Mitigation and best practice options

Some simple steps to minimise the effects of mining activities on water quality and mahinga kai include:

The mitigation options suggested below can be linked to the effects described in the impacts pages.

Return of topsoil and vegetation

Soil should be stripped and stockpiled for later use to backfill and revegetate the site after mine closure. Care must be taken to prevent sediment washing into watercourses.

Capping of overburden dumps

Overburden must conform to existing slopes in the area. The capping and remediation of overburden dumps can be a challenge, but is essential as uncapped dumps are potentially a source of leachate and sediment that can enter streams.

Treatment of surface run off and drainage

Areas disturbed during mining operations and the location of roads and tracks are prime sources of sediments which enter streams as a result of either erosion or mass-wasting processes. These should be carefully sited so as to minimise possible sedimentation problems and any run off passed through sedimentation ponds before leaving the area. Avoid discharging runoff directly into waterways. To avoid subsidence, all holes created during mining are backfilled after mining operations are completed.

Treatment of contaminants and acid mine drainage (AMD)

Implementation of passive treatment methods, such as engineered wetlands, can reduce acid mine drainage impacts.