monitoring year, with irrigation
commencing in late October and concluding in mid-April across the region. Rainfall recorded at the
Council’s monitoring locations over the summer irrigation period ranged between 109% and 163% of
historical mean values. Due to the higher rainfall, irrigation demand was lower with a total water usage of
4,063 ML during the 2022-2023 season. This was lower than the preceding 2021-2022 monitoring year,
which recorded 6,960 ML.
The Council carried out compliance
Waiwhakaiho and Bell Block and as such signage remains in place at these locations to advise
against collecting shellfish.
There were eight unauthorised incidents that occurred at the NPWWTP during the year; three due to
blockages, two due to heavy rainfall, and three due to operator errors. Four events were recorded for sewer
pump stations (all due to high rainfall), and a further 15 reticulation overflows (the majority of which were
due to high rainfall or blockages due to fat and/or wet
downstream of ‘irrigation’ tributary INH000450
Inaha Stream, State Highway 45 INH000470
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6
Figure 1 Wastewater irrigation areas, surface water monitoring and point source discharge locations in the Inaha Stream
and tributaries
Stormwater generated in the main yard, garage and raw material reception areas is diverted to a three-
stage stormwater treatment system (near B, Figure 1). The first flush of a rainfall event is discharged to Pond
1 and after that is
Civil Defence Emergency Management Joint Committee March 2025
presently under
significant pressure. While there may be an increase in demand as people look to move away from less
secure surface water sources, this is not expected to place groundwater under significant pressure in the
short to medium term.
As expected, monitored groundwater sites display fluctuations in water level as a result of seasonal
variations in rainfall recharge. The magnitude of these changes varies considerably by site, ranging from
a few millimetres up to several metres. The …
by NPDC assessed for compliance upon receipt.
The monitoring showed that the activities were generally being carried out in compliance with the
conditions of the resource consent. The results of surface and groundwater quality monitoring undertaken
show no adverse effects of the activity on local fresh water resources. Site visits undertaken found the site
to be tidy and well managed.
During this monitor year, following higher than average rainfall the minimum separation distance
required basis.
The second larger pond is unlined.
The size of the pond provides storage for a 10% annual exceedance rainfall event (AEP) event. The
maximum discharge rate from the pond during large rainfall events is 1,060L/s as this is dictated by the size
of the outfall pipe (750mm). However, there is also provision for the pond to overflow via a spillway
structure to a discharge swale (i.e. bypassing the 750mm discharge pipe).
At the time of the application it was indicated that, as a
water allocation across Taranaki and details the technical work done to help support the
implementation of the NPS-FM requirements.
Overview of surface water quantity
Taranaki receives frequent and plentiful rainfall. The amount of rainfall is extremely variable however,
increases significantly from the region’s coastal fringes to areas of higher elevation across the eastern hill
country and the slopes of Taranaki Maunga. Much of this rainfall rapidly flows to the sea via rivers
Description
Appendix C: HEC-HMS Model Description
Appendix D: HEC-RAS Model Description
Appendix E: Calibration Background
Appendix F: Calibration
Appendix G: Design Rainfall
Appendix H: Inflow Design Flood
Appendix I: Canal Erosion Assessment
Appendix J: Hydraulic Model Result Maps
page
AUCKLAND
4 Fred Thomas Drive, Takapuna, Auckland 0622
PO Box 100253, North Shore, Auckland 0745
Tel: +64 9 489 7872 Fax: +64 9 489 7873
RILEY CONSULTANTS LTD
New Zealand
Email:
Table 11 Summary of performance for consent 10810-1 23
Table 12 Evaluation of environmental performance over time 24
List of figures
Figure 1 Configuration of the HWWTP (adapted from NIWA, 2012) 3
Figure 2 Daily hours where DO is greater than 0 g/m3 in Pond 1 and 2 8
Figure 3 Daily discharge volumes (m3/day) from the HWWTP and daily rainfall data (mm) from a
Council rainfall station located approximately 5 km east of the site (2022-2023) 12
Figure 4 Location of intertidal