Mitigation and best practice options

Ways to minimise the effects of wood processing activities on water quality and mahinga kai are listed below.

Timber

Wetland treatment of effluent

Sawmills and log yards can enhance treatment of runoff and organic matter by using constructed wetlands. Wetlands or oxidation ponds are low cost and require minimal maintenance while they significantly lower the impact of wastewater or stormwater discharged to natural waterbodies. Additionally, the treated waste can then be discharged to land by way of spray irrigation.

Other treatment methods

Other high-tech methods can be used to reduce the impact of contaminated runoff from wood handling sites, such as ozone treatment of log yard runoff which can be combined with biological treatment.

Chemicals in wood processing areas

• Wastewater containing chemical preservatives should be contained as part of a "closed loop" application system.
• Runoff from log yards should be contained through use of impervious surfaces, sealed joints, and spill containment curbs, to prevent leaching of contaminated waters into the soil and groundwater.
• Lumber-dipping tank areas, forklift traffic areas, and storage areas need to be waterproofed.
• A chemical solution recovery system should be used to eliminate dripping from the lumber once it is removed from the fungicide dipping tanks.
• Log ponds should be lined to prevent contaminants leaching into the soil and groundwater.
• Stormwater from process areas should be segregated from stormwater in non-process areas and managed appropriately.

Pulp and paper mills

Recycling of toxic effluent and burning it, using bio-remediation ponds, and employing less damaging agents in the pulping, bleaching, and milling processes can help reduce water pollution from paper and timber processing industries.