2024 sample results, notably an increase of 40mS/m at ARW000999 (downstream location). This
increase is likely a result of the unusually low rainfall in the region, which has reduced the natural mixing
and dilution of stream water.
Figure 5 Potassium trend from April 2021 to March 2024.
Potassium levels also remained at a low level throughout the surface water monitoring, with the exception
of higher levels recorded at all sites in March 2024. As noted in previous reports, control site
investigation and design. No
construction occurred.
During the 2022/23 period expenditure on inflow and infiltration reduction consisted of:
• $457,127 spent on pipe renewals
• $17,774 spent on CCTV.
A wastewater network modelling project has recently been completed. This used rainfall and sewer flow
data to create a calibrated digital model of the entire Inglewood wastewater network. The calibrated model
will be used to assess network performance under different storm events of varying
Daily abstraction volumes under consent 7470-1.2 (July 2009-June 2018) 10
Figure 5 Maximum daily abstraction rate under consent 7470-1.2 (July 2009-June 2018) 10
Figure 6 Observed groundwater levels GND2102 and rainfall (July 2017-June 2018) 11
Figure 7 Observed groundwater levels GND2102 and abstraction (July 2017-June 2018) 12
Figure 8 Observed groundwater levels GND2103 and rainfall (July 2017-June 2018) 12
Figure 9 Observed groundwater levels GND2103 and abstraction (July
.................................................................................................................................................. 8
2.3 CLIMATE .................................................................................................................................................... 8
Table 2: Kaka Road Rainfall Events 2011-17 ............................................................................................. 10
Table 3: High Intensity rainfall data (NIWA) for site ................................................................................ 10
2.4 HYDROLOGY / HYDROGEOLOGY
wet weather from mid July to early
August 2008 resulted in further intermittent overflows of very dilute, treated wastewater to
the stream until mid August 2008. Similar intermittent overflows were recorded after very
wet weather late in the 2009-2010 period, over a four week period in September 2010 and
again, more briefly late in the 2010-2011 period. Seven intermittent overflows, each of one to
four days duration, occurred following heavy rainfall events in the 2011-2012 period. One
climate, with abundant rainfall and high sunshine hours, makes the region lush, green
and fertile.
Rainfall
Annual rainfall varies throughout the region. Some coastal areas receive less than 1,400 mm annually, while
the summit of Mount Taranaki receives around 7,500 mm.
Heavy rainfall events do occur and there can be extremes. In 2012 heavy rain caused a number of slips on
the coastal road around Mount Taranaki, including a large slip at Oākura that covered the road, burying a
nitrogen concentration in the pond and the rainfall 30 days prior to the
sampling event. This was based on 7 ammoniacal nitrogen concentrations
measured between October 2017 and April 2019. The relationship has an
R2 value of 74%.
Using this relationship, the monthly rainfall from 2018 was used to
calculate monthly nitrogen concentrations in the pond. The concentration
was converted to a loading rate in kg/ha/month based on the volume
irrigated (calculated from 2018 irrigation hours and an
REMEDIATION NZ LTD Page 7
Document No: RU-P-650-0500-A
Revision No: V1.3
Date: 1 0-9-2018
Controller: C Kay
page
Leachate & Stormwater
Management Plan
f) Any conspicuous change in the colour visual clarity;
g) Any emissions of objectionable odour;
h) The rendering of fresh water unsuitable for consumption by farm animals; and
i) Any significant adverse effects on aquatic life.
3.4.3 Climate
NIWA virtual Climate Station -38.975, 174.525 Thirty years of rainfall and
“Therefore the calculations provided by RNZ
are extremely conservative, if not a completely unrealistic assessment of
page
10
the effects of nitrogen”. In the defence of using the 225 g/m3 concentration
I make the following points:
A) The amount a nitrogen applied to the irrigation fields is a
combination of the nitrogen concentration in the irrigation pond and
the volume of fluid irrigated. In summer there is less rainfall and
the evaporation from the pond