Annual report 2006-2007 - Taranaki Regional Council

55
acid soluble zinc concentration of 0.127 (g/m 3) and a dissolved zinc concentration of
0.126 (g/m 3), both well above their respective medians. This high zinc content is due
to a historical event, where Taranaki Galvanisers waste was disposed of at the
tannery site.
Zinc (g/m3)
Zinc concentrations in Egmont Tanneries stormwater
discharge (STW001022)
0.2
0.15
0.1
0.05
0
Oct-91
Oct-92
Oct-93
Oct-94
Oct-95
Oct-96
Oct-97
Oct-98
Oct-99
Oct-00
Oct-01
Oct-02
Oct-03
Oct-04
Oct-05
Oct-06
Zinc (acid soluble) Zinc (dissolved) Zinc (total)
Figure 18 Zinc concentrations in the Egmont Tanneries stormwater discharge
4.4.1.3 Results of receiving environment monitoring
Consent condition 1 in resource consent 1816 states that after a mixing zone of 50m
the discharge shall not give rise to the following effects in the receiving Kahouri
Stream tributary:
i) the production of any conspicuous oil or grease films, scums or foams, or floatable
or suspended materials;
ii) any conspicuous change in colour or visual clarity;
iii) any emission of objectionable odour;
iv) the rendering of freshwater unsuitable for consumption by farm animals; and
v) any significant effects on aquatic life.
Water chemistry and biological monitoring were conducted to assess compliance
with the above.
Water chemistry
The chemical water quality survey for the summer low-flow period was performed
on 18 April 2007 during fine weather. The results for all sites in the 2007 survey are
presented in Table 4 (refer to section 2.4.2.2). One chemical monitoring site is located
in the receiving waters downstream of the Egmont Tanneries discharge (site 6,
KHI000369), which also encompasses discharges from Fletcher Concrete and
Taranaki Galvanizers (Figure 1).