Levin Wastewater Land Application Re-Consenting

Levin Wastewater Land Application Re-consenting:

The Pot Site Characterisation

(LEI, 2015:B7a)

Prepared for Horowhenua District Council

Prepared by

February 2017

Levin Wastewater Land Application Re-consenting – The Pot Site Characterisation

Horowhenua District Council

This report has been prepared for the Horowhenua District Council by Lowe Environmental Impact (LEI). No liability is accepted by this company or any employee or sub-consultant of this company with respect to its use by any other parties.

Quality Assurance Statement

Task Responsibility Signature

Project Manager: Hamish Lowe

Prepared by: Sian Cass

Reviewed by: Hamish Lowe, Rob Potts, Katie Beecroft Approved for Issue by: Hamish Lowe

Status: Final

Prepared by:

Lowe Environmental Impact Ref: RE-10093-HDC-Site Characterisation-Pot-170202 P O Box 4467 Palmerston North 4442 Job No.: 10093 | T | [+64] 6 359 3099 | E | [email protected] Date: 02 February 2017 | W| www.lei.co.nz

Revision Status

Version Date Reviewer What Changed & Why

1 17/07/2015 HL Initial draft and review

2 28/11/2016 HL Updated data from more current reports.

3 01/02/2017 KB Soil characteristics report incorporated because of repetitious and small size of report.

TABLE OF CONTENTS

1 EXECUTIVE SUMMARY ...... 1

2 INTRODUCTION ...... 3

2.1 Purpose ...... 3

2.2 Background ...... 3

2.3 Scope ...... 3

3 SITE LOCATION ...... 5

3.1 Site Location ...... 5

3.2 Site Ownership ...... 5

4 SITE CHARACTERISTICS ...... 6

4.1 Landform ...... 6

4.2 Vegetation ...... 7

4.3 Climate ...... 8

4.4 Surface Water & Artificial Water Courses ...... 10

4.5 Buffers ...... 10

5 SOIL CHARACTERISTICS ...... 13

5.1 General ...... 13

5.2 Test Location Selection ...... 13

5.3 Soil Hydraulic Conductivity ...... 14

5.4 Soil Chemistry ...... 19

6 IRRIGATION ASSESSMENT ...... 22

6.1 Current Irrigation ...... 22

6.2 Pine Management ...... 22

6.3 Harvest Strategy ...... 22

6.4 Potential Irrigation Sites at The Pot ...... 23

7 CONCLUSIONS AND RECOMMENDATIONS ...... 24

8 REFERENCES ...... 27

9 APPENDICES...... 28

Appendix A Figures Appendix B Soil Hydraulic Conductivity Graphs Appendix C Soil Chemical Analysis

1 EXECUTIVE SUMMARY

Horowhenua District Council (HDC) is considering modifications to a number of their wastewater treatment plants (WWTP) and associated discharges. This includes the operation of the Levin WWTP and discharges at what is referred to as The Pot. The Pot receives treated wastewater from Levin’s WWTP to a storage pond on-site: Pot Pond). The surrounding area is irrigated from the pond to a mix of pine trees and grass. The pine trees are mature and require harvesting. This report describes the general site characteristics at The Pot including the soils and vegetation.

The attributes relevant for an upgraded irrigation design for the currently irrigated land and any additional irrigation area available at The Pot are listed below. Site Location • The Pot is 110.5 hectares, and located 7 km west of the Levin township. The Tasman sea is 600 m from the most western boundary and the Waiwiri Stream is the property’s southern boundary; • The north and east boundary may permit less buffer distance due to the eastern boundary being owned by HDC and the northern property owners interest in receiving some of the wastewater. Site Ownership • Two land titles at The Pot are owned by HDC and two are owned by Muaūpoko Lands Trust. The land administered by Muaūpoko Lands Trust has renewed the lease to HDC and maintains The Pot site availability for irrigation. Landform • Landform is steep dunes with flat areas in between; • Up to 7% of the site has steep slopes that will require irrigation rates that avoid mobilising the sandy soil and encourages permanent vegetative cover; and • Additional factors are listed in the results and conclusions of the soil report (Landcare 2016:B9). Vegetation (Boffa Miskell, 2016:B10) • Vegetation is mixed grass and pine plantation with isolated patches of natives, swamp species and undeveloped vegetation; • Irrigation will need to avoid ‘kanuka forest’ (north side of the Pot Pond) and ‘carex sedge wetland’ (NW portion of The Pot) because of their recognition as regionally threatened habitat types identified in Horizons One Plan Schedule F; and • Pre-works fish rescue and transfer was recommended (Boffa Miskell 2016:B10) if any drains are diverted or filled in. Climate • Climate data sets from Levin Aws weather station provide a suitable reference for irrigation design; • Wind conditions are unlikely to limit irrigation design; • Irrigation will be beneficial for the site as predicted climate change conditions develop; and • Maintaining tree production on the westerly boundary is a valuable attribute to protect the irrigation infrastructure and spray drift. Surface Water & Artificial Water Courses • The Waiwiri Stream south and the Tasman sea west will require suitable protection from nutrient loads from wastewater irrigation; • Drains around The Pot site direct shallow groundwater to the Waiwiri Stream; • Irrigation should be avoided on wet areas at The Pot; and • Flood risks are low.

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Buffers • Buffer distances set by the Horizons One Plan for other effluent products applied to land are appropriate for the irrigation area at The Pot; • The gas main crosses The Pot north south and located within a 12 m wide buffer; and • All buffers identified above would occupy 43 ha and leave 67 irrigable hectares of the 110 ha property. Soils (McLeod, 2016:B9) • All soils have been correlated to the Part Foxton-Omanuka Association. These are predominantly well drained sandy soils located on dunes. Interdunal areas are wet and peaty and not considered suitable for irrigation. Soil Hydraulic Conductivity • There are no restrictive layers through the soil profiles that would affect irrigation, except some peaty interdunal areas; • One irrigation application rate for the whole property is appropriate; • The K-40mm should be used instead of the Ksat to determine the irrigation application rate because it better represents the soils ability to hold water and limit drainage into groundwater. Holding the water in the soil maximises the opportunity for plant uptake and soil attenuation of nutrients from the wastewater; • The result from the K-40mm tests suggest that a design irrigation rate of 72 mm/day would be an appropriate application rate for irrigation; • A lower application rate may be considered for the following reasons: • Nutrient loading effects; • The sites attenuation ability, which may result in a further reduction of the actual rate; • Avoidance of excessive drainage from the sandy soils to groundwater that may also be contributing to the wetness in low lying areas; and • Physical soil characteristics are itemised in Table 1.1.

Table 1.1: Soil Physical Properties *Bulk *Porosity *Macroporosity Ksat K-40mm density (%) (%) (mm/hr) (mm/hr) (g/cm3) 1.19 ± 0.10 54 ± 4 17 ± 6 964 ± 869 9.0 ± 4.4 *Landcare field tests (2014)

Soil Chemistry • pH is low on irrigated pine production sites and supplemental fertiliser to adjust the pH may be necessary depending on production requirements; • The land is not constrained by fertility issues for pine production but should be monitored to determine if supplemental nutrients are needed to maintain production; • Fertility is not consistent across the site and may require different fertiliser applications per management unit where nutrient concentrations are below that required for optimum production; • Olsen P is high and indications show that phosphorus is held in the organic material, therefore avoidance of erosion is needed to limit nutrient loaded organic material entering the receiving environment; • Application of sodium (Na) in wastewater has caused the soils exchangeable sodium percentage to increase but high wastewater applications over thirty years has not caused structural limitations to the soil or increased concentrations beyond trigger levels. This nutrient should be monitored but no additional action is necessary. Irrigation • Irrigation currently occupies 40.5 ha. Buffers where no irrigation is to be applied occupies 53 ha. Approximately 25 ha of land within The Pot could be irrigated in addition to the current irrigated areas.

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2 INTRODUCTION

2.1 Purpose

The purpose of this report is to assist decisions for the optimum development for land that receives and could potentially receive the treated wastewater discharged from the Levin wastewater treatment plant (LWWTP). The currently irrigated site and the storage pond are located at a site referred to as The Pot. This report includes an assessment of The Pot’s climate, soils and vegetation.

2.2 Background

Horowhenua District Council (HDC) is considering modifications to a number of their wastewater treatment plants (WWTP) and associated discharges. This includes the operation of the Levin WWTP (LWWTP) and discharges at The Pot. Wastewater is transferred to The Pot and stored in a pond (Pot Pond) prior to discharge via irrigation to pine trees. The Levin WWTP and The Pot are operated under existing resource consents (4960, 6610, 6624, 6920, 6921).

HDC has engaged Lowe Environmental Impact (LEI) to investigate the environmental and agronomic performance of The Pot and adjacent wastewater irrigation system. Potential future options for The Pot discharge will be identified on the basis of the land’s capability to accept the wastewater discharge with minimal adverse effects to the receiving environment.

Additional reports that have investigated characteristics of The Pot are referenced throughout this report and refer to the following: • Surface water (Aquanet, 2016:B6b); • Groundwater (LEI, 2016:B3b), • Soil type (Landcare, 2016:B9); and • Ecology (Boffa Miskell, 2016:B10).

2.3 Scope

This report describes and presents, with images, the following site characteristics at The Pot and identifies the general locations that are suitable for irrigation:

• Landforms; • Vegetation; • Climate; • Wet areas and swamps; • Buffers; • Soils including hydraulic properties and chemistry; and • Potential irrigation blocks.

Previous reports that describe a characteristic are identified and additional information to support irrigation modelling are noted.

Section 3 introduces the general description of the site and its location. Section 4 describes the first six site characteristics listed above. Section 5 describes soil characteristics and the tests carried out at the site; and Section 6 discusses The Pot irrigation, pine production and what considerations need to be made for the pine harvest that is due.

Terms used for this report:

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Test location The location where the tests were carried out. This includes 2 locations called Ring Main and Bare Sands. Repeats Each test at the test location. Typically, 3 saturated soil hydraulic conductivity tests, 4 unsaturated soil hydraulic conductivity tests and soil samples were collected from one test location. The Pot Property where the LWWTP wastewater is stored and irrigated to the surrounding land. The Pot Pond The LWWTP wastewater storage pond, located at The Pot.

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3 SITE LOCATION

3.1 Site Location

The area being considered for irrigation includes land referred to as ‘The Pot’. The location of The Pot is identified in Appendix A, Figure A1-P Location - The Pot. It is located along Hokio Sands Road, 7 km on the coastal side of Levin Township.

The most western boundary of The Pot is the Tasman sea. The Waiwiri Stream creates The Pot’s southern boundary. The property to the east is known as the Tucker Block and owned by HDC. Rural farming properties occupy other boundaries, including Jim Mackie’s property to the north that also provides potential irrigation area.

Information pertinent for irrigation modelling includes: • The Pot is 110.5 hectares, and located 7 km west of the Levin township. The Tasman sea is 600 m from the most western boundary and the Waiwiri Stream is the property’s southern boundary; and • The north and east boundary may permit less buffer distance due to the eastern boundary being owned by HDC; and the northern property owners interest in receiving some of the wastewater.

3.2 Site Ownership

There are 4 legal titles to The Pot with a total area of 110.5 ha. Two titles directly over The Pot Pond are owned by the Muaūpoko Lands Trust1, whereas the remaining titles are owned by HDC. Details of The Pot are given in Table 3.2.1 and land titles are presented in Appendix A, Figure A2-P Land Ownership – The Pot.

Table 3.2.1: Location Details, The Pot – Levin Property address Hokio Sands Road, Levin Map ref, NZMG: 2695169E, 6061768N Distance to LWWTP 7.1 km (via Road) Owners Valuation Legal Description Area (ha) 1Muaupoko Lands 3783194 ML2327 (WN9D/199) Horowhenua XIB41 South P 43.2634 Trust Block 1Muaupoko Lands 3953395 276409 276410 Horowhenua XIB41 N1 Block 19.6601 Trust HDC 4048468 WN8D/1360 Horowhenua XIB41 South X Block 10.9543 HDC 3944468 WN33D/668 Lot 1 DP 59628 36.6140

Information pertinent for irrigation modelling includes: • Two land titles at The Pot are owned by HDC and two are owned by Muaūpoko Lands Trust. The land administered by Muaūpoko Lands Trust has renewed the lease to HDC and maintains The Pot site availability for irrigation.

1 Muaūpoko Lands Trust is not identified on the Land Register. The proprietors are Ruth Rore, George MacDonald (also known as George Junior MacDonald), Thomas Peter Hurunui, Sharon Marama Haeata and Dean James Wilson as responsible trustees, jointly, no survivorship.

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4 SITE CHARACTERISTICS

4.1 Landform

The Pot Pond is located in a natural basin in the sand dunes. Figure 4.1.1 depicts The Pot Pond during its original construction phase and as it is today. The pond is unlined and the level rises and drops in a regular pattern throughout the year. This is described in more detail in the Operation and Management Summary report (LEI, 2012:A2).

The physiographic description of The Pot is included in the soil mapping report (Landcare, 2016:B9). Current forestry production indicates the whole site is suitable for pine or grass production.

Figure 4.1.1: The Pot Pond – Construction 1987 (above), 2016 (below)

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Information pertinent for modelling irrigation opportunities at the site includes: • Landform is steep in areas with flat areas in between; • Up to 7% of the site has steep slopes above 25o that will require irrigation rates that avoid mobilising the sandy soil and encourages permanent vegetative cover; and • Additional factors are listed in the results and conclusions of the soil report (Landcare 2016:B9).

4.2 Vegetation

The vegetation was examined in a detailed ecological survey (Boffa Miskell 2016:B10) for The Pot and categorised the vegetation, as listed in Table 4.2.1.. Appendix A, Figure A6-P Vegetation Types – The Pot, adapts the Boffa Miskell survey data for The Pot. Most of The Pot is either in pines or pasture.

Table 4.2.1: Vegetation Types (Adapted from: Boffa Miskell 2016:B10) Vegetation Communities Approximate Area (ha)

Kettle holes (those inspected) 0.1

Kanuka treeland 1.1

Pine 49.5

Pasture 40.0

Kanuka Forest 4.2

Raupo 0.2

Carex sedge Wetland 2.0

Dune Land 4.4

Open Water 8.2

Willow and Poplar 0.8

Flaxland 0.1

Total (ha) 110.5

Information pertinent for modelling irrigation opportunities at the site includes the following as identified in the Boffa Miskell report (2016:B10): • Irrigation will need to avoid ‘kanuka forest’ (north side of the Pot Pond) and ‘carex sedge wetland’ (NW portion of The Pot) because of their significant vegetation and habitat for indigenous fauna and considered regionally threatened habitat types as identified in Horizons One Plan Schedule F; and • Pre-works fish rescue and transfer was recommended (Boffa Miskell 2016:B10) if any drains are diverted or filled in.

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4.3 Climate

Table 4.3.1 summarises the meteorological statistics for Levin during 1 January 1996 to 31 December 2016; the averages and ranges are given for each parameter and month. The NIWA dataset is summarised from the Levin Weather Station (Levin Aws Agent Number 3275) that is located approximately 6 km north east of The Pot. It provides long term relatively complete rainfall and evaporation data.

Table 4.3.1: Monthly Climate Data for Levin During 1996-2016 Priestley-Taylor Evapo- Open Water Average Air Total Rainfall transpiration Evaporation Temperature Month (mm) (mm) (mm) (oC) January 63 (10 – 130) 131 (106 – 159) 116 (79 – 145) 18 (16 – 20) February 73 (14 – 270) 102 (81 – 121) 98 (77 – 126) 18 (16 – 20) March 57 (20 – 134) 77 (63 – 92) 84 (64 – 110) 16 (15 – 19) April 78 (21 – 161) 37 (29 – 42) 49 (29 – 68) 14 (12 – 16) May 92 (18 – 193) 13 (10 – 15) 37 (22 – 48) 12 (9 – 14) June 105 (34 – 172) 2 (0 – 3) 31 (25 – 42) 10 (7 – 12) July 89 (29 – 219) 5 (4 – 7) 33 (24 – 47) 9 (7 – 11) August 84 (19 – 153) 22 (18 – 25) 36 (24 – 46) 10 (8 – 11) September 93 (9 – 189) 45 (39 – 50) 49 (38 – 68) 11 (10 – 13) October 103 (28 – 260) 74 (62 – 86) 68 (55 – 93) 13 (11 – 14) November 86 (35 – 166) 100 (80 – 118) 89 (69 – 112) 14 (12 – 16) December 98 (40 – 149) 121 (108 – 137) 103 (82 – 117) 16 (14 – 18) Annual 1,021 728 792 13 (794 – 1,395) (667 – 800) (689 – 925) (12 – 14)

Figure 4.3.1 presents a wind rose for Levin (NIWA’s station number E05620) for the period of October 1991 to June 2008. This wind rose shows that the predominant wind direction in Levin is west-north-westerly. East-north-easterly winds are the next most common direction, but they are not as strong as the prevailing WNW winds. These most common wind directions will not carry any odours from The Pot towards any sensitive residential areas (i.e. there are no houses down wind).

Typically wind speeds are less than 20 km/hr, but wind speeds reach 31 - 40 km/hr for around 1 % of the time (primarily from the west to north-west quadrant). The overall mean wind speed is 9.2 km/h, and calm conditions occur 4 % of the time.

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Figure 4.3.1: Wind Rose for Levin During 1991-2008

4.3.1 Climate Change By 2090 predictions of climate change for the Manawatu-Whanganui region are as follows: • No significant rainfall change; • Some increase in westerly wind flow during winter and north-easterly during summer; • Drought conditions could reach twice that compared to 1995, increasing the benefits from irrigation but also increasing risk of erosion and hydrophobicity if soil moisture is not maintained; • Some increase in storm intensity; • Warmer, wetter conditions could increase pests, disease and weeds; • Increased flood risk should not be an issue at The Pot; and • Sea level rise and increased storminess may create salt water intrusion into coastal groundwater.

The Ministry for the Environment provides statistical predictions for 2090 for Manawatu - Whanganui as presented in Table 4.3.2.

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Table 4.3.2: Predicted climate change in Manawatu Whanganui by 2090 Season 2090 possible climate changes Spring 0.6 to 2.7oC temperature rise 1% less to 3% more rain Summer 0.7 to 3.3oC temperature rise 0 to 3% more rain Autumn 0.7 to 3.2oC temperature rise 5% less to 2% more rain Winter 0.7 to 3.2oC temperature rise 6 to 11% more rain Source: http://www.mfe.govt.nz/climate-change/how-climate-change-affects-nz/how-might- climate-change-affect-my-region/manawatu-and

Information pertinent for modelling irrigation opportunities at the site includes: • Rainfall and evapotranspiration data sets are relatively complete and up to date from The Levin Aws weather station therefore provide a suitable reference for irrigation design; • Wind has not caused any complaints from odour from the irrigation system at The Pot over its 30 year history and no changes have occurred that suggest this will be an issue in the future for irrigation management; • Climate change predictions suggest irrigation will become increasingly beneficial due to drought and emphasises the need to maintain soil moisture to avoid risks associated to hydrophobicity; and • Tree production on the westerly boundary is a valuable attribute to protect the irrigation infrastructure and spray drift from the predicted increasing storm events and wind flows.

4.4 Surface Water & Artificial Water Courses

Drains, wet areas and wetlands are throughout The Pot. The drains are directed to the Waiwiri Stream that flows from Lake Papaitonga to the coast on the southern boundary of The Pot. These are identified in Appendix A, Figure A7-P Wet Areas and Drains – The Pot. This image includes the following: • The Pot Pond; • Large 2 m deep drains through The Pot that have been installed to intercept surface runoff and shallow groundwater and convey water off site to the Waiwiri Stream; • Drains on the north east side of property that start at the Pot then travel through the Tucker Block before exiting into the Waiwiri Stream; • Wet areas and swamps at The Pot; and • The lagoon at The Pot north-east of the Pot Pond.

Information pertinent for modelling irrigation opportunities at the site includes: • The southern boundary of The Pot is the Waiwiri Stream and the Tasman sea is 600m from the western boundary; • Drains around The Pot site direct shallow groundwater to the Waiwiri Stream and may require controls to limit the contaminant load they receive; • Irrigation should be avoided on wet areas at The Pot; and • Flood risks are limited to already recognisable wet areas on the site and don’t need additional precautionary measures.

4.5 Buffers

Consent 6610 Condition 6 states that sewage sludge shall not be spread within 100 m of Tucker Block, on the eastern boundary. No other limits are identified in the resource consent other than

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daily and weekly irrigation volumes; and no irrigation runoff should go beyond the boundary of the property.

The Horizons One Plan does not specify the buffer distances specifically for treated municipal wastewater, however it does specify limits for other types of effluent and wastewater. It would seem appropriate to utilise buffer distances for The Pot that are consistent with other types of waste applications and are likely to be incorporated into conditions at the time of re-consenting, as follows: • 150 m Residential buildings, public places and amenity areas where people congregate and education facilities; • 50 m Property boundaries; • 50 m Rare habitats, threatened habitats and at-risk habitats; • 20 m Bores surface water bodies, artificial water courses and coastal marine area; and • 50 m Historic heritage areas.

The National Gas main that runs across The Pot, as shown in Appendix A, Figure A5-P, is well marked by white posts at fence lines and is buried up to 1,200 mm deep. Application of wastewater on the ground surface does not occur above the gas line. Communication with First Gas was made by LEI to determine if any limitations to the wastewater irrigation are necessary. A 12 m wide easement is accepted by First Gas as a suitable buffer and requested it to be maintained over the gas main to avoid any erosion of the pipes. This request was made by First Gas after consideration of the low pH developed from irrigation (historical soil tests were provided). The objective is to ensure the soil pH is maintained above pH 5.

The buffer Zones based on the criteria identified above are presented in Appendix A Figure A5-P Buffer Zones -The Pot. These are itemised in Table 4.6.1. Buffer areas occupy approximately 43 ha of the total property area of 110 ha.

Table 4.6.1: Buffer Areas Non irrigation Area Land Feature Buffer Required (m) (approximate ha)* Residential Buildings 150 0 Property Boundary (includes Waiwiri Stream, excludes 50 18 boundary to HDC owned neighbouring land) Drains 20 6.5 Gas Main 12 1.5 Lagoon 20 1.5 The Pot Pond (includes 0 8 embankment area) Kanuka forest Area only 3 Carex sedge wetland Area plus 20 3 Sludge disposal area 0 0.5 Roadways 0 1 Total 43 *Buffer area of features accounted for in the previous buffer in the table are not included.

Information pertinent for modelling irrigation opportunities at the site includes: • Buffer distances set by the One Plan for other effluent products applied to land are appropriate for an initial assessment of the irrigation area at The Pot; • The gas main is located within a 12 m wide easement that should be maintained as a buffer; and

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• All non-irrigable areas occupy 43 ha of the 110 ha property.

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5 SOIL CHARACTERISTICS

5.1 General

A detailed survey of soil types was prepared by Landcare (2016:B9). The survey made a provisional correlation of soil group for most of the property as Part Foxton-Omanuka Association. The main soil classes are presented in Appendix A Figure A4-P Soil Classes – The Pot.

Borelogs from the piezometers installed at The Pot and from bores in the area identifies sandy soil profiles with peaty layers buried at varying depths. The bore logs from the piezometers installed at The Pot in 2015 identified a ‘grey fine to medium sand’ with no peat layers to depths of 7.5 m. The 11 borelogs from within 3 km of The Pot showed organic material in 6 of the soil profiles, mostly at 7 to 12 m from the ground surface.

Soil tests for soil hydraulic conductivity and soil chemistry were performed at The Pot on the 22nd and 23rd February 2016, by LEI staff and are described in this Section.

5.2 Test Location Selection

Two test locations for soil hydraulic conductivity and soil chemistry measurements were chosen as identified in Figure 5.2.1 and identified as: • Bare Sand; and • Ring Main.

Figure 5.2.1: Soil Test Locations

The Ring Main site is a mix of pines and grass on dunes. The Bare Sands site is pines only on a sand plain. Both sites have well drained sandy soils as identified in the soil mapping report (Landcare, 2016:B9). Other considerations for the site selection are listed below:

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• Non–irrigated pines are not represented at a test site. The intention of the project is to irrigate pines therefore a non-irrigated pine test location will not provide useful information towards the design proposal. • The Sand Plain landform is a small area located around the Bare Sands site; and • The wetlands are not considered within this analysis for potential irrigation.

Table 5.2.1: Test location characteristics Characteristics Bare Sand Ring Main Landform sand plain dune Drainage well drained well drained Vegetation pines pasture/pines Irrigation irrigated irrigated Soil Type sand sand

5.3 Soil Hydraulic Conductivity Soil hydraulic conductivity (K) is a measure of the rate at which water is able to enter soil and move through the profile. K is dependent on several properties including, particle size distribution, mineralogy, degree of packing, soil structure and pressure head. Direct measurement of K can be undertaken by the use of field or laboratory testing methods.

The measurement of K was undertaken to allow an assessment of the ability of the site to receive wastewater, and to determine a rate at which wastewater could be applied to avoid ponding, runoff or water-logging occurring.

5.3.1 Testing Methodology Soil hydraulic conductivity measurements for both saturated and unsaturated conductivity are described below.

Soil Saturated Hydraulic Conductivity by Double Ring Infiltrometer For determination of the soils ability to receive wastewater to the soil surface at a high rate, soil saturated hydraulic conductivity (Ksat) was measured in triplicate using double ring infiltrometers which is a preferred method for establishing Ksat near the soil surface. The double ring method measures vertical flow only, eliminating possible overestimation of infiltration due to lateral flow in the soil.

The rings are seated level in the soil, to a depth of several centimetres, then filled with water; the outside ring first, then the internal ring. Timed recording then measures the rate of water level fall in the inner ring over time. Once a constant rate of water level is achieved it can be used to determine Ksat.

Soil Unsaturated Hydraulic Conductivity by Plate Permeameter For determination of the soils ability to receive wastewater to the soil surface at a low rate, soil unsaturated hydraulic conductivity (K-40 mm) at the test locations was measured in quadruplicate using a CSIRO plate permeameter apparatus (Perroux and White, 1988). The permeameter method enables measurement of soil near-saturated hydraulic conductivity. Near-saturated soil conditions are favoured over saturated soil conditions in consideration of low rate application because:

• Near-saturated conditions more closely reflect typical soil conditions; and • Saturated hydraulic conductivity may cause overestimation of infiltration due to the initiation of bypass flow under saturated conditions.

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The goal of near-saturated hydraulic conductivity tests for wastewater irrigation is to determine the rate at which the soil has the capacity to draw water into the soil matrix whereby the potential for ponding, runoff, excessive wetness and bypass flow (excessive flow through the macro-pores) is reduced. Typically, it is desired in a land application system to avoid flow through the larger macro pores. The rate at which water can flow (be absorbed) into the soil avoiding macropores is often defined as the flow rate when the matrix potential is less than –40mm (i.e. K-40 mm) (Sparling et al, 2004).

The plate permeameter comprises a porous plate covered with a membrane. The plate is placed on a levelled soil surface which may have a thin layer of sand added to ensure a good contact between the plate and soil is achieved. Water is held under suction in water towers above the plate. A known suction is applied to the water. The ability of the soil to draw water from the plate reflects the rate at which the soil can effectively and sustainably accept the applied water. The K-40 mm is determined by the measured drop in the water level in the water tower relative to the diameter of the plate.

Measurements of the drop in water level were taken at regular intervals and continued until the drop in water level reached a steady state for at least 3 readings. Replicate tests were performed for each test location.

The plate permeameter apparatus results in three dimensional flow of water under the plate (i.e. vertical and horizontal flow is measured). To avoid overestimation of soil hydraulic conductivity the measured flow is converted to one dimensional flow (i.e. vertical flow only) using the Woodings (1968) equation. Data obtained from three levels of varying matrix potential (-100, - 40 and -20 mm) are used to determine to K-40 mm for vertical flow.

5.3.2 Results Detail of the soil hydraulic conductivity testing results is given below followed by summative statements that will contribute to the irrigation design. Graphed results are presented in Appendix B.

Double Ring Infiltrometer Results & Interpretation The average result for each test location is presented in Table 5.3.1. All Ksat measured were very rapid2, reflecting the predominantly sandy soil texture. The results at both sites had similar averaged results and large variations between repeats. Variations in speed of infiltration may be influenced by dry areas in the sandy soil profile causing hydrophobic conditions or organic material from pine trees roots potentially slowing soil water movement.

2 Speed of soil infiltration terms used are standardised permeability classes identified by Landcare (McQueen 1993).

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Table 5.3.1: Soil Hydraulic Test Averaged Results Saturated Soil Unsaturated Soil Month/ ID Soil Hydraulic Hydraulic Year Conductivity Conductivity mm/hr Std Dev mm/hr Std Dev Sand dune under pines and pasture February/ Ring Main 972 1191 5.1 3.9 – irrigated sand 2016 well drained Sand dune under February/ Bare Sand pines – irrigated 955 547 12.8 4.9 2016 sand, well drained Open pasture - November/ Landcare NA NA 41 NA irrigated 2002 Open pasture - July/ Landcare 150 102 32 30 irrigated 2011 Open pasture - October/ Landcare 392 205 61 61 irrigated 2014 In field tests Laboratory tests

Plate Permeameter Results & Interpretation The average K-40 mm result for each test location is presented in Table 5.3.1 and graphed in Appendix B. The graphs show the K at three matrix potentials as mentioned in Section 5.3.1 above. The Ring Main test location is illustrated in Figure 5.3.1.

Figure 5.3.1 Ring Main Testing Site

Each location produced variable K-40mm results, contributed to by the pine roots and pine litter. Despite the different averaged results from the two sites they can both be categorised as moderately slow. Considering the variabilities across the two locations and the limited range of the results, it is appropriate to average the K-40mm for the two test locations to 9 mm/hr with a standard deviation of 4.4 mm/hr.

5.3.3 Historical Results Landcare have been contracted to satisfy resource consent requirements and carry out soil tests at The Pot that includes soil hydraulic conductivity. Three of the annual reports from 2003 (samples collected 2002), 2011 and 2014 have been obtained.. The test results presented in Table 5.3.1 are variable. This is partly contributed by the following:

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• Different test locations across the site for most occasions tests were carried out; • Different times of year that may create bypass flows in dry conditions; • Different management with pines for the LEI 2016 test locations by comparison to open pasture for Landcare test locations; and • The Landcare test results for Kunsat are higher than Kunsat results achieved by LEI, because Landcare Kunsat results were carried out in the laboratory from soil cores and typically get higher results to those achieved in the field.

The Landcare 2014 report suggests changes in physical characteristics are considered minor. “generally the soil physical properties under irrigation were similar in those non-irrigated soil.”

If standard deviations are considered, the saturated soil hydraulic conductivities are similar from 2002 to 2016, although a slight trend upwards may be taking place; likewise, for the unsaturated soil hydraulic conductivities. This suggests that over time there is an increase in infiltration and drainage that would be contributed to by increases in organic material. The range of results provided by Landcare and LEI suggest a conservative application rate is warranted to accommodate the variability across The Pot.

5.3.4 Determination of Sustainable Hydraulic Loading Rate In addition to allowing for the K, consideration should be given to the effect of wastewater constituents, as opposed to clean water effects which are typically observed during field measurements. Organic material, solids and nutrients in the wastewater can allow the development of microbial growth commonly referred to as biofilm, which in turn can result in a ‘clogging’ effect of the soil pores, particularly near the soil surface. This in turn reduces the soil’s infiltration capacity. In addition, the salt concentration will influence the soil wetting by altering the water surface tension.

There are limited empirical methods for developing an ‘enriched’ water rate from ‘clean’ water observations. This is because the rate is variable depending on the type of wastewater, nutrient and organic content, soil type, application method and application regime. A range in the order of 4 to 10 % is often used for ‘clean’ water to wastewater conversion (USEPA, 2006). The conversion rate implied in AS/NZS 1547:2012 ranges from 0.17 to 5 %. Both references mentioned above refer to a conversion between saturated hydraulic conductivity (not unsaturated conductivity) and wastewater application rates.

The need for ‘clean’ water to wastewater conversion is noted by Crites and Tchobanoglous (1998) who report an empirical method to determine a wastewater rate from a clean water measurement. The measured instantaneous rates can be translated into a daily hydraulic design irrigation rate using the following equation, which is modified from Crites and Tchobanoglous (1998): P (daily) =K-40 mm (0.1-0.3) (24 h/d)

Where: P = the design irrigation rate Is a function of 10-30% of the K-40 mm Over 24 hours in the day.

The use of this equation and adopting a 30% function of the unsaturated (not saturated) infiltration rate at K-40 mm provide a maximum hydraulic design irrigation rate (DIR) of 72 mm/day. At this rate the site is likely to be able to accept water from long term irrigation

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without the generation of adverse effects on the immediate receiving environment and the soils itself.

5.3.5 Hydrophobicity Hydrophobicity is the development of water repellent properties in the soil. Sandy coastal soils are particularly prone to hydrophobicity, typically seasonally, due to the free draining nature of the soil and labile soil organic matter. The onset of hydrophobic conditions is related to the drying of the soils and as a result is more prevalent on ridges and north facing slopes.

Hydrophobicity causes water to run over the surface instead of infiltrating into the soil. This exacerbates soil dryness and puts stress on plants. The water moving over the soil surface increases sheet and rill erosion, and the water accumulates in low lying areas which creates ponding issues. It also has the potential to cause resource consent compliance concerns as a result of runoff into surface waterways.

Within the soil, hydrophobicity causes the development of bypass flow paths, or fingers. Because the water is concentrated along these fingers the localised loading is much higher resulting in a greater rate of drainage. This may cause lesser attenuation of contaminants such as nutrients and pathogens from applied wastewater.

Hydrophobic soil conditions do not exist at the two pine test locations. This is likely to be a consequence of the regular applications of irrigation. Therefore, it is recommended that the irrigation regime is designed to maintain some degree of soil moisture.

Hydrophobic conditions do exist locally and were observed in the soil mapping investigation that included the neighbouring Tucker Block that has no irrigation (Landcare, 2016:B9). This report also recommends hydrophobicity be taken into consideration for the irrigation design. It noted that the sandy soil soon after irrigation showed a wet surface over “dry” sand in the upper subsoil over “wet sand.”

5.3.6 Hydraulic Loading Opportunities Information pertinent for modelling irrigation opportunities includes: • There are no restrictive layers through the soil profiles that would affect irrigation; • One irrigation application rate for the whole property is appropriate because the topography is mostly dunal and the different landform at the sand plain is showing similar results to the dunes, particularly for saturated soil hydraulic conductivity; • The K-40mm should be used instead of the Ksat to determine the irrigation application rate because it better represents the soils ability to hold water and limit drainage into groundwater. This water held in the soil maximises the opportunity for plant uptake and soil attenuation of nutrients from the wastewater; • The result from the K-40mm tests suggest that a design irrigation rate of 72 mm/day would be an appropriate application rate for irrigation; • A lower application rate may be considered for the following reasons: • Nutrient loading effects; • The sites attenuation ability, which may result in a further reduction of the actual rate; • Avoidance of excessive drainage from the sandy soils to groundwater that may also be contributing to the wetness in low lying areas; and • Physical soil characteristics are itemised in Table 5.3.2. Additional physical parameters are added from the latest Landcare tests.

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Table 5.3.2: Soil Physical Properties Bulk density Porosity Macroporosity Ksat K-40mm ID (g/cm3) (%) (%) (mm/hr) (mm/hr) LEI 2016 - - - 964 ± 869 9.0 ± 4.4 Landcare 61 ± 61 1.19 ± 0.10 54 ± 4 17 ± 6 392 ± 205 2014 (laboratory)

5.4 Soil Chemistry Measurement of soil chemistry has been carried out to inform decisions about the current nutrient status of the Pot and the subsequent ability to manage the ongoing addition of nutrients from wastewater applications. Samples were collected on one occasion and the results are presented below. Additional sampling has been carried out for consent compliance at the same time as the historical soil hydraulic conductivity tests were carried out, as described in Section 5.3.3.

5.4.1 Soil Sampling Approximately 20 soil cores at 20 m apart were taken with a 75 mm soil corer across each of the 2 sites identified in Figure 5.2.1. Samples were mixed, packaged and sent to Hill Laboratories, Hamilton for analysis. Hill Laboratories was selected due to holding IANZ accreditation for the tests required.

5.4.2 Results The results from the soil sampling are presented in Table 5.4.1 and the laboratory reports are in Appendix C. The Landcare results are historical data and discussed in Section 5.3.3. Most results are relative to a sandy type soil that has limited ability to hold nutrients. Most parameters are in the low to medium range for pasture soils in New Zealand.

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Table 5.4.1: Soil Analysis Results 2016 Bare Ring Parameter Units Landcare Landcare Landcare Landcare Sands Main Not Irrigation irrigated irrigated irrigated irrigated irrigated irrigated pine/ Vegetation pasture pasture pasture pasture pines pasture Sample 2002 2011 2014 2014 2016 2016 year Sample 0-10 cm 0-10 cm 0-10 cm 0-10 cm 0-7.5 cm 0-7.5 cm depth pH pH Units 6.5 5.55 6.21 6.09 4.5 4.8 Olsen mg/L 52 71 33 83 112 116 Phosphorus Sulphate mg/kg NA NA NA NA 5 15 Sulphur Organic % NA NA NA NA 9.5 10.1 Matter Total % 1.46 1.74 1.11 2.07 5.5 5.9 Carbon Potassium me/100g 0.12 0.27 0.22 0.19 0.27 0.42 Calcium me/100g 2.38 2.3 2.66 3.2 2.1 4.8 Magnesium me/100g 0.36 0.48 0.59 0.28 0.79 1.75 Sodium me/100g 0.67 0.29 0.07 0.28 0.43 0.83 CEC me/100g 4.5 6.4 4.5 5.5 15 22 Total Base % 79 52 78 72 24 35 Saturation Volume g/mL NA NA NA NA 1.01 0.87 Weight

The two irrigated sites have different nutrient results with the Bare Sands location having low concentrations for most nutrients with the exception of the phosphorus and sodium whereas the Ring Main location has medium to high concentrations for all nutrients, although pH is very low for both.

Organic material can influence the soil chemistry and limited leaching loss which is particularly evident at the Ring Main site. Both test locations have 9 to 10 % organic matter which is a moderate percentage for a pastoral soil. The sandy soil is typically free draining that causes nutrients to easily leach from the topsoil. However, these irrigated sites have had an accumulation of organic material from the pine tree litter, pasture growth and the addition of wastewater.

Phosphorus is the only significantly high result that has occurred at the wastewater application test sites; Bare Sands and Ring Main. Each result was above 100 mg/L. This reflects the phosphorus from the wastewater being held in the organic material and not moving out from the top part of the soil environment. This retention of phosphorus is confirmed by no significant concentration of phosphorus in the groundwater (LEI, 2016:B3b).

5.4.3 Historical Soil Chemistry The change in soil chemistry identified by the historical monitoring is an increase in plant available phosphorus and copper. However, copper values are still low at 1 and 11 mg/kg. There was one

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anomalous result of 97 mg/kg on irrigated pasture in 2014, although this result it is not unacceptably high. Soil guideline values developed by Auckland Regional Council for the protection of ecological receptors, as the most sensitive guidelines, has a minimal risk value of 45 mg/kg and serious risk at 135 mg/kg (Cavanagh, 2006).

There are several significant differences in soil chemistry between the 2016 Bare Sands and Ring Main test locations, compared to the historical pastoral locations. The differences relate to organic matter accumulation at the pine forest floor by comparison to less at the open pasture. The results show this by higher carbon recorded at Bare Sand and Ring Main that correlates to higher total base saturation, carbon, cation exchange capacity (CEC), phosphorus and lower pH.

Information pertinent for modelling irrigation opportunities includes: • pH is low on irrigated pine production sites and supplemental fertiliser to adjust the pH may be necessary depending on production requirements; • The land is not constrained by fertility issues for pine production but should be monitored to determine if supplemental nutrients are needed to maintain pasture growth or other types of production; • Fertility is not consistent across the site and will require different fertiliser applications per management unit where nutrient concentrations are below that required for optimum production; • Olsen P is high and indications show that phosphorus is held in the organic material, therefore avoidance of erosion is needed to limit nutrient loaded organic material entering the receiving environment; and • Application of sodium (Na) in wastewater has caused the soils exchangeable sodium percentage to increase but high wastewater applications over thirty years has not caused structural limitations to the soil or increased concentrations beyond trigger levels. This nutrient should be monitored but no additional action is necessary.

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6 IRRIGATION ASSESSMENT

6.1 Current Irrigation

The same irrigation rate is currently applied to all irrigation zones at The Pot. The extensive field investigations confirm that one approach for The Pot is appropriate. Small atypical areas are occupied within buffer zones and do not receive irrigation.

The irrigation layout is depicted in Appendix A, Figure A8-1-P. This layout identifies the valve locations and the spread of irrigation as determined by the survey team from Beca; plus a small area of additional irrigation installed after the 2013 survey. Some minor errors exist on the image provided by Beca because there is no irrigation over the gas main. Two ‘irrigation lines’ cross the gas line but no application of wastewater occurs. This image identifies 48 blocks that irrigate an estimated total area of 40.5 ha.

The irrigation lines are described by two areas; the Ring Main around the pond and the Bare Sands to the west of the site.

The irrigation mainlines are buried close to the ground surface to as much as 1.2 m below. The depths are variable across the site and believed to be a result of sand movement at the time of installation when the ground was not vegetated.

6.2 Pine Management

The pine trees planted at The Pot were all planted 28 years ago, therefore are now mature for harvest. The pine trees are in areas in good condition, with growth comparable to a similar production at Waitarere that has wastewater application. The Waitarere pines were described by Foresters as 5 years ahead of similar pine production without irrigation.

However, the plantation has scattered areas of grass. While initially the entire area was planted in pines, it is unclear why large areas of grass exist. There is the possibility that direct irrigation impact may have damaged the trees, but this is not consistent across the site. Over, or uneven application, of irrigation may have impacted on tree health, but also the closeness to shallow groundwater and ‘wet’ roots may also have had an impact. It is known that wind damage results in windthrown and even the snapping/breaking of trees, with a number of trees falling in a localised storm in December 2014.

6.3 Harvest Strategy

At the time of harvest, the following factors need to be taken into account:

• Ownership of the trees; • Owners’ requests regarding the harvest and destination of the trees; • Irrigation infrastructure and its protection against potential damage; • Potential wind damage during harvest when currently protected trees are exposed; • Maintenance of some trees or vegetative cover to limit potential runoff into surface water; and • Alternative irrigation areas.

An alternative site may be required for irrigation of the wastewater at the time of harvest. The site will require the following: • Appropriate site investigations and irrigation designs for consents to be prepared;

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• Consent for irrigation of wastewater; • Land development for efficient management approach such as fencing; • Production suitable for irrigation; and • Irrigation infrastructure in place.

An alternative to additional land sought for irrigation would be to progressively move irrigation around The Pot. There are 48 existing irrigation blocks plus additional areas within The Pot as described in Section 6.4 that could be available for irrigation.

6.4 Potential Irrigation Sites at The Pot

Information from this report identifies the following factors which assist to determine the irrigable area at The Pot: • Irrigation currently occupies 40.5 ha; • Buffers where no irrigation is to be applied could occupy as much as 43 ha; • An additional 25 ha could be irrigated in addition to the current irrigated areas; • A percentage of this potential 25 ha for irrigation land will be limited due to the following reasons: • Isolated small pockets of land that are impractical to irrigate, e.g wet area between drains in north east corner; • Difficult to access, such as steep ridges; • Land draining into pond may be restricted; and • Wet areas outside of buffer zones occupy approximately 2 ha.

Although a relatively small percentage (40%) of The Pot is being irrigated, there is limited scope for additional irrigation. It appears that despite no consenting requirement for buffers, setbacks have been taken into consideration for the current irrigation. With reference to Appendix A, Figure A8-P, irrigation could extend into the southwest corner and to the east boundary. It could also extend into the northeast corner but this is more complex with drains and wet areas that make access more difficult. This assessment for additional irrigation areas suggests the original irrigation design has utilised most of the practical irrigation areas and new irrigation areas is limited to around 25 ha.

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7 CONCLUSIONS AND RECOMMENDATIONS

The Pot is currently irrigated with treated wastewater from the Levin wastewater storage pond located on site. Re-consenting for the discharge of wastewater is due in 2018 and a change of irrigation scheduling and/or areas may be necessary to allow pine trees to be harvested from The Pot.

The attributes relevant for an upgraded irrigation design for the currently irrigated land and any additional irrigation area available at The Pot are listed below.

Site Location • The Pot is 110.5 hectares, and located 7 km west of the Levin township. The Tasman sea is 600 m from the most western boundary and the Waiwiri Stream is the property’s southern boundary; and • The north and east boundary may permit less buffer distance due to the eastern boundary being owned by HDC, and the northern property owners interest in receiving some of the wastewater. Site Ownership • Two land titles at The Pot are owned by HDC and two are owned by Muaūpoko Lands Trust. The land administered by Muaūpoko Lands Trust has renewed the lease to HDC and maintains The Pot site availability for irrigation. Landform • Landform is steep dunes with flat areas in between; • Up to 7% of the site has steep slopes that will require irrigation rates that avoid mobilising the sandy soil and encourages permanent vegetative cover; and • Additional factors are listed in the results and conclusions of the soil report (Landcare 2016:B9). Vegetation (Boffa Miskell, 2016:B10) • Vegetation is mixed grass and pine plantation with isolated patches of natives, swamp species and undeveloped vegetation; • There are no areas of high indigenous ecological value; • Irrigation will need to avoid ‘kanuka forest’ (north side of the Pot Pond) and ‘carex sedge wetland’ (NW portion of The Pot) because of their significant value as regionally threatened habitat types identified in Horizons One Plan Schedule F; and • Pre-works fish rescue and transfer was recommended (Boffa Miskell 2016:B10) if any drains are diverted or filled in. Climate • Climate data from Levin AWS weather station provide a suitable reference for irrigation design; • Wind conditions are unlikely to limit irrigation design; • Irrigation will be beneficial for the site as predicted climate change conditions develop; and • Tree production on the westerly boundary is a valuable attribute to protect the irrigation infrastructure and spray drift. Surface Water & Artificial Water Courses • The Waiwiri Stream south and the Tasman sea west will require suitable protection from nutrient loads from wastewater irrigation; • Drains around The Pot site direct shallow groundwater to the Waiwiri Stream and may require controls to limit the contaminant load they receive; • Irrigation should be avoided on wet areas at The Pot; and • Flood risks are low.

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Buffers • Buffer distances set by the Horizons One Plan for other effluent products applied to land may be appropriate for the irrigation area at The Pot; • The gas main crosses The Pot north south and located within a 12 m wide buffer; and • All buffers identified above would occupy 43 ha and leave approximately 65 irrigable hectares of the 110 ha property. Soils (McLeod, 2016:B9) • All soils have been correlated to the Part Foxton-Omanuka Association. These are predominantly well drained sandy soils located on dunes; and • Interdunal areas are wet and peaty and not considered for irrigation. Soil Hydraulic Conductivity • There are no restrictive layers through the soil profiles that would affect irrigation; • One irrigation application rate for the whole property is appropriate; • The K-40mm should be used instead of the Ksat to determine the irrigation application rate because it better represents the soils ability to hold water and limit drainage into groundwater. This water held in the soil maximises the opportunity for plant uptake and soil attenuation of nutrients from the wastewater; • The result from the K-40mm tests suggest that a design irrigation rate of 72 mm/day would be an appropriate application rate for irrigation; • A lower application rate may be considered for the following reasons: • Nutrient loading effects; • The sites attenuation ability, which may result in a further reduction of the actual rate; • Avoidance of excessive drainage from the sandy soils to groundwater that may also be contributing to the wetness in low lying areas; and • Physical soil characteristics are itemised in Table 1.1.

Table 1.1: Soil Physical Properties *Bulk *Porosity *Macroporosity Ksat K-40mm density (%) (%) (mm/hr) (mm/hr) (g/cm3) 1.19 ± 0.10 54 ± 4 17 ± 6 964 ± 869 9.0 ± 4.4 *Landcare field tests (2014)

Soil Chemistry • pH is low on irrigated pine production sites and supplemental fertiliser to adjust the pH may be necessary depending on production requirements; • The land is not constrained by fertility issues for pine production but should be monitored to determine if supplemental nutrients are needed to maintain pasture growth or other types of production; • Fertility is not consistent across the site and will require different fertiliser applications per management unit where nutrient concentrations are below that required for optimum production; • Olsen P is high and indications show that phosphorus is held in the organic material, therefore avoidance of erosion is needed to limit nutrient loaded organic material entering the receiving environment; and • Application of sodium (Na) in wastewater has caused the soils exchangeable sodium percentage to increase but high wastewater applications over thirty years has not caused structural limitations to the soil or increased concentrations beyond trigger levels. This nutrient should be monitored but no additional action is necessary.

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Irrigation • Irrigation currently occupies 40.5 ha. Buffers where no irrigation is to be applied occupies 43ha. An additional 25 ha could be irrigated in addition to the current irrigated areas;

At the time of harvest, the following factors need to be taken into account: • Ownership of the trees; • Owners’ requests regarding the harvest and destination of the trees; • Irrigation infrastructure and its protection against potential damage; • Potential wind damage during harvest when currently protected trees are exposed; • Maintenance of some trees or vegetative cover to limit potential runoff into surface water; and • Alternative irrigation areas.

An alternative irrigation area may be required for irrigation of the wastewater at the time of harvest. If so, the following activity is required: • Appropriate site investigations and irrigation designs for consents to be prepared; • Consent for irrigation of wastewater; • Land development for efficient management approach such as fencing; • Suitable production for irrigation; and • Irrigation infrastructure in place.

An alternative to additional land sought for irrigation would be to progressively move irrigation around The Pot. There are 48 existing irrigation blocks plus a maximum of an additional 25 ha within The Pot that provides scope for the harvest.

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8 REFERENCES

Aquanet., (2016:B6b) Levin WWTP Land Application at the Pot: Water quality and ecology of the Waiwiri Stream, 2013-2016.

Boffa Miskell., (2016:B10) Pot and Tucker Land Blocks, Levin: Assessment of Ecological Values

Cavanagh, J.E., (2006) Comparison of Soil Guideline Values in New Zealand and Their Derivations. Prepared for Environment Canterbury by Landcare Research. Sourced: http://ecan.govt.nz/publications/Reports/ComparisonofSoilGuidelineValuesinNewZealand .pdf

Crites, R.W., and Tchobanoglous, G., (1998) Small and Decentralized Wastewater Management Systems. McGraw-Hill Book Company, New York.

EIANZ., (2015) Ecological Impact Assessment (EcIA): EIANZ guidelines for use in New Zealand: Terrestrial and freshwater ecosystems. Melbourne: Environment Institute of Australia and New Zealand.

Landcare., (2016:B9) Levin Wastewater Land Application System: Soil Type Mapping

Lowe Environmental Impact., (2012:A2) Levin Wastewater Land Application: Levin Wastewater Discharge Operation and Management Summary.

Lowe Environmental Impact., (2016:B3b) Levin Wastewater Land Application System: The Pot Groundwater Monitoring.

McLeod, M., (2016:B9) Soils of “The Pot” and “ Tucker Block” – Levin. Landcare Research. Prepared for Lowe Environmental Impact.

McQueen, D. J., 1993. Glossary of soil physical terms. Manaaki Whenua Landcare Research, New Zealand.

Parfitt, R., (2003). Report on soil sampling and evaluation for the Levin Effluent Disposal Facility. Landcare Research New Zealand Ltd.

Perroux, K.M., White, I., (1988) Design for disc permeameters. Soil Science Society of America Journal, 52, 1205-1215.

Ross, C., & Dando, J., (2015) Report on soil sampling and evaluation for the Waitarere and Levin effluent disposal facilities, prepared for HDC. Landcare Research.

Salt, G., (2011) Report on soil sampling and evaluation for the Levin Effluent Disposal Facility. Landcare Research New Zealand Ltd.

Sparling et al., (2004) Rationale for soil quality on soils used for effluent disposal. Waste Water and Land Treatment for Primary Industry and Rural Areas. Annual Proceedings of the Technical Session 25.

United States Environmental Protection Agency (UESPA)., (2006) Process Design Manual: Land Treatment of Municipal Wastewater Effluents. EPA/625/R-06/016.

Wooding, R.A., (1968) Steady infiltration from a shallow circular pond. Water Resources Research 4, 1259-1273.

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9 APPENDICES

Appendix A Figures Appendix B Soil Hydraulic Conductivity Graphs Appendix C Soil Chemical Analysis

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APPENDIX A

Figures

Figure A1-P Location Figure A2-P Land Ownership Figure A4-P Soil Classes Figure A5-P Buffer Zones Figure A6-P – Vegetation Types Figure A7-P – Wet Areas and Drains Figure A8-P – Irrigation Areas

LEGEND

BLOCK BOUNDARY

WAIWIRI STREAM

WET / SWAMP

POND

Hoko Sands Road

A For Consent Application 17.08.2016 REV. DESCRIPTION DATE © L O W E Environmental Impact. 2010 Waiwiri Stream

APPROVED HL 25.08.2016

CHECKED HL 25.08.2016

DESIGNED SC 17.08.2016

DRAWN NSH 17.08.2016

CLIENT

Waiwiri Stream

PROJECT

Levin Wastewater Land Application Reconsenting

DRAWING TITLE

Location

Waiwiri Stream The Pot

DRAWING STATUS Consenting

DATE DRAWING No. 17 August 2016 A1-P

0 100 200 300 400 500 SCALE REVISION

GRAPHIC SCALE (m) 1:10,000 (A3) A LEGEND

CADASTRAL

WAIWIRI STREAM

Horowhenua XIB4I South S Block 109543m² WN8D/1360 Hoko Sands Road Horowhenua XIB4I Lot 1 South P Block DP 59628 432634m² 366140m² A For Consent Application 17.08.2016 WN9D/199 WN33D/668 REV. DESCRIPTION DATE Horowhenua XIB4I © L O W E Environmental Impact. 2010 Waiwiri Stream N1 Block 196601m² 276409 276410

APPROVED HL 25.08.2016

CHECKED HL 25.08.2016

DESIGNED SC 17.08.2016

DRAWN NSH 17.08.2016

CLIENT

Waiwiri Stream

PROJECT

Levin Wastewater Land Application Reconsenting

DRAWING TITLE

Land Ownership

Waiwiri Stream The Pot

DRAWING STATUS Consenting

DATE DRAWING No. 17 August 2016 A2-P

0 100 200 300 400 500 SCALE REVISION

GRAPHIC SCALE (m) 1:10,000 (A3) A LEGEND

POND/ LAGOON

WAIWIRI STREAM

DUNE WELL DRAINED

INTER DUNE IMPERFECTLY DRAINED

N INTER DUNE VERY POORLY DRAINED

SAND PLAIN WELL DRAINED

BLOCK BOUNDARY

Hoko Sands Road

APPROVED HL 17.08.2016

CHECKED HL 17.08.2016

DESIGNED SC 17.08.2016

DRAWN NSH 17.08.2016

CLIENT

Waiwiri Stream

PROJECT

Levin Wastewater Land Application Reconsenting

DRAWING TITLE

Soil Classes The Pot Waiwiri Stream

Source: Landcare March 2016

DRAWING STATUS Consenting

DATE DRAWING No. 17 August 2016 A4-P

0 100 200 300 400 500 SCALE REVISION

GRAPHIC SCALE (m) 1:10,000 (A3) A LEGEND

Hoko Sands Road

APPROVED HL 25.08.2016

CHECKED SC 25.08.2016

DESIGNED SC 17.08.2016

DRAWN NSH 17.08.2016

CLIENT

Waiwiri Stream

PROJECT

Levin Wastewater Land Application Reconsenting

DRAWING TITLE

Buffer Zones

Waiwiri Stream The Pot

DRAWING STATUS Consenting

DATE DRAWING No. 17 August 2016 A5-P

0 100 200 300 400 500 SCALE REVISION

GRAPHIC SCALE (m) 1:10,000 (A3) A 0 100 GRAPHIC SCALE (m) 200 300 400

500 Hoko Sands Road Sands Hoko N DATE DRAWING STATUS SCALE LEGEND DRAWING TITLE PROJECT DRAWN DESIGNED REV. CLIENT CHECKED APPROVED Source: Boffa Miskell 12 May 2016 17 August 2016 A 1:10,000 (A3) © Application Reconsenting Levin Wastewater Land FOR CONSENT APPLICATION DESCRIPTION Vegetation Types HOLE KANUKA TREELAND WAIWIRI STREAM CADASTRAL SCATTERED CABBAGE TREES RAUPO DUNE LAND PINE PASTURE & KAHIKATEA SEDGE WETLAND WET PASTURE & RUSHES WILLOW & POPLAR KANUKA FOREST L O W E Environmental Impact. Consenting The Pot NSH HL HL - / POND REVISION DRAWING No. A6-P A 17.08.2016 17.08.2016 25.08.2016 25.08.2016 17.08.2016 DATE 2010 LEGEND

WAIWIRI N BLOCK BOUNDARY

Hoko Sands Road

APPROVED HL 25.08.2016

CHECKED HL 25.08.2016

DESIGNED SC 17.08.2016

DRAWN NSH 17.08.2016

CLIENT

Waiwiri Stream

PROJECT

Levin Wastewater Land Application Reconsenting

DRAWING TITLE

Wet Areas and Drains

Waiwiri Stream The Pot

DRAWING STATUS Consenting

DATE DRAWING No. 17 August 2016 A7-P

0 100 200 300 400 500 SCALE REVISION

GRAPHIC SCALE (m) 1:10,000 (A3) A

APPENDIX B

Soil Hydraulic Conductivity Graphs

Ring Main

Bare Sand

Ring Main

Bare Sand

Appendix C

Hill Laboratory Soil Analysis Report

R J Hill Laboratories Limited Tel +64 7 858 2000 1 Clyde Street Fax +64 7 858 2001 Private Bag 3205 Email [email protected] Hamilton 3240, New Zealand Web www.hill-labs.co.nz A N A L Y S I S R E P O R T Page 1 of 6

Client: Lowe Environmental Impact Limited Lab No: 1543046 shpv1 Address: PO Box 4667 Date Registered: 25-Feb-2016 Palmerston North 4442 Date Reported: 03-Mar-2016 Quote No: 68883 Order No: 10093 B8 Client Reference: Phone: 06 359 3099 Submitted By: Sian Cass

Sample Name: Sand Dune 23 22-Feb-2016 2:00 pm Lab Number: 1543046.1 Sample Type: SOIL Mixed Pasture (S1) Analysis Level Found Medium Range Low Medium High pH pH Units 5.5 5.8 - 6.2

Olsen Phosphorus mg/L 9 20 - 30

Potassium me/100g 0.70 0.40 - 0.60 Calcium me/100g 4.2 4.0 - 10.0 Magnesium me/100g 1.65 1.00 - 1.60 Sodium me/100g 0.12 0.20 - 0.50

CEC me/100g 15 12 - 25 Total Base Saturation % 44 50 - 85 Volume Weight g/mL 0.95 0.60 - 1.00

Sulphate Sulphur mg/kg 2 10 - 12

Organic Matter* % 9.0 7.0 - 17.0 Total Carbon* % 5.2 Base Saturation % K 4.6 Ca 28 Mg 11.0 Na 0.8 MAF Units K 14 Ca 5 Mg 35 Na 5 The above nutrient graph compares the levels found with reference interpretation levels. NOTE: It is important that the correct sample type be assigned, and that the recommended sampling procedure has been followed. R J Hill Laboratories Limited does not accept any responsibility for the resulting use of this information. IANZ Accreditation does not apply to comments and interpretations, i.e. the 'Range Levels' and subsequent graphs.

This Laboratory is accredited by International Accreditation New Zealand (IANZ), which represents New Zealand in the International Laboratory Accreditation Cooperation (ILAC). Through the ILAC Mutual Recognition Arrangement (ILAC-MRA) this accreditation is internationally recognised. The tests reported herein have been performed in accordance with the terms of accreditation, with the exception of tests marked *, which are not accredited. R J Hill Laboratories Limited Tel +64 7 858 2000 1 Clyde Street Fax +64 7 858 2001 Private Bag 3205 Email [email protected] Hamilton 3240, New Zealand Web www.hill-labs.co.nz A N A L Y S I S R E P O R T Page 2 of 6

Sample Name: Bare Sands 23-Feb-2016 1:00 pm Lab Number: 1543046.2 Sample Type: SOIL Mixed Pasture (S1) Analysis Level Found Medium Range Low Medium High pH pH Units 4.5 5.8 - 6.2

Olsen Phosphorus mg/L 112 20 - 30

Potassium me/100g 0.27 0.40 - 0.60 Calcium me/100g 2.1 4.0 - 10.0 Magnesium me/100g 0.79 1.00 - 1.60 Sodium me/100g 0.43 0.20 - 0.50

CEC me/100g 15 12 - 25 Total Base Saturation % 24 50 - 85 Volume Weight g/mL 1.01 0.60 - 1.00

Sulphate Sulphur mg/kg 5 10 - 12

Organic Matter* % 9.5 7.0 - 17.0 Total Carbon % 5.5 Base Saturation % K 1.8 Ca 14 Mg 5.3 Na 2.9 MAF Units K 6 Ca 3 Mg 18 Na 20 The above nutrient graph compares the levels found with reference interpretation levels. NOTE: It is important that the correct sample type be assigned, and that the recommended sampling procedure has been followed. R J Hill Laboratories Limited does not accept any responsibility for the resulting use of this information. IANZ Accreditation does not apply to comments and interpretations, i.e. the 'Range Levels' and subsequent graphs.

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Sample Name: Ring Main 23-Feb-2016 10:30 am Lab Number: 1543046.3 Sample Type: SOIL Mixed Pasture (S1) Analysis Level Found Medium Range Low Medium High pH pH Units 4.8 5.8 - 6.2

Olsen Phosphorus mg/L 116 20 - 30

Potassium me/100g 0.42 0.40 - 0.60 Calcium me/100g 4.8 4.0 - 10.0 Magnesium me/100g 1.75 1.00 - 1.60 Sodium me/100g 0.83 0.20 - 0.50

CEC me/100g 22 12 - 25 Total Base Saturation % 35 50 - 85 Volume Weight g/mL 0.87 0.60 - 1.00

Sulphate Sulphur mg/kg 15 10 - 12

Organic Matter* % 10.1 7.0 - 17.0 Total Carbon % 5.9 Base Saturation % K 1.9 Ca 22 Mg 7.9 Na 3.8 MAF Units K 7 Ca 5 Mg 34 Na 33 The above nutrient graph compares the levels found with reference interpretation levels. NOTE: It is important that the correct sample type be assigned, and that the recommended sampling procedure has been followed. R J Hill Laboratories Limited does not accept any responsibility for the resulting use of this information. IANZ Accreditation does not apply to comments and interpretations, i.e. the 'Range Levels' and subsequent graphs.

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Sample Name: Interdune 23-Feb-2016 4:20 pm Lab Number: 1543046.4 Sample Type: SOIL Mixed Pasture (S1) Analysis Level Found Medium Range Low Medium High pH pH Units 5.0 5.8 - 6.2

Olsen Phosphorus mg/L 16 20 - 30

Potassium me/100g 0.34 0.40 - 0.60 Calcium me/100g 20.2 4.0 - 10.0 Magnesium me/100g 3.51 1.00 - 1.60 Sodium me/100g 0.35 0.20 - 0.50

CEC me/100g 59 12 - 25 Total Base Saturation % 42 50 - 85 Volume Weight g/mL 0.56 0.60 - 1.00

Sulphate Sulphur mg/kg 28 10 - 12

Organic Matter* % 32.0 7.0 - 17.0 Total Carbon* % 18.6 Base Saturation % K 0.6 Ca 35 Mg 6.0 Na 0.6 MAF Units K 4 Ca 14 Mg 44 Na 9 The above nutrient graph compares the levels found with reference interpretation levels. NOTE: It is important that the correct sample type be assigned, and that the recommended sampling procedure has been followed. R J Hill Laboratories Limited does not accept any responsibility for the resulting use of this information. IANZ Accreditation does not apply to comments and interpretations, i.e. the 'Range Levels' and subsequent graphs.

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Analyst's Comments Samples 1-4 Comment: The medium range guidelines shown in the histogram report relate to sampling protocols as per Hill Laboratories’ crop guides and are based on reference values where these are published. Results for samples collected to different depths than those described in the crop guide should be interpreted with caution. For pastoral soils, the medium ranges are specific for a 75mm sample depth, but if a 150mm sampling depth is used the nutrient levels measured may appear low against these ranges, as nutrients are typically more concentrated in the top of the soil profile. These soil profile differences are altered upon cultivation or contouring.

Samples 1-4 Comment: While soil Mg MAF levels of 8-10 are sufficient for pasture production, soil levels of 25-30 are required to ensure adequate Mg content in pasture for animal health (greater than 0.22%).

Sample 4 Comment: The high CEC level found in this soil indicates that it has a high capacity to retain cation nutrients (potassium, calcium, magnesium and sodium). For crop and horticulture soil sample type codes, the normal ranges and the derived histograms are based on a typical soil with a CEC level between 12 and 25 me/100g, unless otherwise denoted.

Appendix No.1 - Chain of Custody S U M M A R Y O F M E T H O D S The following table(s) gives a brief description of the methods used to conduct the analyses for this job. The detection limits given below are those attainable in a relatively clean matrix. Detection limits may be higher for individual samples should insufficient sample be available, or if the matrix requires that dilutions be performed during analysis. Sample Type: Soil Test Method Description Default Detection Limit Sample No Sample Registration* Samples were registered according to instructions received. - 1-4 Soil Prep (Dry & Grind)* Air dried at 35 - 40°C overnight (residual moisture typically 4%) - 1-4 and crushed to pass through a 2mm screen. pH 1:2 (v/v) soil:water slurry followed by potentiometric 0.1 pH Units 1-4 determination of pH. Olsen Phosphorus Olsen extraction followed by Molybdenum Blue colorimetry. 1 mg/L 1-4 Sulphate Sulphur 0.02M Potassium phosphate extraction followed by Ion 1 mg/kg 1-4 Chromatography. Potassium (MAF) 1M Neutral ammonium acetate extraction followed by ICP-OES. 1 MAF units 1-4 Calcium (MAF) 1M Neutral ammonium acetate extraction followed by ICP-OES. 1 MAF units 1-4 Magnesium (MAF) 1M Neutral ammonium acetate extraction followed by ICP-OES. 1 MAF units 1-4 Sodium (MAF) 1M Neutral ammonium acetate extraction followed by ICP-OES. 2 MAF units 1-4 Organic Matter* Organic Matter is 1.72 x Total Carbon. 0.2 % 1-4 Total Carbon Dumas combustion. 0.1 % 2-3 Total Carbon* Determined by NIR, calibration based on Total Carbon by 0.1 % 1, 4 Dumas combustion. Potassium 1M Neutral ammonium acetate extraction followed by ICP-OES. 0.01 me/100g 1-4 Calcium 1M Neutral ammonium acetate extraction followed by ICP-OES. 0.5 me/100g 1-4 Magnesium 1M Neutral ammonium acetate extraction followed by ICP-OES. 0.04 me/100g 1-4 Sodium 1M Neutral ammonium acetate extraction followed by ICP-OES. 0.05 me/100g 1-4 Potassium (Sat) 1M Neutral ammonium acetate extraction followed by ICP-OES. 0.1 %BS 1-4

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Sample Type: Soil Test Method Description Default Detection Limit Sample No Calcium (Sat) 1M Neutral ammonium acetate extraction followed by ICP-OES. 1 %BS 1-4 Magnesium (Sat) 1M Neutral ammonium acetate extraction followed by ICP-OES. 0.2 %BS 1-4 Sodium (Sat) 1M Neutral ammonium acetate extraction followed by ICP-OES. 0.1 %BS 1-4 CEC Summation of extractable cations (K, Ca, Mg, Na) and 2 me/100g 1-4 extractable acidity. May be overestimated if soil contains high levels of soluble salts or carbonates. Total Base Saturation Calculated from Extractable Cations and Cation Exchange 5 % 1-4 Capacity. Volume Weight The weight/volume ratio of dried, ground soil. 0.01 g/mL 1-4

These samples were collected by yourselves (or your agent) and analysed as received at the laboratory.

Samples are held at the laboratory after reporting for a length of time depending on the preservation used and the stability of the analytes being tested. Once the storage period is completed the samples are discarded unless otherwise advised by the client.

This report must not be reproduced, except in full, without the written consent of the signatory.

Shelley Edhouse Quality Assurance Coordinator - Agriculture Division

Lab No: 1543046 v 1 Hill Laboratories Page 6 of 6 Appendix No.1 - Chain of Custody - Page 1 of 1