monitored. 36
Figure 13 Manganui River water temperature differences between sites upstream
and downstream of the Motukawa HEP weir compared with the flow in
the Manganui River at State Highway 3 from 15 January to 15 February
2015. 37
Figure 14 Cumulative weight of elvers transferred from the Motukawa Power
Station during the 2014-2015 period 41
Figure 15 Elver transfer data for the monitoring years to date 41
Figure 16 Rainfall recorded at the Mangaotea Rd culvert on 19 & 20 June
collects
water from an approximately 136 km2 catchment that originates near the summit of Mount
Taranaki.
The climate is generally mild, with relatively high humidity and fairly high, evenly
distributed annual rainfall - with a catchment-wide annual rainfall of approximately 3,500
mm. The soils are typically volcanic, and include deep ash soils and well-drained alluvial
soils along the rivers. Slopes within the catchment range from gently undulating to
strongly rolling.
The
Trustpower Pātea hydro power scheme resource consent monitoring report 2019-2020
Normally these discharges are in batches with a frequency ranging from daily to weekly, dependent on
rainfall. During and after exceptionally heavy rainfall, the discharge may occur for continuous periods of up
to 24 hours.
In 2021-2022, the maximum daily volume of stormwater discharged from the site was 6,063 m3/d following
rainfall of 120 mm and 87 mm. Given the extremely high rainfall and that there was only one minor non-
compliance instance above the 6,000 m3/d limit the Company was
process chemicals that are discharged
when the factory is operating. These absolute quantities vary from week-to-week
depending on the level of production. The concentration in the effluent also varies
depending on the current level of rainfall runoff. There are also minute quantities of
other chemicals that are used from time-to-time for research purposes.
Table 1 Pacific Natural Gut wastewater composition (approximate) when in operation
Component
Quantity
used per
month
the green waste.
However all the unacceptable materials were removed from the site before the green
waste was compacted and levelled and therefore would have had no long term
effect.
There was no leachate observed discharging from the sand dune area during the
period under review. The sandy substrate combined with low rainfall at the beach
would be restricting the production of leachate from the green waste..
3.3 Evaluation of performance
A tabular summary of STDC’s compliance
Inspections
During the 2014-2015 monitoring period four scheduled inspections of the Company’s
site were conducted by an officer of the Council. The following were found during the
inspections.
12 August 2014
The site was inspected in heavy rainfall conditions. It was observed that there was a
resulting high flow rate discharge of stormwater and it was noted that there was also a
high flow in the receiving water. It was reported that the manhole sumps had been
cleaned out recently and it was
Erosion and Sediment Control Plan that has been approved by the Chief Executive,
Taranaki Regional Council, acting in a certification capacity. This finalised plan shall
conform to the Waikato Regional Council’s Guidelines for Soil Disturbing Activities and
shall detail methodology/ design of stormwater drainage from the cleanfill, and
maintenance of sediment control practices, with a specific focus on rainfall events.
14. This consent shall lapse five years following the date of issue,
is 10 L/s. However as a result of stormwater inputs to the pond, the discharge
rate from the pond to the Mangorei Stream will be highly variable as it is dependent on weather conditions.
The size of the pond will allow storage for a 10% annual exceedance event (AEP) event. The maximum
discharge rate from the pond during large rainfall events is 1,060 L/s as this is dictated by the size of the
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5
outfall pipe (750 mm). However there is also provision for the pond
devices shall be telemetered and report the data electronically to the Chief Executive once
per day, and shall include the rainfall data at hourly intervals from the station established at
the Mangaotea Road culvert.
A land use consent for the damming of the Mako Stream via an existing dam structure to form
Lake Ratapiko for hydro-electric power generation purposes, including the service and auxiliary
spillway structures
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Trustpower – Proposed Conditions