The Tui Mine is an abandoned Pb-Zn mine giving rise to water quality problems
in the Te Aroha region of Coromandel, New Zealand. When sampled in September
2002, for example, both the Tui and Tunakohoia Streams draining the mine site
exceeded ANZECC (2000) water quality guidelines for aquatic life protection (Cu,
Cd and Zn) and recreational quality (Cd). Based on trace metal mass flux (kg/yr)
from parts of the mine site, the principal pathways by which Cu, Zn and Cd
contamination reach these streams have been identified as:
the tailings dam leachate,
the diverted stream water from above the dam,
the drainage from Adit 5 (which accounts for 95 % of Zn and Cd contamination
in Tunakohoia Stream), and
to a lesser extent, run-off from waste
rock piles below Adit 4 level.
Of the various remediation options, which have been proposed for the site,
the following are identified as providing the best protection for the Tui and
Tunakohoia streams:
stabilising the tailings dam embankment and capping the embankment and
tailings,
constructing and/or cleaning out engineered diversion drains around the
perimeter of the tailings dam to divert surface water away from the tailings
dam, and
installing bulkheads within Adit 5.
A formal postal survey of the people of Te Aroha (66 respondents from 230
surveys) indicated that their priority was that the site be made safe for the
public to visit, and used for recreation. As soil samples in potential
recreational areas of the mine site, significantly exceeded guideline values for
Cu, Pb, Zn, Cd and As, soil removal or capping clearly also needs to be part of
a remediation plan. Development of the site as a historical/ecotourism area was
viewed favourably, as this may encourage more visitors to the Te Aroha area as
well as educate local residents.