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
variation of annual
rainfall
mm y-1r
usRainDays10 Catchment average frequency of rainfall > 10 mm days month-1
usRainDays20 Catchment average frequency of rainfall > 20 mm days month-1
usRainDays100 Catchment average frequency of rainfall > 100 mm days month-1
segAveTCold Segment mean minimum winter air temperature degrees C x 10
Hydrology MeanFlow Estimated mean flow m3 s-1
nNeg Mean number of days per year on which flow was less
than that of the previous day
Year-1
simulation model, developed by CSIRO,
Australia. The value of pasture ($/kg-DM) was estimated using local farm parameters
that were developed in consultation with Louise Hofmann, Taranaki FarmWise
consultant. The results of that work showed that the values of pasture in the area range
between $0.17 to $0.25/kg-DM, with an average value of $0.22/kg-DM.
Based on these values the irrigation marginal benefits were calculated for a range of
rainfall and soil combinations for three values of pasture:
monitoring year, with most
commencing irrigation in November or December and concluding in February. Rainfall recorded at the
Council’s monitoring locations over the summer irrigation period ranged between 55 % and 111% of
historical mean values. A particularly dry November and December lead to a drought being declared in
Taranaki during 23 December 2017. As a result, irrigation water demand was high during the 2017-2018
irrigation season, with a total water use across all exercised irrigation
“Therefore the calculations provided by RNZ
are extremely conservative, if not a completely unrealistic assessment of
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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
groundwater beneath the Uruti Composting
Facility Site are moderately impacted with Chloride contamination
Site layout, hydrogeological interactions, soil types and rainfall also influence the level of
Chlorides observed in the soil, groundwater resources and the Haehanga Stream
environment
Offsite impacts have not been quantified and where not part of the scope of this report
The Uruti Composting Facility Management Plan was developed to improve the performance of the
composting
Figure 40 Average rainfall data for Taranaki, November 2018 to April 2019 49
Figure 41 Box and whisker plots of enterococci and specific conductivity at all sites during the 2018-
2019 season (SEM data only) 52
List of photos
Photo 1 Onaero Beach 11
Photo 2 Waitara East Beach 14
Photo 3 Waitara West Beach 17
Photo 4 Fitzroy Beach 20
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vi
Photo 5 East End Beach 23
Photo 6 Ngamotu Beach 26
Photo 7 Back Beach 29
Photo 8 Oakura
Ordinary Council Agenda August 2024
groundwater beneath the Uruti Composting
Facility Site are moderately impacted with Chloride contamination
Site layout, hydrogeological interactions, soil types and rainfall also influence the level of
Chlorides observed in the soil, groundwater resources and the Haehanga Stream
environment
Offsite impacts have not been quantified and where not part of the scope of this report
The Uruti Composting Facility Management Plan was developed to improve the performance of the
composting