timber treatment chemicals

Chemical treatment has been used for many years in New Zealand for preserving timbers, as softwoods such as radiata pine are prone to attack by fungi and insects.

The first timber preservative used in this country was creosote derived from coal tar. After the production of organochlorine pesticides in the late 1940s and 1950s, the timber industry made widespread use of pentachlorophenol (PCP) to combat sapstain fungi. Chlordane and dieldrin were used in the glue of some manufactured wood products. Significant use of these organochlorines in the timber industry ceased in 1988 and they were formally deregistered for these purposes by the end of 1991.

Since the 1970s the timber preservatives in common use have included boron, CCA (a formulation of copper, chromium and arsenic salts), and light organic solvent preservatives (LOSP).

Guidelines

The Ministry for the Environment has worked with experts from central and local government, the timber industry, scientists and consultants to develop guidelines for the assessment and management of contaminants on sawmill and timber treatment sites in New Zealand.

These guidelines, Health and Environmental Guidelines for Selected Timber Treatment Chemicals, published by the Ministry for the Environment and Ministry of Health in June 1997, provide owners, occupiers, regulators and assessors of sawmill and timber treatment sites with detailed, practical advice on site assessment and management.

Contamination

Soil contamination has occurred to varying extents at many of New Zealand's sawmill and timber treatment sites, some of which have now ceased to operate. Contamination would generally be caused by the cumulative effect of drips, leaks, spills and waste disposal practices during an era when less emphasis was placed on the containment of potentially hazardous chemicals.

As part of the Organochlorines Programme, the Ministry for the Environment is funding a study on the Assessment of Dioxin Contamination at Sawmill Sites. This study was initiated to:

  • collect more reliable and nationally representative data on dioxin concentrations at sawmill sites
  • revise the existing estimate of the dioxin reservoirs at sawmill sites
  • detail the types of environmental and risk management conditions that may be found at sawmill sites, and develop a risk profile at these sites
  • identify options for risk reduction measures in New Zealand.

The study is being undertaken by Tonkin and Taylor Ltd and SPHERE.

Last updated: 17 September 2007