Irrigation Water Supply Avocado Orchard …...One in 5-year 7-day low flow (Q5) 0.567 1.74 The...

Irrigation Water Supply Avocado Orchard Development

6258 Mangakahia Road Kaikohe

Resource Consent Application

HONEYTREE FARMS LIMITED

WWA0009 | Rev. 6. Final.

13 September 2017

Honey Tree Farms Limited - Consent Application

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Avocado Irrigation Water Supply

Project no: WWA0006 Document title: Consent Application Document no: WWA0009 Revision: 6. Final. Date: 11 September 2017 Client name: Honeytree Farms Limited Project manager: Jon Williamson Author: Jon Williamson File name: C:\Users\Jon Williamson\Google Drive\WWA\Projects\Honeytree

Farms\WWA0009_Avocado Bore Tahi Block\Deliverables\AEE_HoneyTree Farms Limited_rev6 Final.docx

Williamson Water Advisory

PO Box 314, Kumeu 0841, Auckland T +64 21 654422

Document history and status

Rev Date Description By Review Approved

1 4 Sep 2015 Draft for Honeytree Farms Limited approval Jon Williamson Jon Williamson WWA

2 8 Sep 2015 Draft for NRC pre-lodgement review. Jon Williamson Tony Snushall Honeytree Farms

3 9 Nov 2016 Draft for internal review Ryan Burgess

4 10 Feb 2017 Draft for community consultation Jon Williamson Jon Williamson

5 28 July 2017 Final(a) Jon Williamson Honeytree Farms

6 13 September 2017 Final(b) Jon Williamson Honeytree Farms

Distribution of copies

Rev Date issued Issued to Comments

1 4 Sep 2015 Draft for Honeytree Farms Limited approval Draft for review.

2 8 Sep 2015 Northland Regional Council. Pre-lodgement review.

4 10 Feb 2017 Draft for community consultation Community consultation

5 28 July 2017 Final(a) Lodgement

6 13 September 2017 Final(b) Revised prior to Peer Reviewer


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Contents

Part A – Application Details ......................................................................................................................... 1

Part B – Assessment of Effects .................................................................................................................. 3

1. Introduction ....................................................................................................................................... 4

2. Background Information .................................................................................................................. 5

2.1 Catchment Setting ................................................................................................................................................................ 5

2.2 River Flow ............................................................................................................................................................................. 5

2.3 Climate .................................................................................................................................................................................. 6

2.4 Soils ...................................................................................................................................................................................... 7

2.5 Regional Water Permits ........................................................................................................................................................ 8

2.5.1 Surface Water Take Permits ................................................................................................................................................. 8

2.5.2 Groundwater Take Permits ................................................................................................................................................... 9

2.6 Existing Water Supply ........................................................................................................................................................... 9

2.7 Neighbouring Water Supply ................................................................................................................................................ 10

2.8 Geology .............................................................................................................................................................................. 10

2.8.1 Site Geology ....................................................................................................................................................................... 11

2.8.2 Overview of Groundwater Potential .................................................................................................................................... 12

2.9 Aquifer Hydraulic Characteristics ........................................................................................................................................ 15

2.10 Groundwater Flow Direction ............................................................................................................................................... 16

2.11 Groundwater Recharge....................................................................................................................................................... 16

2.11.1 Annual Recharge Volume ................................................................................................................................................... 17

3. Irrigation Requirements ................................................................................................................. 18

3.1 Peak Application Rates ....................................................................................................................................................... 20

3.2 Peak Requirement and Irrigation System Capacity ............................................................................................................ 21

3.3 Seasonal Water Usage ....................................................................................................................................................... 22

3.4 Summary of Groundwater Take Requirements .................................................................................................................. 24

4. Bore Drilling .................................................................................................................................... 25

4.1 Drilling Results .................................................................................................................................................................... 25

4.1.1 Production Bore Details ...................................................................................................................................................... 25

4.2 Bore Hydraulic Capacity ..................................................................................................................................................... 26

4.3 Bore Test Pumping Analysis ............................................................................................................................................... 27

4.3.1 Test Pump Exercise #1 ....................................................................................................................................................... 27

4.3.2 Test Pump Exercise #2 ....................................................................................................................................................... 30

4.4 Summary of Aquifer Hydraulic Properties ........................................................................................................................... 31

5. Assessment of Effects ................................................................................................................... 33

5.1 Potential Effects .................................................................................................................................................................. 33

5.2 Actual Effects ...................................................................................................................................................................... 33

5.2.1 Groundwater ....................................................................................................................................................................... 33

5.2.2 Surface Water ..................................................................................................................................................................... 35

5.2.3 Ground Subsidence ............................................................................................................................................................ 38

5.2.4 Neighbouring Users ............................................................................................................................................................ 38


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5.2.5 Local Community Socioeconomic ....................................................................................................................................... 38

5.3 Mitigation and Monitoring Proposed ................................................................................................................................... 39

6. Consultation .................................................................................................................................... 40

6.1 Dairy Shed Meeting ............................................................................................................................................................ 40

6.2 Follow-up Personal Contact ................................................................................................................................................ 40

6.3 Letter to Neighbours and Local Iwi ..................................................................................................................................... 40

6.4 Follow-up Meeting with Neighbours and Local Iwi .............................................................................................................. 41

7. Summary and Conclusions ........................................................................................................... 43

7.1 Overview ............................................................................................................................................................................. 43

7.2 Consent Application ............................................................................................................................................................ 43

8. References ...................................................................................................................................... 45


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List of Figures

Figure 1. Locality plan. (see A4 attachment at rear) ..............................................................................................5

Figure 2. Catchment map. (see A4 attachment at rear) .........................................................................................5

Figure 3. Mean monthly rainfall, evaporation and soil moisture deficit. .................................................................7

Figure 4. Mean monthly raindays, and air and grass temperatures. ......................................................................7

Figure 5. Soil map. (see A4 attachment at rear) ....................................................................................................7

Figure 6. Surface water takes in the Punakitere River catchment. (see A4 attachment at rear) ..........................9

Figure 7. Groundwater water takes in the Punakitere River catchment. (see A4 attachment at rear) ..................9

Figure 8. Photos of spring, water take arrangements and culvert 30 m downstream. ........................................ 10

Figure 9. Geological Map (see A4 attachment at rear). ...................................................................................... 11

Figure 10. Basalt lava flow formation. ................................................................................................................. 12

Figure 10. Southwest to northeast cross section. ............................................................................................... 14

Figure 11. Northwest to southeast cross section. ............................................................................................... 14

Figure 12. Topography and groundwater flow direction map (see A4 attachment at rear). ................................ 16

Figure 13. Irrigation module interface showing optimised parameters. ............................................................... 18

Figure 14. Irrigation simulation output example from 2010 to 2015. ................................................................... 20

Figure 15. Assessment of the peak application rate that is most water conservative for Kiripaka soils. ............ 21

Figure 16. Assessment of the peak application rate that is most water conservative for Aponga soils. ............. 21

Figure 17. Seasonal pattern of irrigation demand for Kiripaka soils. ................................................................... 23

Figure 18. Pilot bore drilling locations (see A4 attachment at rear). ................................................................... 25

Figure 19. Aquifer hydraulic conductivity Theis curve fitting analysis. ................................................................ 27

Figure 20. Bore test pumping water level (A) and drawdown (B) data for 19-20 September 2016 (starting at 3

pm). ....................................................................................................................................................................... 29

Figure 21. Stream water level data for 19-20 September 2016 (starting at 3 pm). ............................................. 30

Figure 22. Groundwater response in production and observation bore during test pumping on 27 to 28

September 2016. .................................................................................................................................................. 31

Figure 23. Daily rainfall during test pumping period. ........................................................................................... 31

Figure 24. Impact on groundwater levels from pumping full seasonal volume (267,104 m3) after 125 days

(see A4 attachment at rear). ................................................................................................................................. 34

Figure 25. Hydrogeological cross section in a west-east direction showing relative pressures of spring and

bore. ...................................................................................................................................................................... 36

Figure 26. Stream depletion simulation results from proposed pumping regime. ............................................... 37

Figure 27. Pilot hole #1 lithological log and production bore construction details. .............................................. 54

Figure 28. Pilot hole #2 lithological log. ............................................................................................................... 55

Figure 29. McMillans Drilling production bore as-built details. ............................................................................ 56


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Part A – Application Details (1) Full Name of Applicant(s): Honeytree Farms Limited

c/o Tony Snushall

Mobile 027 577 6339

Email [email protected]

(2) Postal Address: 64 Te Maika Road

Whangarei, 0173

(3) Residential Address: As above

(4) Address for Service of Documents: Jon Williamson


PO Box 314

Kumeu

Mobile 021 65 44 22

Email [email protected]

(5) Owner/Occupier of Land/Water Body: Honeytree Farms Limited

(6) Type of Resource Consent sought from Northland Regional Council:

Water Permit – Groundwater Take

(7) Resource Consents required from the District Council:

None

(8) Description of the Activity: Groundwater take for irrigation purposes between the months of September and April.

Consent Duration 35 years

Instantaneous Rate Not exceeding 25 L/s

Daily Volume Not exceeding 2,160 m3/day

Seasonal Volume Note exceeding 267,104 m3/season


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(9) Location of the Property to which Application

Relates:

Property Address: 6258 Mangakahia Road, Kaikohe

Locality: Kaikohe

Legal Description: Part Motatau No 5E No 23D Block

Blk:

SD:

Other Location Information:


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Part B – Assessment of Effects


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1. Introduction Honeytree Farms Limited are developing a 78 hectare property at 6258 Mangakahia Road Kaikohe into an avocado orchard with a planted area of approximately 54 hectares.

The orchard will require an irrigation system to counter summer soil moisture deficits, and to maintain tree health and fruit growth. The irrigation demand is 25 L/s (see Section 3.2), which will be supplied by one production bore installed during October 2015 (see Section 4).

Williamson Water Advisory (WWA) have been commissioned to prepare a consent application and assessment of effects report. The following provides the background information referred to in the consent application and an assessment of potential and actual effects.


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2. Background Information

2.1 Catchment Setting

The orchard at 6258 Mangakahia Road is located approximately 9 km south of Kaikohe near the small settlement of Tautoro, within the headwaters of the Punakitere River valley (Figure 1).

The property sits within a flat area drained by three separate sub-catchments - two unnamed tributaries of Punakitere River, and one of Te Opou Stream, as shown in Figure 2.

There are no perennial surficial water courses flowing through the property. Perennially flowing water emanates as springs within the two unnamed stream tributaries on the northern and western side of the property, within a few hundred meters of the property boundary. These streams flow to northwest for approximately 2,000-2,500 m before discharging into the Punakitere River. Approximately 1,000 m to the south of the property is the tributary of Te Opou Stream, which drains Lake Tauanui via springs on the slopes of the Tauanui volcanic cone.

The areas of the four catchments shown in Figure 2 are summarised in Table 1.

Table 1. Local catchment areas.

Catchment Area (km2)

Punakitere River 43.25

Te Opou Stream 17.46

Unnamed Stream 3.79

Mangaone Stream 33.20

Figure 1. Locality plan. (see A4 attachment at rear)

Figure 2. Catchment map. (see A4 attachment at rear)

2.2 River Flow

Continuous flow data for the Punakitere River at Taheke has been measured at a water level and flow recording station by the Northland Regional Council (NRC) from December 1994 to May 2014. The catchment area for the station is 325 km2 and is located approximately 16 km downstream of the property.

Analysis of the data from 1994 to 2014 provided mean flow and low flow statistics as shown in Table 2.

Table 2. Mean and low flow statistic for the Punakitere River at Taheke (325 km2).

Flow Statistic (m3/s) (L/s/km2)

Mean daily flow 6.75 20.77

Mean annual 7-day low flow (MALF) 0.721 2.22

One in 5-year 7-day low flow (Q5) 0.567 1.74

The catchment area of the Puakitere River in close proximity to the property is 152 km2, hence flow has been prorated down according to specific discharge shown in Table 2 and the catchment area to derived low flow statistics for the river in close promitiy of the site as shown in Table 3.


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Table 3. Mean and low flow statistic for the Punakitere River adjacent downstream to Honeytree Farms (152 km2).

Flow Statistic (m3/s)

Mean daily flow 3.157

Mean annual 7-day low flow (MALF) 0.337

One in 5-year 7-day low flow (Q5) 0.265

The low flow statistics in Table 3 are considered reliable as they are consistent with the range of spot guaged flows during summer at two nearby sites - one upstream (47558) and one downstream (47589), as shown in Table 4.

The Piccadilly Road gauging site (47599) is located on the mainstem of the Punakitere River approximately 5 km downstream of the property near the Mataraua Road intersection. Data for site 47558 (Ngapipito Road) is from the mainstem of the Punakitere River located approximately 1.9 km downstream of the property and is probably most relevant. It shows summer flows (albeit from a short record) ranging from approximately 85 to 435 L/s. In comparison, the estimated MALF is 337 L/s and Q5 is 265 L/s.

Table 4. Summary of Punakitere River flow gauged by NRC (source: NRC, 1992).

Gauging ID Location Description Date Flow (L/s)

47558 Opposite Ngapipito Road 29/03/1990 408

19/04/1990 248

07/01/1991 152

26/02/1991 85

13/03/1991 93

26/11/1991 435

23/12/1991 175

07/02/1992 140

47589 Piccadilly Road 18/03/1983 567

2.3 Climate

Daily climate data was obtained from NIWA for various stations in Kaikohe (Kaikohe AWS, Kaikohe DSIR and Kaikohe Aero) dating back to 1973, and data relevant to horticultural crops was summarised on a monthly basis as shown in Figure 3 and Figure 4.

Key point of interest from this data are:

• Development of fairly significant summer soil moisture deficits even under average conditions, confirming the need for irrigation;

• Temperate mean air temperatures (11-19 °C), which is good for avocado crop growth; and

• Mean minimum grass temperatures are above zero during winter, which means there is not a significant likelihood of strong frosts and again is good for avocado crop growth.


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Figure 3. Mean monthly rainfall, evaporation and soil moisture

deficit.

Figure 4. Mean monthly raindays, and air and grass

temperatures.

Daily rainfall data was obtained for irrigation demand modelling along with mean monthly evaporation data from Kaikohe AWS, Kaikohe DSIR and Kaikohe Aero. The data was patched together with any missing days replaced with the mean day-of-the-year value to produce a continuous record from 1 January 1973 to 31 May 2015.

Mean annual rainfall from 1973 to 2014 is approximately 1,570 mm and mean annual pan evaporation is 780 mm.

2.4 Soils

A detailed description of the soils in the area is not currently digitally available on Landcare Research’s digital soil spatial information system for New Zealand (SMap) series, but are covered in less detail on the NZ Resource Inventory (NZRI) Map Series and older publications such as Sutherland et. al., (1980) and Wilson and McDonald (1987). The soils of the property and surrounding areas are shown in Figure 5 and described in Table 5.

The soils on the property predominately comprise Kiripaka bouldery silt loam (KB), which is a free draining volcanic soil of low bulk density (0.9 kg/m3), which means the soil will have good drainage and should be aerated, which implies higher biological activity. From visual observation, the soils are a rich reddy brown in colour and highly vesicular basalt boulders are common.

In the northwest of the property the soils are heavier Aponga clays (APH).

Figure 5. Soil map. (see A4 attachment at rear)


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Table 5. Soil mapping units found near the property.

Unit Name Locale

KB Kiripaka bouldery silt loam Over much of the property

APH+AP Aponga clay In the northwest of the property

PKH Papakauri silt loam (Hangunui Pa) In the north of the property

Surrounding areas

OW Ohaeawai silt loam To the northwest

OWb Ohaeawai shallow bouldery silt loam To the northwest

OW Waiotira clay loam To the northeast

RP Riponui clay and sandy clay To the northeast

The physical characteristics of the soils obtained from the NZRI relevant to the irrigation requirements for the property, are summarised in Table 6. Definitions are the soil characteristics discussed are provided in Appendix A.

Macroporosity of the Kiripaka soils was increased from a moderate rating by the NZRI to high (assume 25%), based on:

• conversations with the orchard manager;

• high content of scoria and broken basalt pebbles give the soil a gritty nature; and

• highly vesicular nature of the boulders on the site.

Table 6. Soil physical characteristics.

Parameter Soil Unit

KB APH+AP

Potential rooting depth (m) Slightly deep 0.45-0.59 Deep 0.9-1.19

Plant available water No data avail. No data avail.

Depth to slow permeable horizon (m) 1.36-1.49 0.6-0.89

Soil drainage Well drained Imperfectly drained

Soil permeability (mm/hr) Moderate 4-72 Slow <4

Macroporosity (shallow) High 25 Low 7.5

2.5 Regional Water Permits

2.5.1 Surface Water Take Permits

There are six active water take consents registered with the NRC. These are described in Table 7 with the location of the four in closest proximity to the property shown in Figure 6. All of the current permits are located on sub-catchment tributaries that drain into the Punakitere River a significant distance (>6 km) downstream of the proposed groundwater take.

The closest active takes to the Honeytree Farm are Pinny and Osborne located 5 km and 6 km in a direct route away, respectively.


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Table 7. Summary of active surface water take permits.

Permit Holder Description

Dist.* (km)

Status Date Source Use Category

Daily Volume

(m3/day) (L/s)

Far North District Council

Dam water take for Kaikohe Water Supply

11.0 9/04/2014 Dam Drinking - Public Water Supply

1,300 15

Flowermakers Limited

Take for irrigation of export flowers. Mataraua Road, Te Iringa

6.3 23/06/2010 River/stream/spring

Irrigation - Horticulture

90 1.04


Dam for public water supply. Reservoir Road, Kaikohe

10.4 8/09/1998 Dam Drinking - Public Water Supply

0.00


Water take for public water supply, Kaikohe State Highway 1, Kaikohe


Drinking - Public Water Supply

1,300

Pinny M J Water take for irrigation at Mangakahia Road, Kaikohe

4.6 18/07/2005 Dam Irrigation - Pasture 10,000 115.75

Osborne Family Trust & Others

Water take at Browns Road, Kaikohe. Browns Road, Kaikohe


Irrigation - Horticulture

110 1.27

Note: Distance from Honeytree Farm’s property.

Figure 6. Surface water takes in the Punakitere River catchment. (see A4 attachment at rear)

2.5.2 Groundwater Take Permits

There are thirteen registered bores on the NRC bore database within 5 km of the Honeytree Farm, of which one is a NRC monitoring bore. The bores are listed as being for stock or domestic purposes and are all less than 62 m deep, with the average depth being 25 m, implying relatively low yield requirements. There are no active water take consents associated with any of these bores, suggesting they are permitted takes for reasonable stock and domestic needs provisioned through s14(3)(b) of the RMA. Typically these users take less than 30 m3/day (0.3 L/s).

The location of the bores are shown in Figure 7, which indicates that there are seven neighbouring bores downstream and one upgradient of Honey Tree Farm within approximately 2.3 km.

Figure 7. Groundwater water takes in the Punakitere River catchment. (see A4 attachment at rear)

2.6 Existing Water Supply

The property has one existing 100 mm bore installed in July 1992 for shed and stock watering purposes. The bore is located in the milk tanker turning circle of the old cow shed and is understood to be 33 m deep. The yield is unknown, but anticipated to be in the range of 2-4 L/s. The groundwater table is understood to be at 14.5 m below ground level (mBGL), which indicates 18.5 m of standing water in the bore. There is no information available on pumping water levels or drawdown.

The required water supply of 25 L/s is significantly greater than the existing bore could meet and will be met by the new deeper bore recently installed on the orchard, described in Section 4.


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2.7 Neighbouring Water Supply

There is a spring that emerges in a gully approximately 670 m to the west of the new production bore, which provides domestic water to the local Marae and a number of other properties (see Figure 10) typically via gravity and a water hammer pump.

Through conversion with Mr. Toki Tewhata it is understood the spring is perennial, but historically flow has receded below the stream bed level (i.e. flow only within the rocks) during prolonged drought.

It is estimated that domestic use may account for approximately 30 m3/day (assumed 6x5m3/day per household), which is a combined flow of 0.35 L/s. The spring is estimated to flow at approximately 10 L/s, as it took two second to fill a 20 L bucket at the culvert discharge point immediately downstream of the spring.

Figure 8. Photos of spring, water take arrangements and culvert 30 m downstream.

2.8 Geology

The geology of the site and surrounding areas has been mapped by the Institute of Geological & Nuclear Sciences and is presented in a 1:250 000 map with accompanying text entitled Geology of the Whangarei area


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Edbrooke and Brook (2009). This map was obtained electronically (QMap series) and the local geology is presented in Figure 9.

Figure 9. Geological Map (see A4 attachment at rear).

There are seven geological units mapped within the project area, which are described in summary in Table 8.

Table 8. Description of geological units.

Unit Main Rock

Sub Rock Description Strata Name Age (million years)

Min Max

Q1.alvgvl Mud Sand, gravel, peat

Unconsolidated to poorly consolidated mud, sand, gravel and peat deposits of alluvial, colluvial and lacustrine origins.

Tauranga Group 0 0.014

Q.bas Basalt Basanite Basalt lava and volcanic plugs. Kerikeri Volcanic Group 0.06 1.4

Q.sco1 Scoria Basalt Basalt scoria commonly forming steep-sided cones. Kerikeri Volcanic Group 0.06 1.4

PleQ.sst Sandstone Mudstone, conglomerate, lignite

Thin-bedded, carbonaceous sandstone and carbonaceous mudstone with intercalated conglomerate and lignite.

Tauranga Group

1.4 6.5

eKeOl.bas_all Basalt Dolerite, gabbro, mudstone

Mainly basalt pillow lava, with subvolcanic intrusives of basalt, dolerite and gabbro; locally incorporating siliceous mudstone.

Tangihua Complex

28.5 108.4

IKeE.mst_all Mudstone Sandstone, limestone

Massive to thinly bedded, siliceous mudstone, locally with thin glauconitic sandstone interbeds.

Whangai Formation 53 84

IK.sst6_all Sandstone Mudstone Weakly to moderately indurated, alternating thin- to thick-bedded, quartzofeldspathic sandstone and mudstone.

Punakitere Sandstone 75 95.2

2.8.1 Site Geology

The orchard is underlain by recent basalt lava flows from the Kerikeri Volcanic Group. The slope and geometry of the lava field is such that it is evident the lava flow field during eruption was highly viscous and had a strongly preferred alignment flowing from Mt. Tauanui in the south to the north-northwest down the Punakitere Valley.

Basalt lava flow often comprise multiple layers of lava that were created from pulses in volcanism, and the interface between the layers often presents a contrast in material types (e.g. lava, scoria, buried soils or vegetation if phases between volcanism were long enough for these to develop). Two other features commonly associated with basalt lava flows are rapid cooling joints (near vertical) typical near the surface or basal contacts, and lava conduits and tubes associated with flow of lava of different viscosity, as described in Figure 10.

These conduits and small lava tubes are what we consider has been encountered in the production bore on this orchard and the reason for such as high specific discharge from the bore, as discussed later in the bore drilling and hydraulic testing Section 4.


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Figure 10. Basalt lava flow formation.

Two inferred geological cross sections that transect the property (located as shown in Figure 9) are presented in Figure 11 and Figure 12. The cross sections are useful for delineating the deepest and widest parts of the basalt lava flows and hence assist in selecting future borehole positions as well as considering impacts on springflow. The property boundaries are marked with grey arrows on each section.

Note that the only controls on the depth of basalt lava utilised in generating the cross sections were at the outcrops on the basalt flow margins, and at the cowshed bore (which has been presumed to hit siltstone baserock at 33 m) and the two exploratory bores. The cross-section analysis has shown the following key features:

• Basalt lava has flowed down and infilled the palaeovalley;

• In a general sense the thickest parts of the basalt are near the vents and in the widest parts of the valley;

• Basalt has flowed around high points in the underlying basement siltstone, which have created separate groundwater flow compartments in the basalt lava

• Typically groundwater discharges occur at the margins of the lava flow, particularly downstream where groundwater level or pressures exceed ground level at the basement outcrop.

2.8.2 Overview of Groundwater Potential

The indicative water supply potential geological of each unit is summarised in Table 9, with commentary for each type of rock provided in the following sections.

Table 9. Water supply potential of each geological unit.

Unit Strata Name Hydrogeological Description / Potential Overall Rating

Q1.alvgvl Tauranga Group Fine grained unconsolidated sediment of low to moderate permeability.

Low to moderate

Q.bas Kerikeri Volcanic Group

Vesicular and fractured rock. Greatest water supply potential in middle of lava flows or close to lava source.

Moderate to high

Q.sco1 Kerikeri Volcanic Group

Vesicular typically unconsolidated scoria deposit. Greatest water supply potential in middle of lava flows or close to lava source.

Moderate to high

PleQ.sst Tauranga Group Fine grained consolidated sediment of low permeability. Low

eKeOl.bas_all Tangihua Complex Typically fine grained and low fracture propensity or high clay content in fractures. Low to moderate permeability.

Low to moderate


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IKeE.mst_all Whangai Formation Massive fine grained highly consolidated deposit of low permeability.

Low

IK.sst6_all Punakitere Sandstone

Fined grained and well consolidated deposit of low permeability. Low


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Figure 11. Southwest to northeast cross section.

Figure 12. Northwest to southeast cross section.


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Volcanic Rocks

Groundwater yield is likely to be greatest in the younger Kerikeri Volcanic Group rocks, where vesicles (cavities formed from gas bubbles) and fractures are common. The older volcanic rocks from the Tangihua Complex remain as prominent surface features in the area due to their typically greater inherent rock strength, which implies more fine grained, massive rock with less rock defeats, hence resilience to erosion. These rock characteristics are less conducive to larger groundwater yields unless structural deformities and/or geological boundaries (interface drainage pathways) are encountered.

The thickest parts of the volcanic lava flows would potentially provide higher yields and better quality groundwater, which are typically located in the middle of the lava flows or nearer the source.

The majority of bores drilled within the Kaikohe area are concentrated within areas of basalt, which suggests that groundwater potential is greatest in these areas.

Alluvial Sediments

The unconsolidated Quaternary alluvial sediments are also likely to have low groundwater yield in this area due to their mud content, and the limited depth and lateral extent of these sediments will also be a limiting factor.

Sandstones and Mudstones

In comparison to the basalt and alluvial deposits, the sandstones and mudstone will be relatively impermeable due to the fine-grained and consolidated nature of the rocks. Groundwater yield from these rocks would most likely only be sporadic and only viable in areas where faults or other defects are present, and/or with significant drilling depths.

Very few bores are located within the sandstone and mudstone, which suggest groundwater potential is comparatively low in these areas.

2.9 Aquifer Hydraulic Characteristics

Aquifer hydraulic characteristics for Northland basalt aquifer have been investigated and summarised in a number of previous studies, the most recent of which is the study entitled Groundwater/Surface Water Integrated Management by Sinclair Knight Merz (SKM) in 2012.

The SKM (2012) report investigated management options for the basalt aquifers of Kaikohe and the Maunu-Maungatapere-Whatitiri basalt aquifer complexes, and developed an analytical method for estimating effects on surface water of groundwater pumping in basalt aquifers. During development of the analytical method, conceptual models were generated for different hydrogeological settings within basalt complexes and modelled with a numerical model (FEFLOW) for comparison to developed analytical model. The typical aquifer hydraulic properties applied by SKM (2012) to the different basalt hydrogeological settings are here reproduced in Table 10.

Table 10. Summary of hydraulic properties of various basalt geological settings in Northland (from SKM, 2012).

Rock Type Kh (m/s) Kh/Kv Sy Ss (1/m)

Scoria 1.7x10-5 3 0.1 5x10-6

Hard Basalt (minor fractures) 1.7x10-6 10 0.01 5x10-6

Fractured Basalt 1.5x10-5 10 0.01 5x10-6


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2.10 Groundwater Flow Direction

While there is not enough bore data in the area to construct an accurate piezometric (groundwater level) surface map, the groundwater gradient follows topography albeit flatter, and is locally influenced by the presence of scoria cones (volcanic intrusions) and basement highs.

The topography and inferred groundwater flow direction are shown in Figure 10, of which the key features to note are as follows:

• Groundwater flow from scoria cones typically radiate in all directions from the centre of the scoria cone;

• The production bore is located on a groundwater flowpath that heads in north-northwestwardly direction;

• The western boundary of the property is situated near a scoria cone/ridge, which while internally is likely to be highly permeable, the outside margin of the cone on the upgradient side is likely to be of significantly lower permeability1 and act as a barrier to flow, hence deflecting flow to the north;

• The location of the spring is on a westward groundwater flow path emanating from the scoria cone ridge;

• Funnelling or bottlenecking of groundwater in the area of the bore is likely as inferred by the groundwater flow direction arrows. This is caused by basal rock outcrops to north east and northwest of the property, and potentially a shallower basement under the scoria cone to the south of the property (as indicated by geological log for the second pilot bore).

In the Tautoro area downstream of the property where the central and eastern limbs or flow paths of the basalt meet, groundwater seepage to the surface appears prevalent over a reasonable area within approximately 500 m of the Punakitere River.

Figure 13. Topography and groundwater flow direction map (see A4 attachment at rear).

2.11 Groundwater Recharge

Numerous studies have previously been undertaken to determine aquifer recharge within basalt aquifers throughout Northland (SKM (2006a), SKM (2006b), SKM (2007) and SKM (2010)). Recharge values as a percentage of annual rainfall vary between 5% to 49% for basalt lava and can be as high as 60% for scoria cones. The large range in recharge is a reflection of i) the variable material characteristics of the different types of basalt. For example, the older Tangihua Complex basalts are typically finer grained, massive and have limited fracturing and therefore typically display much lower recharge than the younger, highly vesicular and fractured Kerikeri Volcanic Group basalts and scoria cones. Also, the older basalts tend to display greater thicknesses of clays derived from weathering at the surface, which are also unconducive to high rates of recharge.

The most relevant hydrogeological study for assessing recharge in this area is the Kaikohe Hydrogeological Investigation (SKM, 2007), which is approximately 10 km to the north.

Groundwater recharge was assessed in SKM (2007) using an 83-year simulation of a soil moisture water balance model (SMWBM) that had been calibrated to low flow monitoring records for Squires Spring and Tokakopura Tributary. Groundwater recharge was estimated for recharge areas of these surface water resources (Monument Hill and the Kaikohe basalt, respectively) at 16.5% and 13.2% of rainfall, respectively.

1 Due to the hot lava cooking the insitu rock during its eruption and the formation of debris apron.


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For comparison, the Maunu – Maungatapere - Whatitiri Aquifers - Sustainable Yield Assessment (SKM, 2010), which considered another basaltic aquifer complex in Northland near Whangarei produced three distinct zones of groundwater recharge in their calibrated groundwater model, which varied from 6-62% as follows:

1) Bulk Aquifer – 6% groundwater recharge was assigned to areas where there is high proportion of quickflow. This assumption made is that the majority of rainfall runs across the surface rather than percolating into the groundwater;

2) Volcanic Cones – 18% groundwater recharge assigned to both the Whatitiri and Maunu cones. These areas were assigned higher recharge as there were less streams originating from these cones, indicating that a higher proportion of rainfall percolates into the groundwater.

3) Poroti and Maunu Springs Channel – 62% of rainfall was assigned to the Poroti Channel and the ‘Tunnel” branch of Maunu Springs. Increased recharge in this area was required to generate the required spring flow from each of these springs and is consistent with a large area of highly permeable material located within the basalt flows.

2.11.1 Annual Recharge Volume

In this study, we have assumed an average annual recharge rate for the basalt of 225 mm, which is 15% of mean annual rainfall (1,500 mm). We consider this an appropriate assumption because it is likely the Tauanui scoria cone would provide significantly greater rate of recharge (i.e. ~60%), while the rate of recharge would decrease down the flanks of the cones as the aquifer becomes more confined to perhaps 6% as calculated in SKM (2010).

The estimated annual recharge volume of the direct groundwater flow path is 679,500 m3 based on the recharge area as shown in Figure 10 of approximately 3.02 km2 and the annual recharge of 225 mm. However, the basalt is of significantly larger area than that used in this calculation and the basal geometry of the paleo valleys is such that funnelling or bottlenecking of groundwater in the area of the bore is likely as inferred by the groundwater flow direction arrows (i.e. outcrops to north east and northwest and the second pilot bore in the south showed shallower basalt).

The funnelling of groundwater implies that the recharge area of the bore is potentially larger than that shown on the map, but the reduction in groundwater throughflow or down gradient stream depletion effect is likely to be localised to the area downgradient of the bottle neck.


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3. Irrigation Requirements The irrigation requirements of the two soil types (KB and APH+AP) within the property were estimated using the irrigation module of WWA’s Soil Moisture Water Balance Model (SMWBM). The model is described in Appendix B. The irrigation module calculates soil moisture dynamics on an hourly basis during the irrigation season, given specified irrigation application depths and rules governing when to start and stop irrigating.

The model interface is shown in Figure 14, while Table 11 provides a summary description of each parameter and the optimised parameter values.

Figure 14. Irrigation module interface showing optimised parameters.


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Table 11. Summary of irrigation module parameters utilised.

Parameter Description Values Basis of Values

KB APH+AP

Maximum Soil Moisture Content (ST)

The capacity of water in mm in the soil at field capacity.

138 134 Estimated from potential rooting depth (PRD) and macroporosity (n). PAW = PRD x n/100.

KB APH+AP

PRD (mm) 550 1,005

n (%) 25 7.5

Plant Available Water (PAW)

The amount of water physically accessible by the plants in the root zone in mm.

96.6 93.8 Table 22 of Crop Evapotranspiration - Guidelines for Computing Crop Water Requirements from the Food and Agricultural Organisation of the United Nations (FAO)2 states that 70% of Total Available Soil Water (interpreted as equivalent to ST in the SMWBM) can be depleted before the point where avocado trees suffer stress. Therefore, PAW = 0.7 x ST

Allowable Deficit (AD)

Soil moisture level where irrigation ceases.

90% of PAW

The avocado is very flood-sensitive with even short periods of waterlogging resulting in reduced shoot growth, altered mineral uptake and root death. To avoid flooding and surface runoff, soil moisture levels during irrigation should not exceed 90% of field capacity.

Minimum/

Critical Deficit (CD)

Percentage of PAW at which further drying of soil would start to have an impact on plant growth rates, and hence CD represents the soil moisture level at which irrigation commences.

40% of PAW

The rule of thumb for critical deficit is 50% of PAW. However, a grower aiming to maximise crop yield may want a small critical deficit of only 20% (80% PAW)3. A balance is also required between a small critical deficit (high soil moisture levels) and water wastage, which results under high moisture conditions when rainfall occurs during summer. Through trial and error, we have used CD values of 40% PAW.

Peak Application Depth

Maximum daily irrigation depth applied to soil (mm/day).

4.6 mm 4.0 mm

Selected through optimisation target of minimisation in losses, while maintaining moisture levels at or above the CD. Note. This is the amount of irrigation water reaching the soil surface, which is less that the amount applied by the irrigator per se. due to application inefficiencies (losses).

Application Duration

Duration in hours over which the peak application depth is applied

5 hours Data provided by Honey Tree Farms irrigation system installer.

Rain Threshold

Daily rainfall total in mm when a farmer would choose not to irrigate.

10 mm Judgement

Season Irrigation season start and finish October – April General irrigation season length.

2 http://www.fao.org/docrep/x0490e/x0490e0e.htm 3 Anon. Scheduling overview. NZ Avocado Industry 11 Mar 2010. (accessed 16 Jul 2015) <http://www.hortinfo.co.nz/factsheets/fs110-68.asp>.


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The model was simulated using historical rainfall as described in Section 2.3 from January 1973 to May 2015. Figure 15 provides an example of the model output for the Kiripaka soils showing irrigated and unirrigated soil moisture profiles for a five year snapshot from 2010 to 2015, along with the daily irrigation (soil) loadings.

Figure 15. Irrigation simulation output example from 2010 to 2015.

3.1 Peak Application Rates

A numbers of simulations were undertaken to determine the application depth that minimised losses through surface runoff and groundwater percolation while meeting the irrigation rules. Minimisation of surface runoff and groundwater percolation losses is achieved through applying less water on a seasonal basis, while failure to meet the irrigation rules results in soil moisture level receding significantly below the CD level.

Simulation results indicated an optimal peak irrigation application rate to the Kiripaka and Aponga soils of 4.6 and 4.0 mm/day, respectively. This is shown in Figure 16 and Figure 17, which also show the mean annual irrigation demands for each simulation.


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Figure 16. Assessment of the peak application rate that is most water conservative for Kiripaka soils.

Figure 17. Assessment of the peak application rate that is most water conservative for Aponga soils.

3.2 Peak Requirement and Irrigation System Capacity

The model simulation results indicate that during peak months irrigation is required almost every day, except when significant (>10 mm) summer rainfall occasionally occurs. The average return period during the peak month of January calculates out at 1.07 and 1.15 days for Kiripaka and Aponga soils, respectively. The actual average monthly soil requirement is therefore the application rates (4.6 and 4.0 mm/day) divided by the return


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periods (1.07 and 1.15 days), which equates to 4.30 mm/day and 3.50 mm/day for the Kiripaka and Aponga soils, respectively.

However, there are unavoidable irrigation system losses that need to be accounted for when determining the water allocation requirement. Assuming an application efficiency of 90%, the optimal daily application rates relate to an irrigation system capacity or peak daily take requirement for the Kiripaka and Aponga soils are equivalent to 4.80 and 3.90 mm/day.

Given the difficulty in accurately delineating the soil types on a block by block basis and risk of under watering, the irrigation system will be designed assuming Kiripaka soils through the entire block. On this basis the peak water requirement for the 54.4 ha canopy area is 25 L/s, which has been calculated on the basis of the orchard block and sprinkler setup described by the client, which is summarised in Table 12.

Table 12. Summary of Irrigation Water Requirements.

Sprinkler Configuration

Flow rate (L/hr) 34

Sprinkler radius (m) 3

Coverage (m2) 28.27

Rate (mm/hr) 1.20

Appl. (hrs) 4

Peak Appl. (mm) 4.80

Row Configuration Sprinkler pattern conceptual layout, with blue circles representing sprinkler coverage area and grey lines representing row centres.

Width (m) 5

Rows per ha 19

Sprinklers per row 15.7

Sprinkler coverage area per ha (%) 84

Water Requirement

Vol (L/ha) 42923.27

Flow rate (L/ha/s) 2.8

No. blocks to irrigate 6.0

Total area (ha) 54.4

Ave. block size (ha) 9

Flow rate per block (L/s) 25

3.3 Seasonal Water Usage

The model was simulated for 43 years from 1973 to 2015 to define the seasonal pattern of irrigation demand, including mean and maximum monthly volumes, and annual volumes.

Figure 18 shows monthly profiles from the 43 year simulation with application efficiency accounted for in the demand requirements. The figure also shows the frequency of the monthly volumes in the form of quartile markers (25% percentiles and the median), which provides a good indication of the frequency that the system operates at maximum capacity. Table 13 summarises the monthly frequency and annual volume data.


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Figure 18. Seasonal pattern of irrigation demand for Kiripaka soils.

Table 13. Monthly irrigation demand frequency statistics (mm/day)* for Kiripaka soils.

Statistic Oct Nov Dec Jan Feb Mar Apr Season (mm/year)

Min 0.0 0.0 0.0 0.0 0.0 0.0 0.0 138

25%ile 0.2 0.7 1.3 1.4 2.0 0.7 0.0 307

Mean 0.8 1.4 1.7 2.8 2.5 1.9 0.5 348

75%ile 1.3 2.0 2.6 3.8 3.2 2.6 1.3 429

85%ile 1.5 2.6 3.1 4.3 3.5 3.5 1.5 450

0.90%ile 1.6 2.9 3.3 4.3 3.9 3.6 1.7 491

0.99%ile 2.5 3.5 4.6 4.6 4.4 4.2 2.5 597

Note: * including additional water to account for application efficiency of 90 %.

The 90%ile seasonal volume, which equates to 491 mm is taken as the volume to apply in the consent. This means that 9 years out of 10 years, the orchard will be able to meet it demand without any shortfalls. It also means that the orchard could supply at the peak rate of 4.8 mm for approximately 102 days per season.


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3.4 Summary of Groundwater Take Requirements

Table 14 summarises the groundwater take requirements, constituting the key parameters of the resource consent application, including a maximum annual usage of 491 mm and a sprinkler coverage area of 84% of the 54 hectare orchard.

Table 14. Summary of groundwater take consent requirements.

Parameters Rates

Peak Instantaneous Rate (L/s) 25

Max. Daily Volume (m3/day) 2,160

Seasonal Volume (m3/season) 267,104


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4. Bore Drilling Given the site geology presented in Section 2.7 and irrigation total peak water requirements of 25 L/s, it was initially thought that two production bores would be required to meet orchard demand and provide operational flexibility, premised on the assumption that the maximum yield achievable per bore will be less than 20 L/s.

However, two pilot bores were drilled and one production bore was installed, as described in the following section, and following test pumping it was thought a single production bore could meet the entire orchard demand.

4.1 Drilling Results

McMillan Well Drillers of Auckland were commissioned to undertake pilot hole and production bore drilling. The scope of the drilling work undertaken was governed by the nature of the geological profile encountered, resulting in a requirement for only two pilot holes and one operational production bore at this stage. The pilot bore drilling was undertaken using diamond coring between 17 to 21 September 2015, and the production bore at the location of first pilot hole was drilled using air percussion and installed between 14 to 23 October 2015.

The location of the pilot holes is shown in Figure 19. The rationale for these site selections was as follows:

• Bore 1 –fairly central to demand and close to power;

• Bore 2 – future potential bore to irrigate back of the block if needed.

Figure 19. Pilot bore drilling locations (see A4 attachment at rear).

The geology encountered in each bore is summarised in Table 15, and borelogs and core photos for the pilot bores and production bore are provided in Appendix C.

Pilot bore #1 encountered a sequence of alternating massive and fractured basalt to a depth of 58.6 m, with more massive basalt near the top and frequent highly fractured basalt from 29 m to the base of the bore. A key feature of pilot bore #1 was that the rock was dry until 23 m. Then from 29 m a pressurised zone was encountered and the static water table jumped 5 m from 23 m back to 18 m. This indicated the production zone is semi-confined or confined, and thus cannot be directly connected to surface features such as the nearby spring beside the Marae.

Pilot hole #2 was not as promising, with the basalt only 22.5 m thick, hence a production bore was only installed at the location of pilot hole 1.

4.1.1 Production Bore Details

The production bore constructed comprises a cement grouted 250 mm ID steel casing to 23 m followed by a 250 mm OD open hole to the base at 59.70 m. The construction details are provided in Appendix C. The production bore design basis included provision:

• of casing deep enough to provide wall security for a submersible pump and to allow for potential drawdown; and

• open hole (unscreened) to base through the highly fractured but stable ground as determined during pilot hole drilling and hydraulic testing.


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Table 15. Geological profile for the pilot bores.

Pilot Bore 1 Pilot Bore 2

Depth (m) Description Depth (m) Description

0 – 10.5 Alternating bands of vesicular (10-15 mm) and massive hard BASALT. Dry.

0-7.5 Scoria and scoriaceous BASLT.

10.5 - 23 Hard massive BASALT with alternating bands of vesicular basalt. Small fracture zones at 7.2 m and 12.2 m. Dry to 23 m.

7.5-10.4 Soft Basalt. Very light grey layered and vesicular soft gritty tuffaceous pumice/ash. SWL was recorded at 8.6 m.

23 - 29 Hard massive grey/green BASALT. 10.4 – 15.9 BASALT. Slowly becoming darker and more massive basalt with depth.

29 - 31 Highly fractured, rubbly and vesicular BASALT.

Pressurised water encountered with SWL increasing to 18 m.

15.9 – 17.0 BASALT. Massive basalt with some vesicles.

31 - 33 BASALT with large cavities and scoria. 17.0 – 18 Fractured scoriaceous BASALT.

33 - 36 Vesicular hard BASALT. 18 – 19.5 Fractured and moderately vesicular BASALT.

36 - 41 Broken BASALT and scoria rubble. 19.5 – 21.0 BASALT becoming less vesicular and more massive.

41 - 45 Massive BASALT with some fractures 21 – 22.5 Massive BASALT.

45 - 57.5 Massive BASALT with occasional fractures and small vesicles.

22.5 – 26.6 SILTSTONE. Light grey and light orange/yellow mottled soft highly weathered clayey siltstone

57.5 - 59.5 Rubbly BASALT.

59.5 - 60.4 SILTSTONE. Light grey / tan highly weathered siltstone.

4.2 Bore Hydraulic Capacity

Airlifting and recovery testing were undertaken on the production bore by the drillers following development to provide an indication of the specific capacity (drawdown with yield) of the bore and hydraulic conductivity of the aquifer.

Air lifting was conducted for 5 hours with an average flow rate of 22.5 L/s and no noticeable drawdown measured, indicating the bore is extremely permeable and capable of very high yields – far in excess of the design requirement.

Recovery testing was undertaken three times following injection of a 1000 L slug of water at a flow rate of 6.9 L/s (over 145 seconds). The three tests gave identical results with maximum rise detected of 0.1 m and full recovery occurring after approximately 6 minutes. The detail of the data collected by the drillers was not sufficient for injection test analysis, however a number of Theis curves were roughly fitted to the data to provide an indication of the aquifer hydraulic conductivity, as shown in Figure 26. The curve that fits best has a hydraulic conductivity of 1x10-3 m/s. This value is typically associated with very high permeability clean coarse river gravels for example, but in this case is most likely representative of a large number of fractures or lava tubes within the basalt.


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Figure 20. Aquifer hydraulic conductivity Theis curve fitting analysis.

4.3 Bore Test Pumping Analysis

In addition to the drillers air lift test, two test pumping exercises were conducted by WWA on the production bore, with automated pressure transducers4 monitoring groundwater levels in the production bore, the dairy shed bore and the stream culvert downstream of the spring.

The objective of the testing was to confirm aquifer hydraulic conductivity and assess whether any impact from pumping occurred on the spring flows during testing.

The testing used the submersible pump installed in the bore for irrigation pumping. The discharge water was reticulated approximately 400 m from the bore using the orchard rising main.

The details of the tests are summarised in Figure 19 and results are discussed in the sections that follow.

Table 16. Summary of test pump details.

Test No. Date Type Flow Rate Duration Weather Conditions

#1 19 Sep 2016 Constant rate 18 L/s 10.5 hours Dry on day of testing.

#2 27 to 29 Oct 2016 Constant rate 20 L/s 48 hours Dry during testing, but heavy rainfall over the three days preceding the test.

4.3.1 Test Pump Exercise #1

The first test was started at 3:00 pm on 19 September and terminated after approximately 10.5 hours due to mechanical failure of the pump. However, as shown in Figure 21-B the data indicates only approximately 4 cm of drawdown occurred after 10.5 hours pumping at approximately 18 L/s. Following pump failure, a 2 cm recovery occurs and then groundwater continues to slowly decline due to barometric effects (Figure 21-A). The maximum drawdown induced by pumping of 4 cm is very small given the flow rate and represents a specific capacity of 450 L/s/m, hence the aquifer is extremely permeable as previously suggested.

Figure 22 shows the water level5 data for the stream culvert leading up to (-ve time) and during the period of test pumping of the bore, indicated by the green and red dashed lines. The data shows that stream water level 4 Solinst Leveloggers. 5 Compensated for barometric pressure.


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(flow) was decreasing prior to the test starting, which is consistent with the groundwater level in the bore. At the time the test was initiated, the stream began to increase in water level (flow) and after approximately 6 hours of pumping the stream began to decline in water level (flow), which continued for approximately 10 hours, when the stream began to rise in water level for approximately 2 hours and then began declining again.

There was no appreciable rainfall during the period of testing and the oscillatory response in the stream water levels of 6 cm over the entire period is similar to that observed in the bore (after removing the small drawdown effect) as evident from Figure 21-A. Furthermore, the rapid rise in groundwater levels in both the bore and stream at 16 hours elapsed time occurs approximately 6 hours after the pump cut out, hence this is not attributed to pumping from the bore.

Given the extremely high permeability of the aquifer, if the aquifer was directly connected with the spring we would expect to see an almost immediate impact on the stream. However, we do not consider the spring impacted from this test at all – i.e. oscillations in water level in the spring are barometric effects.


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A)

B)

Figure 21. Bore test pumping water level (A) and drawdown (B) data for 19-20 September 2016 (starting at 3 pm).


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Figure 22. Stream water level data for 19-20 September 2016 (starting at 3 pm).

4.3.2 Test Pump Exercise #2

The second test was started at 12:00 pm on 27 September and terminated after 48 hours at midday on 29 September. Figure 23 provides the overserved groundwater pressures6 in the pumping bore and dairy shed bore, along with 10-minute rainfall recorded within the orchard, Figure 24 provides the daily rainfall totals.

The testing data indicates a general steady increase in pressure (negative drawdown) from 25 September until the end of the monitoring on 4 October. The key point to note is that there is no drawdown observed in the bores from pumping at 20 L/s. We conclude from the steady rise in groundwater level and the lack of change in this rise (i.e. from drawdown) that the aquifer:

a) responds slowly to rainfall on previous days within the catchment and hence is not directly connected to the surface; and

b) is extremely permeable with a hydraulic conductivity probably in the order of >1x10-3 m/s.

6 Compensated for barometric pressure.


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Figure 23. Groundwater response in production and observation bore during test pumping on 27 to 28 September 2016.

Figure 24. Daily rainfall during test pumping period.

4.4 Summary of Aquifer Hydraulic Properties

Table 17 provides a summary of the estimated aquifer hydraulic property from the various testing proceedures that were applied on the bore. The conclusion is that the hydraulic conductivity is >1x10-3 m/s and porosity is estimated from experience at >0.3. Both values are very high and representative of a highly permeable materials with large void space.

It should be noted that the basalt encountered in the production borehole has hydraulic characterisitcs that are significantly higher than the upper range of typical values for Northland basalts (summarised in Section 2.9). The values estimated for the production bore aquifer on this property reflect the site specific conditions encountered.


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Table 17. Summary of estimated aquifer hydraulic properties.

Test Type Flow (L/s)

Drawdown (m)

Hydraulic Conductivity (m/s)

Specific storage (-)7

#1 Air development 22.5 0 Very high n/a

#2 5 x recovery test (injection) 1000 L slug 0.1 1x10-3 5x10-6

#3 10 hours constant rate test pumping 18 2 cm >1x10-3 5x10-6

#4 48 hours constant rate test pumping 20 0 cm >1x10-3 5x10-6

Conclusion >1x10-3 5x10-6

7 Calculated from porosity of 0.3 and compressibility of aquifer material as hard rock of 4.4x10-20 m.d2/kg.


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5. Assessment of Effects

5.1 Potential Effects

Potentially affected parties from the exercising of the proposed application will be limited to the extent of and boundaries of the lava flow itself with respect to groundwater effects, and the rivers that are recharged by seepage from the basalt with respect to surface water effects. The extent of groundwater impacts is limited to the basalt because the high permeability Quaternary basalt lava flows are contained by an underlying low permeability siltstone basement.

The potential negative of the proposed abstraction are as follows:

1. Groundwater Level - The pumping induced drawdown cone of depressurisation impacting on the ability of neighbouring bore operators to abstract water;

2. Groundwater quality – The pumping induced reduction in groundwater flow may change the chemistry of the remaining water in the aquifer;

3. Stream Depletion - The flow removed from the aquifer system will impact on surface waters at some points within the catchment at some time following the commencement of pumping. This has the potential to impact on minimum flow in the surface water bodies and hence reduce existing users reliability. Specific issues identified include the neighbouring spring used for domestic purposes and the general flow in the Punakitere River;

4. Ground Subsidence Effects - The pumping induced drawdown cone of depressurisation could lead to ground settlement.

The potential positive effects of the proposed abstraction are local community socioeconomic benefits, and both positive and negative effect are addressed in the following section.

5.2 Actual Effects

The estimated actual effects from the operation of this consent have been considered in a conservative manner assuming the full entitlement under the consent is utilised for every day of the summer season, whereas in reality some summer days are wet and irrigation is not required. The following sections present the analysis results and conclusions.

5.2.1 Groundwater

Groundwater Level

We consider the groundwater flow system of the basalt at this location is governed by preferential flows within conduits and lava tubes and therefore aligned with the general flow direction of the lava flow. It is difficult to assess the impact from pumping on such a system because it is more akin to a subterranean stream than a conventional groundwater system. For the same reason it was difficult to produce a tangible impact on groundwater levels during test pumping.

While acknowledging that conventional groundwater drawdown analysis methods are not ideal for this type of system, we have nevertheless undertaken what we consider a conservative estimate (on the basis of continuous pumping) of the maximum potential effect on the groundwater levels using the Theis drawdown analysis method.

Parameters values used in the analysis for hydraulic conductivity were 1x10-3 m/s and storativity of 0.01 (consistent with the stream depletion analysis). The lapsed time considered in the analysis was 125 days,


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which represents the time required to consume the annual volume (267,104 m3/yr) at the maximum daily pump volume (2,160 m3/day).

The Theis method was developed for confined aquifers, but is also appropriate for unconfined aquifers where certain conditions are valid. As mentioned previously, we consider the aquifer to be locally confined, due to the pressure jump encountered during drilling as described in Section 4.1.

As mentioned above, the analysis method is considered conservative for this application because:

• The drawdown is significantly smaller than the saturated thickness (with distance from the well i.e. at neighbouring bores), which is a prerequisite for application of the Theis equation to unconfined aquifers.

• Delayed yield from the aquifer (unconfined) which would serve to maintain higher groundwater levels (reduce drawdown) are ignored.

• Time considered was after 125 days of pumping, which avoids early time effects and also equates to the maximum seasonal volume and hence groundwater impact.

The magnitude and extent of the impact on groundwater levels (cone of depression) expected from pumping the maximum seasonal volume of 267,104 m3 at the end of the irrigation season (after 125 days) is shown in Figure 25.

The analysis results indicate that three neighbouring permitted activity (PA) bores within 1,200 m of the pumping bore may experience up to 0.04 m (4 cm) of drawdown. This is considered insignificant.

There are two additional PA bores located within 1,800 m from the pumping bore that may experience up to 0.02 m of drawdown, and there are another three PA bores located approximately 2,700 m from the pumping bore that are unlikely to experience any drawdown.

The simulated impacts are considered insignificant – in fact they would be difficult to differentiate from normal climate induces variations in groundwater level.

Nevertheless, mitigation and monitoring is suggested to safeguard the closest neighbouring PA bores, as described in Section 5.3.

Figure 25. Impact on groundwater levels from pumping full seasonal volume (267,104 m3) after 125 days

(see A4 attachment at rear).

Groundwater Quality

The location and elevation of the orchard is significantly inland and above sea level, and given the basal depth of the pumping bores is designed for approximately 100 mAMSL, saline intrusion is near impossible. The landuse activity resulting from the take does not involve intensive fertiliser or other non-biodegradable chemical applications that could harm groundwater quality.

The quantum of water being abstracted would appear to be small in relation to what is available in the aquifer given the limited drawdown, hence loss of dilution effects is considered unlikely.

In summary, no groundwater quality impacts are considered likely from the proposed groundwater take and use of that water.

Sustainable Yield


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The sustainable yield of this aquifer is governed by recharge, but the difficulty with this bore is that it potentially taps a source that is far larger than can be mapped directly. For example, there is:

a) the direct recharge area as mapped (Figure 13);

b) possibility of additional recharge from seepage out of Late Tauanui, which has an additional surface area to the south; and

c) possibility of seepage from the older Tangihua Basalt complex further to the south of Lake Tauanui.

The bore appears to have tapped a subterranean stream (lava tube) and it is likely that this discharges further downgradient along the flow path of the lava field, as the lava thins, becomes unconfined and starts to seepage to the surface and the Punakitere River.

With consideration of just the direct recharge, the proposed annual volume represents approximately 40% of the annual recharge volume, which in its own right would normally be considered sustainable. However, as stated above, we consider the actual recharge volume to be significantly greater and therefore the proposed take would represent a smaller proportion of the annual volume.

Any risk concerning the sustainability of the aquifer will be mitigated by the standard monitoring conditions as part of the consent conditions, and through the agreement with local Iwi.

5.2.2 Surface Water

Marae Spring

As discussed in Section 4.1, the production bore constructed taps into a pressurised aquifer. This confirms that the aquifer is semi-confined and not directly connected to nearby surface waters such as the spring.

Figure 26 shows that the initial groundwater level encountered in the bore (at 23 m below ground level) is actually below the spring level, which suggest the shallowest groundwater in the bore is not flowing towards the spring. The deeper aquifer in the bore (from 29 m below ground level) has a relative groundwater pressure


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higher than the spring, but if it was connected with the spring the pressures would be similar. Our conclusion from this is that groundwater at the bore site is flowing down the valley in a north-northwestwardly direction Tautoro and not towards the spring.

Figure 26. Hydrogeological cross section in a west-east direction showing relative pressures of spring and bore.

Punakitere River

Because the aquifer is confined it is unlikely there will be any effects on surface water resources until the basalt lava flow becomes unconfined further downstream. This is likely to be some 1 to 2 km downstream, hence the effects will be felt on the seepages that drain into the Punakitere River.

Analysis of stream depletion on the Punakitere River was undertaken using the analytical tool presented in SKM (2012)8, which is based on an adaption of the Hunt (2007) bounded aquifer equation for Northland basalt.

The fractured basalt (95%) hydrologic setting was chosen given this default setting of the model is closest to the site geology (Section 2.8) and has the highest hydraulic conductivity assignment, albeit 2 orders of magnitude lower at 3.81x10-5 m/s than the bore test results indicate (>1x10-3 m/s). Parameters adapted for the model are as presented in Table 18 and Table 19.

Table 18. Stream depletion model pumping parameters.

Parameter Value

Annual Allocation (m3/annum) 267,104

Peak Abstraction Rate (L/s) 25

Distance to Stream (m) 1,500

Shallow Aquifer Thickness (m) 15

Total Aquifer Thickness (m) 60

Boundary Distance (m) 1,500

Table 19. Stream depletion model hydraulic parameters.

Parameter Value

Hydrogeological setting Fractured Basalt (95%ile)

Aquifer hydraulic conductivity

Kh

Kv

3.81x10-5 m/s

3.81x10-6 m/s

Top layer hydraulic conductivity 3.81x10-6 m/s

Storativity (upper and lower units) 0.01

Results are show in Figure 27 and indicate that:

8 The analytical tool was designed for the Northland Regional Council by SKM New Zealand. It uses the Hunt (2007) stream depletion method

developed by Bruce Hunt of the University of Canterbury to make predictions of stream depletion rates resulting from abstraction in a range of conceptual basalt aquifer settings. The aquifer settings are pre-built into the spreadsheet tool using conservative hydraulic parameters for each setting. This method was verified against trial numerical simulations based on basalt aquifer settings that are typically found in the Northland area.


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• The groundwater take results in a maximum impact on the surface water resource of approximately 80% of the take volume (or 20 L/s), however the maximum impact occurs at the end of the irrigation season (April).

• The impact during mid-summer (Dec/Jan) is approximately 40% of the take volume or 12 L/s.

• Full recovery occurs over the winter period, hence there is no long term effect.

During development and testing of the SKM (2012) model, a like-for-like comparison of the analytical model to results from a FEFLOW numerical model showed that the bounded analytical method of Hunt (2007) was more conservative than the numerical model. This suggest the analytical model is appropriate for high level or first pass assessment of stream depletion effects in localised basalt flows or compartmentalised basalt catchments.

In this regard, if impact results from the analytical model are considered minor in relation to available stream flow, given its conservativeness, further more complex analysis using numerical models would show a lesser impact and therefore not be deemed necessary. This infers an appropriate and pragmatic approach to catchments with low allocation levels and limited contentiousness, which we believe the current application to be.

Figure 27. Stream depletion simulation results from proposed pumping regime.

The maximum impact of approximately 20 L/s has been assessed in the context of the lowflow of the Punakitere River downstream of the site. The take impact represents approximately 6% of the mean annual low flow (MALF) and 7.5% of the one in five year low flow (Q5) (see Table 3).

It is difficult to gauge the cumulative level of impact on the river at this location because while there are four other surface water users (three District Council and Pinny’s) only one is a direct surface water take (the Wairoro Stream take at SH1, Kaikohe) with the others being from dam storage. Considering the Wairoro Stream in the cumulative impact assessment takes the allocation level to 7% and 9% of MALF and Q5, receptively.


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To place this level of allocation into context, the proposed interim allocation limits for rivers and streams where the mean flow of the river is greater than 5 m3/s (this applies to the Punakitere River) is 50% of MALF according to the Proposed National Environmental Standard on Ecological Flows and Water Levels9.

Therefore, the level of cumulative impact at between 7-9% on the Punakitere River is considered minor.

Other Surface Waters

Analysis of impacts on other surface water bodies such as Te Opou Stream the has not been undertaken because Te Opou Stream is considered to be in a different flow compartment of the basalt lava flow (see Figure 10) and for the same reason the impacts on the Marae spring were considered unlikely – i.e. the bore is confined in this area and flows in a different direction (to the north-northwest).

5.2.3 Ground Subsidence

The likelihood of ground subsidence occurring as a result of groundwater pumping is nil because i) drawdown is negligible10 and ii) the permanently saturated ground conditions comprise basaltic rock, which is naturally uncompressible (as opposed to say peats or clays).

5.2.4 Neighbouring Users

As discussed in Section 5.2.1, it is understood that the two closest neighbouring bores (203064 and 203039) are used for supply of domestic and stock drinking water at the neighbouring property, which is understood to be used as an Iwi training facility.

Section 5.3 discusses how any groundwater impacts that affect the water supplies will be monitored and mitigated if materialising.

5.2.5 Local Community Socioeconomic

The avocado orchard development will result in a tangible impact on the local community, which can only fully materialise with the irrigation water being sought under this application. Table 20 summarises the community impact

9 https://www.mfe.govt.nz/publications/fresh-water/proposed-national-environmental-standard-ecological-flows-and-water-leve-12 10 Pressure reduction in void space of earth material is required to induce compression of earth materials.


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Table 20. Summary of community impact of the proposed groundwater take.

Number of local employees

4-7 FTE's but this is a little bit seasonal, but would grow and become less seasonal with the orchard development

Estimate of annual spend on local suppliers

Irrigation $50,000 PA

Fertiliser $100,000 PA

Equipment $20-$50,000 PA

Repairs & Maintaining equipment $20,000 PA

Training and personal development $10,000 PA

Employ and train local workers

Create full time rather than seasonal part time jobs.

Provide blueprint for local community to further develop horticulture ventures on Iwi land.

5.3 Mitigation and Monitoring Proposed

Monitoring and mitigation is proposed as summarised in Table 21 in the event that groundwater effects manifest differently to that predicted and cause issues for the landowners at localised positions.

Table 21. Proposed monitoring and mitigation for groundwater level impacts.

Subject Bores Mitigation Monitoring/Inspection

203215 Self management - Honeytree Farms.

Monthly water level measurement on the last week of each month during the irrigation.

203064, 203039 Provision of supplementary water supply during the irrigation season will be made available from the irrigation bore if water becomes insufficient, as confirmed through monitoring/inspection.

An independent expert commissioned by Honeytree Farms will inspect these bores to determine the pump level in relation to groundwater level and bore depth, should problems arise with these bores.


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6. Consultation Extensive consultation has been undertaken with the local community.

6.1 Dairy Shed Meeting

An invitation was sent to neighbouring properties and the meeting was held at the dairy shed on Friday 3 June 2016 (Appendix D). At the meeting eleven people attended and their names are recorded in Table 22.

Table 22. Attendees at consultation site meeting of 3 June 2016.

Attendees

Joe Matene Mana TeWhata Kate TeWhata

Mitai Matene Jenny TeWhata Hinera TeRangi

Syrah Jane Matene Andrew Matene Jack Wood

Hone Matene Taura Matene

6.2 Follow-up Personal Contact

During the consultation process, mobile or local phone numbers were obtained for all members of neighbouring properties. The purpose of corresponding with the neighbours was to obtain a physical or electronic addresses for the distribution of a consultation letter identifying the proposed activity and potential environmental impacts.

On 24 January 2017 all neighbours were contacted. If there was no answer, a voice message was left (when possible). All voice messages detailed the purpose of the call and asked the individual to return the call or supply a physical or electronic address via a provided contact email.

On 27 January 2017 any neighbours that had not provided a response or had been spoken to previously were called again. Voice messages were left again with anyone who did not answer. The voice message detailed in full the purpose of the call and asked the individual to return the call or get in touch via email.

This process was repeated again on the 8 February 2017. Contact was made with all but two neighbours by the end of this process – Hinera Te Rangi and Taura Matene (although Taura works for Honeytree Farms and is fully aware of this application). One of the contact numbers for an individual was incorrect and the other had not answered any calls and did not have a voice message system to leave details of the purpose of call or contact information.

6.3 Letter to Neighbours and Local Iwi

Following these phone calls, a letter dated 10 February 2017 (Appendix E) was sent out to a number of neighbours and Iwi representatives, as advised by the NRC. The list of people the consultation letter was sent to is provided in Table 23. The timeframe for responses to this letter given was by close of business Friday 3 March 2017 (2-3 weeks depending on when letter received).


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6.4 Follow-up Meeting with Neighbours and Local Iwi

A follow-up meeting was held at Te Riingi Marae on Sunday 9 April 2017, where presentations were made by Honeytree Farms on the vision and strategy for the orchard development, and by WWA on the hydrogeology of the area and potential environmental effects. A robust questions and answers session followed, and subsequent to this a Water Management Committee was formed and further discussion occurred between the local community, Hapu, the Water Management Committee and the applicant. This is summarised in the letter to Honeytree Farms provided by the Te Riingi Marae dated 26 June 2017, and included as Appendix F. Everything in the letter from Te Riingi Marae has been fully agreed with by Honeytree Farms and will be implemented as a side agreement outside of the consent conditions.


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Table 23. Consultation letter sent list.

Name Phone Property Address Postal Address Email

Jason and Penelope Bill

5794A Mangakahia RD 45 Kendall Road, Kerikeri, 0230

Syrah Jane, Joe and Hone Matene

(09) 401 1097 6336 Mangakahia Road, Tautoro

Mitai Matene (09) 405 2543 [email protected]

Taura Matene Honeytree Farms employee

Andrew Matene 027 252 3607 PO Box 48, Kaikohe

Mana Te Whata 027 477 0448 [email protected]

Te Whata Farming Limited

(09) 401 2192 264 Orakau RD c/o

Jenny TeWhata

PO Box 230, Kaikohe, 0440

Kate Te Whata C/o Jenny

Tokikapu Te Whata 6259 Mangakahia RD 6259 Mangakahia Road, RD 1, Kaikohe, 0474

Te Whanau Tame Te Whata Trust

6270 Mangakahia RD C/- Mr Isacc Te Whata, 20 Cedar Avenue, MASSEY, AUCKLAND, 0614

Hinera Te Rangi (09) 401 0627

Jackie and Jack Wood

(09) 401 2543 350 Orakau Road, RD 1, Kaikohe, 0474 [email protected]

Tono Matthews 6278 Mangakahia RD 6278 Mangakahia Road, RD 1, Kaikohe, 0474

Haereata Matthews 6276 Mangakahia RD 6276 Mangakahia Road, RD 1, Kaikohe, 0474

Wi Whiu 6082 Mangakahia RD C/- JR & NJ Wood, 390 Orakau Road, RD 1 KAIKOHE, 0474

Susan Whiu 6084 Mangakahia RD C/- Nl Bedggood, 49 Orrs Road, Kaikohe, 0405

Te Tumu Paeroa 6180 Mangakahia RD PO Box 5038, Lambton Quay, Wellington, 6145

Tarahau Farming Limited

6220 Mangakahia RD 6259 Mangakahia Road, RD 1, Kaikohe, 0474

Te Runanga A Iwi O Ngapuhi

C/- Tanya Martin, PO Box 263, Kaikohe 0440

[email protected]

Te Aroha Marae C/- Chairperson - Te Reo Hau, 2875 Mangakahia Road, RD 2, Whangarei 0172

Nga Tirairaka O Ngati Hine

021 0221 7760 PO Box 8, Moerewa 0244 [email protected]

mailto:[email protected]








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7. Summary and Conclusions

7.1 Overview

Honeytree Farms Limited are developing a 70 hectare property at Tautoro near Kaikohe into a 54.4 canopy hectare avocado orchard. The orchard is implementing state of the art techniques for avocado propagation and fruit management and this will require irrigation. The orchard development has already employed three fulltime staff from the local community and by the end of the development is anticipating that up to seven full time equivalent staff members will be required.

A drilling program and aquifer testing program was undertaken to establish the orchard water supply. Two pilot bores were drilled and one of these was successfully converted into a high yielding 250 mm production bore that is easily capable of delivering the peak instantaneous water requirement of 25 L/s.

During drilling, the bore was dry to 23 m and from 23 m to 29 m a layer of hard massive very low permeability basalt was encountered. At 29 m, a highly fractured basalt layer followed by rubbly and scoriaceous basalt layer was encountered. In this layer, groundwater was pressurised and rose above the overlying massive basalt layer to a level of 18 m, suggesting the basalt from 29 m is confined.

The drillers experienced rapid drops in circulation pressure and drill rod depths as they progressed through the highly fractured and cavernous zones from 29 m indicating the possibility of lava tubes in the rock. These conduits are likely orientated in the direction of the lava flow, which at the production bore location is towards the north-northwest. Any effects of pumping are likely to manifest downgradient along this alignment and where the basalt becomes unconfined as it thins towards the Punakitere River.

7.2 Consent Application

This application is for a groundwater take for avocado orchard irrigation purposes in accordance with the following limits:

• Peak Instantaneous Rate 25 L/s

• Max. Daily Volume 2,160 m3/day

• Max. Seasonal Volume 267,104 m3/season

The irrigation demand has been determined by a Soil Moisture Water Balance Model and the maximum rate being applied to the soils of 4.8 mm/day is considered efficient.

The impact on the groundwater and surface water resources of the proposed maximum seasonal volume was assessed.

Test Pumping

Test pumping of the bore has determined that the aquifer is extremely permeable, with a hydraulic conductivity in the order of 1x10-3 m/s – equivalent to a basalt with lava tubes or coarse gravels (like within a riverbed). During pumping at between 18-20 L/s, a maximum drawdown of 4 cm was induced after 6 hours in the pumping bore. The highly fractured basalt that the production zone of the bore taps is pressurised by 5 m in comparison to the overlying rock units, which infers there is no direct connection with any nearby surface waters. The lava flow heads in a northward direction towards Tautoro and it is likely any connection with or discharge to surface waters is downgradient near the Punakitere River.

Groundwater Impacts

The impact on groundwater levels (cone of depression) expected from pumping of the maximum seasonal allocation volume of 267,104 m3 at the end of the irrigation season (125 days) was assessed. The analysis


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results indicate that three neighbouring permitted activity (PA) bores within 500 m of the pumping bore may experience up to 0.31 m (31 cm) of drawdown. This is considered insignificant at this distance.

There are five additional PA bores located within 1,800 m from the pumping bore that may experience up to 0.19 m (19 cm) of drawdown, and there are another three PA bores located approximately 2,700 m from the pumping bore that may experience an impact of up to 0.16 m.

None of the simulated impacts are considered more than minor, however mitigation in the form of supplementary water supply and monthly groundwater level monitoring is suggested to safeguard the closest neighbouring PA bores.

Surface Water Impacts

A stream depletion assessment indicated the maximum level of impact from the 25 L/s groundwater take on the Punakitere River downstream of the site would be approximately 20 L/s, but this level of impact does not manifest in the stream until the end of the season (i.e. after the peak) and with continuous abstraction during the entire irrigation season.

The stream depletion effect was considered as part of the surface water allocation for the catchment and along with other takes the cumulative level of allocation was considered between 7-9% of MALF. This is significantly less than the suggested allocation level in the proposed NES on ecological flows and water levels, which is 50% MALF for a river of this size with a mean flow > 5 m3/s.

Local Community Socioeconomic Benefits

The proposed orchard development will enable the realisation of a number of socioeconomic benefits in terms of additional employment (4-7 FTE's) and additional spending on support products (approximately $250,000 per annum).

Overall the proposal is considered to have a significant number of socioeconomic benefits and only minor environmental impact, of which all can be mitigated if realised (albeit minor).

Consultation

Significant effort was made by the applicant and their consultant to conduct open dialogue with the community and local Iwi. The net upshot of the consultation was a letter of support for the Te Riingi Marae and the formation of a Water Management Committee that the applicant has agreed to engage in and collaboratively work with in the future to management the water resources of Tautoro.


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8. References Clayden, B., Webb, T. H. 1994: Criteria for defining the soil form – the fourth category of the New Zealand Soil Classification. Landcare Research Science Series 3. Lincoln, New Zealand, Manaaki Whenua Press. 36p

Griffiths, E. 1985: Interpretation of soil morphology for assessing moisture movement and storage. New Zealand Soil Bureau Scientific Report 74. 20p.

Hewitt, A. E. 1993: Methods and rationale of the New Zealand Soil Classification. Landcare Research Science Series 2. Lincoln, New Zealand. Manaaki Whenua Press. 71p.

Milne, J. D. G.; Clayden, B; Singleton, P. L.; Wilson, A.D.1995: Soil description handbook. Lincoln, New Zealand, Manaaki Whenua Press. 157p.

Northland Regional Council, 1992. Kaikohe Water Resources Assessment. Unpublished report.

SKM (2006a). Preliminary Hydrogeological Investigations – Four Northland Aquifers – Three Mile Bush Groundwater Resource. Report Prepared for Northland Regional Council.

SKM (2006b). Preliminary Hydrogeological Investigations – Four Northland Aquifers – Maungakaramea Groundwater Resource. Report Prepared for Northland Regional Council.

SKM (2007). Preliminary Hydrogeological Investigations – Four Northland Aquifers – Kaikohe Groundwater Resource. Report Prepared for Northland Regional Council.

SKM (2010). Maunu – Maungatapere - Whatitiri Aquifers - Sustainable Yield Assessment. Report Prepared for Northland Regional Council.

SKM (2012). Groundwater/Surface Water Integrated Management. Maunui-Maungatapere-Whatitiri Basalt Aquifers. Report prepared for Northland Regional Council.

Sutherland, C.F.; Cox. J.E.; Taylor. N.H.; Wright. A.C.S. 1980: Soil map of Mangakahia-Dargaville area (sheets P06/O7), North Island, New Zealand. Scale 1:100 000 N.Z. SoiI Bureau Map 186.

Webb, T. H., Wilson, A. D. 1995: A manual of land characteristics for evaluation of rural land. Landcare Research Science Series 10. Lincoln, New Zealand, Manaaki Whenua Press. 32p.

Wilson, A.D. and McDonald, W.S., 1987. Soils of Northland 2. Kohumaru Suite (Mangakahia, Kohumaru, Pakotai, Parakao Soil Sets). NZ Soil Bureau District Office Report Kk3. Department of Scientific and Industrial Research.


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Appendix A. Soil Physical Characteristics The following soil characteristics are summarised from Landcare Research’s web page http://smap.landcareresearch.co.nz/glossary and references where provided.

A.1 Potential Rooting Depth

Potential rooting depth describes the minimum and maximum depths (in metres) to a layer that may impede root extension, hence the depth of soil that a plant can exploit water from. Such a layer may be defined by penetration resistance, poor aeration or very low available water capacity. In soil with a deep potential rooting depth, some grass roots will penetrate to over 100 cm deep. When plants extract water and nutrients from deep in the soil they are more resistant to drought, hence require less irrigation water, and the soil is less prone to leaching.

Potential rooting depth classes are described fully in Webb and Wilson (1995) and are as summarised in Table A.1.

Table A.1. Potential rooting depth classes (m).

Depth profile Min Max

Very shallow 0.15 0.24

Shallow 0.25 0.44

Slightly deep 0.45 0.59

Moderately deep 0.6 0.89

Deep 0.9 1.19

Very deep 1.2 1.5

A.2 Plant Available Water

Plant available water (PAW) is the amount of water potentially available to plant growth that can be stored in the soil to a depth of 100 cm, or to the potential rooting depth (whichever is the lesser). PAW takes into account variations in soil horizons and is expressed in units of millimetres of water, i.e. in the same way as rainfall. A PAW of 100 mm implies that 10% of the soil volume is water available to plants. Low PAW is <60 mm, moderate is between 60 and150 mm, and high is ≥150 mm, as described in Table A.2.

Plants can only extract water where roots can grow. Thus, where a root barrier occurs within 100 cm, the PAW reported will be the PAW to the root barrier. It is important to recognise that PAW is a potential value and not all the water is equally available. For example, as the soil dries out the water becomes more difficult to extract. As a general ‘rule of thumb’, plant growth will begin to slow down when 50% of PAW has been extracted. There are some crops that have shallow rooting depth, e.g. potatoes usually only root to a depth of 60 cm. In this case the PAW to 60 cm depth should be used.

http://smap.landcareresearch.co.nz/glossary


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Table A.2. Plant available water classes (mm).

Depth profile Min Max

Very low 0 29

Low 30 59

Moderate 60 89

Moderately high 90 149

High 150 249

Very high 250 350

A.3 Depth to Slow Permeable Horizon

Depth to a slowly permeable horizon describes the minimum and maximum depths (in metres) to a horizon where the permeability is less than 4 mm/hr as measured by techniques outlined in Griffiths (1985). If no slowly permeable horizon is observed, the taxon is allocated to Class 6. Table A.3 summarises the depth for each class.

Table A.3. Depth to slow permeable horizon (mm).

Class Min Max

1 0 0.44

2 0.45 0.59

3 0.60 0.89

4 0.90 1.19

5 1.20 1.49

6 Not encountered

A.4 Drainage Class

Soil drainage is considered a class that indicates how wet a soil is likely to be under high rainfall conditions. Well-drained soils allow water to drain through the profile in all periods of the year. Poorly drained soils either have a water table close to the surface, or a compact subsurface layer that limits the rate that water can drain through the soil. Imperfectly drained soils are in an intermediate condition between well-drained and poorly drained.

A poorly drained soil is susceptible to pugging and it will lose nitrogen to the atmosphere. A deep, poorly drained soil will cope better in a drought. Well-drained soils can sometimes be droughty, but are less likely to pug. Provided they are not prone to bypass flow, poorly drained soils will not leach to the same extent as well-drained soils.

Drainage classes are assessed using criteria of soil depth and duration of water tables inferred from soil colours and mottles, or from reference to diagnostic horizons, as described in Table A.4. Drainage classes used here are the same as those used in the NZ Soil Classification (Hewitt 1993), and outlined by Milne et. al. (1995).


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Table A.4. Soil drainage classes.

Class Description

Water table depth below A horizon

Compacted subsurface depth

Low chroma on ped or cut surfaces

High Chroma redox mottles

(cm) (cm) (%) (%)

1 Very poor 1 ≤10 ≥50

2 Poor ≤15 ≤30 ≥50

3 Imperfect ≤15 ≤30 ≤50 and/or ≥2

>15 30–90 ≥50

4 Moderately well 30–90 ≥2

60–90 ≥50

5 Well >90 <2

A.5 Permeability

Permeability is the rate that water moves through saturated soil and hence defines the ability of a soil to drain (regardless of external influences on water tables, e.g. being low-lying in the landscape). The permeability of a soil profile is related to potential rooting depth, depth to a slowly permeable horizon and internal soil drainage, which is governed by texture, structure and soil density.

A soil with moderate permeability is better for soil productivity, drainage, nutrient retention and effluent adsorption than a soil with slow permeability. Permeability profile is often expressed as two values such as ‘moderate over slow’. This is where a layer of moderate-draining soil sits above a layer of slow-draining soil. Permeability of a profile under extended rainfall conditions is governed by the permeability of the layer that is most slowly permeable. Permeability classes and their equivalent flow rates (mm/h) from Clayden and Webb (1994) are as shown in Table A.5.

Table A.5. Soil permeability classes.

Class Rate (mm/hr)

Slow < 4

Moderate 4-72

High > 72

A.6 Macroporosity

Macroporosity is an expression of the air-filled porosity of the soil at ‘field capacity’. It is a measure of the proportion of large pores greater than 60 µm in the soil and is currently defined as the proportion of soil drained between the pressure levels of 0 and –10 kPa. Macroporosity is usually expressed as a percentage of the total volume of the soil.

Macropores drain quite rapidly after rainfall and provide the circulation of oxygen to roots. Where macroporosity is limited the proportion of air is restricted, and when a low macroporosity soil becomes wet, air is excluded more readily than a high porosity soil. Consequently, reduced diffusion of oxygen will lead to the comparatively more rapid onset of anaerobic conditions. Very low macroporosity may also limit the extension of roots and drainage of water.


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Values are minimum values over the specified profile section (0–0.6 m), and are expressed as a percentage of the soil volume (Webb and Wilson, 1995), as shown in Table A.6. Macroporosity along with potential rooting depth is used to calculate total soil moisture content in mm of water.

Table A.6. Macroporosity classes.

Class Min (%) Max (%)

Very low 0 6

Low 6 7.5

Moderate 7.5 10

High 10 30

Very high 30 40


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Appendix B. Description of the Soil Moisture Water Balance Model.

B.1 Overview

The soil moisture water balance model (SMWBM) is a deterministic lumped parameter model originally developed by Pitman (1976) to simulate river flows in South Africa. The code was reworked into a Windows environment and the functionality extended to include a surface ponding function, additional evaporation functions and an irrigation module.

The model utilises daily rainfall and mean-monthly evaporation data to calculate soil moisture conditions and the various components of the catchment water balance under natural rainfall or irrigated conditions. The model operates on a time-step with a maximum length of daily during dry days, with smaller hourly time-steps implemented on wet days.

The model incorporates parameters that characterise the catchment in terms of:

• interception storage,

• evaporation losses,

• soil moisture storage capacity,

• plant available water capacity,

• soil infiltration,

• sub-soil drainage;

• surface runoff (quickflow);

• stream baseflows (groundwater contribution); and

• the recession and/or attenuation of groundwater and surface water flow components, respectively.

B.2 Fundamental Operation

The fundamental operation of the model is as follows:

When a rainday occurs, daily rainfall is disaggregated into the hourly time-steps based on a pre-defined synthetic rainfall distribution, which includes peak intensities during the middle of the storm. This time stepping approach ensures that rainfall intensity effects and antecedent catchment conditions are considered in a realistic manner by refined accounting of soil infiltration, ponding and evaporation losses.

Rainfall received must first fill a nominal interception storage (PI – see below) before reaching the soil zone, where the net rainfall is assessed as part of the runoff/infiltration calculation.

Water that penetrates the soil fills a nominal soil moisture storage zone (ST). This zone is subject to evapotranspiration via root uptake and direct evaporation (R) according to the mean monthly evaporation rate and current soil moisture deficits. The soil moisture zone provides a source of water for deeper percolation to the underlying aquifer, which is governed by the parameters FT and POW.

If disaggregated hourly rainfall is of greater intensity than the calculated hourly infiltration rate (ZMAX, ZMIN) surface runoff occurs. Surface runoff is also governed by two other factors, which are the prevailing soil moisture deficit and the proportion of impervious portions of the catchment directly linked to drainage pathways (AI).

Rainfall of sufficient intensity and duration to fill the soil moisture storage results in excess rainfall that is allocated to either surface runoff or groundwater percolation depending on the drainage and slope characteristics of the catchment (DIV).


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Finally, the model produces daily summaries of the various components of the catchment water balance and calculates the combined surface runoff/percolation to groundwater to form a total catchment discharge.

B.3 Model Parameters

Table B.1 summarises the model parameters and value assignments for this study, while Figure B.1 shows the user interface for the Kiripaka soils model.

Table B.1. Model parameter summary.

Parameter Name Parameter Values Description

Kiripaka Aponga

ST (mm) Maximum soil water content.

138 134 ST defines the size of the soil moisture store in terms of a depth of water. ST is approximately equivalent to root zone depth divided by soil porosity.

SL (mm) Soil moisture content where drainage ceases.

0 0 Soil moisture storage capacity below which sub-soil drainage ceases due to soil moisture retention.

ZMAX (mm/hr)

Maximum infiltration rate.

15 5 ZMAX and ZMIN are nominal maximum and minimum infiltration rates in mm/hr used by the model to calculate the actual infiltration rate ZACT. ZMAX and ZMIN regulate the volume of water entering soil moisture storage and the resulting surface runoff. ZMIN is usually assigned zero. ZMAX is usually assigned the saturated infiltration rate from field testing. ZACT may be greater than ZMAX at the start of a rainfall event. ZACT is usually nearest to ZMAX when soil moisture is nearing maximum capacity.

ZMIN (mm/hr)

Minimum infiltration rate.

0 0

FT (mm/day)

Sub-soil drainage rate from soil moisture storage at full capacity.

6 3 Together with POW, FT (mm/day) controls the rate of percolation to the underlying aquifer system from the soil moisture storage zone. FT is the maximum rate of percolation through the soil zone.

POW (>0) Power of the soil moisture-percolation equation.

2 2 POW determines the rate at which sub-soil drainage diminishes as the soil moisture content is decreased. POW therefore has significant effect on the seasonal distribution and reliability of drainage and hence baseflow, as well as the total yield from a catchment.

AI (-) Impervious portion of catchment.

0 0 AI represents the proportion of impervious zones of the catchment directly linked to drainage pathways.

R (0,1,10) Evaporation-soil moisture relationship

10 10 Together with the soil moisture storage parameters ST and SL, R governs the evaporative process within the model. Three different relationships are available. The rate of evapotranspiration is estimated using either a linear (0,1) or power-curve (10) relationship relating evaporation to the soil moisture status of the soil. As the soil moisture capacity approaches full, evaporation occurs at a near maximum rate based on the mean monthly pan evaporation rate, and as the soil moisture capacity decreases, evaporation decreases according to the predefined function.

DIV (-) Fraction of excess rainfall allocated directly to pond storage.

1 1 DIV has values between 0 and 1 and defines the proportion of excess rainfall ponded at the surface due to saturation of the soil zone or rainfall exceeding the soils infiltration capacity to eventually infiltrate the soil, with the remainder (and typically majority) as direct runoff.

TL (days) Routing coefficient for surface runoff.

1 1 TL defines the lag of surface water runoff. This is not necessary to define for this study as we are only interested in the groundwater percolation component of the water balance.

GL Groundwater recession parameter.

1 1 GL governs the lag in groundwater discharge or baseflow from a catchment.


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Figure B.1. SMWBM calibrated model parameters in the user interface.


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Appendix C. Drilling Results - Geological Profiles


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Figure 28. Pilot hole #1 lithological log and production bore construction details.


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Figure 29. Pilot hole #2 lithological log.


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Figure 30. McMillans Drilling production bore as-built details.


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Table 24. Geological profile for pilot bore #1.

Depth (m) Description Core box photo

0 – 10.5 Alternating bands of vesicular (10-15 mm) and massive hard BASALT. Dry.


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10.5 - 23 Hard massive BASALT with alternating bands of vesicular basalt. Small fracture zones at 7.2 m and 12.2 m. Dry to 23 m.


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23 - 29 Hard massive grey/green BASALT.


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29 - 31 Highly fractured, rubbly and vesicular BASALT.

Pressurised water encountered with SWL increasing to 18 m.

31 - 33 BASALT with large cavities and scoria.

33 - 36 Vesicular hard BASALT.


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36 - 41 Broken BASALT and scoria rubble.

41 - 45 Massive BASALT with some fractures


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45 - 57.5 Massive BASALT with occasional fractures and small vesicles.


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57.5 - 58.5 Rubbly BASALT.


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58.5 - 60.4 SILTSTONE. Light grey / tan highly weathered siltstone.

Table 25. Geological profile for pilot bore #2.

Depth (m)

Description Core box photo

0-7.5 Scoria and scoriaceous BASLT.


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Depth (m)


7.5-10.4 Soft Basalt. Very light grey layered and vesicular soft gritty tuffaceous pumice/ash.


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Depth (m)


10.4 – 15.9

BASALT. Slowly becoming darker and more massive basalt with depth.

15.9 – 17.0

BASALT. Massive basalt with some vesicles.

17.0 – 18 Fractured scoriaceous BASALT.


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Depth (m)


18 – 19.5 Fractured and moderately vesicular BASALT.

19.5 – 21.0

BASALT becoming less vesicular and more massive.

21 – 22.5 Massive BASALT.


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Depth (m)


22.5 – 26.6

SILTSTONE. Light grey and light orange/yellow mottled soft highly weathered clayey siltstone


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Appendix D. Consultation Invitation

Invitation to Honeytree Farms Tahi Avocado Orchard site:

6258 Mangakahia Road

1 PM Friday 3rd June 2016

To discuss Honeytree Farms proposed ground water application.

Please come along to discuss;

The consultation process.

Local Iwi’s cultural and traditional concerns regarding water.

The aquifer.

Our plans.

Tony Hayward

Tony Snushall

Honeytree Farms Ltd

027 5372373


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Appendix E. Further Consultation Letter


PO Box 314

Kumeu 0814

Auckland, New Zealand

T +64 21654422

E [email protected]


Filename: Let_Honeytree Farms Consultation_100217 PAGE 1

Document no.: 1

10 February 2017 WWA0009

To whom it may concern,

Honeytree Farms Limited – Avocado Irrigation Groundwater Supply, 6258 Mangakahia Road Kaikohe

Consultation Letter for Resource Consent Application under the Resource Management Act (RMA)

1. Introduction

Honeytree Farms Limited are developing a 78 hectare property at 6258 Mangakahia Road Kaikohe into an avocado orchard with a planted area of approximately 54 hectares.

The orchard will require an irrigation system to counter summer soil moisture deficits, and to maintain tree health and fruit growth. The irrigation demand is 25 L/s, which will be supplied by one production bore installed during October 2015.

An open invitation to neighbouring property owners was extended to attend an on-site meeting on 3 June 2016 to hear from one of the company directors about their plans and aspirations, and ourselves as the water experts preparing the resource consent application and assessment of environmental effects (AEE).

1.1 Letter objective

The objective of this letter is to provide a second more formal opportunity for consultation with us on the proposed activity. In the following we will provide:

• a brief description and plan of our proposed activity;

• a preliminary assessment of environmental effects; and

• a description of measures proposed to reduce the extent or impact of those effects.

1.2 What is Consultation?

In the context of seeking a resource consent, consultation is the process of communicating with people or groups who may be interested in or affected by a proposed activity, in this case a groundwater take consent.

Public participation is one of the key principles underlying the RMA. People are affected every day by the actions and activities of our neighbours, and by those that use the same resources as us. Therefore, we should talk with others about any plans to change our activities or resource use, and what the implications might be.

Honeytree Farms Limited – Consultation Letter

10 February 2017


Document no.: 1

The RMA does not require an applicant to consult anyone about their application for resource consent.

However, the RMA does require people applying for resource consent to submit a record of any consultation undertaken and the responses received. This can give decision-makers the information they need to make well-founded decisions. In particular, consultation can have a significant bearing on the Council’s notification process, whether that be a decision for “no notification”, “limited notification” or full “public notification”.

While it is not obligatory to consult or get written approvals from affected parties, doing both will usually allow the smooth processing of the consent by the council, and save time and money.

1.3 Follow-up or feedback

We would like to extend an offer of follow-up contact to discuss the proposal in the following days. Please email your feedback, thoughts or concerns to [email protected].

We will also try to contact you via telephone to confirm you have received the information and to arrange further communication (preferably face-to-face) if there are any issues.

Subject to the feedback received, Honeytree Farms are also open to another site meeting if there is interest.

The timeframe for providing your feedback is by close of business Friday 3 March 2017.

2. Proposed Activity

The proposed activity and associated assessment of environmental effects (AEE) are described in detail in the attached AEE document. The following provides a summary.

As described above, Honeytree farms have constructed a production bore and seek consent from the Northland Regional Council for a groundwater take for avocado orchard irrigation purposes in accordance with the following limits:

• Peak Instantaneous Rate 25 L/s

• Max. Daily Volume 2,160 m3/day

• Max. Seasonal Volume 285,336 m3/season

The irrigation demand has been determined by a Soil Moisture Water Balance Model and the maximum rate being applied to the soils of 4.8 mm/day is considered efficient.

2.1 Assessment of Effects

The impact on the groundwater and surface water resources of the proposed maximum seasonal volume was assessed.

Test Pumping



10 February 2017


Document no.: 1

Test pumping of the bore has determined that the aquifer is extremely permeable, with a hydraulic conductivity in the order of 1x10-3 m/s – equivalent to a basalt with lava tubes or coarse gravels (like within a riverbed). During pumping at between 18-20 L/s, a maximum drawdown of 4 cm was induced after 6 hours in the pumping bore. The highly fractured basalt that the production zone of the bore taps is pressurised by 5 m in comparison to the overlying rock units, which infers there is no direct connection with any nearby surface waters. The lava flow heads in a northward direction towards Tautoro and it is likely any connection with or discharge to surface waters is downgradient near the Punakitere River.

Groundwater Impacts

The impact on groundwater levels (cone of depression) expected from pumping of the maximum seasonal allocation volume of 285,336 m3 at the end of the irrigation season (132 days) was assessed. The analysis results indicate that three neighbouring permitted activity (PA) bores within 1,200 m of the pumping bore may experience up to 0.04 m (4 cm) of drawdown. This is considered insignificant at this distance.

There are two additional PA bores located within 1,800 m from the pumping bore that may experience up to 0.02 m (2 cm) of drawdown, and there are another three PA bores located approximately 2,700 m from the pumping bore that will experience no impact whatsoever.

None of the simulated impacts are considered more than minor, however mitigation in the form of supplementary water supply and monthly groundwater level monitoring is suggested to safeguard the closest neighbouring PA bores.

Surface Water Impacts

A stream depletion assessment indicated the maximum level of impact from the 25 L/s groundwater take on the Punakitere River downstream of the site would be approximately 20 L/s, but this level of impact does not manifest in the stream until the end of the season (i.e. after the peak) and with continuous abstraction during the entire irrigation season.

The stream depletion effect was considered as part of the surface water allocation for the catchment and along with other takes the cumulative level of allocation was considered between 7-9% of mean annual low flow (MALF). This is significantly less than the suggested allocation level in the proposed National Environment Standard on ecological flows and water levels, which is 50% MALF for a river of this size with a mean flow > 5 m3/s.

Local Community Socioeconomic Benefits

The proposed orchard development will enable the realisation of a number of socioeconomic benefits in terms of additional employment (4-7 FTE's) and additional spending on support products (approximately $250,000 per annum).

Overall the proposal is considered to have a significant number of socioeconomic benefits and only minor environmental impact, of which all can be mitigated if realised (albeit minor).

2.2 Mitigation (if required)

Provision of supplementary water supply during the irrigation season will be made available from the irrigation bore if water becomes insufficient, as confirmed through monitoring/inspection.


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3. Closure

We trust this letter outlines the proposal, assessment of effects, and mitigations measures proposed (if needed). Please do not hesitate to contact me if further clarification is required.

You are not required or obliged to send your approval of this proposed development to us, but if you would like to signal support, please could you place your name and signature in the space provided below.

Thank you for your time.

Yours sincerely,

Jon Williamson Managing Director +64 21 654422 | [email protected] I/We support the application by Honeytree Farms Limited for the groundwater take at 6258 Mangakahia Road Kaikohe, described herein: Name ........................................................................ Signature ...........................................................



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Appendix F. Response to Consultation from Te Riingi Marae

Irrigation Water Supply Avocado Orchard …...One in 5-year 7-day low flow (Q5) 0.567 1.74 The...

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Transcript of Irrigation Water Supply Avocado Orchard …...One in 5-year 7-day low flow (Q5) 0.567 1.74 The...