remediation pad. Any rain run-off and leachate that is
generated, drains into a series of ponds for treatment. Between each pond there is a
baffle that skims off any floating hydrocarbons as the leachate passes through. These
ponds also treat the leachate and stormwater from pad 1 where remediated drilling
wastes are stored and/or processed further. The treated liquid from the pond
treatment system (PTS) is then irrigated to cut and carry pasture on two irrigation
areas.
Run off and leachate
Company
communicated that two different delivery systems were used during the 2023/24 monitoring year:
1. Dribble bar – main method of effluent application, depths applied (~3mm)
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12
2. ‘Weta’ travelling rain gun – used to apply effluent to the Sand Dune block at 8-10mm depths during
7 months of the year.
Type of crops grown
Two crops were grown under the cut and carry system in 2023/24. Maize Silage paddocks (37.2ha) which
were cultivated in October and
reduced as rain
eased. An incident report was
provided by NPDC. An
infringement notice was issued.
2.3.2 Sewage pump station incidents
There were no unauthorised discharges from sewage pump stations (SPSs) during the 2023/24 monitoring
year.
2.3.3 Reticulation overflow incidents
Five unauthorised discharges to surface water occurred due to overflows in the reticulation network during
the 2023/24 monitoring period (Table 18).
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18
NPDC has continued work
sea, but these are generally few in number and only the rare spills have a major and
indeed measurable impact on seafoods in the area.
“Indirect” discharges is a term used to generally describe the effects of rivers on the
coast, and therefore include the considerable amounts of faecal bacteria, nutrients and
solids carried down the Waitara River after rain on the farms and hill country
upstream (now seen as the major source of these in local seafoods). The material and
is approximately 6.1 km2. The length
of the catchment, from the headwaters between Paraite and Corbett Roads to the sea at Bell Block beach, is
approximately five kilometres.
The industrial area at Bell Block is situated mid-catchment (Figure 1). Historically, the industrial areas were
located predominantly on the western side of the stream however ongoing development since 2016 has
resulted in more sites on the eastern side. These sites fall under permitted activity rules and are not
Table 3 Summary of monitoring activity for 2023/24 13
Table 4 Chemical analysis of Colson Road landfill combined site leachate discharge 27
Table 5 Sample results for characterisation of Stage 1 and 2 and Stage 3 leachate 28
Table 6 Results of analysis of under liner drainage for the year under review. 31
Table 7 Sample results for the characterisation of the under liner groundwater drainage 35
Table 8 Results of rain event monitoring–discharge and Puremu Stream, 26 September
between inlet works and
screenings building blocked up
with rags causing wastewater
discharge.
N No
Blockage cleared, site cleaned
and sanitised. Procedures
updated to prevent
reoccurrence.
22 August
2022
Heavy rainfall caused high flows
at the inlet works overwhelming
band screens
N No
Problem resolved as rain
eased and inflows reduced.
22 August
2022
High rainfall caused Clarifier 3 to
overwash. N No
Overwash stopped as rain
eased.
26
being undertaken to reduce the footprint of the pad. This would greatly reduce the volume of stormwater
collected within the pad. Consequently there would be less pumping to the wetland treatment system and
therefore, generally an increase of retention time within the treatment system. RNZ were instructed to
ensure that uncontaminated storm water runoff was unable to enter the paunch pad, so that only the rain
that falls into the pond is required to be pumped through the wetland treatment
site. The consent (7645-1) is held by Alby M Limited,
and compliance monitoring of consent 7645-1 is not included in this report
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6
Results
2.2.1 Inspections
21 September 2022
It was raining with a light breeze at the time of the inspection. The cap was in good condition and was
showing no signs of slumping. There was some ponding present, but the inspection was during a rain event,
thus this would be expected. There was evidence of good stock rotation and
however the bung was missing allowing rainwater and possibly contaminants to discharge onto the ground.
One solution would be to place an oliophillic mat below the pump to capture any hydrocarbon while
allowing rainwater to drain, this was discussed with staff at the time of the inspection. Also discussed was
the purposed and use of plastic matting under the rig. For some areas plastic matting is suitable, however
for others the matting needs to be used to capture solid/liquid that falls from the