contract no: 15-069 wastewater review and options …

CONTRACT NO: 15-069

Wastewater Review and Options Study for Edgecumbe and Matatā Incorporating a High Level Review of Tāneatua and Te Teko

Contract 15-069 - Work Streams 2a and 2b

Prepared for Whakātane District Council

22 September 2015

Wastewater Review and Options Study for Edgecumbe and Matatā Contract 15-069 - Work Streams 2a and 2b

Status: Final Project No.: 805 08148 22 September 2015 Our ref: \\NZAKL1S01\Projects\2012 Onwards\Whakatane District Council\805 08148 WDC Edgecumbe WW Options\4.0 Technical\2a-2b Report\WW Review and Options Study for Edgecumbe & Matata Report Final 22-09-15.docx

QUALITY STATEMENT

PROJECT MANAGER PROJECT TECHNICAL LEAD

Garrett Hall Jim Bradley

PREPARED BY

Jim Bradley/Garrett Hall/Rainer Hoffman/Darren Wilson

CHECKED BY

Rainer Hoffman/Darren Wilson

REVIEWED BY

Jim Bradley

APPROVED FOR ISSUE BY

Garrett Hall

AUCKLAND MWH House Level 3, 111 Carlton Gore Road, Newmarket, Auckland 1023 PO Box 9176, Newmarket, Auckland 1149 TEL +64 9 580 4500, FAX +64 9 580 7600


Status: Final 22 September 2015 Project number: 805 08148 Our ref: WW Review and Options Study for Edgecumbe & Matata Report Final 22-09-15

Executive Summary Introduction

Whakatāne District Council (WDC) has a number of urgent and pending wastewater infrastructure and associated consenting matters that require addressing in a comprehensive and efficient manner.

MWH has been engaged by WDC to assist in these matters. This Report includes the following five Tasks:

Task 1: Consideration of the future treatment and disposal/discharge options for Edgecumbe (referred to as Edgecumbe standalone) given the existing resource consent for the discharge from the Edgecumbe Wastewater Treatment Plant (WWTP) expires in 2026;

Task 2: Consideration of combined Matatā and Edgecumbe treatment and disposal/discharge options. A joint scheme will allow comparison with the Matatā standalone shortlist options being separately developed by WDC and AECOM Consultants (formerly URS) following the Matatā Environment Court decision in May 2015;

Task 3: High level consideration for the future treatment and disposal/discharge from the existing sewerage scheme in Tāneatua (this consent also expires in 2026);

Task 4 High level considerations of a possible future reticulated sewerage scheme for Te Teko; and

Task 5: Review WDC’s Infrastructure Strategy 2015-45 as it relates to Council’s wastewater services. This part of MWH’s engagement is separately reported on as Work Stream 1 of this Contract 15-069.

Methodology

In developing and assessing the various options available to WDC, Tasks 1 and 2 follow the same broad methodology and staged approach being:

Stage 1: Identification and development of long list options;

Stage 2: Refinement and assessment of the long list to the confirmed long list;

Stage 3: Refinement and assessment of the confirmed long list to the short list;

Stage 4: Compilation of information to enable the short list to be assessed; and

Stage 5: Assessment and ranking of the short-list.

This draft Report has been prepared to Stage 4 and will be used to inform the further assessment and ranking of the short listed options for Stage 5. It is proposed by WDC that Stage 5 will also include the Matatā standalone options being developed by WDC and AECOM Consultants.

Edgecumbe Standalone Options

The following long list options for the standalone Edgecumbe scheme were developed and identified under the following subheadings:

Conveyance Options

Option 1 - Conveyance of Edgecumbe raw sewage to Kawerau WWTP;

Option 2 - Conveyance of Edgecumbe oxidation pond treated wastewater to new ocean outfall around Matatā;

Option 3 - Conveyance of Edgecumbe from a new WWTP at Edgecumbe to new ocean outfall around Matatā;

Option 4 - Conveyance of Edgecumbe oxidation pond treated wastewater to Whakatāne existing ocean outfall;

Option 5 - Conveyance of Edgecumbe raw sewage to Whakatāne WWTP oxidation pond .



Treatment at Edgecumbe Options and Land Application at Edgecumbe

Option 6 - Upgrade of existing Edgecumbe oxidation ponds and Land Application at Edgecumbe;

Option 7 - New WWTP at Edgecumbe and Land Application at Edgecumbe.

Treatment at Edgecumbe Options and Land Application at Thornton

Option 8 - Upgrade of existing Edgecumbe oxidation ponds and Land Application at Thornton Dunes;

Option 9 - New WWTP at Edgecumbe and Land Application at Thornton Dunes.

Treatment at Edgecumbe Options and Discharge to Tarawera River Catchment

Option 10 - New WWTP at Edgecumbe and Tarawera River Discharge.

Treatment at Edgecumbe Options and Discharge to Rangitaiki River Catchment

Option 11 - New WWTP at Edgecumbe and Rangitaiki River discharge; and

Option 12 - Upgrade of existing Edgecumbe oxidation ponds and Rangitaiki River discharge.

These options were then refined and assessed to the following short list after an assessment based on qualitative environmental, social, economic, key advantages and disadvantages and risk factors. Maori cultural considerations have not been included in the assessment to date although some information made available to WDC has been recorded in this Report.

Option 1 - Conveyance of Edgecumbe raw sewage (LPS) to Kawerau WWTP;

Option 4 - Conveyance of Edgecumbe oxidation pond treated wastewater to Whakatāne ocean outfall;

Option 5 - Conveyance of Edgecumbe raw sewage to Whakatāne WWTP oxidation pond ;

Option 8 - Upgrade of existing Edgecumbe oxidation ponds and Land Application at Thorn ton Dunes;


For Option 8 an alternative land application area was also considered by WDC is part of the expansive Whakatāne Airport land. This option was subsequently identified as Option 8A.

A more detailed risk assessment was then compiled alongside the high level cost estimating of these options to assist the further WDC decision making process.

The summarised cost breakdown for these short list options for the Edgecumbe standalone scheme is shown below.



CAPEX ($M) OPEX – Year 1 ($M)

OPEX - Year 20

($M)

(for Comparison)

NPV ($M)

Option Conveyanc

e Treatment Total Capital

Maintenance/ Replacement includes KDC Bulk Charge

for EDG1

Power Dosing Total Year 1 - OPEX

Total Year 20 - OPEX

TOTAL COST

EDG1 $10.520 $0.300 $10.820 $0.315 $0.020 $ - $0.335 $0.590 $15.705

EDG4 +Actiflo + UV

$10.080 $0.520 $10.600 $0.040 $0.010 $ - $0.050 $0.125 $11.470

EDG5 + Actiflo + UV

$10.400 $0.440 $10.840 $0.040 $0.035 $0.045 $0.120 $0.290 $12.890

EDG8 $6.150 $5.550 $11.700 $0.085 $0.185 $0.030 $0.295 $1.425 $18.355

EDG8A $7.670 $5.550 $13.220 $0.090 $0.185 $0.03 $0.305 $1.425 $19.895

EDG12 $1.625 $4.315 $5.940 $0.080 $0.185 $0.025 $0.295 $1.410 $12.515

Taking into account a range of considerations through a Multi-Criteria Analysis (MCA) including cost, the ranking of the top three options were:

1. Option 4 – Oxidation Pond Wastewater to Whakatāne WWTP Ocean Outfall;

2. Option 5 – Raw Sewage to Whakatāne WWTP; and

3. Option 8A – Upgraded Oxidation Ponds and Land Application at Whakatāne Airport.

Options 4 and 5 propose the conveyance of either wastewater treated in the oxidation ponds at Edgecumbe or raw sewage to Whakatāne WWTP. Both options utilise the existing infrastructure at the Edgecumbe and Whakatāne WWTP’s, and would require a condition change to the existing resource consent for the discharge of treated wastewater from the Whakatāne WWTP, or a new consent to be applied for.

Land application at the Whakatāne Airport also ranks highly, and may be possible to combine with a future treatment option at the Whakatāne WWTP, where land application of treated wastewater from the Whakatāne ponds may be possible in the future.

Combined Matatā and Edgecumbe Options

The following long list options for a combined Matatā and Edgecumbe scheme were developed and identified under the following subheadings:

At Kawerau

Option KL1 - Conveyance of Matatā and Edgecumbe raw sewage to Kawerau WWTP and Rapid Infiltration Bed (RIB) Land Disposal.

At Edgecumbe

Option EL1 - Conveyance of Matatā raw sewage to Edgecumbe Oxidation Ponds - Land Application at Edgecumbe

Option EL2 - Conveyance of Matatā raw sewage to new WWTP at Edgecumbe – Land Application at Edgecumbe;

Option ER1 - Conveyance of Matatā raw sewage to new WWTP at Edgecumbe and Omeheu Channel Discharge;

Option ER2 - Conveyance of Matatā raw sewage to new WWTP at Edgecumbe and discharge to Rangitaiki River; and

Option ER3 - Conveyance of Matatā raw sewage to Edgecumbe oxidation ponds upgraded as necessary and discharge to Rangitaiki River.



At Matatā

Option ML1 - Conveyance of Edgecumbe raw sewage to new WWTP at Matatā - Land Application at Matatā;

Option ML2 - Conveyance of Edgecumbe oxidation pond treated wastewater to Matatā Land Application. Matatā standalone treatment and joint land application with Edgecumbe at Matatā;

Option MR1 - Conveyance of Edgecumbe raw sewage to Matatā joint treatment and discharge to Lower Tarawera River;

Option MR2 - Conveyance of Edgecumbe upgraded oxidation pond treated wastewater to Matatā. Matatā standalone treatment – joint discharge to Tarawera River;

Option MO1 - Conveyance of Edgecumbe raw sewage to Matatā, joint treatment and discharge to ocean at Matatā; and

Option MO2 - Conveyance of Edgecumbe oxidation pond treated wastewater to Matatā. Matatā standalone treatment – joint ocean discharge at Matatā;

At Thornton

Option TL1 - Conveyance of Edgecumbe raw sewage to Matatā. Joint treatment at Matatā, land application at Thornton;

Option TL2 - Conveyance of Edgecumbe upgraded oxidation pond treated wastewater to Matatā. Matatā standalone treatment and joint land application at Thornton; and

Option TL3 - Conveyance of Matatā raw sewage to Edgecumbe. Joint treatment at Edgecumbe upgraded oxidation ponds and conveyance to land application at Thornton.

At Whakatāne

Option WO1 - Conveyance of Matatā to Thornton and Edgecumbe to Thornton – then combined conveyance to Whakatāne WWTP upgraded and Ocean Outfall Discharge;

Option WO2 - Conveyance of Matatā to Whakatāne WWTP and Edgecumbe to Whakatāne WWTP upgraded (via Awakeri) and Ocean Outfall Discharge;

Option WO3 - Conveyance of Matatā to Thornton and Edgecumbe Oxidation Pond treated wastewater to Thornton to the Whakatāne ocean outfall;

Option WO4 - Conveyance of Matatā raw sewage to Whakatāne WWTP and Edgecumbe Oxidation Pond treated wastewater to Whakatāne (via Awakeri) for joint Whakatāne ocean outfall;

Option WO5 - Conveyance of Matatā raw sewage to Edgecumbe oxidation ponds. Edgecumbe oxidation ponds treated wastewater for joint Whakatāne ocean outfall discharge Route Option A – via Thornton; and

Option WO6 - Conveyance of Matatā raw sewage to Edgecumbe oxidation ponds. Edgecumbe oxidation ponds treated wastewater for joint Whakatāne ocean outfall discharge Route Option B – via Awakeri.

These options were then refined and assessed to the following short list after an assessment based on qualitative environmental, social, economic, key advantages and disadvantages and risk factors. As per the Edgecumbe standalone option, Maori cultural considerations have not been included in the assessment to date although some information made available to WDC has been recorded in this Report.

Option KL1 - Conveyance of Matatā and Edgecumbe raw sewage to Kawerau WWTP and Rapid Infiltration Bed (RIB) Land Disposal.


Option TL2 - Conveyance of Edgecumbe oxidation pond treated wastewater to Matatā. Matatā standalone treatment and joint land application at Thornton; and



Option TL3 - Conveyance of Matatā raw sewage to Edgecumbe. Joint treatment at Edgecumbe oxidation ponds and conveyance to land application at Thornton.

Option WO1 - Conveyance of Matatā raw sewage to Thornton and Edgecumbe to Thornton – then combined conveyance to Whakatāne WWTP and Ocean Outfall Discharge .

Option WO5 - Conveyance of Matatā raw sewage to Edgecumbe oxidation ponds. Edgecumbe oxidation ponds treated wastewater for joint Whakatāne ocean outfall discharge Route Option A – via Thornton.

For Option TL2 and TL3 an alternative land application area currently also being considered by WDC is part of the expansive Whakatāne Airport land. These were subsequently labelled Options TL2A and TL3A.

A more detailed risk assessment including identification of further mitigation measures was then compiled alongside the high level cost estimating of these options to assist the further WDC decision making process.

The summarised cost breakdown for these short list options for the combined Matatā and Edgecumbe scheme options is shown below.


OPEX - Year 20 ($M) (for

Comparison)

NPV ($M)

Option Matatā

Reticulation Conveyance Treatment Total Capital


for KL1

Power Dosing Total Year 1

- OPEX Total Year 20 - OPEX

TOTAL COST

KL1 $6.000 $18.955 $0.300 $25.255 $0.365 $0.030 $0.065 $0.460 $0.855 $32.085

ER3 $6.000 $9.765 $5.155 $20.920 $0.115 $0.200 $0.045 $0.360 $1.540 $28.495

TL2 $6.000 $10.490 $8.985 $25.475 $0.115 $0.255 $0.040 $0.410 $1.625 $33.810

TL2A $6.000 $13.585 $8.985 $28.570 $0.120 $0.255 $0.040 $0.415 $1.630 $36.945

TL3 $6.000 $13.310 $6.540 $25.850 $0.120 $0.200 $0.045 $0.365 $1.555 $33.515

TL3A $6.000 $14.835 $6.540 $27.375 $0.120 $0.200 $0.045 $0.365 $1.555 $35.045

WO1 + Actiflo + UV

$6.000 $16.240 $0.625 $22.865 $0.090 $0.020 $0.065 $0.175 $0.410 $25.705

WO5 + Actiflo + UV

$6.000 $17.125 $0.700 $23.825 $0.075 $0.025 $0.015 $0.115 $0.280 $25.760

MW1 + Actiflo + UV

$6.000 $9.410 $0.180 $15.590 $0.060 $0.010 $0.015 $0.085 $0.185 $16.915

Taking into account a range of considerations through a Multi-Criteria Analysis (MCA) including cost, the ranking of the top three options were:

1. Option WO5 – Conveyance of Matatā raw sewage to Edgecumbe oxidation ponds. Edgecumbe

oxidation ponds treated wastewater for joint Whakatāne Ocean Outfall discharge

2. Option WO1 – Conveyance of Matatā raw sewage to Thornton and Edgecumbe raw sewage to

Thornton – then combined to Whakatāne WWTP and Ocean Outfall Discharge; and

3. Option TL3A - Conveyance of Matatā raw sewage to Edgecumbe. Joint treatment at

Edgecumbe oxidation ponds and conveyance to land application at the Whakatāne Airport.

Similar to the Edgecumbe standalone options, the conveyance of treated wastewater to Whakatāne in option WO5 has a number of advantages over the conveyance of raw sewage in WO1. Land application at Whakatāne airport also ranks highly and should be included in further considerations.


Status: Final 22 September 2015 Project No.: 805 08148 Our ref: WW Review and Options Study for Edgecumbe & Matata Report Final 22-09-15

Whakatāne District Council

Wastewater Review and Options Study for Edgecumbe and Matatā

Contract 15-069 - Work Streams 2a and 2b

CONTENTS

Executive Summary ................................................................................................................................... i

1 Project Context ................................................................................................................................... 1

1.1 Background .................................................................................................................................... 1

1.2 Project Scope and Overall Approach ............................................................................................. 1

1.3 Inter-related Projects and Decision Making ................................................................................... 3

1.4 Existing Investigations and Documentation ................................................................................... 3

1.5 Whakatāne District Council – Key Project Drivers ......................................................................... 4

1.6 Community and Tāngata Whenua Consultation – Key Considerations ......................................... 4

1.7 Work Stream 1 Output and Relationship to this Project ................................................................ 5

2 Project Inputs, Assumptions and Methodology ................................................................................... 7

2.1 Project Inputs and Assumptions .................................................................................................... 7

2.2 Study Area ..................................................................................................................................... 7

2.3 Wastewater Volumes and Flows .................................................................................................... 7

2.3.1 Matatā Design Flows .............................................................................................................. 8

2.4 Technical Approach ..................................................................................................................... 10

2.5 Building up a Complete Scheme.................................................................................................. 11

2.6 Concept Design Assumptions - Conveyance ............................................................................... 12

2.6.1 Managing Septicity and Odourous Gases in Conveyance Systems ..................................... 14

2.6.1.1 Chemical Dosing (Liquid Phase Odour Control) ........................................................... 15

2.6.1.2 Odour Treatment (Gas Phase Odour Control) .............................................................. 15

2.6.2 Balancing of Raw Wastewater .............................................................................................. 16

2.6.3 Balancing of Treated Wastewater ......................................................................................... 16

2.7 Concept Design Assumptions - Odour Management of Conveyance Systems ........................... 17

2.8 Concept Design Assumptions – Treatment ................................................................................. 17

2.9 Natural Hazards and Climate Change ......................................................................................... 18

2.10 Environmental Effects Assessment ............................................................................................. 18

2.11 Land Application Options ............................................................................................................. 18

2.12 Existing Resource Consents ........................................................................................................ 23

2.13 Risk Considerations ..................................................................................................................... 24

2.14 Discharge / Disposal Options – Land, Freshwater, Marine.......................................................... 24

3 Legislation and Planning Instruments ............................................................................................... 26

3.1 Overview ...................................................................................................................................... 26

3.2 National Policy Statement for Freshwater Management 2014 ..................................................... 26



3.3 New Zealand Coastal Policy Statement 2010 .............................................................................. 26

3.4 Regional Policy Statement and Regional Plans .......................................................................... 27

3.4.1 Operative and Proposed Regional Policy Statement ............................................................ 27

3.4.2 Regional Air Plan .................................................................................................................. 28

3.4.3 Regional Water and Land Plan ............................................................................................. 28

3.4.4 Regional Plan for the Tarawera River Catchment ................................................................. 29

3.5 Matatā Wastewater Consents and Designation: Environment Court Decision 2015 ................... 32

4 Cost Estimates ................................................................................................................................. 33

4.1 Basis of Cost Estimates ............................................................................................................... 33

5 Edgecumbe Standalone Options ...................................................................................................... 35

5.1 Methodology ................................................................................................................................ 35

5.2 Identification of Long List Options ............................................................................................... 35

5.3 Evaluation of Long List Options ................................................................................................... 39

5.4 Assessment of Confirmed Long List Options ............................................................................... 41

5.4.1 Option 1 (EDG1) - Conveyance of Edgecumbe to Kawerau WWTP ..................................... 42

5.4.2 Option 2 - Conveyance of Edgecumbe Oxidation Pond Treated Wastewater to New Ocean Outfall around Matatā ....................................................................................................................... 43

5.4.3 Option 4 (EDG 4) - Conveyance of Edgecumbe Oxidation Pond Treated Wastewater to Whakatāne Ocean Outfall ................................................................................................................. 44

5.4.4 Option 5 - Conveyance of Edgecumbe Raw Sewage to Whakatāne WWTP ........................ 45

5.4.5 Option 8 (EDG 8) - Upgrade of Existing Edgecumbe Oxidation Ponds and Land Application at Thornton Dunes ............................................................................................................................ 46

5.4.6 Option 9 – New WWTP at Edgecumbe and Land Application at Thornton Dunes ................ 47

5.4.7 Option 10 - New WWTP at Edgecumbe and Tarawera River Discharge .............................. 48

5.4.8 Option 11 - New WWTP at Edgecumbe and Rangitaiki River Discharge ............................. 49

5.4.9 Option 12 (EDG 12) - Upgrade of existing Edgecumbe Oxidation Ponds and Rangitaiki River discharge .......................................................................................................................................... 50

5.5 Confirmed Long List Assessment Summary ................................................................................ 51

5.6 Comparison of Short Listed Options ............................................................................................ 53

5.6.1 Estimated Costs .................................................................................................................... 54

5.6.2 Short List Options: Information Summary ............................................................................. 55

5.6.3 Ranking of Short Listed Option ............................................................................................. 55

5.7 Discussions and Findings ............................................................................................................ 62

6 Combined Matatā and Edgecumbe Options ..................................................................................... 63

6.1 Matatā Stand Alone Scheme Option............................................................................................ 63

6.2 Methodology ................................................................................................................................ 63

6.3 Identification of Long List Options ............................................................................................... 63

6.4 Evaluation of Long List Options ................................................................................................... 70

6.5 Assessment of Confirmed Long List Options ............................................................................... 74

6.5.1 Option KL1 - Conveyance of Matatā and Edgecumbe to Kawerau WWTP ........................... 75

6.5.2 Option ER2 - Conveyance of Matatā to new WWTP at Edgecumbe and Discharge to Rangitaiki River ................................................................................................................................. 76



6.5.3 Option ER3 - Conveyance of Matatā to Edgecumbe Oxidation Ponds Upgraded as Necessary and Discharge to Rangitaiki River ................................................................................... 77

6.5.4 Option MO2 - Conveyance of Edgecumbe Oxidation Pond Treated Wastewater to Matatā. Matatā Standalone Treatment – Joint Ocean Discharge at Matatā .................................................. 78

6.5.5 Option TL1 - Conveyance of Edgecumbe Raw Sewage to Matatā. Joint Treatment at Matatā, Land Application at Thornton ............................................................................................................ 79

6.5.6 Option TL2 - Conveyance of Edgecumbe Oxidation Pond Treated Wastewater to Thornton. Matatā Standalone Treatment and Joint Land Applica tion at Thornton ............................................ 80

6.5.7 Option TL3 - Conveyance of Matatā Raw Sewage to Edgecumbe. Joint Treatment at Edgecumbe Oxidation Ponds and Conveyance to Land Application at Thornton ............................. 81

6.5.8 Option WO1 - Conveyance of Matatā to Thornton and Edgecumbe to Thornton – then combined to Whakatāne WWTP and Ocean Outfall Discharge ........................................................ 82

6.5.9 Option WO5 - Conveyance of Matatā Raw Sewage to Edgecumbe Oxidation Ponds. Edgecumbe Oxidation Ponds Treated Wastewater for Joint Whakatāne Ocean Outfall Discharge Route Option A – via Thornton.......................................................................................................... 83

6.5.10 Option WO6 - Conveyance of Matatā Raw Sewage to Edgecumbe Oxida tion Ponds. Edgecumbe Oxidation Ponds Treated Wastewater for Joint Whakatāne Ocean Outfall Discharge Route Option B – via Awakeri ........................................................................................................... 84

6.6 Confirmed Long List Assessment Summary ................................................................................ 85

6.7 Assessment of Short-Listed Options ........................................................................................... 89

6.7.1 Estimated Costs .................................................................................................................... 90

6.7.2 Short List Options: Information Summary ............................................................................. 91

6.7.3 Ranking of Short Listed Option ............................................................................................. 91

6.8 Discussions and Findings ............................................................................................................ 99

7 Conveyance Issues and Considerations for Short Listed Options .................................................. 100

7.1 Vertical Alignment ...................................................................................................................... 100

7.1.1 Individual Short-List Route Option Long-sections ............................................................... 101

7.2 Start-up Flows ........................................................................................................................... 104

7.3 Other Considerations ................................................................................................................. 104

8 Risk Assessment, Management and Mitigation .............................................................................. 106

8.1 Risk Management Background and Approach .......................................................................... 106

8.2 Evaluation of Risk ...................................................................................................................... 107

9 Tāneatua and Te Teko Options ...................................................................................................... 119

9.1 Tāneatua.................................................................................................................................... 119

9.2 Te Teko Options ........................................................................................................................ 119

10 Conclusions and Next Steps .......................................................................................................... 121

10.1 Conclusions ............................................................................................................................... 121

10.1.1 Edgecumbe Standalone Options ........................................................................................ 121

10.1.2 Matatā/Edgecumbe Combined Options .............................................................................. 121

10.1.3 Taneatua and Te Teko ........................................................................................................ 121

10.2 Next Steps ................................................................................................................................. 122

11 Acknowledgements......................................................................................................................... 123

12 References ..................................................................................................................................... 124



13 Glossary of Terms and Abbreviations............................................................................................. 127

LIST OF TABLES

Table 1-1: Long Term Plan Key Principles................................................................................................. 4

Table 2-1: Matata and Edgecumbe Wastewater Volumes and Flows ...................................................... 8

Table 2-2: Matata Concept Design Flows for Low Pressure Reticulated Network .................................... 9

Table 2-3: Existing Resource Consents ................................................................................................. 23

Table 3-1: Regional Plan for the Tarawera River Catchment –Limits for Edgecumbe WWTP ............... 30

Table 5-1: Long list Options for Edgecumbe Schemes ............................................................................ 36

Table 5-2: Evaluation Criteria for Long List Options .............................................................................. 39

Table 5-3: Long List Option Assessment Summary ................................................................................. 40

Table 5-4: Confirmed Long List Option Assessment Summary ............................................................... 51

Table 5-5: Edgecumbe Standalone Shortlisted Options .......................................................................... 53

Table 5-6: Estimated Costs for Edgecumbe Standalone Options ............................................................ 54

Table 5-7: Edgecumbe Standalone Shortlisted Options – MCA Analysis Criteria (Independent of Cost) 57

Table 5-8: Edgecumbe Standalone Shortlisted Options – MCA Analysis Weighting ............................... 58

Table 5-9: Edgecumbe Standalone Shortlisted Options – MCA Scoring Results (Independent of Cost) . 59

Table 5-10: Edgecumbe Standalone Shortlisted Options – MCA Results Scoring Rationale (Independent of Cost) 60

Table 5-11: Edgecumbe Standalone Shortlisted Options – MCA Summary Results ............................... 61

Table 6-1: Long list Options for Combined Matatā and Edgecumbe Schemes ........................................ 65

Table 6-2: Evaluation Criteria for Long List Options .............................................................................. 70

Table 6-3: Long List Option Assessment Summary ................................................................................. 71

Table 6-4: Confirmed Long List Option Assessment Summary ............................................................... 85

Table 6-5: Matatā and Edgecumbe Standalone Shortlisted Options ....................................................... 89

Table 6-6: Estimated Costs for Combined Matatā and Edgecumbe Options ........................................... 91

Table 6-7: Combined Matatā/Edgecumbe Shortlisted Options – MCA Analysis Criteria (Independent of Cost) 94

Table 6-8: Combined Matatā/Edgecumbe Shortlisted Options – MCA Analysis Weighting ..................... 95

Table 6-9: Combined Matatā/Edgecumbe Shortlisted Options – MCA Scoring Results (Independent of Cost) 96

Table 6-10: Combined Matatā/Edgecumbe Shortlisted Options – MCA Results Scoring Rationale (Independent of Cost) .............................................................................................................................. 97

Table 6-11: Combined Matatā/Edgecumbe Shortlisted Options – MCA Summary Results ..................... 98

Table 7-1: Summary of Main Conveyance Routes for Shortlisted Options ............................................ 104

Table 8-1: Likelihood Scale .................................................................................................................... 107

Table 8-2: Consequence Scale .............................................................................................................. 108

Table 8-3: Risk Matrix Definitions .......................................................................................................... 109

LIST OF FIGURES

Figure 1-1: Inter-relationship of Projects .................................................................................................... 2



Figure 1-2: Decision Making Flow Chart .................................................................................................... 3

Figure 2-1: Treated Wastewater Land Application Option within 7.5 km of Edgecumbe Wastewater Treatment Plant ....................................................................................................................................... 20

Figure 2-2: Treated Wastewater Land Application Option at Thornton Dunes ......................................... 21

Figure 2-3: Treated Wastewater Land Application Option at Whakatāne Airport ..................................... 22

Figure 3-1: Regional Plan for the Tarawera River Catchment Map ......................................................... 31

Figure 5-1: Schematic for Option 1 .......................................................................................................... 42






Figure 5-7: Schematic for Option 10 ........................................................................................................ 48



Figure 5-10: Schematic for Option 8A ...................................................................................................... 54

Figure 6-1: Schematic for Option KL1 ...................................................................................................... 75

Figure 6-2: Schematic for Option ER2 ..................................................................................................... 76

Figure 6-3: Schematic for Option ER3 ..................................................................................................... 77

Figure 6-4: Schematic for Option MO2 .................................................................................................... 78

Figure 6-5: Schematic for Option TL1 ...................................................................................................... 79



Figure 6-8: Schematic for Option WO1 .................................................................................................... 82

Figure 6-9: Schematic for Option WO5 .................................................................................................... 83

Figure 6-10: Schematic for Option WO6 .................................................................................................. 84

Figure 6-11: Schematic for Option TL2A .................................................................................................. 90

Figure 6-12: Schematic for Option TL3A .................................................................................................. 90

APPENDICES

Edgecumbe Oxidation Ponds Flow Balancing Technical Memorandum

Whakatāne Oxidation Ponds – Capacity Assessment Technical Memorandum

Legal Advice on Regional Plan for the Tarawera River Catchment

Edgecumbe Standalone Options – Long List Assessment

Edgecumbe Standalone Options – Short List Route Alignments

Matatā and Edgecumbe Combined Options – Long List Assessment

Matatā and Edgecumbe Combined Options – Short List Route Alignments

Conveyance Capital and Annual Operating and Maintenance Costs



Treatment and Disposal / Discharge Capital and Annual Operating and Maintenance Costs

Net Present Value Estimated Costs

Actiflo® and MBBR Treatment Processes Supplier Information


Status: Final 22 September 2015 Project number: 805 08148 Page 1 Our ref: WW Review and Options Study for Edgecumbe & Matata Report Final 22-09-15

1 Project Context

1.1 Background

Whakatāne District Council (WDC) has a number of both urgent and pending wastewater infrastructure

and associated consenting matters that need addressing in a comprehensive and efficient manner.

WDC has engaged MWH Consultants to work with WDC Officers and prepare this Report

In summary, these matters as addressed in this Report include the following five Tasks:

Task 1: Consideration of the future treatment and disposal/discharge options for Edgecumbe (referred to as Edgecumbe standalone);

Task 2: Consideration of combined Matatā and Edgecumbe treatment and disposal/discharge options. A joint scheme will allow comparison with the Matatā standalone shortlist options being separately developed by WDC and AECOM Consultants (formerly URS);

Task 3: High level consideration for the future treatment and disposal/discharge from the existing sewerage scheme in Tāneatua;

Task 4 High level considerations of a possible future reticulated sewerage scheme for Te Teko; and

Task 5: Review WDC’s Infrastructure Strategy 2015-45 as it relates to Council’s wastewater services. This part of MWH’s engagement is separately reported on as discussed in Section 1.6 below. This is referred to as Work Stream 1 in the Contract 15-069.

1.2 Project Scope and Overall Approach

The scope of Tasks 1 and 5 are set out in Appendix 3 of WDC’s “Professional Services for Wastewater

Review and Options Study for Edgecumbe Wastewater Treatment and Disposal” document 15 -069

issued on 19 May 2015.

Soon after award of the 15-069 contract to MWH, WDC expanded the brief by adding Task 2 above to

include consideration of joint options for Matatā and Edgecumbe. This was done as it was both prudent

and necessary in terms of further assessing alternatives for Matatā (following the 2015 Matatā

Wastewater Scheme Environment Court decision). Following that Tasks 3 and 4 were also added.



Figure 1.1 (prepared by WDC) diagrammatically shows the inter linkages between Tasks 1, 2, 5 and the

WDC/AECOM Matatā standalone further options assessment.

Figure 1-1: Inter-relationship of Projects

In summary the approach to Tasks 1, 2, 3 and 4 of this Project has involved the following:

Further definition of the Project Tasks with WDC;

Confirmation of key background information from WDC (question and answer emails from Inka Krawcyzk (16 July 2015) and Santha Agas (17 July 2015) and Tom McDowell of Kawerau District Council (refer references to this Report) for Kawerau District Council correspondence;

Site drive over and walkover survey with WDC Officers;

Workshops with WDC Officers on 8 July 2015 and 27 July 2015, the later also attended by Terry Long of the Bay of Plenty Regional Council (BOPRC);

Review and use of previous investigations and reports (refer Section 1.4 below and Project reference list in this Report);

Formulation of “Long List” and “Short List” options for both Edgecumbe stand alone and Edgecumbe and Matatā combined options and comparison of these using a wide range of criteria and identification of advantages, disadvantages and key risks for the options, part icularly for the short listed options;

Further assessment of the evaluation criteria for comparison of short listed joint Matatā and Edgecumbe options with Matatā standalone shortlisted options separately being compiled by WDC and AECOM; and

Compilation of this Report.



1.3 Inter-related Projects and Decision Making

The key inter-related project in terms of securing various subsidy monies, is the Matatā Wastewater

(standalone) Scheme. This inter-relationship is introduced in Sections 1.1 and 1.2 above.

The output of this Report as it relates to the shortlisted options for a Joint Matatā/Edgecumbe Scheme is

to be used along with the output from the Matatā standalone shortlisted options. Figure 1.2 shows how

WDC propose to bring these two projects together in terms of assessing the Best Practicable Option

(BPO) for the Matatā community.

Figure 1-2: Decision Making Flow Chart

Other interrelated projects include:

Task 5 the review of WDC’s “Infrastructure Strategy 2015-45”. This is Work Stream 1 of Contract

15-069 and is commented on in Section 1.7 below; and

Future consideration of the Whakatāne Wastewater treatment and Ocean Outfall Discharge

Consent which expires in 2026 as it relates to these options for both Matatā standalone and

Matatā and Edgecumbe. Also briefly addressed is the question of the possibility of a future

abattoir discharging to the Whakatāne wastewater system.

1.4 Existing Investigations and Documentation

As listed in the references to this Report, there are many WDC reports on former wastewater

investigations along with the Matatā Wastewater Scheme Assessment of Effects on the Environment



(AEE) document (December 2013) and associated 10 Support Documents, and related National and

Regional Planning Instruments that all provide some relevant background information for this Report.

Those issues of greater importance and relevance to this Project include:

Matatā Wastewater Scheme Support Document 2: Natural Hazards, Constraints and Risk Assessment; and

Matatā Wastewater Scheme Support Document 4: Alternatives Assessment Information.

1.5 Whakatāne District Council – Key Project Drivers

Council’s Vision as set out in their Long Term Plan (LTP) 2015-2025 sets the high level key driver for all

its activities, being:

“To be known as the place of choice for people to live, work and play. In achieving our vision, our community will be safe and surrounded by people who are friendly and caring, businesses will be thriving, there will be respect for, and pride in our history and we will be successful guardians of our natural environment”.

Underpinning this vision there are a number of other strategies and policies that all are in effect key

drivers for these Projects. These include WDC’s Sustainability Strategy (2012-2015) the objective of

which is to integrate sustainable decision-making and actions into the way the Council does business.

In terms of infrastructure development in the LTP, Council has identified for key principles as shown in

Table 1-1.Table 1-1: Long Term Plan Key Principles

Table 1-1: Long Term Plan Key Principles

Responsible We will work with the community to prioritise core services and prudent infrastructure management which will meet their needs

Sustainable We will undertake good stewardship of our assets and services, managing these in a way that does not compromise our ability to provide quality, affordable services to the community in the future

Affordable We will be responsive and sensitive to the issue of rates affordability across the District, in particular when making decisions about infrastructure investments and funding mechanisms

Enabling We will provide the infrastructure required to support and enable growth and prosperity in our district and work with others towards this goal

These principles are particularly relevant in terms of determining the most appropriate wastewater

infrastructure options for Matatā, Edgecumbe and other communities.

1.6 Community and Tāngata Whenua Consultation – Key Considerations

It is outside MWH’s brief for this Project to undertake or consider in detail community and tāngata

whenua consultation output.

It is however, most appropriate that this Report does take into account community, key stakeholders and

tāngata whenua’s key considerations that are apparent at the present time as have been mentioned by

WDC Officers, Terry Long of the BOPRC, AECOM in relation to a Matatā standalone scheme including

these matters raised in the earlier Matatā Wastewater Scheme Stakeholder consultation.

These key considerations include:

Need to protect and if possible enhance water environments into which treated wastewater disposal/discharge would/could be made for the options considered;

Appropriate protection of ground and surface water for land application options;



Well sited and sufficiently off shore discharges for new (offshore) ocean outfall options;

Selection of conveyance routes that minimise disturbance of road carriage ways and other services as these will have less construction related adverse effects (e.g. traffic disturbance) than alternative conveyance route options;

Options that minimise and mitigate as far as reasonable and economically possible construction

impacts (e.g. traffic control, noise dust etc.);

Options that as far as practicable and practical use, even if upgraded or expanded existing key

wastewater infrastructure. This for example includes the Edgecumbe Oxidation Ponds, the

Whakatāne Oxidation ponds and the Whakatāne ocean outfall;

Use of treatment technologies compatible with WDC’s existing schemes and operator abilities;

If possible use of low energy treatment and conveyance pumping options; and

Adoption of a scheme or schemes for which long term resource consents can be secured at

reasonable costs within a reasonable timeframe and which have community and other

stakeholder and tāngata whenua acceptance.

In terms of tāngata whenua consultation undertaken by WDC Officers, and the range of the options

under consideration the following views have been offered.

A new ocean outfall in the vicinity of Matatā would not be supported; and

Conveyance of raw wastewater from Matatā to Edgecumbe, or to Kawerau or Whakatāne would

be supported (if proceeded with). This implies that conveyance of treated wastewater would also

be supported and probably to a greater extent than conveyance of raw sewage.

As set out later in this Report for the shortlisted options, while an initial comment is made in respect to

tāngata whenua considerations, it is most appropriately recorded that tāngata whenua input is required

in terms of further consideration of shortlisted and preferred options.

1.7 Work Stream 1 Output and Relationship to this Project

As indicated in Section 1.1, Task 5, the MWH review of the wastewater sections of the LTP and

Infrastructure Strategy 2015-45 is being separately reported on. Notwithstanding this will be reported

separately, there are some important key considerations that are relevant to the assessment and

comparison of options and output of this Project. These include:

Core Outcomes

Delivery quality core services;

Encouraging communities and businesses to thrive;

Working together to meet community needs; and

Rates affordability.

Key issues to be addressed

Gaining infrastructure and in Edgecumbe’s case earthquake damaged wastewater collection (reticulation) system;

New legislation leading to stricter environmental controls e.g. National Policy Statement on Freshwater Management 2014 (NPS-FM) (refer section 3 following);

The District being prone to natural hazards; and

Ageing and fairly static population e.g. in Edgecumbe and by contrast reasonable growth is project in Matatā.

Planning Assumptions

Natural hazards risks (earthquake, flooding, tsunami, debris flows, slips and volcanic activity) ;



Environment processes susceptibility (soil erosion, sediment build-up beach erosion etc.); and

Climate change and predicted sea level rise.

Service Delivery

Consent conditions;

Disaster preparedness; and

Infrastructure needs for growth related development.

Land Use

Assumptions on present residential zoning based on Proposed District Plan.



2 Project Inputs, Assumptions and Methodology

2.1 Project Inputs and Assumptions

A wide range of Project inputs has been used in developing this Report. In summary these include:

Information contained in the extensive references as set out in the reference list and further recorded in Section 1.4 above;

The Questions and Answers (Q&A) received from WDC Officers (refer Section 1.3) and from Kawerau District Council;

LIDAR (as provided by WDC) and other GIS data publically available and received from BOPRC;

Existing WDC and Kawerau District Council Resource Consents;

MWH wastewater infrastructure databases;

WDC workshops on the Project; and

Local knowledge from WDC Officers and Terry Long from BOPRC.

Three following are the key assumptions made for this Project. Additional topic specific assumptions are

set out in the conveyance and treatment and discharge sections of this Report.

Conveyance pipelines have been sized and costed to cater for long-term flow projections (50

year horizon – 2064/65);

Treatment processes have been sized and costed for medium-term flow projections (20 year

horizon – 2044/45);

Chemical dosing facilities at pump stations for the conveyance of raw wastewater has been

allowed for; and

Bio-filtration beds/carbon cartridge units have not been allowed for at air valves. Further

investigation is required into the needs and details of this through a septicity and odour study.

2.2 Study Area

The study area comprises of:

The community areas of Matatā and Edgecumbe for the options assessment;

The conveyance routes between communities and treatment and disposal/discharge facilities;

Areas considered for land application (disposal);

The existing wastewater treatment and discharge facilities at Kawerau (Kawerau District

Council) and Whakatāne; and

The communities of Tāneatua (which has a community sewage scheme) and Te Teko (which

does not have a community scheme).

2.3 Wastewater Volumes and Flows

The projected wastewater volumes and flows are a key consideration for the assessment of both the

combined Matatā and Edgecumbe options and the standalone Edgecumbe treatment and conveyance

options.

Table 2-1 provides a summary of the wastewater volumes and flows used in this Report. In determining

these volumes and flows the following reports have been reviewed (refer reference list).

1. Wastewater Scheme for the Towns of Edgecumbe, Matatā and Te Teko (Harrison Grierson,

2009);



2. Wastewater Treatment and Management Options for Edgecumbe and Matatā (Opus, 2013);

3. Matatā WWTP – Flow Rate and Mass Load Assessment for Determination of Land Disposal Area Requirements Reference 42790250-R004 (URS, 2013);

4. Matatā WWTP – Final Design Flows for Employer Requirements – Part 402 (URS, 2014);

5. First Time Sewerage for the Community of Matatā – Preliminary Design Report (Harrison Grierson, 2009); and

6. Matatā Sewerage Scheme – Review of Projected Hydraulic Flow Rates to WWTP (MWH, 2014).

Table 2-1: Matata and Edgecumbe Wastewater Volumes and Flows

Header Matatā1 (assumed population growth)2

Edgecumbe (assume static growth)3

Combined Matatā and Edgecumbe

ADF (existing) (m3/day)

204 7644

ADWF (existing)

(m3/day)

5605

PWWF (existing)

(m3/day)

270 5,600 (peak flows to be balanced within Edgecumbe pond)

Peak flows from Edgecumbe pond assumed to be 1,680 m3/day

1,950

ADF (20 yr)

(m3/day)

375 560 935

PWWF (20 yr)

(m3/day)

415 1,680 2,095

ADF (50 yr)

(m3/day)

423 560 983

PWWF (50 yr)

(m3/day)

555 1,680 2,235

Design Flow (L/s) 156 30 45

2.3.1 Matatā Design Flows

A number of studies have been undertaken for a Matatā scheme in terms of flow estimates. The two

main sources for these figures have been provided below in Table 2-2, are as follows:

1 Matatā Township is currently not serviced by a reticulated sewerage system. Flows are based on population equivalents. 2 Matatā flows sourced from Matatā WWTP Flow Rate and Mass Load Assessment (URS, June 2013) and Matatā Wastewater

Scheme Employer Requirements – Connected Population and Flow Rates (URS, 2014) 3 The actual population of Edgecumbe is 1,700 and static or declining – flows are sourced from Wastewater Treatment and

Management Options for Edgecumbe and Matatā (Opus, 2013). 4 Calculated by adding Matatā ADF and Edgecumbe ADWF. 5 Peak flows based on flow data supplied by WDC. WDC’s proposal is to replace the damaged Edgecumbe collection system with

a lower pressure system (LPS) grinder pump system as included in the Long Term Plan (LTP 2015-25) for 2026-28 at a cost of $17.7M. The current assumption is that the reticulation will be replaced as per the LTP, however this decision is being revisited. Peak flows are assumed to be balanced within the Edgecumbe oxidation pond system both before and after the LPS is installed. 6 Refer Section 2.3.1 for assessment of Design Flow Rate for Matatā for a low pressure grinder pump scheme (LPS).



1. Contract 14-026 Matatā Wastewater Scheme: Design/Build/Operate for Wastewater Treatment

Plant and Land Application Employer’s Requirements – Part 402 (URS, 2014) – These figures

were developed for the design of a local WWTP at Matatā.

2. Matatā Pressure Wastewater Collection System – Detailed Design Report (Feb 2014, Harrison

Grierson). These figures have been developed in support of the detailed design of the Matatā

low pressure wastewater collection system (LPS). No 2064 figures were developed as the

project was focussed on the design of the collection system to the 2034 planning horizon.

3. 2064 figures have been developed based upon a mix of the URS (now AECOM) and Harrison

Grierson data sources.

4. It is noted there are some gaps in Table 2-2. These are because the information was not

included in the Reports referenced.

5. PE – Population Equivalent and other abbreviations are included in the Glossary of Terms and

Abbreviations in Section 13 of this Report.

Table 2-2: Matata Concept Design Flows for Low Pressure Reticulated Network

Flow Estimate REF1 REF2

Flow Forecast Source

Contract 14-026 Matatā Wastewater Scheme: Design/Build/Operate for Wastewater Treatment Plant and Land Application Employer’s Requirements – Part 402 (URS, 2014)

Matatā Pressure Wastewater Collection System – Detailed Design Report (Feb 2014, H&G)

Time Frame 2014 2034 2064 2014 2034 2064*

Residential (Dwellings) (nr) 250 350 500 250 350 500

Residential (Occupancy) (rate) 2.75 2.75 2.75 2.75 2.75 2.75

Residential (Population) (nr) 687.5 962.5 1375 687.5 962.5 1375

Camping Sites (nr) 40 70 100 40 100 100

Camping Sites (Occupancy) (rate) 2.64 2.64 2.64 2.64 2.64 2.64

Camping Sites (Population) (nr) 105.6 184.8 264 105.6 264 264

Primary School (School Roll nr) 92 130 190 115 160 190

Commercial Sites (nr) 7 7 7

Total PE (nr) 1015.62 1567.06 2109.3 785.82 1119.05 1536.05

Residential PCF (L/hd/d) 200 200 200 200 200 200

School PCF (L/hd/d) 30 30 30 30 30 30

Camp Site PCF (L/hd/d) 65 65 65 65 65 65

Residential Daily Volume (m3/d) 137.5 192.5 275 137.5 192.5 275

School Daily Volume (m3/d) 2.76 3.9 5.7 3.45 4.8 5.7

Camping Daily Volume (m3/d) 6.864 12.012 17.16 6.864 17.16 17.16

Commercial Daily Volume (m3/d) 56 105 124 9.35 9.35 9.35

Nr Lots 290 420 600 288 372 522

Total DDWF Volume (m3/d) 203.124 313.412 421.86 157.164 223.81 307.21

Growth 1.54 2.08 1.42 1.37

Total AWWF Volume (m3/d) (10%) 223.4364 344.7532 464.046

Design Daily Volume (m3/d) 245 375 555 157.164 223.81 307.21

Design Peak Flow (l/s) 28 8.1 9.25

Max Flow (l/s) Power Out 15-20 15-20



Average DWF (l/s) 2.59 3.99 5.37 1.82 2.59 3.56

3 x ADWF (l/s) 7.76 11.97 16.11 5.46 7.77

4 x ADWF (l/s) 10.34 15.96 21.48 7.28 10.36

5 x ADWF (l/s) WDC CoP 12.93 19.95 26.85 9.10 12.95

US EPA Design PF (1991) 4.09 3.69 3.82 5.78 5.10

Peaking Factor (Walski 2002) 4.26 3.44 2.97 4.84 4.06 3.47

Single Pump Flow (L/s) 0.58 0.58 0.58 0.58 0.58 0.58

Single Pump Flow (L/min) 34.8 34.8 34.8 34.8 34.8 34.8

Probable Max Pumps (E/one 2001) 14 18 23 14 16 21

Peaking Factor 3.14 2.62 2.48 4.46 3.58 3.43

US EPA Design Flow (1991) 10.58 14.74 20.50 10.52 13.20 18.00

Design Flow (Walski 2002) 11.02 13.71 15.94 8.81 10.51 12.33 Peak Design Flow Pumps running (e/one ,2001) 8.12 10.44 13.34 8.12 9.28 12.18

The above references developed detailed flows for the Matatā7. This assessment was largely focused

on delivering local reticulation or assets for the 2034 planning horizon. The conveyance network would

be sized to cater for the ultimate 2064 planning horizon. As such the daily peak flows provided range

between 8 – 16 L/s. An initial check on peak flows of 10 L/s indicated that as the flows were so low this

required the use of pipe internal diameters below 150mm (which increases the risk of blockages) and

higher friction losses per km length of main requiring additional pumping stations.

Given the potential range of flows from the above sources this concept option assessment has been

based on the assumption that the conveyance capacity should be 15 L/s with the potential to upsize the

scheme to cater for larger flows without the need to replace the rising main. This also allows more future

flexibility/capacity for growth over that projected at this time.

This can be achieved by the provision of the future additional pumping station, if and when required,

mid-way along the rising main. This ‘booster’ pumping station would allow the capacity of the rising main

to be increased between 25-50% but requires a more detailed assessment on the effect of the rising

main pressure rating and potential surge issues. A detailed design of this conveyance system should

revisit these issues.

2.4 Technical Approach

In developing options and in assessing these against each other MWH have used the following technical approaches:

Relied on LIDAR information obtained from WDC;

Utilised wastewater generation dates derived by AECOM (formerly URS) for Matatā (as set out

in Section 2.3 above) and Opus for Edgecumbe (based on a future grinder pump/low pressure

system (LPS)) along with existing Edgecumbe pumping records for the flows to the oxidation

ponds;

Undertake conveyance (pumping and pipelines) assessment using industry accepted design

basis and pumping station concepts as agreed with WDC (refer Section 2.5) below and also

where relevant included for in WDC’s technical specifications;

Developed treatment requirements from a “bottom up” approach building up components of the

total treatment need from the components parts;

7 Note that e/one is a proprietary of grinder pump.



Used typical industry cost figures for cost estimating;

Used data supplied by Kawerau District Council for the options conveying to the Kawerau

WWTP, as they relate to treatment and disposal/discharge at Kawerau;

Used the current Resource Consents (rights to discharge) for Edgecumbe, Whakatāne and

Kawerau where these (may) have relevance to options under consideration (refer Section 2.10);

Been guided by Regional and National Planning Documents for the quality needed for the

disposal discharge to land and water environments, e.g. Regional Plan for the Tarawera River

Catchment, National Policy Statement for Freshwater Management 2014 (NPS-FM); and

Used published soil drainage flooding, natural hazard, biodiversity and other maps and

information for land applications and conveyance.

2.5 Building up a Complete Scheme

A typical small community wastewater system requires up to four components, or “building blocks”,

namely:

1. Collection System: to collect wastewater from groups of properties and transport it to a

decentralised wastewater treatment plant or to a common point for connection to a conveyance

system.

2. Conveyance: to transport raw wastewater from local collection systems to an existing treatment

plant or conveyance from a treatment plant to disposal/discharge and/or reuse.

3. Treatment: to change the wastewater characteristics to meet the standards required for eco-

system re-entry, reuse or conveyance to another treatment facility. The disposal of sludge

arising from the treatment process is also required, although in oxidation pond systems this is

stored and periodically removed.

4. Disposal, discharge and/or Re-Use of Treated Wastewater: discharge pipework is required to

return fully treated wastewater to the environment and/or to a re-use point.

For a new Matatā Wastewater Scheme a low pressure grinder pump collection scheme is proposed. The

design of this is well advanced and output from this is well advanced and output from that in terms of

wastewater flows and volumes and the nature of the raw ground up sewage.

For Edgecumbe, the existing collection system is subject to high wet weather flows that MWH

understand has to a large part resulted from the earthquake damage of the collection network.

WDC’s LTP and AMP have provision to completely replace this system with a new low pressure grinder

pump collection system. A financial allowance of $17.7M is included for this in the 2026-2028 period. A

condition assessment of the existing gravity system has shown that system in uneconomical to repair

and may be deteriorating fast. Considering the high groundwater table and flat nature of the area,

replacing the existing system with a low pressure grinder pump system is currently understood to be

more feasible and economical than a conventional gravity system. Generally, the ground deformation in

Edgecumbe is about 10mm to 20mm per year. However, the timing of this project will depend on further

studies on the pipe deterioration rate to be undertaken in the next three years. After these studies are

completed, the final form and timing of the replacement of the existing reticulation system will be

determined.

As discussed in Section 2.6.3 this may not be necessary for some of the Options considered.

This Report does not include further consideration of estimated costs for collection systems.

For a number of Options it is proposed to continue use of the Edgecumbe oxidation ponds for cost

effective treatment.



For combined Matatā and Edgecumbe Schemes, these oxidation ponds would either be upgraded to

provide additional treatment capacity and/or expanded with additional treatment units where a higher

degree of treatment is needed. Such proposals are separately shown for each option.

Continued use of existing wastewater infrastructure assets is considered a sound and prudent financial

approach where they have an effective remaining useful economic life, and well fit into the concept of

the option being developed. In this Project a number of options, many of which have been shortlisted

for the more detailed evaluation, include use of the following existing wastewater infrastructure. For

shortlisted options these include:

Edgecumbe Oxidation Ponds for treatment – Combined Matatā and Edgecumbe Options ER3, TL2, TL3, WO5,and Edgecumbe Options 4, 5, 8 and 12.

Whakatāne Oxidation Ponds (in addition for Whakatāne) – Option WO1

Whakatāne Ocean Outfall – Option WO5

In terms of the future of the Edgecumbe existing damaged collection system, note above, the

AMP/Infrastructure Strategy includes $17.7million in the 2026-28 for complete replacement of this

system. Some other options, namely KL1 and WO1, include part or all the oxidation pond structures for

flow balancing.

A number of the options shortlisted which involve continued use of the Edgecumbe oxidation pond for

treatment may/could mean that this full expenditure is not needed providing the higher wet weather

flows can continue to be accommodated in that particular option. Notwithstanding this, it is noted that

the existing gravity collection system is deteriorating and further studies will be completed within the

next three years to determine the final form and timing of the replacement of the existing reticulation

system.

This matter is further discussed in MWH’s separate Contract 15-069 Work Stream 1 Report.

2.6 Concept Design Assumptions - Conveyance

The technical assumptions used in the concept design to size the various conveyance schemes options

are as follows:

Rising Main – The acceptable absolute minimum velocity for raw sewage is 0.60 m/s, this

achieves transport and re-entrainment of the solids contained within raw sewage. Given the

potential long retention time of sewage in the rising mains, which may increase solids

deposition, it is consider preferable to achieve a higher cleansing velocity of at least 0.7 m/s.

Below the minimum of 0.6 m/s there is a significant risk that deposited solids will not be re-

entrained during pump cycles, leading to anaerobic digestion and production of H 2S, methane

and other gases. Treated wastewater contains significantly less gross and settleable solids and

therefore the minimum acceptable velocities for pumping treated effluent can be relaxed from

those stated above. The minimum acceptable velocity for treated effluent has been assumed to

be 0.3 m/s but this will depend upon the quality of that effluent and the quantity and nature of

total suspended solids (TSS) remaining. These velocities should be reviewed during a

preliminary or detail design stage.

Slime Shearing Velocity (critical pipe wall shear stress of 0.3 kg/m2) is preferred, in raw

sewage rising mains, to help reduce the risk of septicity and odour issues as well as helping to

limit friction losses. Where slime shearing velocities can be achieved the friction losses will be

calculated based upon a pipe roughness of Ks (Colebrook-White) = 0.3mm (HDPE pipe may be

able to achieve a lower Ks but other materials may have higher Ks values). Where slime

shearing cannot be achieved the pipes have been assumed to slime and have a pipe roughness

of Ks (Colebrook-White) = 1.5mm. It is assumed that given the long-length of rising mains under

consideration that it will not be practical to achieve slime shearing velocity without a large

number of intermediate pumping stations to overcome the resulting high friction losses. The



preliminary and detailed design phase should investigate whether there is a cost benefit to

achieving slime shearing velocities over the on-going cost of chemical dosing/maintenance.

Where the rising main is pumping treated effluent it has been assumed that slime growth will not

be an issue and has therefore not been accounted for. This assumption should be revisited

during the preliminary and detailed design phase.

Slime shearing velocity varies with pipe diameter and is typically higher than normal self -

cleansing velocity target velocities are as follows:

Pipe INTERNAL Critical Slime Shearing Velocity (m/s)

Diameter (ID mm) Shear Stress = 0.3kg/m2

100 0.90

150 0.95

200 0.99

250 1.01

300 1.02

375 1.04

Maximum velocity allowed in the rising main will be limited to less than 3 m/s. Increases in pipe

velocity while helping to keep the pipe clean, result in higher friction losses, pipe pressures,

pump heads and ultimately pumping energy costs. Velocities higher than this maximum become

uneconomic and can damage the rising main and valves.

The target maximum retention time for wastewater within rising mains should be 12 hours.

This helps reduce the risk of septicity but does not eliminate the effects of wastewater arriving at

the next pump station or the downstream WWTP that may already be septic or significantly

aged.

Maximum Total Dynamic Head - (TDH = static lift + friction losses + local losses) for standard

wastewater centrifugal pumps is assumed to be in the order of 60-70m. It should be noted that

this range of TDH can significantly limit choice of manufacturer, available pump types and limit

the range of performance curves. Centrifugal pumps capable of TDH’s above 70m may be

possible with specialist pumps. It is possible to use specialist progressive cavity pumps that can

operate at significantly higher heads. As progressive cavity pumps are non-standard and will

require significantly higher pressure pipe lines this option while feasible is not preferred. It has

been assumed that where high head rising mains are required that it is preferred to build two -

stage pumping stations (where 2 pumps operate in series) to achieve the required head. This

approach requires the rising main be designed for the increase pressure but limits the number of

actual pumping stations.

Assume local losses for the rising main to around 10% of friction losses. In reality these losses

should be less given the terrain being crossed;

Resilience – where the rising main is difficult to access for repair or maintenance purposes, the

rising main should duplicated. This has been assumed to apply for marine or critical

infrastructure crossings (e.g. railways) or where the rising main is greater than 5m deep or

installed via horizontal directional drilling techniques (HDD);

Pumping Station Emergency Overflow and Storage – it has been assumed that an

emergency overflow will not be allowed and that emergency storage will be provided at the

pumping station to allow operational response within a reasonable time. WDC have indicated

that this should be a period of up to 8 hours of DWF storage prior to any overflow occurring. All



pumping stations will be designed to accept power from an external back-up generator that will

be provided by WDC’s specialist provider within a 1 hour time frame;

Sewage Septicity and Odour is caused by the anaerobic decomposition of raw wastewater

(organic matter containing sulphur and nitrogen). This decomposition produces gases including

hydrogen sulphide (H2S) which can be unsafe and malodourous (e.g. rotten egg smell). Long

rising mains provide anaerobic conditions and significant retention times of wastewater within

the main, leading to a high potential of septicity.

H2S is initially produced in solution, this dissolved H2S then transfers into gaseous H2S. The

longer the retention time within the pipeline the more H2S will be transferred to the gaseous

phase. The issues that can be caused by septicity are listed below:

o H2S can be a health and safety hazard for operators and the public;

o H2S is malodourous and can lead to disturbance and complaints if it reaches certain

concentration levels;

o H2S is released intermittently at rising main air valves as air is released from the main;

o H2S is released at the rising main discharge chamber (break pressure chamber)

whenever the pumps are running;

o H2S will continue to be released from the wastewater as it passes through the

downstream gravity system, especially at locations of turbulence; and

o Where H2S is oxidised by bacteria that are present in condensation/damp pipe walls this

leads to the production of sulphuric acid (H2SO4) which dissolves susceptible materials.

This leads to corrosion where H2S meets these suitable conditions.

Excessively long retention times, where the wastewater organic matter is anaerobically digested,

can also lead to methane production. Methane is flammable and can present a health and safety

issue if not dealt with appropriately in the design process; and

The health and safety risks associated with septicity, methane and other potential gases, are in

relation to the operation of the system, particularly confined spaces and the opening of

manholes/chambers/structures. The risks to operators (and the public in close proximity) can be

managed through appropriate design and operational procedures.

2.6.1 Managing Septicity and Odourous Gases in Conveyance Systems

There are a number of methods that can be employed to manage septicity for raw sewage conveyance,

these are:

The retention time of wastewater in the rising main should typically be kept to less than 12 hours

to avoid septicity. This is an approximate limit of used within the wastewater industry based

upon the standard depletion rates of dissolved oxygen within a main to prevent full anaerobic

conditions. Furthermore it reduces the quantities of dissolved H2S that can be produced. A

detailed septicity modelling study is required to determine what is the acceptable retention time

and would take into account the actual sewage constituents (e.g. chemicals and loads),

temperature, pH and how aged it is when it arrives at the pumping station; and

Control the growth of sewer slime on the rising main pipe wall. This is achieved by intermittently

running the rising main at velocities that increase the shear stress exerted on the wall enough to

strip the slime off and prevent substantial growth. This significantly reduces the production of

H2S, the quantity that transfers to the gas phase and has the additional benefit of

reducing/controlled pipe roughness at the cost of high energy costs.



2.6.1.1 Chemical Dosing (Liquid Phase Odour Control)

Chemical dosing has a lower capital outlay (chemical storage, dosing and injection equipment) but

reasonably higher on-going operational cost than other methods to avoid septicity (e.g. multiple rising

mains of different sizes, full treatment or full odour treatment and corrosion protection). The most

commonly used approaches are:

Magnesium Hydroxide is a non-hazardous alkali which is added to the wastewater to maintain

a high pH (target of around pH 8.6-9.0 - alkali) and preventing sulphide transfer from the liquid to

gas phase (and therefore the atmosphere). This level of pH also stops methane production.

Magnesium hydroxide can be dosed automatically from relatively small installations, does not

suffer from over-dosing risks (adding too much cannot raise pH above 9), is widely used across

NZ/Australia and is friendly to biological systems (should overflows to the environment occur).

The main disadvantage of dosing with Magnesium Hydroxide is that is costs around four times

as much as Iron salts per treated cubic metre of wastewater. Another potential disadvantage of

Magnesium Hydroxide dosing is that it can leave a chalky residue;

Iron Salts (Ferric or ferrous chloride) can be used to control odour in wastewater networks by

binding the generated sulphides into a non-soluble precipitate. It has also been shown in studies

that ferric dosing could suppress sulphate production and methane generation. This process will

however, cause additional solids to precipitate in the rising main. This chemical can be corrosive

and has Health and Safety issues associated with storage and handling, furthermore spills from

the network to the environment should be avoided. Iron Salts is a quarter of the cost of

magnesium hydroxide per treated cubic metre of wastewater and therefore would have

significant annual cost savings for very large flows; and

Calcium Nitrate prevents the onset of anaerobic conditions by providing an alternative source

of oxygen. Dosing with nitrates can remove generated H2S and reduces any further anaerobic

digestion. Calcium nitrate requires accurate dosing as excess nitrate can impair downstream

treatment processes, which can include uncontrolled denitrification at the wastewater treatment

plant. Under dosing of calcium nitrate may exacerbate H2S release along the sewerage system.

Multiple dosing points may be necessary to achieve the required degree of control.

Magnesium Oxide/Hydroxide is the most benign and easily handled of the above chemicals and is

preferable from a number of aspects, apart from annual running costs. However, the need for chemical

dosing will require a detailed understanding of the upstream wastewater network, sewage age and

should be determined through a detailed Septicity Modelling study as part of further detailed

investigation and design.

2.6.1.2 Odour Treatment (Gas Phase Odour Control)

The aim of gas phase odour control is to reduce the gas phase H2S (and other odour causing compounds)

concentrations to levels below the limit of detection at the nearest receptor site to the air discharge.

Common gas phase technologies that are typically used to remove H2S from foul air discharges that will

are available include:

Biotrickling filters (For larger odour control facilities) - Typically used for larger odour control

facilities, these odour control devices utilise a biomass system whereby foul air is passed

through a medium that supports a bacterial culture (the biomass). The airflow passes through

the medium, where the odorous compounds are absorbed into the liquid film surrounding the

biomass. The biomass consumes the contaminants, hence removing these odorous compounds

from the air;

Activated carbon filters (Carbon canisters for air valves and carbon filters for larger odour

control facilities) - Activated carbon has been used widely over many years for the removal of

contaminants from air and water streams. The adsorption qualities of activated carbon have



been improved through chemical impregnation using caustic, chlorine based compounds and in

some cases copper; and

Conventional biofiltration (For air valves and larger odour control facilities) - Conventional

biofilters generally consist of compost, bark, peat, heather or other organic material (or a

combination of them) to provide a media for biological growth. They are ideal solutions to treat

odours of low-medium flow with low-medium stable contaminant concentrations. Foul air is

passed through the media bed. These facilities require a water supply to keep the bark moist to

support the biological growth and therefore may not be ideal for isolated locations.

2.6.2 Balancing of Raw Wastewater

The balanced of raw (untreated) wastewater is assessed in some options where raw wastewater could

potentially be balanced in the existing Edgecumbe oxidation ponds. At times of dry weather flow no

balancing would occur, however at times of higher flow, the ponds could be used to temporarily store

excess flows of raw wastewater, prior to conveyance. The matters are relevant when considering

options that propose the storage of raw wastewater. It should be noted that these comments do not

apply to the balancing of treated wastewater at Edgecumbe where the wastewater would be screened

and aerated.

Raw wastewater, even diluted by stormwater, stored in an open pond is a potential health

hazard. This is potentially no different to the current Edgecumbe oxidation pond arrangement

but should be considered against the Health and Safety requirements of an upgraded/improved

facility (e.g. are full height fences, locking gates etc. required).

The stored wastewater may generate odour issues that are difficult to manage (aeration would

be required);

Unscreened wastewater entering the pond will deposit rags, fat, oil, grease and sewage derived

litter on the pond banks – this will be difficult to clean and may become an odour issue and an

attraction to pests/vermin;

The ponds will also collect floatable debris which the pump station may not capture and pass

forward to the conveyance pipeline and downstream WWTP;

The ponds will still settle solids to some degree and will require de-sludging and potentially

some form of treatment to prevent odour as the sludge decomposes;

The pond will likely suffer from algae blooms and mats;

Flow balancing will allow rainwater to contribute to the pumped flow rates – for raw wastewater

transfer this significantly increases the volume requiring chemical dosing and therefore the

annual cost. Ferric iron salts are quite sensitive to load and would need careful monitoring of the

required dosing, which would increase the cost of the installation;

River flooding into the ponds would be a worse quality outcome than if the ponds were in the

process of treatment; and

Should the ponds overflow due to extreme wet weather events the quality of flow entering the

environment would be of worse quality than if the ponds were in the process of treatment.

2.6.3 Balancing of Treated Wastewater

The balancing of treated wastewater at the Edgecumbe ponds is also considered for certain options.

Wastewater entering the ponds would be screened and then aerated in the primary pond. The various

issues traversed in Section 2.6.2 would generally be avoided through this treatment process.

The capacity of the existing Edgecumbe ponds to balance flows from both Matatā and Edgecumbe has

been assessed in Appendix A. This matter is further discussed in later sections of this Report.



2.7 Concept Design Assumptions - Odour Management of Conveyance Systems

This Report has made the following assumptions to develop the concept options:

The rising main retention time will be kept to less than 12 hours to avoid septicity, where

possible. For this Project it is unlikely that this criteria will be met, given the length of rising main

and the low flows under consideration;

The rising main velocity will be used to control the growth of sewer slime under DWF conditions

if possible and it does not result in excessive friction head (that would require additional

pumping stations to overcome);

Bio-filtration beds/carbon cartridge units have not been allowed for at air valves. Further

investigation is required into the needs and details of this through a septicity and odour study;

Chemical dosing with magnesium hydroxide has been assumed to be required for untreated

wastewater rising mains and has been allowed for. Further invest igation is required into the

needs and details of this through a septicity and odour study; and

Corrosion protection of any gravity sewer sections downstream of the discharge from an

untreated wastewater rising main may need to be considered but has not been specifically

allowed for.

2.8 Concept Design Assumptions – Treatment

A broad treatment concept has been developed for treatment options at Edgecumbe for land application

and Rangitaiki River discharge for the short-listed options. These treatment concepts encompass:

1. Upgrade of the existing oxidation ponds to provide aeration to support the BOD loading on

the primary pond and to supplement to the currently consented 84 kg BOD/ha/day (although a

consent condition change may be required in this respect). This is proposed to be achieved

through the use of mechanical surface aeration;

2. Upgraded Oxidation Pond located at the Edgecumbe site using a combination of:

a. Moving bed bioreactors contain plastic carrier media that are have been designed to provide an

increased protected surface area per unit for microbial biofilm growth. The microorganisms that

grow in the biofilm layer treat influent wastewater by breaking down biodegradable organic

matter. Through use of an anoxic zone and recycle MBBR systems can remove nitrogen (to

concentrations of 10 mg/L or less) from wastewater but this requires dosing to provide a carbon

source and a separate mixing system to keep the carriers suspended. A sieve arrangement at

the outlet of each compartment retains the solids and carrier media within the tank.

b. Actiflo units are sand-ballasted, high-rate clarifiers and combine advantages of weighted

flocculation and lamella settling combined with a small footprint. Coagulant is injected into the

wastewater where rapid mixing begins the coagulation process. The coagulated raw water then

enters the injection tank where microsand and polymer are added. The sand particles provide a

nucleus for flocculation of particulate matter (including algae) and this material is then settled

out within the lamella clarifier. Clarified water is discharged to an overflow trough, while a

hydrocyclone separates the sand and sludge in the solids stream returning the microsand to the

process for reuse.

c. The treated wastewater is disinfected by exposing the flow to ultraviolet (UV) light emitted from

lamps arranged within a UV reactor system. Remaining microbes (after aerobic treatment and

clarification) are irradiated by the light becoming deactivated and unable to replicate reducing

their ability to cause and spread illness.

d. Peak storage pond using the former oxidation pond (for wet weather flow balancing).



An upgraded Edgecumbe oxidation ponds with MBBR, Actiflo and UV disinfection following the above

concept would typically achieve median treated wastewater quality of:

BOD < 10 mg/L

TSS < 10 mg/L

TN < 10 mg N/L (with carbon dosing)

E.coli < 1000 cfu/100mL (or less)

For options of conveying raw wastewater to the Kawerau WWTP an allowance has been made for the

addition of a foul air management system to mitigate odour release at the inlet works to the Kawerau

WWTP.

For options of conveying raw wastewater to the Whakatāne WWTP an allowance has been made

provide aeration to support the BOD loading on the primary pond and to supplement to the currently

consented 84 kg BOD/ha/day. This is proposed to be achieved through the use of surface aeration.

Appendix B further examines the existing capacity of the Whakatāne oxidation ponds. This matter is

further discussed in later sections of this Report.

For Edgecumbe options that combine with a potential future Matatā standalone WWTP, costs have been

based on the latest AECOM estimate for dated February 2014.

For options that discharge to a potential Land Application Field (LAF) at Thornton, costs for the land

disposal field have been based on the latest AECOM estimate for dated February 2014, with allowances

made for a return flushing pump station (to be located at the LAF) and a return flushing pump station to

the WWTP.

2.9 Natural Hazards and Climate Change

The Whakatāne District and in particular the Bay of Plenty region is at risk of a range of natural hazards

such as earthquakes, flooding, tsunami, debris flows, landslides and volcanic activity. This fact is clearly

spelt out in the planning assumptions section of WDC’s Infrastructure Strategy 2015-2045 and in

Section 7.1.6 ‘Natural Hazards’ of the Matatā Wastewater Scheme AEE (November 2013) and Support

Document 2 to that AEE.

Matatā and Edgecumbe areas have as such witnessed such natural hazard events with the Matatā

debris flows/landslides particularly in the 2005 storm event and Edgecumbe with the 1987 earthquake.

There was also a major flood events in 2004. All these and other potential further events need to be

appropriately considered in the siting, design and operation of new (and existing) infrastructure, as they

have been in the earlier Matatā Wastewater AEE documents.

2.10 Environmental Effects Assessment

Any future discharge consents sought for the discharge of treated wastewater will be subject to the

provisions of the relevant statutory framework from National Policy Statements (NPS) through to the

relevant Regional Plans. As such, detailed Assessment of the Effects on the Environment (AEE) will be

required to support any future resource consent applications.

For the purposes of this study no site-specific assessment of adverse environmental effects has been

undertaken to inform the development and refinement of options. The option assessment process has

however been informed by expert judgement gained by MWH in obtaining consents for the discharge of

treated wastewater to similar land, water and coastal environments and taking into account the relevant

planning instruments discussed in Section 3.

2.11 Land Application Options

To inform the assessment of potential for the land application of treated wastewater in the vicinity of

Edgecumbe, an assessment of potential available land has been undertaken. A screening GIS exercise



was undertaken of land with 7.5km radius of the Edgecumbe WWTP, to identify land that may be

suitable for land disposal of treated wastewater. The following screening criteria were used:

Land zoning – land zoned residential, commercial or industrial being not available for land disposal;

Ground slope – land with a slope greater than 7 degrees not being suitable for wastewater disposal;

Soil drainage – only soil classed as ‘well drained’ was considered appropriate; and

Flood zones – areas within the 1 in 100 year floodplain of the Rangitaiki and Tarawera Rivers were excluded (flood extent data provided by BOPRC, but did not include flood data to the west of the Tarawera River).

These criteria are generally consistent with the criteria used by AECOM in both the previous and Matatā

standalone options investigations for land application]. The following Figure 2-1 shows the available land

within 7.5km of the WWTP that may be suitable for treated wastewater disposal.

The screening process confirmed that sufficient land potentially suitable for treated wastewater disposal

may exist within a 7.5km radius of the WWTP, this land is to the west and southwest of Edgecumbe on

well drained soils. The land available as being potentially suitable for treated wastewater disposal is

predominantly used for dairying.

During the option development process, WDC coastal reserve land at Thornton was also identified as a

potential site for the application of treated wastewater. A further GIS screening process was undertaken

for this land to inform the assessment of options. The following screening criteria were used:

Proposed Regional Coastal Environment Plan – Biodiversity Sites A and B;

Areas Sensitive to Coastal Hazards 1;

Existing and potential extents of sand extraction activities; and

Western Recreation Reserve Boundary.

Figure 2-1 shows the potentially available land. The broad high level assessment identified

approximately 14.8ha of land that could potentially be used for the land application of treated

wastewater at Thornton Dunes (Figure 2-2).

Part of the large Whakatāne Airport site covering around 225 hectares has also been identified as a

possible land application area (as noted above an area of 14.8ha would be required for a combined

Matatā and Edgecumbe coastal area) . Both the mown grass areas around the runway (which would

benefit from treated wastewater in summer dry periods) and/or some of the dune areas between the

mown grass areas and the coast could be used for land application. Subject to WDC’s ownership and

zoning and the proving of environmental effects associated with sub-surface irrigation and/or low

pressure spray irrigation on the more coastal dune area.

WDC are currently investigating the current possible use of this area as an alternative and maybe more

preferable area than the Thornton WDC Coastal Reserve area, or a nearer Edgecumbe area if one did

become available and proven but at this stage this option is not shortlisted but parked.

This Airport area may also be a further possibility for the discharge of treated wastewater from

Whakatāne’s WWTP after the expiry of the current resource consent in 2026.


Status: Final 22 September 2015

Project number: 805 08148 Page 20 Our ref: WW Review and Options Study for Edgecumbe & Matata Report Final 22-09-15

Figure 2-1: Treated Wastewater Land Application Option within 7.5 km of Edgecumbe Wastewater Treatment Plant




Figure 2-2: Treated Wastewater Land Application Option at Thornton Dunes




Figure 2-3: Treated Wastewater Land Application Option at Whakatāne Airport



2.12 Existing Resource Consents

WDC currently holds the following resource consents for the discharge of treated wastewater. These

existing consents are summarised in Table 2-3.

Table 2-3: Existing Resource Consents8

Discharge Location

Number Consent Holder

Purpose Volume / Rate of Discharge

Date of Granting

Expiry Date

Edgecumbe WWTP

20702 Whakatāne District Council

A right to discharge effluent from Edgecumbe oxidation ponds to the Omeheu Canal

500 cubic metres per day

1 May 1980 1 October 2026

Whakatāne WWTP


A right to discharge treated effluent from oxidation ponds into the Bay of Plenty

8,180 cubic metres per day

8 June 1978

1 October 2026

Tāneatua WWTP


Right to discharge wastewater from oxidation ponds to be constructed at Tāneatua into the natural waters of the Whakatāne River

0.008627 cubic metres per second

6 April 1971 1 October 2026

Kawerau WWTP

65081 Kawerau District Council

Discharge Treated Municipal Wastewater from Kawerau Wastewater Treatment Plant onto Land (Rapid Infiltration Basins)

22,000 cubic metres over any seven day period

29 October 2009

31 October 2032

In developing the options due consideration has also been taken of finding solutions for both

“Edgecumbe Standalone” and “Joint Matatā and Edgecumbe” that could “fit within” the existing

Whakatāne, Edgecumbe and Kawerau resource consents as appropriate to a particular option. The

basis for these considerations is to find solutions that may/would not require at this time extensive new

resource consents with their consequent (high) costs.

If this is possible, then in each case at least a condition changes would need to be made respective

consents for a particular option to include the wastewater catchment to which the consent applied. For

example if the Whakatāne consent No. 20368 was to include Matatā and Edgecumbe, then Condition 1

purpose would need to be changed to include Matatā and Edgecumbe as well as the Whakatāne urban

area.

A number of options are considered further in this report where wastewater (either raw or treated) is

considered for conveyance from Matatā and Edgecumbe to the existing Whakatāne WWTP.

8 The consents for Edgecumbe, Whakatāne and Tāneatua were granted prior to the RMA 1991 and are correctly referred to as

‘Rights in Respect of Natural Water’. The term ‘resource consent’ has been adopted in this Report for consistency purposes.



Option WO5 (conveyance of Matatā raw sewage to Edgecumbe oxidation ponds. Edgecumbe oxidation

ponds treated wastewater for joint Whakatāne ocean outfall discharge via Thornton) and Option WO6

(conveyance of Matatā raw sewage to Edgecumbe oxidation ponds. Edgecumbe oxidation ponds treated

wastewater for joint Whakatāne ocean outfall discharge via Awakeri) which use the Whakatāne Ocean

outfall could provide a good fit in terms of operating under existing consents for Edgecumbe and

Whakatāne in terms of the oxidation pond BOD5 loading and retention of the existing consents which

expire on 1 October 2026.

In this case it may be possible to seek consent changes that could be relatively easy to obtain. Option

WO1 (conveyance of Matatā raw sewage to Edgecumbe and combined raw sewage to Whakatāne

WWTP) would involve more changes to the Whakatāne consent in terms of the oxidation pond BOD5

loading but mean the Edgecumbe consent could be surrendered. There would be air discharge matters

still to consider however.

As discussed with WDC Officers and recorded in this section legal and planning advice is required in

this respect.

As set out in Section 4, Cost Estimates, no allowances have been included in the estimates for resource

consent processes. This needs to be well appreciated and taken into account in the next stage of

decision making (refer Section 1.3 of this Report).

2.13 Risk Considerations

A two stage approach has been used in this Report to address the risk assessment of options. This

approach is outlined in Section 7 of this Report. Included in that section are risk matrix tables for the

shortlisted Edgecumbe standalone and combined Matatā and Edgecumbe shortlisted options.

2.14 Discharge / Disposal Options – Land, Freshwater, Marine

The shortlisted options identified for both a standalone Edgecumbe scheme and a combined Matatā and

Edgecumbe scheme cover disposal discharge to land, to the Rangitaiki River and the Pacific Ocean out

to the existing Whakatāne ocean outfall.

There are many advantages/disadvantages of each of these three receiving environments in terms of

discharge and disposal of treated wastewater. Key determinants of these advantages and

disadvantages to the site specific nature of the land, freshwater and marine water and their uses along

with the size of the scheme and the quality of treated wastewater.

The following generalisations based on MWH and other experiences considered appropriate in terms of

the shortlist options assessment in this Project

Key considerations of land disposal options:

Land use;

Groundwater contamination;

Groundwater levels;

Areas with cultural and/or social importance;

Land use – cops/animals/contamination transfer;

Soil contamination;

Surface water contamination;

Habitats and ecosystems;

Aerosol spray drift (for surface application options); and

Implications of the NPS-FM 2014 in terms of ‘maintain and enhance water quality’.



Long-term sustainability.

Key considerations of freshwater discharges:

Surface water quality effects particularly in terms of BOD, TSS, pathogens and nutrients;

Implications of the NPS-FM 2014 in terms of ‘maintain and enhance water quality’;

Areas with cultural and/or social importance;

Contact recreation uses;

Effects on fish and aquatic ecology; and

Cultural effects.

Key considerations of ocean discharges include:

Any shoreline impacts;

Ocean current movements;

Implications of the NZCPS 2010;

Marine ecosystem including fisheries and wildlife;

Any visual effects; and

Effects on the physical environment e.g. foredunes and sea bed.



3 Legislation and Planning Instruments

3.1 Overview

There are a number of legislative and planning instruments that provide key drivers for the Project. The

following sections outlines the key legislative and planning instrument requirements.

3.2 National Policy Statement for Freshwater Management 2014

The National Policy Statement for Freshwater Management (2014) (NPS-FM) sets out the objectives

and policies for freshwater management (including groundwater) under the Resource Management Act

1991 (RMA). The NPS-FM is relevant to any discharges to surface water or land. Decision makers on

resource consent applications must have regard to any relevant provisions of the NPS-FM as required

by section 104(1) (b)(iii) of the RMA.

Key policy themes of the NPS-FM include:

Water Quality - safeguarding ecosystems in sustainably managing the use and development of

land and discharges of contaminants. Maintenance or improvement of water quality.

(Objectives A1 and A2);

Integrated Management – Improvement of the integrated management of fresh water and the

use and development of land in catchments. (Objective C1); and

Tāngata Whenua Roles and Interests – To provide for the involvement of iwi and hapū, and to

ensure that tāngata whenua values and interests are identified and reflected in the management

of fresh water including associated ecosystems. (Objective D1).

The most recent case law in relation to wastewater discharge consents being considered under the

NPS-FM is the Matatā Wastewater Environment Court decision 2014 and also the Ngati Kahungunu /

Hawkes Bay Regional Council decision. The implications of these decisions are discussed further in

Section 3.5. There is also the Parliamentary Commission for the Environments recent report on the

NPS-FM and recommendations in Policy A2 to remove the word “region”, as “unders and overs” is not

appropriate.

3.3 New Zealand Coastal Policy Statement 2010

The purpose of the New Zealand Coastal Policy Statement 2010 (NZCPS) is to state policies in order to

achieve the purpose of the RMA in relation to the coastal environment. The NZCPS is relevant to any

discharge within the coastal environment. As per the NPS-FM, decision makers on resource consent

applications must have regard to any relevant provisions as required by section 104(1)(b)(iii) of the

RMA.

Key policy themes of the NZCPS include:

Safeguarding the Coastal Environment – maintaining and enhancing natural biological

processes, protecting representative or significant natural ecosystems, maintaining water

quality, enhancing water quality where it has deteriorated. (Objective 1);

Preserving the Natural Character of the Coastal Environment – recognising characteristics

and qualities that contribute to natural character, features and landscape values of the coastal

environment. (Objective 2, Policies 6 and 13);

Tāngata Whenua – recognising the role of tāngata whenua as kaitiaki, recognising that tāngata

whenua have traditional and cultural relationships with the coastal environment, incorporating

mātauranga Māori in consent processes. (Objective 3, Policy 2);

Public Open Space – maintain and enhance public open space qualities and recreation

opportunities of the coastal environment, recognise the need for public open space within and



adjacent to the coastal marine area including active and passive recreation. (Objective 4, Policy

18);

Coastal Hazards – To ensure that coastal hazard risks taking account of climate change are

managed by locating new development away from areas prone to such risk. (Objective 5) ;

Providing for People and Communities Four Well-beings – is intended to enable people and

communities to provide for their social, economic, and cultural wellbeing and their health and

safety, (in the coastal marine area). (Objective 6, Policy 6);

Biodiversity – avoiding significant adverse effects on areas of predominantly indigenous

vegetation, habitats of indigenous species, habitats important to migratory species, ecological

corridors. (Policy 11);

Discharge of contaminants – having regard to sensitivity of the receiving environment, the

nature of the contaminants, capacity of the receiving environment to assimilate the

contaminants, avoid significant adverse effects on ecosystems and habitats after reasonable

mixing, use the smallest mixing zone necessary to achieve the required water quality, minimise

adverse effects on the life-supporting capacity of water within a mixing zone. (Policy 23); and

Human sewage – not allow the discharge of human sewage directly to coastal waters without

treatment, not allow the discharge of human sewage to coastal waters unless there has been

adequate consideration of alternative methods, sites and routes for undertaking the discharge

and informed by an understanding of tāngata whenua values and the effects on them. (Policy

23).

3.4 Regional Policy Statement and Regional Plans

3.4.1 Operative and Proposed Regional Policy Statement

The operative and proposed Regional Policy Statement (RPS) will be relevant to any resource consents decision making processes. Key policy themes of the operat ive RPS include:

Tāngata Whenua – To recognise the principles of the Treaty of Waitangi, the rights of tāngata

whenua and individual iwi, provision for the relationship of Maori and their culture and traditions

with their ancestral lands, water, sites, waahi tapu, and other taonga. (Objectives 5.3.1(a) and

5.3.2(a), Policies 5.3.1(b)(i), 5.3.1(b)(iv), 5.3.1(b)(v), 5.3.2(b)(i) and 5.3.2(b)(v))

Well-being - To avoid remedy or mitigate adverse effects on social, economic and cultural well -

being and to manage the use, development and protection of natural and physical resources in a

way, or at a rate, which enables people and communities to provide for their social, economic

and cultural well-being and for their health and safety. (Objective 5.3.6(a), Policies 5.3.6(b)(i),

5.3.6(b)(ii), 6.3.1(b)(viii) and 8.3.1(b)(i))

Land - The adoption of sustainable land use and management practices, to sustain the potential

of land resources to meet the reasonably foreseeable needs of current and future generations,

to safeguard the life-supporting capacity of the soil and associated ecosystems, particularly

indigenous ecosystems, and to protect soil from degradation, to avoid, remedy or mitigate

adverse effects on the environment associated with the inappropriate use and development of

land, to enable land use practices that are consistent with established water quality standards,

to recognise that, subject to appropriate controls, the discharge of contaminants onto or into soil

may be an appropriate method of industrial, agricultural and other waste disposal, to protect

water quality from the adverse effects of land use. (Objective 6.3.1(a), Policies 6.3.1(b)(i),

6.3.1(b)(ii), 6.3.1(b)(iii), 6.3.1(b)(v), 6.3.1(b)(xiii) and 6.3.1(b)(xiv))

Air Emissions - No significant adverse effects on people and the environment result from

discharges of chemical, odorous and particulate contaminants into the air, to provide for the



discharge of contaminants to air with no significant adverse effects on air quality. (Objective

7.3.2(a), Policies 7.3.2(b)(i), 7.3.2(b)(ii) and 7.3.2(b)(iii))

Water Quality – To maintain/enhance water quality to a level sufficient to safeguard aquatic life,

to sustain the potential of water resources to be used and developed to meet existing and

reasonably foreseeable future needs, and to provide for the protection of aesthetic or cultural

values associated with water. To improve the quality of the region’s water resources by avoiding,

remedying or mitigating the adverse effects of diffuse and point source discharges of

contaminants onto or into land or into water, to maintain/enhance the quality of the region’s

groundwater resources by avoiding, remedying or mitigating the adverse effects of diffuse and

point source discharges of contaminants onto or into land or into water, to avoid, remedy or

mitigate the potential adverse effects on water quality due to the inappropriate location and

management of activities. (Objective 8.3.1(a), Policies 8.3.1(b)(ii), 8.3.1(b)(iii) and 8.3.1(b)(v))

Coastal Environment – Recognition and provision for natural character, outstanding natural

features/landscapes, and significant vegetation and habitats in the coastal environment,

maintain water quality and allow for public access to the coastal marine area. (Objectives

9.3.1(a), 9.3.2(a), 9.3.3(a), Policies 9.3.1(b)(i), 9.3.1(b)(ii), 9.3.1(b)(iii) and 9.3.2(b)(i))

Natural Hazards – The vulnerability to natural hazards of the regions physical resources is

avoided or mitigated. (Objective 11.3.1(a))

Waste Management – Waste production is minimised and residual wastes are disposed of with

no significant adverse effects on the environment (Objective 12.3.3(a), Policy 12.3.3(b)(i))

Built Environment - A built environment that enables efficient use, development and protection

of natural and physical resources while avoiding, remedying and mitigating adverse effects on

the environment, to promote the efficient use and development of existing and future

infrastructure and utility networks. (Objective 13.3.1(a), Policy 13.3.1(b)(v))

Natural Character – Preservation of the natural character of the region, including the protection

of significant indigenous habitats and ecosystems, having particular regard to intrinsic values of

ecosystems, to recognise indigenous marine habitats and ecosystems as being

underrepresented in the reserves network of the Bay of Plenty Region. (Objective 16.3.1(a),

Policies 16.3.1(b)(v) and 16.3.1.(b)(vi))

3.4.2 Regional Air Plan

The Bay of Plenty Regional Air Plan provides for the control of discharges of contaminants into air,

including odour, for the whole of the Bay of Plenty region. Key policy themes of the Regional Air Plan

include:

Air Quality – Maintain and protect high air quality in the Bay of Plenty region including requiring

that the disposal and storage of waste be undertaken in a manner that avoids, remedies or

mitigates adverse effects on air quality. (Objective 1, Policy 6)

3.4.3 Regional Water and Land Plan

The purpose of the Regional Water and Land Plan is to promote the sustainable and integrated

management of land and water resources within the Bay of Plenty Region and includes matters relating

to discharges to land. Key policy themes of the Regional Water and Land Plan include:

Kaitiakitanga – principles of the Treaty of Waitangi are taken into account, water and land

concerns of tāngata whenua are taken into account and addressed, regard to be had to iwi

resource management planning documents, maintenance of mauri of water and land, particular

regard to kaitiakitanga, appropriate consultation with tāngata whenua, avoid, remedy or mitigate

adverse effects on water, land, or sites of spiritual cultural or historical significance to tāngata



whenua where these resources and sites have been identified by tāngata whenua (Objectives 1,

4, 5, 6, Policies 2, 5, 9, 11, 14, 15, 17, 18 and 20).

Integrated Management of Land and Water – land use and management practices are

appropriate to the environmental characteristics and limitations of the site; maintenance of

cultural, ecological, amenity, natural character and landscape values, maintenance of high

quality groundwater and health of the regions soils; management of riparian margins to protect

and enhance soil conservation, water quality and heritage values; protection of vulnerable areas

from erosion; maintain and improve the protective function of coastal sand dunes; allowance of

resource use and development where there are beneficial effects on the social, cultural and

economic wellbeing of people and communities and adverse effects on the environment are

avoided, remedied or mitigated. (Objectives 8, 9, 10, 15, 17, 19, 20, 21 Policies 21 and 32).

Discharges to Water and Land – Management of discharges of contaminants to land with

respect to the treatment capacity of the soil, run off to surface water, adverse effects on

groundwater. Appropriate management of stormwater. Early and on-going consultation with

tāngata whenua during consideration of wastewater treatment systems, encouragement of

discharge of contaminants to land based treatment and disposal (rather than to water) where

appropriate and environmentally sustainable including disposal of sewage by passage through

land, soil or wetlands. Consideration of contamination of fresh water and ecosystems when

considering applications for discharge consent onto land, requirement for appropriate

management of discharges of contaminants to land where it may enter water, encouragement of

discharge activities to comply with current best engineering practice and best practicable options

to avoid or mitigate adverse effects. (Objectives 26, 31, 32 and 34, Policies 41, 42, 43A, 44, 48

51 and 54)

Under the Regional Water and Plan, the discharge of contaminants (treated wastewater) to water or

land is a discretionary activity under rule 37. For discharges to surface water, these are required to be

assessed against the Water Quality Classification of the receiving water body. The various water bodies

that could be discharged to as part of the options and their classification is as follows:

Omeheu Channel – Modified Watercourse with Ecological Values;

Tarawera River – Fish Purposes Lower Tarawera River;

Rangitaiki River – Contact Recreation - downstream of Te Teko;

Rangitaiki River – Aquatic Ecosystem (Bay of Plenty) – upstream of Te Teko; and

Whakatāne River (near Tāneatua) – Water Supply.

3.4.4 Regional Plan for the Tarawera River Catchment

The purpose of the Bay of Plenty Regional Plan for the Tarawera River Catchment (RPTRC) is to assist

Environment Bay of Plenty to promote the sustainable management of natural and physical resources

within the Tarawera River catchment.

As shown in Figure 3-1, the towns of Matatā and Edgecumbe lie within the Tarawera River catchment.

The Rangitaiki River to the east of Edgecumbe lies outside of the RPTRC boundary.

The RPTRC contain specific rules relating to future discharges to human sewage (or contaminants

derived from human sewage into surface water within the Tarawera River catchment.

The relevant rule in relation to the discharge of treated wastewater is rule 15.8.4(r) which states:

“Except for the provisions of the Operative On-Site Effluent Treatment Regional Plan, and for the provisions for Kawerau township and Edgecumbe township set out in (a) to (d) of this rule, and the provisions of rule 15.8.49x), all new or existing discharges of human sewage or contaminants derived from human sewage into surface water within the Tarawera River catchment will become a Prohibited Activity on the date on which this regional plan becomes operative”.



When the existing resource consent for the discharge of treated wastewater from the Edgecumbe

WWTP to the Omeheu Canal expires in 2026, and new discharge to into surface water will become a

discretionary activity subject to the following limits as shown in Table 3-1.

Table 3-1: Regional Plan for the Tarawera River Catchment –Limits for Edgecumbe WWTP

Parameter Unit Limit

cBOD5 mg/L < 10

Suspended Solids mg/L < 15

Total Nitrogen mg/L < 25

Faecal coliform No./100mL < 10,000

Rule 15.8.4(r) also contains provisions which limit the source of wastewater that can be discharged at

both Edgecumbe and Kawerau. In the process of assessing the various options WDC obtained legal

advice that confirmed that the discharge of wastewater sourced from outside either Edgecumbe or

Kawerau townships (e.g. the discharge of wastewater sourced from Matatā at Kawerau) would be a

prohibited activity under the RPTRC. A copy of this legal advice is attached as Appendix C.

BOPRC have advised that the review of the TRCMP is scheduled for 2018. While a plan change to the

limits in Figure 3-1 could be expected and justified to use current day practice of median and upper

percentiles (e.g. 90 percentile) limits it is not expected that there will be any relaxation in the limits.



Figure 3-1: Regional Plan for the Tarawera River Catchment Map



3.5 Matatā Wastewater Consents and Designation: Environment Court Decision 2015

The decision of the Environment Court related to the Sustainable Matatā appeal against the decision of

the BOPRC (Decision No. [2015]NZEnvC90) contains a number of matters that require careful

consideration in relation to the assessment of effects of wastewater discharges to land and/or

freshwater and air. Key considerations includes:

The effects of the discharge of odour on future papakainga (regardless of whether these are

consented or permitted developments);

The effects of wastewater discharged to land and subsequent effects on surface water quality

and ecology;

The implications of the NPS-FM 2014 in terms of ‘maintain and enhance’ water quality;

Effects on water quality versus effects on aquatic ecology;

Sensitivity of the Tarawera Catchment in terms of nutrient effects related to nitrogen and

phosphorous;

The need to provide an assessment of the quantitative benefits of the removal of septic tank

discharges from the township of Matatā; and

The need to ensure a readily transparent site selection process for the siting of any new WWTP

including the clear recording of the decision making process so that it is readily understood by

others, including mechanisms for reviewing the process if assumptions changes through initially

unforeseen circumstances.



4 Cost Estimates

4.1 Basis of Cost Estimates

The following assumptions have been made in compiling the cost estimates:

Capital cost estimates have been developed using a ‘bottom-up’ approach as agreed with WDC Officers at the time of defining the Project scope. Costs are based upon recent tendered prices for similar sized projects and specific rates obtained from contractors;

Total capital cost estimates have been determined on the following basis:

o Preliminary and General items 12% of physical works cost

o Commissioning and completion 1.5% of physical works cost

o Design and construction management 14% of construction cost

o Capital contingency 30% of construction cost

For conveyance options, the following assumptions have been made:

o Air valves 1 per 500m

o Scour valves 1 per 2 km

o For river crossing pipeline will be attached to outside of bridges in pipe sleeve

For those options involving upgrading the Edgecumbe oxidation ponds with MBBR, Actiflo and UV treatment the same capital cost estimates have been used for Edgecumbe standalone options and the combined Matatā and Edgecumbe options. This is because for the Actiflo unit it is the minimum commercial size for both options. For the MBBR or UV smaller units could be used for Edgecumbe alone with some saving of that used.

No allowance in capital costs has been made for:

o Goods and services taxes (GST) or any import duties;

o Obtaining resource consents or building consents; (note this is currently being further assessed and the next draft – final may include indicative resource consent costs.

o The use of existing infrastructure for combined schemes e.g. Matatā using the Edgecumbe oxidation ponds and Matatā and Edgecumbe using the Whakatāne WWTP and ocean outfall. Costs are allowed for new plant items e.g. upgrade of Edgecumbe oxidation pond; and

o Any work associated with de-establishment of existing WWTP plant and/or other wastewater infrastructure no longer required under each option or rehabilitation of the site.

Operating cost estimates have been developed on the following basis:

o Energy costs (power) $0.18 per KWh

o Energy (line rental) $5 per day

o Labour $30 per hour

o Specialist labour $60 per hour

o Travel $1.50 per km

o Chemical dosing (conveyance) for raw $0.2 per m3 sewage only (not for treated wastewater conveyance)

o Maintenance and replacement costs (treatment) 0.5% of capital works

o Discharge of wastewater to Kawerau WWTP $1.10 per cubic metre

o Dosing costs (treatment at Edgecumbe options) 50 L/d ethanol



o Spares and consumables $3000 per pump station pa.

o Labour (conveyance) 2 x 2hr visits per week

o Specialist labour 2 days per annum

Whole of Life Costs or Net Present Value (NPV) - an economic comparison of the respective options has been conducted in an analysis of NPV costs. For the purposes of this assessment, costs have been assessed over a period of 20 years using a discount rate of 6 percent (averaged) as advised by WDC. Mechanical and instrument maintenance and replacement costs have been added at assumed life cycle stages.



5 Edgecumbe Standalone Options

5.1 Methodology

The assessment of Edgecumbe standalone options has followed a four stage assessment being the:

Stage 1: Compilation of long list options broadly arranged around the groupings of options for conveyance, treatment at Edgecumbe and land application at Edgecumbe, treatment at Edgecumbe and land application at Thornton, treatment at Edgecumbe and discharge to the Tarawera River catchment and treatment at Edgecumbe and discharge to the Rangitaiki River;



Stage 4: Compilation of information to enable the short list to be assessed; and


This draft Report has been prepared to stage 4 and will be used to assessment and rank the short listed options stage 5.

5.2 Identification of Long List Options

The following long list of 12 options for the standalone Edgecumbe options were identified under the following subheadings:

These options are described further in Table 5-1 below which identifies the infrastructure components and locations that make up the total option.

Conveyance Options

Option 1 - Conveyance of Edgecumbe to Kawerau WWTP;

Option 2 - Conveyance of Edgecumbe oxidation pond treated wastewater to new ocean outfall around Matatā;

Option 3 - Conveyance of Edgecumbe from new WWTP to new ocean outfall around Matatā ;

Option 4 - Conveyance of Edgecumbe oxidation pond treated wastewater to Whakatāne ocean outfall;

Option 5 - Conveyance of Edgecumbe raw sewage to Whakatāne WWTP oxidation pond ;

Treatment at Edgecumbe Options and Land Application at Edgecumbe

Option 6 - Upgrade of existing Edgecumbe oxidation ponds and Land Application at Edgecumbe;

Option 7 - New WWTP at Edgecumbe and Land Application at Edgecumbe;

Treatment at Edgecumbe Options and Land Application at Thornton

Option 8 - Upgrade of existing Edgecumbe oxidation ponds and Land Application at Thornton Dunes;

Option 9 - New WWTP at Edgecumbe and Land Application at Thornton Dunes;

An alternative to the land application on the Thornton Dunes maybe land application on the Whakatāne Airport site owned by WDC. Refer discussion in Section 2.11.

Treatment at Edgecumbe Options and Discharge to Tarawera River Catchment

Option 10 - New WWTP at Edgecumbe and Tarawera River Discharge;

Treatment at Edgecumbe Options and Discharge to Rangitaiki River Catchment

Option 11 - New WWTP at Edgecumbe and Rangitaiki River discharge; and





Table 5-1: Long list Options for Edgecumbe Schemes

Option Code & Number

Option Title Collection system1

Conveyance Treatment

Discharge/Disposal of Treated Wastewater

Use of Existing Infrastructure

(upgraded as appropriate)2

Reference Previous Reports2

Type Type Location

Conveyance Options

Option 1 Conveyance of Edgecumbe raw sewage to Kawerau WWTP

Edgecumbe existing then LPS as per LTP (WDC’s Long Term Plan 2015 – 25)

Edgecumbe pumped to Kawerau

Chemical Treatment (Alum Dosing)

Kawerau

Disposal to land via Rapid Infiltration Beds adjacent to Tarawera River

Kawerau WWTP and RIB’s

Opus July 2013, Option 2

Option 2

Conveyance of Edgecumbe oxidation pond treated wastewater to new ocean outfall around Matatā

Edgecumbe existing then LPS as per LTP

Edgecumbe pumped to Matatā new ocean outfall

Existing Oxidation ponds upgraded

Edgecumbe Discharge to new ocean outfall at Matatā

Edgecumbe oxidation ponds

Option 3

Conveyance of Edgecumbe from new WWTP to new ocean outfall around Matatā


Edgecumbe pumped to Matatā new ocean outfall

“In tank” treatment with ex oxidation pond for high wet weather flows

Edgecumbe Discharge to new ocean outfall at Matatā

Edgecumbe oxidation ponds for wet weather storage.

Option 4

Conveyance of Edgecumbe oxidation pond treated wastewater to Whakatāne ocean outfall


Edgecumbe pumped to Whakatāne WWTP

Existing Oxidation ponds upgraded

Edgecumbe Discharge to existing outfall at Whakatāne ocean outfall


Option 5

Conveyance of Edgecumbe raw sewage to Whakatāne WWTP oxidation pond


Edgecumbe pumped to Whakatāne WWTP

Whakatāne oxidation ponds

Whakatāne Discharge to existing outfall at Whakatāne WWTP


Treatment at Edgecumbe Options (Land Application at Edgecumbe)

Option 6

Upgrade of existing Edgecumbe oxidation ponds and Land Application at Edgecumbe


N/A

Existing Oxidation ponds upgraded with Actiflo, MBBR and UV disinfectant.

Edgecumbe Disposal to land by slow rate irrigation in general Edgecumbe area












Type Type Location

Option 7 New WWTP at Edgecumbe and Land Application at Edgecumbe


N/A


At Edgecumbe oxidation pond site (or elsewhere)

Disposal to land by slow rate irrigation in general Edgecumbe area


MWH, Jan 2002

Treatment at Edgecumbe Options (Land Application at Thornton)

Option 8

Upgrade of existing Edgecumbe oxidation ponds and Land Application at Thornton Dunes


Edgecumbe pumped to Thornton Dunes

Existing Oxidation ponds upgraded with Actiflo, MBBR and UV Treatment

Edgecumbe Disposal to land by slow rate irrigation in Thornton dunes area


Option 9

New WWTP at Edgecumbe and Land Application at Thornton Dunes


Edgecumbe pumped to Thornton Dunes



Disposal to land by slow rate irrigation in Thornton dunes area

Edgecumbe oxidation ponds (part of) for wet weather storage.

Treatment at Edgecumbe Options (Discharge to Tarawera River Catchment)

Option 10 New WWTP at Edgecumbe and Tarawera River Discharge


N/A

“In tank” treatment with ex oxidation pond for high wet weather flows and treatment Standard to meet Regional Plan for Tarawera River Catchment (TCMP) treated wastewater quality


Omeheu Channel, the Tarawera River

Edgecumbe oxidation ponds (part of) for wet weather storage

Existing Omeheu Channel discharge

H&G, 2009











Type Type Location

Treatment at Edgecumbe Options (Discharge to Rangitaiki River Catchment)

Option 11

New WWTP at Edgecumbe and Rangitaiki River discharge


N/A

“In tank” treatment with ex oxidation pond for high wet weather flow balancing

Edgecumbe To Rangitaiki River (near Edgecumbe)

Edgecumbe oxidation ponds (part of) for wet weather storage


H&G, 2009 but discounted

Option 12

Upgrade of existing Edgecumbe oxidation ponds and Rangitaiki River discharge


N/A

Existing Oxidation ponds upgraded with Actiflo, MBBR and UV disinfection




Matatā AEE Table 6.4



5.3 Evaluation of Long List Options

This long list of 12 options were then assessed against a range of criteria as described in Table 5-2

below.

Table 5-2: Evaluation Criteria for Long List Options

Criteria Components

Technical/Functional

Reliability

Flexibility

Constructability

Engineering Resilience (refer Glossary of Terms)

Operational

Complexity

Safety

Septicity risk

Odour/noise management

Social/Public Health

Public health protection

Public safety

Visual/amenity

Location/neighbours

Construction effects odour/noise nuisance

Tangata Whenua Considerations (tangata whenua input required)

Discharge to fresh water

Discharge to land

Discharge to coastal water

Maori land

Transfer of wastewater from one rohe to another

RMA Consentability

RMA

NPS - FM (2014)

NZCPS (2010)

Regional & District Planning Instruments including RPTRC

Local Government Act (2002)

Existing and future consents and designation ease or difficulty

Relevant case law

Economic Relative Assessment of indicative capital,

operation and life cycle (NPV) costs

Overall Sustainability

Alignment with WDC’s Sustainability Strategy 2010-2015

Energy use/carbon footprint

Natural hazards/climate change

Adverse effects on natural environment

Sustainable development

Future proofing



Criteria Components

Key Risks (without mitigation) Note that specific mitigation will be developed

for shortlisted options

Advantages

Disadvantages

Appendix D provides the full assessment of the long list options under a range of criteria. This Appendix

also includes (in summary form) “key advantages and disadvantages” and also a high level key risks

identification. These high level risks are identified before further mitigation measures that could be

identified to reduce the risks further than those allowed fro in the options as developed in Section 8

includes a much more detailed risk assessment on shortlisted options.

Following the assessment of 12 long list options, a confirmed long list of 5 options were taken forward

for further assessment. A WDC officer /MWH workshop was used to advance this assessment. Table

5-3 provides a summary of this long list option assessment.

Legend used in Table 6-3 is:

√ = Option on confirmed long list

X = Option parked – parked means these options are not being proceeded with in the confirmed long list

evaluation – but remain available should the proceeding evaluation process mean they should be

reconsidered.

Table 5-3: Long List Option Assessment Summary

Long List Option Option on Confirmed Long List or

Parked?

Conveyance Options

Option 1 Conveyance of Edgecumbe raw sewage to Kawerau WWTP

√

Option 2 Conveyance of Edgecumbe oxidation pond treated wastewater to new ocean outfall around Matatā

√

Option 3 Conveyance of Edgecumbe from new WWTP to new ocean outfall around Matatā

X

Parked

Significant cultural issues are likely to make future discharge consents difficult to obtain

High capital and operating costs for new WWTP at Edgecumbe and new ocean outfall around Matatā

Option 4 Conveyance of Edgecumbe oxidation pond treated wastewater to Whakatāne ocean outfall √

Option 5 Conveyance of Edgecumbe raw sewage to Whakatāne WWTP

√





Parked?

Option 6 Upgrade of existing Edgecumbe oxidation ponds and Land Application at Edgecumbe

X

Parked High-risk that any land disposal at Edgecumbe

would be technically unfeasible / unsustainable

Expected high costs which would include land purchase or leasing


X

Parked High-risk that any land disposal at Edgecumbe

would be technically unfeasible / unsustainable



Option 8 Upgrade of existing Edgecumbe oxidation ponds and Land Application at Thornton Dunes √

Option 9 New WWTP at Edgecumbe and Land Application at Thornton Dunes

√


Option 10 New WWTP at Edgecumbe and Omeheu Channel Discharge

√


Option 11 New WWTP at Edgecumbe and Rangitaiki River discharge √

Option 12 Upgrade of existing Edgecumbe oxidation ponds and Rangitaiki River discharge

√

5.4 Assessment of Confirmed Long List Options

Following the assessment of the long list of 12 options, the nine options taken forward to the confirmed

long list were assessed further in terms of topographical maps and schematic diagrams with a summary

of key features and key matters that would be required in the option assessment and decision making.

These are described in the following sections for each option on the confirmed long list.



5.4.1 Option 1 (EDG1) - Conveyance of Edgecumbe to Kawerau WWTP

Figure 5-1: Schematic for Option 1



5.4.2 Option 2 - Conveyance of Edgecumbe Oxidation Pond Treated Wastewater to New Ocean Outfall around Matatā




5.4.3 Option 4 (EDG 4) - Conveyance of Edgecumbe Oxidation Pond Treated Wastewater to Whakatāne Ocean Outfall




5.4.4 Option 5 - Conveyance of Edgecumbe Raw Sewage to Whakatāne WWTP




5.4.5 Option 8 (EDG 8) - Upgrade of Existing Edgecumbe Oxidation Ponds and Land Application at Thornton Dunes




5.4.6 Option 9 – New WWTP at Edgecumbe and Land Application at Thornton Dunes




5.4.7 Option 10 - New WWTP at Edgecumbe and Tarawera River Discharge




5.4.8 Option 11 - New WWTP at Edgecumbe and Rangitaiki River Discharge




5.4.9 Option 12 (EDG 12) - Upgrade of existing Edgecumbe Oxidation Ponds and Rangitaiki River discharge




5.5 Confirmed Long List Assessment Summary

Following the assessment of 9 confirmed long list options, a short list of 5 options were taken forward for

further assessment. Table 5-4 provides a summary of the confirmed long list option assessment showing

in the middle column those options identified for the confirmed long list and the 5 options identified for

the short list as shown in the right hand column ticked ().

This assessment was undertaken in a workshop with WDC Officers, Mr Terry Long of EBOPRC and

MWH staff. The evaluation drew on the material earlier in this section and Appendices E and F in this

Report.

Legend:

√ = Option on confirmed long list or short list


evaluation – but remain available should the proceeding evaluation process mean they should be

reconsidered.

Table 5-4: Confirmed Long List Option Assessment Summary

Long List Option Option on Confirmed Long

List or Parked?

Option on Short List

or Parked?

Conveyance Options

(EDG1) Option 1

Conveyance of Edgecumbe raw sewage to Kawerau WWTP

√ √

Option 2

Conveyance of Edgecumbe oxidation pond treated wastewater to new ocean outfall around Matatā

√

X

Parked


Option 3

Conveyance of Edgecumbe from new WWTP to new ocean outfall around Matatā

X

Parked


High capital and operating costs for new WWTP at Edgecumbe and new ocean outfall around Matatā

X

Parked

(EDG4)

Option 4


√ √

(EDG5)

Option 5

Conveyance of Edgecumbe raw sewage to Whakatāne WWTP

√ √




List or Parked?


or Parked?


Option 6

Upgrade of existing Edgecumbe oxidation ponds and Land Application at Edgecumbe

X

Parked High-risk that any land

disposal at Edgecumbe would be technically unfeasible / unsustainable


X

Parked


X

Parked High-risk that any land

disposal at Edgecumbe would be technically unfeasible / unsustainable


X

Parked


(EDG8)

Option 8


√ √

Option 9

New WWTP at Edgecumbe and Land Application at Thornton Dunes

√

X

Parked High capital and

operating costs for new WWTP at Edgecumbe


Option 10

New WWTP at Edgecumbe and Tarawera River Discharge

√

X

Parked Difficulty in meeting NPS

Freshwater objectives as a result of discharging additional contaminants to Tarawera River catchment than allowed for in the TCMP

Maximum values in future consent may cause issues with future consent compliance i.e. one single sample could cause non-compliance




List or Parked?


or Parked?

High technology and expensive to run WWTP to meet the very high treated wastewater quality in the TCMP


Option 11

New WWTP at Edgecumbe and Rangitaiki River discharge

√

X

Parked High cost for new

WWTP

Does not use the existing infrastructure at Edgecumbe oxidation ponds

(EDG12)

Option 12


√ √

5.6 Comparison of Short Listed Options

Following the assessment of the confirmed Long List of 9 options, then as set out in Section 5-5 a short

list of five options was arrived at. These are further stated for ease of reference in Table 5-5 below.

Each of these options were further developed in respect to Preliminary (high level) concept design of

conveyance, treatment and treated wastewater discharges and disposal.

Table 5-5: Edgecumbe Standalone Shortlisted Options

Short Listed Edgecumbe Standalone Options

(EDG1) Option 1

Conveyance of Edgecumbe raw sewage to Kawerau WWTP

(EDG4)

Option 4


(EDG5)

Option 5

Conveyance of Edgecumbe raw sewage to Whakatāne WWTP

(EDG8)

Option 8


(EDG12)

Option 12


Please refer to

Table 5-1 for the component parts of each option.

The schematics in Section 5-4 for key features.

The marked up topographical plans in Appendix E for conveyance routes used in the assessment.



Following consultation with BOPRC, a variation of Option 8 was developed with land application at Whakatāne airport (as shown in Figure 2-3). This option was coded Option 8A (schematic shown below).

Figure 5-10: Schematic for Option 8A

5.6.1 Estimated Costs

Section 4 above sets out the basis of cost estimates. These also include those items for which capital cost estimates have not been included. This includes no provision for GST, resource consents, any land purpose and possible WWTP’s upgrades at Whakatāne, Edgecumbe or Kawerau when the respective resource consents expire. Refer to Section 4 for other items.

Table 5-6 below summarises the Estimated Costs for Edgecumbe Standalone Options.

Table 5-6: Estimated Costs for Edgecumbe Standalone Options


OPEX - Year 20

($M)

(for Comparison)

NPV ($M)

Option Conveyanc

e Treatment Total Capital


for EDG1

Power Dosing Total Year 1 - OPEX

Total Year 20 - OPEX

TOTAL COST

EDG1 $10.520 $0.300 $10.820 $0.315 $0.020 $ - $0.335 $0.590 $15.705

EDG4 +Actiflo + UV

$10.080 $0.520 $10.600 $0.040 $0.010 $ - $0.050 $0.125 $11.470

EDG5 + Actiflo + UV

$10.400 $0.440 $10.840 $0.040 $0.035 $0.045 $0.120 $0.290 $12.890

EDG8 $6.150 $5.550 $11.700 $0.085 $0.185 $0.030 $0.295 $1.425 $18.355

EDG8A $7.670 $5.550 $13.220 $0.090 $0.185 $0.03 $0.305 $1.425 $19.895

EDG12 $1.625 $4.315 $5.940 $0.080 $0.185 $0.025 $0.295 $1.410 $12.515



In addition to the basis of the estimates details for the makeup of these estimated costs are given in

Appendices H, I and J for conveyance, treatment and disposal/discharge and NPV accordingly.

5.6.2 Short List Options: Information Summary

The information contained in this report pertaining to these 5 short listed standalone Edgecumbe options, includes:

Table 5-1 Components Parts of the Options

The Schematics for these options in Section 5-4 above.

The Appendix D Comparison Evaluation Table.

The Appendix E Conveyance Routes

The Estimated Cost Summaries in Section 5-6-1 above, Section 3 of this Report and detailed cost estimates in Appendices H - Conveyance), I - Treatment and Discharge/Disposal and J – Net Present Value (NPV).

The Risk Assessment and Risk Mitigation in Section 8 and Table 8-4 for these options.

Appendix K – Supplier Information on Actiflo and MBBR Treatment processes.

Technical, land application and consenting information in Sections 2 and 3 of this Report.

5.6.3 Ranking of Short Listed Option

The ranking of short listed options was undertaken using a Multi-Criteria Assessment (MCA) tool. Key

considerations to inform the MCA included the following:

The provisions within the Regional Plan for the Tarawera River Catchment that prohibit the discharge of wastewater sourced from outside Kawerau Township at Kawerau;

The various issues associated with the conveyance of raw wastewater long distances that relate to the maintenance of adequate flushing velocities, odour management and mitigation (including the requirement for chemical dosing at pump stations) and the corrosive effects of septic raw wastewater on downstream wastewater treatment facilities;

The relative benefits of conveying treated wastewater from the Edgecumbe oxidation ponds that avoid the adverse effects that relate to the conveyance of raw wastewater;

Preferences expressed for the land application of treated wastewater through the relevant statutory planning framework;

The implications of the National Policy Statement for Freshwater Management 2014 and the interpretation for discharges to freshwater to demonstrate the ‘maintenance and enhancement of water quality’;

The implications of the Matatā wastewater Scheme Environment Court decision in terms of adverse effects of the land application of treated wastewater, the over-allocation of water bodies and the maintenance and enhancement of water quality;

The implications of other key statutory planning documents;

Tāngata whenua preferences and documents such as ‘Pathways of the Rangitaiki’;

The potential risk of submissions and later appeals to any future resource consent process;

The preference to utilise as far as practicable existing infrastructure;

The potential to remove the existing discharge of treated wastewater to the Tarawera River catchment from the Edgecumbe WWTP;

The relative capital, operating and whole of life costs of the various preferred option;

The risks profile of each shortlisted option in terms of likelihood, consequence and mitigation;

The future development of an overall District Wide Wastewater Strategy as part of WDC’s Infrastructure 2015-2025;



The advantages/disadvantages of combining townships for treatment and discharge compared to standalone schemes;

The likely future pros and cons of where the treated wastewater is disposed/discharged i.e. surface water, land, ocean – assuming beneficial reuse is not available;

For the options based on discharge out of the Whakatāne ocean outfall what is likely to be the consent requirements and (any) additional treatment and/or disposal infrastructure after 2026 when the existing resource consent (Water Right) expires;

Any viable beneficial reuse options for treated wastewater;

The question of whether it is necessary to fully replaced the damaged Edgecumbe collection system if an option that can account for higher wet weather flows is adopted;

The compatibility of options with WDC’s present and planned wastewater schemes; and

The need for ongoing community, other stakeholder and tāngata whenua participation in decision making; and

Whether the Whakatāne Airport site is available and suitable for the land application rather than the Thornton dunes site (in this respect both options were assessed).

An MCA workshop with officers from WDC and BOPRC and representatives from MWH and AECOM

was held at WDC Offices on 31 August 2015. The following Tables are the outputs of that MCA

workshop:

Table 5-7 shows the MCA analysis criteria and associated criteria used for the basis of assessment;

Table 5-8 shows the relative weighting given to each criteria – based on a relative scoring of 1 being the least important and 10 being the most important;

Table 5-9 shows the results of the MCA scoring for each of the short listed options – based on a relative scoring of 1 being the lowest score and 5 being the highest score; and

Table 5-10 shows the rationale for the MCA scoring; and Table 5-11 shows the overall summary results, in terms of overall score excluding cost, overall score includ ing a 30% weighting for cost and an overall score including a 50% weighting for cost.



Table 5-7: Edgecumbe Standalone Shortlisted Options – MCA Analysis Criteria (Independent of Cost)

Ref Analysis Criteria Criteria Description Notes Classification Qualitative or Quantitative?

G1 Sustainability

Alignment with WDC Sustainability Strategy, Energy

Use/Carbon Footprint, Natural Hazards/Climate Change,

Adverse Effects on the Natural Environment, Sustainable

Development, Future Proofing

Scoring will be influenced by the amount of energy use,

reilience to natural hazards, climate change, potential for

adverse effects on the environment, and ability to respond

to population growth

Other Qualitative

G2 Social / Public Health

Public Health Risk, Safety, Visual Amenity, Proximity to

Neighbours and Effects on Them, Construction Effects,

Public Acceptance

Scoring will be influenced by the degree of public health

risk, removal of direct discharges to freshwater

environments, proximity to neighbours, and overall

likelihood of public acceptance

Social Qualitative

G3 Cultural

Matauranga Maori, Archaeological Sites, Discharge to

Freshwater, Discharge to Land, Discharge to Coastal

Water, cultural sites, Transfer of Wastewater from one

rohe to another

Scoring will be influenced by preference to discharge to

land over freshwater and coastal water, avoidance of

cultural sites and archaeological sites

Cultural Qualitative

G4Planning and

Regulatory

Consentability, RMA, Freshwater NPS, NZCPS, Regional

Plan for the Tarawera River Catchment, complexity and

viability of obtaining future consents and designations

Scoring will be influenced by the need (or not) to obtain

new discharge consents and designations, or whether

existing consent conditions could be changed via a

potentially non-notified process and future resource

consent requirements, the avoidance of discharges to the

Tarawera River catchment and freshwater generally, and

the potential effects on the coastal environment and

ecology. Overall marking will be from a complexity and

viability of consenting/planning process.

Environmental Qualitative

G5 Technical / Functional

Reliability, flexibility, constructability, proven engineering,

engineering resilience, soil type, distance to road,

distance to high voltage, use of existing infrastructure

Scoring will be influenced by proven technolgoy, that is

relatively easy to operate and maximises the use of

existing infrastructure. New and complex options to

contruct options will score more poorly.

Other Qualitative

G6 Operational

Complexity, safety, septicity risk/corrosion, centralised

vs decentralised, complementary to existing

infrastructure, reliability

Scoring will be influenced by the operation of the option

i.e. proven technology and can be supported in NZ, are

there other examples in NZ? Centralisation of treatment

plants is a beneficial factor.

Other Qualitative

G7 OwnershipLease, freehold, Maori land, Council owned/controlled

land and infrastructure

Security and influence of long term access/use. Council

owned or controlled land will score more highly, lease

arrangements will score more poorly.

Other Qualitative

Goal based Analysis Criteria - Independent of Cost



Table 5-8: Edgecumbe Standalone Shortlisted Options – MCA Analysis Weighting

Attribute

Refs:G1 G2 G3 G4 G5 G6 G7 C13 C14 C15

10 1 1 1 1

9 1

8 1 1

7

6 1 1

5 1

4

3

2

1

0

Cri

teri

a

Su

sta

ina

bilit

y

So

cia

l / P

ub

lic

He

alt

h

Cu

ltu

ral

Pla

nn

ing

an

d

Re

gu

lato

ry

Te

ch

nic

al /

Fu

nc

tio

na

l

Op

era

tio

na

l

Ow

ne

rsh

ip

Ca

pit

al C

os

t

Op

era

tin

g C

os

t

NP

V

Weight: 6 6 8 10 8 5 9 10 10 10

Sum of Goals 52 Sum of Cost 30

Goal Based Analysis Criteria - Independent of Costs Cost Based Criteria



Table 5-9: Edgecumbe Standalone Shortlisted Options – MCA Scoring Results (Independent of Cost)

# Scenario

Su

stai

nab

ilit

y

So

cial

/ P

ub

lic

Hea

lth

Cu

ltu

ral

Pla

nn

ing

an

d R

egu

lato

ry

Tec

hn

ical

/ F

un

ctio

nal

Op

erat

ion

al

Ow

ner

ship

Criteria Weighting 0.115 0.115 0.154 0.192 0.154 0.096 0.173

1Edgecumbe - EDG1 - Raw

Sewage to Kawerau2 3 4 2 3 2 3

2

Edgecumbe - EDG4 -

Oxidation Pond

Wastewater to Whakatāne

4 4 3 4 4 3 5

3Edgecumbe - EDG5 - Raw

Sewage to Whakatāne3 3 3 4 3 2 5

4

Edgecumbe - EDG8 -

Upgrade Oxidation Ponds

and Land Application at

Thornton

3 3 4 3 3 3 5

5

Edgecumbe - EDG12 -

Upgrade Oxidation Ponds

and Discharge to Rangitāiki

River

2 2 1 1 4 3 5

6

Airport - EDG8A - Upgrade

Oxidation Ponds and Land

Application at Airport

4 4 4 4 3 3 5

7

Edgecumbe - Upgrade

Oxidation Ponds and

Discharge to Omeheu

Channel

2 3 2 2 2 2 5

Goal Based Analysis Criteria - Independent of Cost



Table 5-10: Edgecumbe Standalone Shortlisted Options – MCA Results Scoring Rationale (Independent of Cost)

# Scenario

Su

stai

nab

ilit

y

So

cial

/ P

ub

lic

Hea

lth

Cu

ltu

ral

Pla

nn

ing

an

d

Reg

ula

tory

Tec

hn

ical

/

Fu

nct

ion

al

Op

erat

ion

al

Ow

ner

ship


1

Edgecumbe -

EDG1 - Raw

Sewage to

Kawerau

2 1. Utilising existing facilities

at Kawerau with surplus

capacity

2. High energy consumption

to pump to Kawerau

3. Long raw sewage pipeline

exposed to multiple active

faults, shorter than from

Matata

4. Risk of NPS to continuity of

service in the future

31. Political support from KDC

2. Removes direct discharge to

freshwater environment

41.Initial anecdotal support

from iwi authority

representatives

2. Rohe to rohe issue may be

lesser due to the same iwi

living in Kawerau and

Edgecumbe

21. NPS for Freshwater

Management

2. Need to vary KDC air and

water discharge consents

31. Long raw sewage pipeline,

shorter than from Matatā

2. Rising main with approx

35m static head

3. Additional complexity to

manage septicity, odour,

corrosion, and friction loss

21. Odour

2. Septicity

3. Safety

4. Costs of pumping

5. Monitoring and

maintenance of valves and

pipelines

6. Control over continuity of

treatment and disposal

systems

31. Owned by KDC

2

Edgecumbe -

EDG4 - Oxidation

Pond Wastewater

to Whakatāne

41. Centralised disposal

solution

2. Use of exisitng Edgecumbe

treatment facility

3. Use of exisitng Whakatāne

treatment facility

4. Conveyance of treated

wastewater from Edgecumbe

to Whakatāne

41. Reduced effects upon

neighbours in comparison

with EDG5

2. Likely to be supported by

the majority of the public

3. Reduces potential health

risk through centralising

wastewater disposal

4.Removes direct discharge of

wastewater to fresh water

environment

31. May not be supported by iwi

2. Rohe to rohe potential

issue, iwi in Whakatāne area

different than Edgecumbe

41. Requires change to exisitng

consents for Whakatāne and


(air and wastewater)

2. Positive effect of ceasing

discharge to Tarawera River

catchment

41. Does not affect spare

capacity and operation of

existing oxidation ponds

2. Uncertainty over upgrade

requirements in the future

(>2026)

3. Complexity in connecting to

existing outfall

4. Upgrade of Edgecumbe

ponds required

31. Costs of pumping

2. Operation of 2 treatment

plants

3. Monitoring and


pipelines

51. Council owned scores 5

3

Edgecumbe -

EDG5 - Raw

Sewage to

Whakatāne

31. Centralised treatment


treatment facility

3. Retain Edgecumbe ponds

for storage of raw sewage

4. Natural hazard risk from

conveyance of raw sewage

from Edgecumbe to

Whakatāne

31. Neighbours to Whakatāne

oxidation pond likely to not

readily support

2. One facility likely to be

supported by the majority of

the public

3. Minimises potential health



4. Removes direct discharge of


environment

3 1. May not be supported by iwi

2. Rohe to rohe potential

issue, iwi in Whakatāne area

different than Edgecumbe


consents for Whakatāne

oxidation ponds (air and

wastewater)



catchment and surrender of

consent

31. Conveyance of raw sewage

over long distance

2.Additional complexity to





(>2026)

21. Odour

2. Septicity

3. Safety

4. Costs of pumping

5. Monitoring and


pipelines


4

Edgecumbe -

EDG8 - Upgrade

Oxidation Ponds

and Land

Application at

Thornton

31. Retains use of existing

treatment facility at

Edgecumbe

2. Land based disposal

3. Irrigation of treated

wastewater to dunes aids

biodiversity development

4. Tsunami risk 3

5. Coastal erosion to

foredunes

31. Ground water flow direction

unproven

2. Potential impact upon

shellfish and coastal

environment if groundwater

flows towards the coast

3. Number of houses around

200m from site

4 1. No archeological site

2. Distance to marae >500m


coastal water quality

31. BOPRC planning

documents support land-

based disposal



catchment

3. High public use of reserve

and adjoining coast

31. Cost effective use of

Edgecumbe oxidation pond

2. Design and construct

upgrade of Edgecumbe

oxidation pond

3. High perched ground water

table


2. Additional maintenance and

operational requirements for

land based disposal


5

Edgecumbe -

EDG12 - Upgrade

Oxidation Ponds

and Discharge to

Rangitāiki River

21. Use of upgraded facility at

Edgecumbe

2. Significant upgrading

required to meet discharge

quality criteria of receiving

water

3. Disposal to fresh water

environment

21. Low public acceptance - eg

Rangitāiki River Forum

2. High receational use and

food gathering resource

3. Direct discharge to


11. Highly likely to be culturally

unacceptable to iwi


Management

2. Removes discharge from

Tarawera River catchment

3. Significant dilution

available in Rangitāiki River

4. Difficult to satisfy RMA

requirements despite plant

upgrade

5. Inconsistent with

philosophy of Pathways to

Rangitaiki document which is

to improve overall water

quality

41. Upgrade treatment

processes compatible with

existing oxidation pond

2. Short conveyancing

distance from treatment plant

to disposal outfall

31. Cost of pumping

2. Higher costs of treatment

and maintenance due to

disposal to freshwater


6

Airport - EDG8a -

Upgrade

Oxidation Ponds

and Land

Application at

Airport



Edgecumbe






unproven





3. Public acceptance may be

an issue

41. No archeological site




4. Likely to be an issue with iwi

acceptance due to Ngāti Awa

Settlement Act provisions

41. BOPRC planning

documents support land-

based disposal



catchment

3. Will require Ministerial

approval as an ancilliary use

to the airport





oxidation pond

3. Potential use of surface

irrigation for a portion of the

land application field?


2. Additional maintenance and

operational requirements for

land based disposal


7

Edgecumbe -

Upgrade

Oxidation Ponds

and Discharge to

Omeheu Channel

21. New high tech WWTP

required with use of existing

ponds for balancing flows

2. Discharge into Omeheu

canal not sustainable in long

term


4. Site subject to flooding

5. Quality of existing

discharge will be improved



2. Public acceptance could be

low in comparison with other

options

3. Existing resource consent,

upgrade of the plant and

increased quality of discharge

will improve quality of water in

the Omehu Canal.

21. Unlikely to be supported by

iwi

21. Exisitng discharge not

meeting existing consent

conditions

2. BOPRC Regional Plan for

the Tarawera River Catchment

(TRCMP)


Management

4. May require new air

discharge consent

21. High tech treatment plant

2. Complex design and

construction

3. Requires additional land to

be reclaimed from oxidation

ponds

21. Higher costs of treatment

and maintenance due to

disposal to freshwater than for

disposal to Rangitāiki River

due to TRCMP provisions





Table 5-11: Edgecumbe Standalone Shortlisted Options – MCA Summary Results

# Scenario Capital Cost Operating Cost NPV

Overall

Score of

Analysis

Criteria

Excluding

Cost

RankCost Based

ScoreCost Rank

Overall

Score

including

Cost 30%

Overall Rank

30%

Overall

Score

including

Cost 50%

Overall Rank

50%

1Option 1 - Raw Sewage to

Kawerau10,820,000$ 335,000$ 15,705,000$ 2.75 5.00 1.52 5.00 2.38 7.00 2.14 7.00

2

Option 4 - Oxidation Pond

Wastewater to Whakatāne

WWTP

10,080,000$ 50,000$ 11,470,000$ 3.92 2.00 3.02 1.00 3.65 1.00 3.44 1.00

3Option 5 - Raw Sewage to

Whakatāne WWTP10,400,000$ 120,000$ 12,890,000$ 3.44 4.00 2.61 2.00 3.19 2.00 3.00 2.00

4

Option 8 - Upgrade Oxidation

Ponds and Land Application at

Thornton

11,700,000$ 295,000$ 18,355,000$ 3.50 3.00 1.42 6.00 2.87 4.00 2.53 6.00

5


Ponds and Discharge to

Rangitāiki River

5,940,000$ 295,000$ 12,515,000$ 2.58 7.00 2.39 3.00 2.52 6.00 2.50 5.00

6

Option 8A - Upgrade Oxidation

Ponds and Land Application at

Airport

13,220,000$ 305,000$ 19,895,000$ 3.92 1.00 1.12 7.00 3.08 3.00 2.52 3.00

7



Omeheu Channel

5,940,000$ 295,000$ 12,515,000$ 2.63 6.00 2.39 3.00 2.56 5.00 2.53 4.00

Assessment Criteria Scores and Ranking



5.7 Discussions and Findings

As shown in Table 5-11, the following summary of findings can be made:

In terms of the non-price scoring, Option 8A (Upgraded Oxidation Ponds and Land Application at

Whakatāne Airport) scored the highest, followed by Option 4 (Oxidation Pond Wastewater to

Whakatāne WWTP ) and Option 8 (Upgraded Oxidation ponds and Land Application at

Thornton). However, it should be noted that a scoring margin of 0.3 or greater should be

considered significant and less than that non-significant. Consequently, options 8A and 4 should

be considered equivalent with Option 8 third;

Option 8A scored highly in terms of sustainability, social/public heath, cultural, planning and

regulatory, and ownership and moderately in terms of technical/functional and operational.

Whilst WDC owns the Whakatāne airport site, there are a number of leases to consider and the

land is subject to the Ngati Awa Settlement Act provisions. However, WDC has obtained advice

that land application scheme could be progressed at the site and that this could be

encompassed within the existing airport use of the site;

Option 4, the conveyance of oxidation pond treated wastewater to the Whakatāne WWTP ocean

outfall, scored highly in terms of sustainability, public health, planning and regulatory,

technical/functional and ownership, and moderately in terms of cultural and operational;

In terms of overall scoring once cost was accounted for at a weighting of 30%, Option 4 was

ranked first, followed by Option 5 (Raw Sewage to Whakatāne WWTP) and Option 8A. The

ranking order was unaffected by increasing the cost weighting to 50%.

As discussed in Section 2.6.3 the balancing of treated wastewater at Edgecumbe has significant

advantages over balancing and conveying raw wastewater, particularly in terms of odour management,

corrosion and the maintence of adequate velocities within pipeline to maintain self-cleansing.

Consequently, for these reasons Option 4 scored higher than Option 5.

Additionally, preliminary legal advice has been obtained that it may be possible to apply for a change of

resource consent condition to the existing Whakatāne WWTP discharge consent that would allow the

acceptance of wastewater sourced from Edgecumbe. If this option was to be progressed further, an

application under Section 127 of the RMA would need to be submitted to the BOPRC.



6 Combined Matatā and Edgecumbe Options

6.1 Matatā Stand Alone Scheme Option

WDC and AECOM Consultants are concurrently assessing potential new sites for a standalone Matatā

WWTP and associated Land Application Field (LAF). The results of this assessed of potential combined

Matatā and Edgecumbe Scheme will be brought together for assessment against the range of

standalone Matatā options as described in Section 1.3.

6.2 Methodology

The assessment of combined Matatā and Edgecumbe options has followed a four stage assessment

being the:

Stage 1: Compilation of long list options broadly arranged around the groupings of options for conveyance to and treatment at Kawerau, conveyance to and treatment at Edgecumbe, conveyance to Matatā, land application at Thornton, and conveyance to Whakatāne;



Stage 4: Compilation of information to enable the short list to be assessed alongside Matatā standalone options; and


This draft Report has been prepared to stage 4 and will be used to assessment and rank the short listed

options for stage 5 and compare these to the Shortlisted Standalone Matatā Option though an MCA (and

other) processes.

6.3 Identification of Long List Options

The following long list of 21 options for a combined Matatā and Edgecumbe scheme were identified

under the following subheadings. The bold title (e.g. Kawerau, Edgecumbe etc.) relates to the point of

disposal/discharge of the treated wastewater.

At Kawerau

Option KL1 - Conveyance of Matatā and Edgecumbe raw sewage to Kawerau WWTP - Rapid Infiltration Bed (RIB) Land Disposal.

At Edgecumbe

Option EL1 - Conveyance of Matatā raw sewage to Edgecumbe Oxidation Ponds - Land Application at Edgecumbe

Option EL2 - Conveyance of Matatā raw sewage to new WWTP at Edgecumbe – Land Application at Edgecumbe;

Option ER1 - Conveyance of Matatā raw sewage to new WWTP at Edgecumbe and Omeheu Channel Discharge;

Option ER2 - Conveyance of Matatā raw sewage to new WWTP at Edgecumbe and discharge to Rangitaiki River; and


At Matatā

Option ML1 - Conveyance of Edgecumbe raw sewage to new WWTP at Matatā - Land Application at Matatā;



Option ML2 - Conveyance of Edgecumbe oxidation pond treated wastewater to Matatā Land Application. Matatā standalone treatment and joint land application with Edgecumbe at Matatā;

Option MR1 - Conveyance of Edgecumbe raw sewage to Matatā joint treatment and discharge to Lower Tarawera River;

Option MR2 - Conveyance of Edgecumbe oxidation pond treated wastewater to Matatā. Matatā standalone treatment – joint discharge to Tarawera River;

Option MO1 - Conveyance of Edgecumbe raw sewage to Matatā joint treatment and discharge to ocean at Matatā; and

Option MO2 - Conveyance of Edgecumbe oxidation pond treated wastewater to Matatā. Matatā standalone treatment – joint ocean discharge at Matatā;

At Thornton

Option TL1 - Conveyance of Edgecumbe raw sewage to Matatā. Joint treatment at Matatā, land application at Thornton;

Option TL2 - Conveyance of Edgecumbe oxidation pond treated wastewater to Matatā. Matatā standalone treatment and joint land application at Thornton; and

Option TL3 - Conveyance of Matatā raw sewage to Edgecumbe. Joint treatment at Edgecumbe oxidation ponds and conveyance to land application at Thornton.

An alternative to the land application on the Thornton Dunes maybe land application on the Whakatāne Airport site owned by WDC. Refer discussion in Section 2.11.

At Whakatāne

Option WO1 - Conveyance of Matatā raw sewage to Thornton and Edgecumbe to Thornton – then combined conveyance of Edgecumbe raw sewage to Whakatāne WWTP and Ocean Outfall Discharge;

Option WO2 - Conveyance of Matatā raw sewage to Whakatāne WWTP and Edgecumbe raw sewage to Whakatāne WWTP (via Awakeri) and Ocean Outfall Discharge;

Option WO3 - Conveyance of Matatā to Thornton and Edgecumbe Oxidation Pond treated wastewater to Thornton for joint Whakatāne ocean outfall;

Option WO4 - Conveyance of Matatā to Whakatāne WWTP and Edgecumbe Oxidation Pond treated wastewater to Whakatāne (via Awakeri) for joint Whakatāne ocean outfall ;

Option WO5 - Conveyance of Matatā raw sewage to Edgecumbe oxidation ponds . Edgecumbe oxidation ponds treated wastewater for joint Whakatāne ocean outfall discharge Route Option A – via Thornton; and

Option WO6 - Conveyance of Matatā raw sewage to Edgecumbe oxidation ponds. Edgecumbe oxidation ponds treated wastewater for joint Whakatāne ocean outfall discharge Route Option B – via Awakeri.

These 21 long list options are described further in Table 6-1 below which identifies the infrastructure

components and locations that make up the total option.



Table 6-1: Long list Options for Combined Matatā and Edgecumbe Schemes

Tre

at

&

Dis

ch

arg

e






(upgraded as appropriate)

Reference Previous Reports

Type Location Type Location

At

Ka

we

rau

Land 1 (KL1)

Conveyance of Matatā raw sewage and Edgecumbe raw sewage to Kawerau WWTP.

Rapid Infiltration Bed (RIB) Land Disposal.


Matatā LPS

Matatā & Edgecumbe pumped to Kawerau

Refer marked up schematic

Chemical Treatment (Alum Dosing)

Kawerau WWTP

Disposal to land via Rapid Infiltration Beds adjacent to Tarawera River

Kawerau WWTP and Rapid Infiltration Basins (RIB’s)

Opus July 2013, Option 2

Matatā AEE Table 6.4 for Matatā

At

Ed

ge

cu

mb

e Land 1

(EL1)

Conveyance of Matatā raw sewage to Edgecumbe Oxidation Ponds.

Land Application at Edgecumbe.


Matatā LPS

Matatā pumped to Edgecumbe


Existing Oxidation ponds upgraded by Actiflo

Edgecumbe Disposal to land by slow rate irrigation in general Edgecumbe area


Land 2 (EL2)

Conveyance of Matatā raw sewage to new WWTP at Edgecumbe – Land Application at Edgecumbe


Matatā LPS





Disposal to land by slow rate irrigation in general Edgecumbe area


MWH, Jan 2002

9 WDC’s proposal is to replace the damaged Edgecumbe collection system with grinder pump lower pressure system (LPS) grinder pump system. Current assumption is that the reticulation will

be replaced as per the Long Term Plan. After the reticulation system is upgraded raw sewage is assumed (i.e. the oxidation ponds will be decommissioned). However, this decision is being revisited.



Tre

at

&

Dis

ch

arg

e









River 1 (ER1)

Conveyance of Matatā to new WWTP at Edgecumbe and Omeheu Channel Discharge


Matatā LPS



“In tank” treatment with ex oxidation pond for high wet weather flows and treatment Standard to meet Regional Plan for Tarawera River Catchment treated wastewater quality


Omeheu Channel, the Tarawera River

Edgecumbe oxidation ponds for wet weather storage

Existing Omeheu Channel discharge

H&G, 2009

River 2 (ER2)

Conveyance of Matatā to new WWTP at Edgecumbe and discharge to Rangitaiki River


Matatā LPS



“In tank” treatment with ex oxidation pond for high wet weather flow balancing




River 3

(ER3)

Conveyance of Matatā to Edgecumbe oxidation ponds upgraded as necessary and discharge to Rangitaiki River


Matatā LPS



Existing Oxidation ponds upgraded by Actiflo, MBBR and UV disinfection




Matatā AEE Table 6.4

At

Ma

tatā

Land 1 (ML1)

Conveyance of Edgecumbe raw sewage to Matatā joint treatment at Matatā, Land Application


Matatā LPS

Edgecumbe LPS pump raw sewage


“In tank” WWTP Matatā Joint Land Application Area

Nil

Land 2

(ML2)

Conveyance of Edgecumbe Oxidation Pond treated wastewater to Matatā Land

Edgecumbe existing

Matatā LPS

Edgecumbe oxidation pond pumped


“In tank” WWTP for Matatā

Existing Oxidation Pond (upgraded) for

Matatā and Edgecumbe

Joint Land Application Edgecumbe oxidation pond



Tre

at

&

Dis

ch

arg

e









Application. Matatā standalone treatment and joint land application with Edgecumbe

Edgecumbe by Actiflo, MBBR and UV disinfection

River 1

(MR1)

Conveyance of Edgecumbe raw sewage to Matatā joint treatment and discharge to Lower Tarawera River


Matatā LPS



“In tank” WWTP with tidal discharge storage basin

Matatā area

Outgoing tidal discharge to lower reach of Tarawera River (within Coastal Marine Area)

Nil

River 2

(MR2)

Conveyance of Edgecumbe oxidation pond treated wastewater to Matatā. Matatā standalone treatment – joint discharge to Tarawera River

Edgecumbe existing

Matatā LPS



Edgecumbe Oxidation Pond by Actiflo, MBBR and UV disinfection

Matatā “in tank” WWTP

Oxidation Pond Edgecumbe

Matatā standalone WWTP

Outgoing tidal discharge to lower reach of Tarawera River (within Coastal Marine Area)

Edgewater oxidation pond

Ocean 1 (MO1)

Conveyance of Edgecumbe raw sewage to Matatā joint treatment and discharge to ocean at Matatā


Matatā LPS



In Tank with WTP tidal storage basin



Offshore ocean outfall in general Matatā area

Nil Opus July 2013 Option 3A

Ocean 2 (MO2)

Conveyance of Edgecumbe oxidation pond treated wastewater to Matatā. Matatā standalone treatment – joint ocean discharge at Matatā

Edgecumbe existing

Matatā LPS



Edgecumbe Oxidation Pond

Matatā “in tank” WWTP



Offshore ocean outfall in general Matatā area


Opus July 2013 Option 3A

At

Th

orn

ton

At

Th

orn

ton

Land 1 (TL1)

Conveyance of Edgecumbe raw sewage to Matatā. Joint treatment at Matatā, land application at Thornton


Matatā LPS

Edgecumbe LPS Pump raw sewage


“In tank” WWTP at Matatā area

Matatā Joint Land Application Area at Thornton

Nil



Tre

at

&

Dis

ch

arg

e









Land 2 (TL2)

Conveyance of Edgecumbe Oxidation Pond treated wastewater to Matatā. Matatā standalone treatment and joint land application at Thornton.

Edgecumbe existing

Matatā LPS



“In tank” WWTP for Matatā

Existing Oxidation Pond (upgraded) for Edgecumbe by Actiflo, MBBR and UV disinfection

Matatā and Edgecumbe

Joint Land Application Area at Thornton


Land 3 (TL3)

Conveyance of Matatā raw sewage to Edgecumbe. Joint treatment at Edgecumbe oxidation ponds and conveyance to land application at Thornton

Edgecumbe existing

Matatā LPS



Existing Oxidation Pond (upgraded) for Edgecumbe and Matatā by Actiflo, MBBR and UV disinfection

Edgecumbe Joint Land Application Area at Thornton


At

Wh

ak

atā

ne

Ocean 1 (WO1)

Conveyance of Matatā raw sewage to Thornton and Edgecumbe raw sewage to Thornton – then combined conveyance to Whakatāne WWTP and Ocean Outfall Discharge


Matatā LPS

Edgecumbe pumped

Matatā pumped

Joint pipeline from Thornton Pump Station


Upgraded Whakatāne Oxidation Pond System

Whakatāne WWTP

Out of existing Whakatāne ocean outfall

Whakatāne WWTP and ocean outfall

Opus 2013 Option 4

Matatā AEE Table 6-4

Ocean 2 (WO2)

Conveyance of Matatā raw sewage to Whakatāne WWTP and Edgecumbe raw sewage to Whakatāne WWTP (via Awakeri) and Ocean Outfall Discharge


Matatā LPS

Edgecumbe pumped

Matatā pumped


Upgraded Whakatāne Oxidation Pond System

Whakatāne WWTP

Out of existing Whakatāne ocean outfall


Matatā AEE Table 6-4

Ocean 3 (WO3)

Conveyance of Matatā raw sewage to Thornton and Edgecumbe Oxidation Pond treated wastewater to Thornton

Edgecumbe Oxidation Pond Treated wastewater

Matatā LPS



Oxidation Pond at Edgecumbe

Whakatāne WWTP

Edgecumbe

Whakatāne

Whakatāne ocean outfall (by passes Whakatāne WWTP) for Edgecumbe oxidation pond flow




Tre

at

&

Dis

ch

arg

e









for joint Whakatāne ocean outfall

Matatā LPS pumped (requires separate conveyance lines from Thornton)

Whakatāne ocean outfall for Matatā flow

Ocean 4 (WO4)

Conveyance of Matatā raw sewage to Whakatāne WWTP and Edgecumbe Oxidation Pond treated wastewater to Whakatāne (via Awakeri) for joint Whakatāne ocean outfall


Matatā LPS

Edgecumbe oxidation pumped

Matatā LPS pumped



Whakatāne WWTP upgraded if necessary for Matatā

Edgecumbe

Whakatāne

Whakatāne ocean outfall (by passes Whakatāne WWTP) for Edgecumbe oxidation pond flow

Whakatāne ocean outfall for Matatā flow


At

Wh

ak

atā

ne

Ocean 5 (WO5)

Conveyance of Matatā raw sewage to Edgecumbe oxidation ponds. Edgecumbe oxidation ponds treated wastewater for joint Whakatāne ocean outfall discharge Route Option A – via Thornton


Matatā LPS


Matatā LPS pumped



Edgecumbe Whakatāne ocean

outfall (by passes Whakatāne WWTP)


Whakatāne ocean outfall

Ocean 6 (WO6)

Conveyance of Matatā raw sewage to Edgecumbe oxidation ponds. Edgecumbe oxidation ponds treated wastewater for joint Whakatāne ocean outfall discharge Route Option B – via Awakeri


Matatā LPS


Matatā LPS pumped



Edgecumbe Whakatāne ocean

outfall (by passes Whakatāne WWTP)


Whakatāne ocean outfall



6.4 Evaluation of Long List Options

The long list of 21 options were assessed against a range of criteria as described in Table 6-2 below.

Table 6-2: Evaluation Criteria for Long List Options

Criteria Components

Technical/Functional

Reliability

Flexibility

Constructability

Engineering Resilience

Operational

Complexity

Safety

Septicity risk

Odour/noise management

Social/Public Health

Public health protection

Public safety

Visual/amenity

Location/neighbours

Construction effects odour/noise nuisance

Tangata Whenua Considerations (tangata whenua input required)

Discharge to fresh water

Discharge to land

Discharge to coastal water

Maori land

Transfer of wastewater from one rohe to another

RMA Consentability

RMA

NPS - FM (2014)

NZCPS (2010)

Regional & District Planning Instruments including RPTRC

Local Government Act (2002)

Existing and future consents and designation ease or difficulty

Relevant case law

Economic Relative Assessment of indicative capital,

operation and life cycle (NPV) costs

Overall Sustainability

Alignment with WDC’s Sustainability Strategy 2010-2015

Energy use/carbon footprint

Natural hazards/climate change

Adverse effects on natural environment

Sustainable development

Future proofing

Key Risks (without mitigation) Note that specific mitigation will be developed

for shortlisted options

Advantages



Criteria Components

Disadvantages

Appendix F provides the full assessment of the 21 long list options against these criteria. This Appendix

also includes (in summary form) key advantages and disadvantages and also a high level risk

assessment. These high level risks are identified before further mitigation measures that could be

implemented to further reduce these risks overt that allowed in the preliminary options concept

development and cost estimating. Section 8 includes a much more detailed risk assessment of the

Short Listed Options.

Following the assessment of 21 long list options, a confirmed long list of 11 options were taken forward

for further assessment. Table 6-3 provides a summary of the long list option assessment. This

assessment was undertaken by a WDC Officer, Mr Terry Long of the BOPRC and MWH staff workshop.

Legend:

√ = Option on confirmed long list


evaluation – but remain available should the proceeding evaluation process mean they should for some

reason that may arise be reconsidered.

Table 6-3: Long List Option Assessment Summary


Parked?

At Kawerau

Land 1 (KL1)

Conveyance of Matatā and Edgecumbe raw sewage to Kawerau WWTP.


√

Yet to address implications of TCMP

At Edgecumbe

Land 1 (EL1)



X

Parked Discharge of wastewater sourced from outside

Edgecumbe township at Edgecumbe a prohibited activity in TCMP

High-risk that any land disposal at Edgecumbe would be technically unfeasible / unsustainable


Land 2 (EL2)

Conveyance of Matatā to Edgecumbe joint WWTP Land Application

X








Parked?

River 1 (ER1)

Conveyance of Matatā raw sewage to Edgecumbe, joint, “in tank” treatment at Edgecumbe and Omeheu Channel Discharge

X



Difficulty in meeting NPS Freshwater objectives as a result of discharging additional contaminants to Tarawera River catchment than allowed for in the TCMP




River 2 (ER2)

Conveyance of Matatā raw sewage to new WWTP at Edgecumbe and discharge to Rangitaiki River

√

River 3

(ER3)

Conveyance of Matatā raw sewage to Edgecumbe oxidation ponds upgraded as necessary and discharge to Rangitaiki River

√

At Matatā

Land 1 (ML1)


X

Parked Not enough land available for land disposal

Difficulty in meeting NPS Freshwater objectives as a result of discharging additional contaminants to Tarawera River catchment

High cost for new WWTP


Land 2

(ML2)

Conveyance of Edgecumbe Oxidation Pond treated wastewater to Matatā Land Application. Matatā standalone treatment and joint land application with Edgecumbe

X

Parked Not enough land available for land disposal


River 1

(MR1)


X

Parked


Usage of Lower Tarawera River (white baiting, fishing, recreation etc.) and public health protection




Parked?

River 2

(MR2)


X

Parked



Ocean 1 (MO1)


X

Parked High capital and operating costs for new WWTP at

Matatā to cater for Matatā and Edgecumbe flows

Ocean 2 (MO2)


√

At Thornton

Land 1 (TL1)


√

Land 2 (TL2)

Conveyance of Edgecumbe Oxidation Pond treated wastewater to Matatā. Matatā standalone treatment and joint land application at Thornton.

√

Land 3 (TL3)


√

At Whakatāne

Ocean 1 (WO1)

Conveyance of Matatā to Thornton and Edgecumbe to Thornton – then combined to Whakatāne WWTP and Ocean Outfall Discharge

√

Ocean 2 (WO2)

Conveyance of Matatā to Whakatāne WWTP and Edgecumbe to Whakatāne WWTP (via Awakeri) and Ocean Outfall Discharge

X

Parked Very high conveyance operating costs related to

pumping wastewater long distances

Very long pipe distance between Edgecumbe and Whakatāne (via Awakeri)

Ocean 3 (WO3)

Conveyance of Matatā to Thornton and Edgecumbe Oxidation Pond treated wastewater to Thornton for joint Whakatāne ocean outfall

X

Parked Requires separate conveyance lines from Thornton

to Whakatāne

Ocean 4 (WO4)

Conveyance of Matatā to Whakatāne WWTP and Edgecumbe Oxidation Pond treated wastewater to Whakatāne WWTP (via Awakeri) for joint Whakatāne ocean outfall

X

Parked Very high conveyance operating costs related to

pumping wastewater long distances





Parked?

Ocean 5 (WO5)


√

Ocean 6 (WO6)


√

6.5 Assessment of Confirmed Long List Options

Following the assessment of the topographic of the 21 long list options, the 10 options taken forward to

the confirmed long list were assessed further in terms of maps and schematic diagrams with a summary

of key features and key matters that would be required in the option assessment and decision making .

These are described in the following sections for each option on the confirmed long list.



6.5.1 Option KL1 - Conveyance of Matatā and Edgecumbe to Kawerau WWTP

Figure 6-1: Schematic for Option KL1



6.5.2 Option ER2 - Conveyance of Matatā to new WWTP at Edgecumbe and Discharge to Rangitaiki River

Figure 6-2: Schematic for Option ER2



6.5.3 Option ER3 - Conveyance of Matatā to Edgecumbe Oxidation Ponds Upgraded as Necessary and Discharge to Rangitaiki River

Figure 6-3: Schematic for Option ER3



6.5.4 Option MO2 - Conveyance of Edgecumbe Oxidation Pond Treated Wastewater to Matatā. Matatā Standalone Treatment – Joint Ocean Discharge at Matatā

Figure 6-4: Schematic for Option MO2



6.5.5 Option TL1 - Conveyance of Edgecumbe Raw Sewage to Matatā. Joint Treatment at Matatā, Land Application at Thornton

Figure 6-5: Schematic for Option TL1



6.5.6 Option TL2 - Conveyance of Edgecumbe Oxidation Pond Treated Wastewater to Thornton. Matatā Standalone Treatment and Joint Land Application at Thornton




6.5.7 Option TL3 - Conveyance of Matatā Raw Sewage to Edgecumbe. Joint Treatment at Edgecumbe Oxidation Ponds and Conveyance to Land Application at Thornton




6.5.8 Option WO1 - Conveyance of Matatā to Thornton and Edgecumbe to Thornton – then combined to Whakatāne WWTP and Ocean Outfall Discharge

Figure 6-8: Schematic for Option WO1



6.5.9 Option WO5 - Conveyance of Matatā Raw Sewage to Edgecumbe Oxidation Ponds. Edgecumbe Oxidation Ponds Treated Wastewater for Joint Whakatāne Ocean Outfall Discharge Route Option A – via Thornton




6.5.10 Option WO6 - Conveyance of Matatā Raw Sewage to Edgecumbe Oxidation Ponds. Edgecumbe Oxidation Ponds Treated Wastewater for Joint Whakatāne Ocean Outfall Discharge Route Option B – via Awakeri




6.6 Confirmed Long List Assessment Summary

Following the assessment of 11 confirmed long list options, a short list of 6 options were taken forward for further assessment. Table 6-4 provides a summary of the confirmed long list option assessment as included in the middle column of the table and the 6 shortlisted options in the right hand column.

Legend:

√ = Option on confirmed long list or short list


evaluation – but remain available should the proceeding evaluation process mean they should for some

reason that may arise be reconsidered.

Table 6-4: Confirmed Long List Option Assessment Summary


List or Parked?


or Parked?

At Kawerau

Land 1 (KL1)

Conveyance of Matatā and Edgecumbe raw sewage to Kawerau WWTP.


√


√


At Edgecumbe

Land 1 (EL1)



X

Parked Discharge of wastewater sourced

from outside Edgecumbe township at Edgecumbe a prohibited activity in TCMP



X

Parked

Land 2 (EL2)

Conveyance of Matatā raw sewage to Edgecumbe joint WWTP Land Application

X





X

Parked




List or Parked?


or Parked?

River 1 (ER1)

Conveyance of Matatā raw sewage to Edgecumbe, joint, “in tank” treatment at Edgecumbe and Tarawera River Discharge

X



Difficulty in meeting NPS Freshwater objectives as a result of discharging additional contaminants to Tarawera River catchment than allowed for in the TCMP


Expected high costs


X

Parked

River 2 (ER2)

Conveyance of Matatā raw sewage to Edgecumbe, joint “in tank” treatment at Edgecumbe and discharge to Rangitaiki River

√

X

Parked High cost for new WWTP


River 3

(ER3)

Conveyance of Matatā raw sewage to Edgecumbe oxidation ponds upgraded as necessary and discharge to Rangitaiki River

√ √

At Matatā

Land 1 (ML1)


X

Parked Not enough land available for land

disposal


High cost for new WWTP


X

Parked




List or Parked?


or Parked?

Land 2

(ML2)

Conveyance of Edgecumbe Oxidation Pond treated wastewater to Matatā Land Application. Matatā standalone treatment and joint land application with Edgecumbe

X

Parked Not enough land available for land

disposal


X

Parked

River 1

(MR1)


X

Parked



X

Parked

River 2

(MR2)


X

Parked



X

Parked

Ocean 1 (MO1)


X

Parked High capital and operating costs for

new WWTP at Matatā to cater for Matatā and Edgecumbe flows

X

Parked

Ocean 2 (MO2)


√

X

Parked

At Thornton

Land 1 (TL1)


√

X

Parked


Land 2 (TL2)

Conveyance of Edgecumbe Oxidation Pond treated wastewater to Thornton. Matatā standalone treatment and joint land application at Thornton.

√ √




List or Parked?


or Parked?

Land 3 (TL3)


√ √

At Whakatāne

Ocean 1 (WO1)

Conveyance of Matatā raw sewage to Thornton and Edgecumbe raw sewage to Thornton – then combined to Whakatāne WWTP and Ocean Outfall Discharge

√ √

Ocean 2 (WO2)

Conveyance of Matatā to Whakatāne raw sewage WWTP and Edgecumbe to Whakatāne WWTP (via Awakeri) and Ocean Outfall Discharge

X

Parked Very high conveyance operating

costs related to pumping wastewater long distances


X

Parked

Ocean 3 (WO3)

Conveyance of Matatā raw sewage to Whakatāne WWTP via Thornton and Edgecumbe Oxidation Pond treated wastewater via Thornton for joint Whakatāne ocean outfall

X

Parked Requires separate conveyance

lines from Thornton to Whakatāne

X

Parked

Ocean 4 (WO4)

Conveyance of Matatā to Whakatāne WWTP and Edgecumbe Oxidation Pond treated wastewater to Whakatāne WWTP (via Awakeri) for joint Whakatāne ocean outfall

X

Parked Very high conveyance operating

costs related to pumping wastewater long distances


X

Parked

Ocean 5 (WO5)


√ √

Ocean 6 (WO6)


√

X

Parked




6.7 Assessment of Short-Listed Options

Following the assessment of the confirmed Long List of 9 options, then as set out in section 5-5 a short list of 6 options was arrived at. These are further stated for ease of reference in Table 6-5 below. Each of these options were further developed in respect to Preliminary (high level) concept design of conveyance, treatment and treated wastewater discharges and disposal.

Table 6-5: Matatā and Edgecumbe Standalone Shortlisted Options

Short Listed Matatā and Edgecumbe Standalone Options

At Kawerau Land 1 (KL1)

Conveyance of Matatā and Edgecumbe raw sewage to Kawerau WWTP

At Edgecumbe River 3 (ER3)

Conveyance of Matatā raw sewage to Edgecumbe oxidation ponds upgraded as

necessary and discharge to Rangitaiki River

At Thornton Land 2 (TL2)

Conveyance of Edgecumbe Oxidation Pond treated wastewater to Thornton. Matatā standalone treatment and joint land application at Thornton.

Land 3 (TL3) Conveyance of Matatā raw sewage to Edgecumbe. Joint treatment at Edgecumbe oxidation ponds and conveyance to land application at Thornton.

At Whakatāne Ocean 1 (WO1)

Conveyance of Matatā raw sewage to Thornton and Edgecumbe raw sewage to Thornton – then combined to Whakatāne WWTP and Ocean Outfall Discharge.

Ocean 5 (WO5) Conveyance of Matatā raw sewage to Edgecumbe oxidation ponds. Edgecumbe oxidation ponds treated wastewater for joint Whakatāne Ocean Outfall discharge Route Option A – via Thornton.

Please refer to

Table 6-1 for the component parts of each option.

The schematics in Section 6-4 for key features.

The marked up topographical plans in Appendix E for conveyance routes used in the assessment.

As with the Edgecumbe standalone options, following consultation with BOPRC, a variation of the

Thornton land applications were developed with land application at Whakatāne airport (as shown in

Figure 2-3). These options were coded TL2A and TL3A (schematics shown below).

An option of conveying Matatā standalone wastewater directly to Whakatāne WWTP (MW1). This option

has been developed as the Project has progressed to compare directly with standalone Matatā

wastewater treatment and disposal options.



Figure 6-11: Schematic for Option TL2A

Figure 6-12: Schematic for Option TL3A

6.7.1 Estimated Costs

Section 4 above sets out the basis of cost estimates. These also include those items for which capital

cost estimates have not been included. This includes no provision for GST, resource consents, any land

purpose and possible WWTP’s upgrades at Whakatāne, Edgecumbe or Kawerau when the respective

resource consents expire. Refer to section 4 for other items.

Table 6-6 below summarises the Estimated Costs for the Combined Matatā and Edgecumbe Options.



Table 6-6: Estimated Costs for Combined Matatā and Edgecumbe Options


OPEX - Year 20 ($M) (for

Comparison)

NPV ($M)

Option Matatā

Reticulation Conveyance Treatment Total Capital


for KL1

Power Dosing Total Year 1

- OPEX Total Year 20 - OPEX

TOTAL COST

KL1 $6.000 $18.955 $0.300 $25.255 $0.365 $0.030 $0.065 $0.460 $0.855 $32.085

ER3 $6.000 $9.765 $5.155 $20.920 $0.115 $0.200 $0.045 $0.360 $1.540 $28.495

TL2 $6.000 $10.490 $8.985 $25.475 $0.115 $0.255 $0.040 $0.410 $1.625 $33.810

TL2A $6.000 $13.585 $8.985 $28.570 $0.120 $0.255 $0.040 $0.415 $1.630 $36.945

TL3 $6.000 $13.310 $6.540 $25.850 $0.120 $0.200 $0.045 $0.365 $1.555 $33.515

TL3A $6.000 $14.835 $6.540 $27.375 $0.120 $0.200 $0.045 $0.365 $1.555 $35.045

WO1 + Actiflo + UV

$6.000 $16.240 $0.625 $22.865 $0.090 $0.020 $0.065 $0.175 $0.410 $25.705

WO5 + Actiflo + UV

$6.000 $17.125 $0.700 $23.825 $0.075 $0.025 $0.015 $0.115 $0.280 $25.760

MW1 + Actiflo + UV

$6.000 $9.410 $0.180 $15.590 $0.060 $0.010 $0.015 $0.085 $0.185 $16.915

In addition to the basis of the estimates details for the makeup of these estimated costs are given in

Appendices H, I and J for conveyance, treatment and disposal/discharge and NPV accordingly.

6.7.2 Short List Options: Information Summary

The information contained in this report pertaining to these 6 short listed standalone Matatā and

Edgecumbe options, includes:

Table 6-1 Components Parts of the Options

The Schematics for these options in Section 6-4 above.

The Appendix D Comparison Evaluation Table.

The Appendix E Conveyance Routes

The Estimated Cost Summaries in Section 6-7-1 above, Section 3 of this Report and detailed cost estimates in Appendices H - Conveyance), I - Treatment and Discharge/Disposal and J – Net Present Value (NPV).

The Risk Assessment and Risk Mitigation in Section 8 and Table 8-5 for these options.

Appendix K – Supplier Information on Actiflo and MBBR Treatment processes.

Technical, land application and consenting information in Sections 2 and 3 of this Report.

6.7.3 Ranking of Short Listed Option

The ranking of short listed options is proposed to be undertaken using a Multi-Criteria Assessment (MCA) tool alongside the Matatā standalone options being developed. Key considerations to inform the MCA include the following:

The provisions within the Regional Plan for the Tarawera River Catchment that prohibit the discharge of wastewater sourced from outside Kawerau Township at Kawerau;

The various issues associated with the conveyance of raw wastewater long distances that relate

to the maintenance of adequate flushing velocities, odour management and mitigation (including



the requirement for chemical dosing at pump stations) and the corrosive effects of septic raw

wastewater on downstream wastewater treatment facilities;

The relative benefits of conveying treated wastewater from the Edgecumbe oxidation ponds that

avoid the adverse effects that relate to the conveyance of raw wastewater;

Preferences expressed for the land application of treated wastewater through the relevant

statutory planning framework;

The implications of the National Policy Statement for Freshwater Management 2014 and the

interpretation for discharges to freshwater to demonstrate the ‘maintenance and enhancement of

water quality’;

The implications of the Matatā wastewater Scheme Environment Court decision in terms of

adverse effects of the land application of treated wastewater, the over-allocation of water bodies

and the maintenance and enhancement of water quality;

The implications of other key statutory planning documents;

Tāngata whenua preferences and documents such as ‘Pathways of the Rangitaiki’;

The potential risk of submissions and later appeals to any future resource consent process;

The preference to utilise as far as practicable existing infrastructure;

The potential to remove the existing discharge of treated wastewater to the Tarawera River

catchment from the Edgecumbe WWTP;

The potential to remove the discharge of on-site wastewater discharges to the Tarawera River

catchment from the Matatā township;

Public health benefits of removing the discharge of on-site wastewater from Matatā township;

The relative capital, operating and whole of life costs of the various preferred option;

The position with respect to retaining the Ministry of Health and BOPRC subsidy for a Matatā

Wastewater Scheme;

The risks profile of each shortlisted option in terms of likelihood, consequence and mitigation;

The future development of an overall District Wide Wastewater Strategy as part of WDC’s

Infrastructure 2015-2025;

The advantages/disadvantages of combining townships for treatment and discharge compared

to standalone schemes;

The likely future pros and cons of where the treated wastewater is disposed/discharged i.e.

surface water, land, ocean – assuming beneficial reuse is not available;

For the options based on discharge out of the Whakatāne ocean outfall what is likely to be the

consent requirements and (any) additional treatment and/or disposal infrastructure after 2026

when the existing resource consent (Water Right) expires;

Any viable beneficial reuse options for treated wastewater;

The question of whether it is necessary to fully replaced the damaged Edgecumbe collection

system if an option that can account for higher wet weather flows is adopted;

The compatibility of options with WDC’s present and planned wastewater schemes; and

The need for ongoing community, other stakeholder and tāngata whenua participation in

decision making.

Whether the Whakatāne Airport site is available and suitable for the land application rather than the Thornton dunes site



An MCA workshop with officers from WDC and BOPRC and representatives from MWH and AECOM

was held at WDC Offices on 31 August 2015. The following Tables are the outputs of that MCA

workshop:

Table 6-7 shows the MCA analysis criteria and associated criteria used for the basis of assessment;

Table 6-8 shows the relative weighting given to each criteria – based on a relative scoring of 1 being the least important and 10 being the most important;

Table 6-9 shows the results of the MCA scoring for each of the short listed options – based on a relative scoring of 1 being the lowest score and 5 being the highest score;

Table 6-10 shows the rationale for the MCA scoring; and Table 6-11 shows the overall summary results, in terms of overall score excluding cost, overall score including a 30% weighting for cost and an overall score including a 50% weighting for cost.




Table 6-7: Combined Matatā/Edgecumbe Shortlisted Options – MCA Analysis Criteria (Independent of Cost)

Ref Analysis Criteria Criteria Description Notes Classification Qualitative or Quantitative?

G1 Sustainability

Alignment with WDC Sustainability Strategy, Energy

Use/Carbon Footprint, Natural Hazards/Climate Change,

Adverse Effects on the Natural Environment, Sustainable

Development, Future Proofing

Scoring will be influenced by the amount of energy use,

reilience to natural hazards, climate change, potential for

adverse effects on the environment, and ability to respond

to population growth

Other Qualitative

G2 Social / Public Health

Public Health Risk, Safety, Visual Amenity, Proximity to

Neighbours and Effects on Them, Construction Effects,

Public Acceptance

Scoring will be influenced by the degree of public health

risk, removal of direct discharges to freshwater

environments, proximity to neighbours, and overall

likelihood of public acceptance

Social Qualitative

G3 Cultural

Matauranga Maori, Archaeological Sites, Discharge to

Freshwater, Discharge to Land, Discharge to Coastal

Water, cultural sites, Transfer of Wastewater from one

rohe to another

Scoring will be influenced by preference to discharge to

land over freshwater and coastal water, avoidance of

cultural sites and archaeological sites

Cultural Qualitative

G4Planning and

Regulatory

Consentability, RMA, Freshwater NPS, NZCPS, Regional

Plan for the Tarawera River Catchment, complexity and

viability of obtaining future consents and designations

Scoring will be influenced by the need (or not) to obtain

new discharge consents and designations, or whether

existing consent conditions could be changed via a

potentially non-notified process and future resource

consent requirements, the avoidance of discharges to the

Tarawera River catchment and freshwater generally, and

the potential effects on the coastal environment and

ecology. Overall marking will be from a complexity and

viability of consenting/planning process.

Environmental Qualitative

G5 Technical / Functional

Reliability, flexibility, constructability, proven engineering,

engineering resilience, soil type, distance to road,

distance to high voltage, use of existing infrastructure

Scoring will be influenced by proven technolgoy, that is

relatively easy to operate and maximises the use of

existing infrastructure. New and complex options to

contruct options will score more poorly.

Other Qualitative

G6 Operational

Complexity, safety, septicity risk/corrosion, centralised

vs decentralised, complementary to existing

infrastructure, reliability

Scoring will be influenced by the operation of the option

i.e. proven technology and can be supported in NZ, are

there other examples in NZ? Centralisation of treatment

plants is a beneficial factor.

Other Qualitative

G7 OwnershipLease, freehold, Maori land, Council owned/controlled

land and infrastructure

Security and influence of long term access/use. Council

owned or controlled land will score more highly, lease

arrangements will score more poorly.

Other Qualitative

Goal based Analysis Criteria - Independent of Cost




Table 6-8: Combined Matatā/Edgecumbe Shortlisted Options – MCA Analysis Weighting

Attribute

Refs:G1 G2 G3 G4 G5 G6 G7 C13 C14 C15

10 1 1 1 1

9 1

8 1 1

7

6 1 1

5 1

4

3

2

1

0

Cri

teri

a

Su

sta

ina

bilit

y

So

cia

l / P

ub

lic

He

alt

h

Cu

ltu

ral

Pla

nn

ing

an

d

Re

gu

lato

ry

Te

ch

nic

al /

Fu

nc

tio

na

l

Op

era

tio

na

l

Ow

ne

rsh

ip

Ca

pit

al C

os

t

Op

era

tin

g C

os

t

NP

V

Weight: 6 6 8 10 8 5 9 10 10 10

Sum of Goals 52 Sum of Cost 30

Goal Based Analysis Criteria - Independent of Costs Cost Based Criteria




Table 6-9: Combined Matatā/Edgecumbe Shortlisted Options – MCA Scoring Results (Independent of Cost)

# Scenario

Su

stai

nab

ilit

y

So

cial

/ P

ub

lic

Hea

lth

Cu

ltu

ral

Pla

nn

ing

an

d R

egu

lato

ry

Tec

hn

ical

/ F

un

ctio

nal

Op

erat

ion

al

Ow

ner

ship


1KL1 - Raw Sewage to

Kawerau WWTP2 3 4 1 2 1 3

2

ER3 - Upgraded

Edgecumbe Oxidation


Rangitaiki River

2 2 1 1 4 3 5

3

TL2 - Upgraded

Edgecumbe Oxidation

Pond and Discharge at

Thornton Dunes. Matata

standalone WWTP and

discharge at Thornton

Dunes.

3 3 4 3 3 2 5

4

TL3 - Matata to Upgraded

Edgecumbe Oxidation


Thornton Dunes

3 3 4 3 3 3 5

5WO1 - Raw Sewage to

Whakatane WWTP3 3 3 4 2 2 5

6

WO5 - Oxidation Pond

Treated Wastewater to

Whakatane WWTP

4 4 3 4 4 3 5

7

TL2A - Upgraded

Edgecumbe Oxidation


Whakatane Airport. Matata

standalone WWTP and

discharge at Whakatane

Airport.

3 4 4 4 3 3 5

8

TL3A - Matata to Upgraded

Edgecumbe Oxidation


Whakatane Airport

3 4 4 4 3 3 5




Table 6-10: Combined Matatā/Edgecumbe Shortlisted Options – MCA Results Scoring Rationale (Independent of Cost)

# Scenario

Su

stai

nab

ilit

y

So

cial

/ P

ub

lic

Hea

lth

Cu

ltu

ral

Pla

nn

ing

an

d

Reg

ula

tory

Tec

hn

ical

/

Fu

nct

ion

al

Op

erat

ion

al

Ow

ner

ship



Kawerau WWTP

21. Utilising existing facilities

at Kawerau with surplus

capacity


to pump to Kawerau

3. Long raw sewage pipelines

exposed to multiple active

faults

4. Risk of NPS to continuity of

service in the future

31. Political support from KDC

2. Removes direct discharge to


41.Initial anecdotal support

from iwi authority

representatives

2. Rohe to rohe issue

11.Prohibited activity under

BOPRC Regional Plan for the

Tarawera River Catchment

(TRCMP)


Management

3. Need to vary KDC air and

water discharge consents

21. Longest raw sewage

pipeline in provincial NZ

2. Rising main with approx

35m static head

3. Additional complexity to



11. Odour

2. Septicity

3. Safety

4. Costs of pumping

5. Monitoring and maintenance

of valves and pipelines

6. Control over continuity of


systems

31. Owned by KDC

2

ER3 - Upgraded

Edgecumbe Oxidation

Ponds and Discharge

to Rangitaiki River

21. One treatment facility

2. Use of upgraded facility at

Edgecumbe

3. Significant upgrading

required to meet discharge

quality criteria of receiving

water

4. Natural hazard risk

associated with conveyance

of raw sewage from Matatā to

Edgecumbe

5. Disposal to fresh water

environment

21. Low public acceptance - eg

Rangitāiki River Forum

2. High receational use and

food gathering resource



11. Highly likely to be culturally

unacceptable to iwi


Management

2. Removes discharge from

Tarawera River catchment

3. Significant dilution available

in Rangitāiki River

4. Difficult to satisfy RMA

requirements despite plant

upgrade

5. Inconsistent with

philosophy of Pathways to

Rangitaiki document which is

to improve overall water

quality.

41. Upgrade treatment

processes compatible with

existing oxidation pond

2. Short conveyancing

distance from treatment plant

to disposal outfall

3. 16km raw sewage

conveyance distance from

Matatā to Edgecumbe

31. Odour

2. Septicity

3. Safety

4. Costs of pumping


3

TL2 - Upgraded

Edgecumbe Oxidation


Thornton Dunes.

Matata standalone

WWTP and discharge

at Thornton Dunes.

31. Two treatment facilities


wastewater only over long

distances



Edgecumbe





6. Tsunami risk 3


foredunes


unproven






200m from site





31. BOPRC planning documents

support land-based disposal

2. Matatā WWTP site requires

designation and resource

consents

3. Until site identified

uncertainty will remain



catchment

5. Proximity to lifestyle blocks

31. One new treatment plant to

design and construct and one

to design and implement

upgrade

2. Only conveying treated

wastewater

3. 2 separate pipelines from

WWTPs to land disposal area


table

21. Maintaining and operating 2

separate and different

treatment systems


separate rising mains

3. Increased costs associated

with above


4

TL3 - Matata to

Upgraded Edgecumbe

Oxidation Pond and

Discharge at Thornton

Dunes





Edgecumbe



Edgecumbe





6. Tsunami risk 3



unproven






200m from site

4. Use of enhaced existing

treatment facility likley to be

perceived better than

providing a new facility for

Matata









catchment

3. No need for designation for

standalone WWTP at Matatā

4. Proximity to lifestyle blocks





oxidation pond


from Matatā to Edgecumbe


table

31. Maintaining and operating

one treatment system


one rising main of raw sewage


3. Odour

4. Septicity

5. Safety

6. Costs of pumping



Whakatane WWTP

31. Centralised treatment


treatment facility

3. Retain Edgecumbe ponds

for storage of raw sewage

4. Natural hazard risk from

conveyance of raw sewage

from Matatā and Edgecumbe

to Whakatāne

5. Shared conveyance line

from Thornton to Whakatāne

31. Neighbours to Whakatāne

oxidation pond likely to not

readily support

2. One facility likely to be

supported by the majority of

the public

3. Minimises potential health



4. Removes direct discharge of


environment


2. Rohe to rohe potential issue


consents for Whakatāne

oxidation ponds (air and

wastewater)



catchment and surrender of

consent



4. Does not require new

wastewater site designation or

consents for a Matata WWTP

scheme


over long distance

2.Additional complexity to





(>2026)

21. Odour

2. Septicity

3. Safety

4. Costs of pumping




6

WO5 - Oxidation Pond

Treated Wastewater to

Whakatane WWTP

41. Centralised disposal

solution

2. Use of exisitng Edgecumbe

treatment facility


treatment facility




wastewater from Edgecumbe

to Whakatāne

41. Reduced effects upon

neighbours in comparison

with WO1

2. Likely to be supported by

the majority of the public

3. Reduces potential health


wastewater disposal

4.Removes direct discharge of


environment


2. Rohe to rohe potential issue


consents for Whakatāne and


(air and wastewater)



catchment



4. Does not require new

wastewater site designation or

consents for a Matata WWTP

scheme

41. Does not affect spare

capacity and operation of

existing oxidation ponds



(>2026)

3. Complexity in connecting to

existing outfall

4. Upgrade of Edgecumbe

ponds required

31. Odour

2. Septicity

3. Safety

4. Costs of pumping




7 TL2A - Airport

31. Two treatment facilities


wastewater only over long

distances



Edgecumbe






unproven






an issue





4. Likely to be an issue with

iwi acceptance due to Ngāti

Awa Settlement Act provisions



2. Matatā WWTP site requires

designation and resource

consents

3. Until site identified

uncertainty will remain



catchment



to the airport

31. One new treatment plant to

design and construct and one

to design and implement

upgrade

2. Only conveying treated

wastewater

3. 2 separate pipelines from

WWTPs to land disposal area





separate and different

treatment systems


separate rising mains

3. Increased costs associated

with above


8 TL3A - Airport





Edgecumbe



Edgecumbe






unproven





3. Use of enhaced existing

treatment facility likley to be

perceived better than

providing a new facility for

Matata


an issue





4. Likely to be an issue with

iwi acceptance due to Ngāti

Awa Settlement Act provisions





catchment





catchment



to the airport





oxidation pond



4. One pipeline from WWTPs to

land disposal area





one treatment system


one rising main of raw sewage


3. Odour

4. Septicity

5. Safety

6. Costs of pumping






Table 6-11: Combined Matatā/Edgecumbe Shortlisted Options – MCA Summary Results

# Scenario Capital Cost Operating Cost NPV

Overall

Score of

Analysis

Criteria

Excluding

Cost

RankCost Based

ScoreCost Rank

Overall

Score

including

Cost 30%

Overall Rank

30%

Overall

Score

including

cost 50%

Overall Rank

50%


Kawerau WWTP25,255,000$ 460,000$ 32,085,000$ 2.31 8.00 1.33 7.00 2.01 8.00 1.82 8.00

2

ER3 - Upgraded Edgecumbe

Oxidation Ponds and

Discharge to Rangitaiki River

20,920,000$ 360,000$ 28,495,000$ 2.58 7.00 1.95 3.00 2.39 7.00 2.26 7.00

3

TL2 - Upgraded Edgecumbe

Oxidation Pond and

Discharge at Thornton Dunes.

Matata standalone WWTP and

discharge at Thornton Dunes.

25,475,000$ 410,000$ 33,810,000$ 3.40 5.00 1.40 5.00 2.80 6.00 2.40 6.00

4

TL3 - Matata to Upgraded


and Discharge at Thornton

Dunes

25,850,000$ 365,000$ 33,515,000$ 3.50 4.00 1.53 4.00 2.91 5.00 2.51 4.00


Whakatane WWTP22,865,000$ 175,000$ 25,705,000$ 3.29 6.00 2.50 2.00 3.05 3.00 2.89 2.00

6

WO5 - Oxidation Pond Treated

Wastewater to Whakatane

WWTP

23,825,000$ 115,000$ 25,760,000$ 3.92 1.00 2.63 1.00 3.53 1.00 3.27 1.00

7

TL2A - Upgraded Edgecumbe

Oxidation Pond and

Discharge at Whakatane

Airport. Matata standalone

WWTP and discharge at

Whakatane Airport.

28,570,000$ 415,000$ 36,945,000$ 3.81 2.00 1.13 8.00 3.00 4.00 2.47 5.00

8

TL3A - Matata to Upgraded


and Discharge at Whakatane

Airport

27,375,000$ 365,000$ 35,045,000$ 3.81 2.00 1.40 6.00 3.09 2.00 2.60 3.00

Assessment Criteria Scores and Ranking



6.8 Discussions and Findings

As shown in Table 6-11, the following summary of findings can be made:

In terms of the non-price scoring, Option WO5 (Matatā Raw Sewage to Edgecumbe. Edgecumbe

Oxidation Pond Treated Wastewater to Whakatāne WWTP Ocean Outfall) scored the highest,

followed by Option TL2A (Matatā Raw Sewage to Edgecumbe Upgraded Oxidation Pond and

Discharge at Whakatāne Airport Land Application Field. Matatā Standalone WWTP and

discharge at Whakatāne Airport) and TL3A (Matatā Raw Sewage to Edgecumbe Upgraded

Oxidation Pond and Discharge at Whakatāne Airport Land Applica tion Field) joint second.

Option WO5, the conveyance of oxidation pond treated wastewater to the Whakatāne WWTP

ocean outfall, scored highly in terms of sustainability, social/public health, planning and

regulatory, technical/functional and ownership, and moderately in terms of cultural and

operational;

Options TL2A and TL3A scored highly in terms of social/public heath, cultural, planning and

regulatory, and ownership and moderately in terms of sustainability, technical/functional and

operational. Whilst WDC owns the Whakatāne airport site, there are a number of leases to

consider and the land is subject to the Ngati Awa Settlement Act provisions. However, WDC has

obtained advice that land application scheme could be progressed at the site and that this cou ld

be encompassed within the existing airport use of the site;

In terms of overall scoring once cost was accounted for at a weighting of 30%, Option WO5 was

ranked first, followed by Option TL3A and Option WO1 (Raw Sewage to Whakatāne WWTP) .

At a cost weighting of 50%, Option WO5 continued to be ranked first, with WO1 ranked second

and TL3A ranked third.

As discussed in Section 2.6.3 the balancing of treated wastewater at Edgecumbe has significant

advantages over balancing and conveying raw wastewater, particularly in terms of odour management,

corrosion and the maintence of adequate velocities within pipeline to maintain self -cleansing.

Consequently, for these reasons Option WO5 scored higher than Option WO1.

Preliminary legal advice has been obtained that it may be possible to apply for a change of resource

consent condition to the existing Whakatāne WWTP discharge consent that would allow the acceptance

of wastewater sourced from Edgecumbe. If this option WO5 was to be progressed further, an application

under Section 127 of the RMA would need to be submitted to the BOPRC.



7 Conveyance Issues and Considerations for Short Listed Options

There are a number of potentially significant issues that require suitable consideration at a further

detailed assessment and design stage including the previously mentioned septicity/odour assessment.

For long raw sewage rising mains this includes the LPS systems. These are discussed below:

7.1 Vertical Alignment

Several of the rising main routes have high (more elevated) spots along their length. Typically it is

preferred for the discharge end to be the highest point on the rising main. This keeps the rising main full

at all times. Where this is not the case it can lead to the following issues:

The rising main will sit, at times, with portions empty (full of air) – this air needs to be expelled

for the main to run full. The expelled air can be malodourous and may need odour treatment.

The air release points need to be carefully selected to ensure the main does not air -lock;

While the rising main is filling it may not be able to run at its design flow/head. This will require

the injection of a volume of flow before the main is full and will run at the designed rate;

When the pumps turn off, the rising main will empty under gravity – this will draw more air in. This will require selection of two-way air valves, in some locations, to prevent negative pressure and potential pipe collapse; and

Depending on the length of rising main that will drain and the daily volume of flow served the

pipe may never run full. The volume of wastewater pumped in may not fill the air gap before the

pumps turn off again. In this case main does may never run at design flows. Sections of rising

main that form permanent air pockets will collected fat/grease and may become

operational/maintenance issues. These sections will effective operate as gravity sewers and will

require to draw in and expel air regularly, potentially requiring odour treatment.

These issues can be overcome for the rising mains on this Project by considering the following options

but they add complexity, cost and risk to the Project.

The downstream of the rising main is raised above ground to the same level as the highest

elevation on the rising main to keep it full. This type of barometric loop is normally built as a

tower. These types of towers can be up to 10m.

Lay the rising main deeper along sections that are at the high points. This can be very costly

depending upon the length of the high point. Ideally this is used where the rising main can be

easily trenched deeper or the high point is only a short distance. Rising mains have been

directionally drilled on some projects to remove the high point but this can lead to access issues

and high cost replacement should the main suffer a burst. This can be combined with a short

barometric loop to achieve best cost. The costs estimates have been prepared on the basis of

trenching down the, by and large, reasonably wide grass verges in the WDC road reserve;

Provide a valve at the discharge end of the rising main. It is intended that this valve shuts when

the pumps are not running to keep the main full. The complexity of this option is that the pumps

must start against a closed valve and the valve must open before the pump increase speed. This

adds significant pump control/SCADA communication complexity and risk of failure.

The sections of rising main that drain could be designed to operate as gravity pressure

lines/inverted siphons. This may require careful consideration of air/odour management and self -

cleansing velocities in all portions of the main. Sections of the rising main around scour valves,

river crossing and local dips may collect solids and wi ll need to consider cleaning /main pigging

options.

Select an alternate route that removes the high point (e.g. across fields or private land).



7.1.1 Individual Short-List Route Option Long-sections

The following long-sections have been developed from a bare-earth digital terrain model (DTM)

developed from WDC LIDAR topographical data provided. The data provided has been taken at face

value and requires confirmation prior to detailed design. This information was deemed suitable for this

high level concept options investigation. Table 7-1 below summarises the route lengths and static (head)

lifts.

Matatā Pumping Station to Edgecumbe WWTP (along Greig Road) (KL1, ER3, TL3 and WO5)

This route is used for options KL1, ER3, TL3 and WO5 and was used in the cost estimates as decided with WDC Officers rather than the alternate State Highway 2 route. The route is relatively flat with a few minor high points around the 3-3.5m level. The ground level at both ends of the rising main are around 1-1.5m lower than this. It is expected that the Tarawera River will be bridged and therefore raise the main above ground level at this location. For this option a 2m barometric loop has been allowe d for at the Edgecumbe WWTP to keep the rising main full.

Matatā Pumping Station to Edgecumbe WWTP (along State Highway) (KL1, ER3, TL3 and WO5)

This route is an alternative route for the transfer of flows from Matatā to Edgecumbe along State

Highway 2 (Matatā Road). This route is approximately 11.5 km long compared to the longer Greig Road

route of 16.7 km as discussed above. This route could be used for options KL1, ER3, TL3 and WO5.

The route rises rapidly from Matatā to a high point of around 20m as SH2 passes around the base of

hills between Matatā and Flax Road. The route then falls slowly to the Tarawera River and then is

relatively flat to Edgecumbe. It is expected that the Tarawera River will be bridged and therefore raise

the main above ground level at this location.

For this route a 20m barometric loop would be required which is consider impractical;

Running the fall section of rising main as a gravity line is unlikely to achieve suitable velocities

as there is not enough fall to Edgecumbe. A second pumping station just to the north of

Awakaponga to pump to Edgecumbe may allow a short gravity section from the high point to

Awakaponga. This gravity section would probably require deep sections and given the diameter

of the line this would seem inappropriate; and



The most feasible option for this alignment would probably be to control the draining of the rising

main with a terminal valve. This will add complexity to the Project and may pose optional risk as

the valve and pumping station will need to communicate to ensure seem less operation. Typical

SCADA telemetry over radio may not be suitable as this can be disrupted by interference and

other atmospheric effects such as lightning.

For this study the complexities of this route led to this being dropped at the long-list stage and the longer

but less complicated route along Greig Road selected. There were a number of reasons for this:

No construction on a State Highway (construction would be cheaper, traffic management simpler and less disruption to public);

Improved access for maintenance along a non-State Highway;

Wider berms and construction space along Greig Road; and

Greig Road was a flatter less complicated route.

When the Project is taken forward to preliminary design it is appropriate that this route is re-examined to

confirm whether this shorter route can be cost-effectively delivered compared to the Greig Road

preferred option.

Edgecumbe WWTP to Kawerau WWTP (KL1)

The route from Edgecumbe WWTP to Kawerau WWTP is used for option KL1. Overall the rising main

would rise from around 2m ground level to around 27m at the Tarawera River crossing. The WWTP has

a ground level of around 26m. It has been assumed that a 2m barometric loop has been allowed for at

the Kawerau WWTP to keep the rising main full.

Matatā to Thornton (TL2, WO1)



This route is used for options TL2 and W01 and transfers wastewater from Matatā to Thornton, either for

local disposal or for conveyance further on to Whakatāne. Overall the alignment is relatively flat and can

either be catered for by the rise to the sand dunes at Thornton for land application or by slightly deeper

trenching along the route.

Edgecumbe to Thornton (TL2, TL3, WO1 and WO5) (Land Application Shown)

This route transfers flow from Edgecumbe to Thornton either for local disposal or for conveyance further

on to Whakatāne. The route has a local rise of ground level of up to 5m along its route. The ground level

at Thornton is 7.5m and therefore for the local disposal options TL2 and TL3 this is acceptab le. For

further transfer onto Whakatāne (WO1 and WO5), the Thornton pumping station is likely to be at a

slightly lower level and may require a short barometric loop. It has been assumed that a 2m barometric

loop will be required at the Thornton pump station for options WO1 and WO5, to keep the rising main

full.

Edgecumbe to Whakatāne (WO1 and WO5)

This route shows the full length transfer of flows from Edgecumbe to Whakatāne which is used for

options WO1 and WO5. Only option WO1 accepts additional flow at Thornton from Matatā. In option

WO5 Matatā is transferred to Edgecumbe first. Overall the route from Thornton to Whakatāne is flat but

may require a short 2m barometric loop at the Whakatāne WWTP to keep the rising main full. Table 7-1

provides a summary of the main conveyance routes and relevant considerations.



Table 7-1: Summary of Main Conveyance Routes for Shortlisted Options

Route Included in

Option Length

(km) Static

Lift (m) Comments

Matatā Pumping Station to Edgecumbe WWTP (Greig Road)

KL1, ER3, TL3, WO5

16.7 5.25 2m barometric loop assumed at Edgecumbe WWTP

Matatā Pumping Station to Edgecumbe WWTP (along State Highway) (KL1, ER3, TL3 and WO5)

KL1, ER3, TL3, WO5

11.5 5.25 Dropped at long list stage - should be reconsidered at preliminary design stage

Edgecumbe WWTP to Kawerau WWTP

KL1

Edgecumbe 4, 5

18.5 27.5 2m barometric loop assumed at Kawerau WWTP

Matatā to Thornton TL2

MW1 10.4 9.7 -

Edgecumbe to Thornton (TL2, TL3, WO1 and WO5) (Land Application Shown)

TL2, TL3

Edgecumbe option 4 & 8

9.8 8.9 -

Thornton to Whakatāne WWTP WO1, WO5,

MW1 8.4 3.2

2m barometric loop assumed at Thornton PS

Edgecumbe WWTP to Rangitaiki River Outfall

ER2, ER3, Edgecumbe

4, 11, 12 1.9 -

7.2 Start-up Flows

It is expected that start-up flows from Matatā will be low and the retention times of wastewater in the

rising main will be high. Even for fully developed future flows the retention time of wastewater in the

rising main is significant. Given the length of the rising mains under consideration it is not considered

economic to build a smaller initial rising main to be upgraded or duplicated in the future. The start -up

and low flow conditions will need to be managed. It has been assumed that chemical dosing will be

required from the outset to manage odour and septicity; and this will mitigate low flows. It will be

important to make sure that the majority of the connections to existing properties are bought on -line as

quickly as possible to increase daily flows and reduce the risk of operational issues. Furthermore

potable water (both Edgecumbe and Matatā have mains water supply) can be used to supplement initial

wastewater flows and be used as a flushing volume (for the pumping of raw sewage) if required.

7.3 Other Considerations

Other key considerations include:

Low Pressure System Power Outage – the planned low pressure sewer network for Matatā

requires power to operate. In the event of a power outage all of the pumps will stop operating

and store wastewater. The transfer pumping station will also stop operating but the low pressure

sewer network will only be discharging what can be driven under gravity. Providing back up

power or generators for the transfer pumping station only has a benefit if flow is arriving. When

power is restored to the low pressure network a large number of pumps will attempt to turn on

and empty. Most of these pumps will turn off as the pressure in the main will be too high – but

there is the risk of an immediate high peak flow arriving at the transfer pumping station that will

need to be allowed for either through wet well capacity or by using a valve that wi ll limit the flow



discharge from the main into the pump station. The details of this arrangement will need to be

considered further at later Project stages.

Air Valving - Long flat rising mains with numerous watercourse crossings will need to carefully

consider the number and locations of air valves. Given that air valves often require a suitable

seating pressure (5m or more) some of them may occasionally leak. There will be no nearby

sewers to drain air valve chambers to. This issue as well as potential management of emitted

odours will need careful consideration.

Wash-out/Scour Chambers – Long sewer pumping mains even of small diameter hold

significant volumes of wastewater. Scour chambers will not be located near to existing sewers to

be drained to and therefore need to consider suitable tanker access. A large number of tankers

will be required to completely empty the rising main as a single tanker can hold only around 8m 3.

Sections of such a long-rising main may not achieve desirable scour velocities and consideration

should be given during the design for the ability to clean sections of the rising main using

‘pigging’ techniques.

Energy - Long conveyance rising mains of this nature require significant energy to pump the

flow against the friction head. The cost of energy over the life of the asset is uncertain and a

potential risk.

Slime – Sewer slime builds up on the pipe wall of the rising main where there is not sufficient

velocity to strip it away. Bacteria within sewer slime around the pipe wall are the largest (90%)

producer of sulphides within sewer mains and potentially significant risk of hydrogen sulphide

(H2S) production (see Sewage septicity and odour below). Furthermore sewer slime takes up a

portion of the pipe capacity effectively increasing the pipe friction losses.

Septicity Study - A specialist septicity study will be required to fully determine the issues and

requirements of designing and operating the selected option for the pumping of raw sewage.

This will identify and quantify the risks and determine suitable mitigation measures to address

any septicity issues. This will provide more accurate cost estimates for chemical dosing and

odour treatment facilities and annual operation costs.

Surge Analysis - Due to the significant length of rising mains under consideration, specialist

surge analysis will be required as part of the design process in order to define the risks and

requirements of the selected option.

For the options conveying oxidation pond treated wastewater, or otherwise treated

wastewater from Edgecumbe, the comments on a slime and a septicity study do not apply. As

previously outlined pumping treated wastewater over long distances over long conveyance lines

has considerable advantages over pumping raw sewage.



8 Risk Assessment, Management and Mitigation

8.1 Risk Management Background and Approach

Prudent wastewater management includes the activities of risk assessment and management and

adoption of appropriate mitigation measures. Local government statutes and procedures including

those in AS/NZS ISO 31000: 2009 Standard on Risk set out appropriate procedures. These are

summarised below.

The risk assessment performed previously and continued in this Report was designed to be consistent

with recognised good practice and the requirements of AS/NZS ISO 31000: 2009 Standard on Risk

Management, which states:

“Risk management is the term applied to a logical and systematic method of establishing the context,

identifying, analysing, evaluating, treating, monitoring and communicating risks associated with any

activity, function or process in a way that will enable organisations to minimise losses and maximise

opportunities. Risk management is as much about identifying opportunities as avoiding or mitigating

losses.”

This risk is a combination of the severity of potential undesirable events or outcomes (here collectively

termed the consequences), the likelihood (probability or frequency) that these consequences occur and

the degree of exposure of people, assets or the environment to those consequences.

As this Project also includes RMA consenting, risk management consideration in terms of the RMA, are

encompassed by the interpretation of ‘effects’. The interpretation includes:

“Any potential effect of a high probability” and “any potential effect of a low probability which

has a high potential impact.”

Risk management categories titled as Hazard Threat Risk were identified at a relatively high level and

grouping of light risks. Each of the hazard/risk types were also grouped under the source of generic risk

grouping which included ‘Environmental’, ‘Economic’, ‘Social’, ‘Cultural’ and ‘Other’. The ‘Other’

category included factors such as predicted growth in wastewater generation not eventuating.

A two stage high level Risk Assessment approach:

Stage 1 involved a high level key risk identification for all options in scoping Long List for both

Edgecumbe “alone”. These are included in the “Key Risks (without mitigation)” in Appendix D

and F respectively;

Stage 2 takes the shortlisted options for Edgecumbe stand alone and joint Matatā and

Edgecumbe and further expands the key risks of these options by identifying additional risks and

their assessing these as to “likelihood” “consequences” and “risks”. These are set out in Table

8-1 and Table 8-2 respectively along with mitigation measures over those allowed for in the

Option concept and development to date that would further reduce or manage each of the risk

categories – this is shown in Table 7-4 and 7-5.

The assessment approach is generally following the accepted AU/NZ 4360:1999 Risk Management

Standard adopted by NZ local authorities.

Initial work shows main identified risks can be well mitigated against, although remains the question of

natural disasters with long pipelines – partly mitigated through resilient engineering and appropriate

infrastructure location and operation.

The above-referenced appraisal is considered to be consistent with the interpretation of risk based

‘effects’ under the RMA.

The output of the risk assessment would be further used in the determination of procedures to avoid,

remedy and mitigate measures associated with potential and actual adverse effects of the Scheme

implemented.



8.2 Evaluation of Risk

In Table 8-4 and 8-5, some 30 separate hazards or threats were identified in brain-storming discussions

amongst the MWH project team. The hazards or threats were recorded within a spread sheet system,

the Risk Register, and the associated level of risk for each option was assessed. In general, different

levels of risk were assigned to a specific hazard or threat depending on the disposa l / discharge option

being considered and hence, overall, the different options may be seen as more or less risky.

The risk arising from each of the hazards or threats was determined by allocating five category semantic

scales to the likelihood that the hazards or threats would occur, and the level of consequence that would

result. These five category scales are defined in Table 8-1 and Table 8-2 below. If the instance that a

particular hazard or threat does not apply to the option being assessed, its associated likelihood and

consequence was denoted as ‘N/A’ (Not Applicable).

Table 8-1: Likelihood Scale

The definitions of likelihood given in the table above were used to guide the evaluation and assignment of the likelihood that each hazard or threat would occur for each of the options. Similarly the definitions of consequences given in the table above were used to guide the assignment of consequence categories.




Table 8-2: Consequence Scale



The level of risk associated with the likelihood – consequence category combinations were then

determined using the Risk Matrix definition given in the Table 6-3 below.

Table 8-3: Risk Matrix Definitions

LIKELIHOOD CONSEQUENCES

1 2 3 4 5

Rare L L M H H

Unlikely L L M H E

Possible L M H E E

Moderate M M H E E

Almost Certain M H H E E

Key: Consequence - 1: Insignificant, 2: Minor, 3: Severe, 4: Major, 5: Catastrophic Risk - L: Low, M: Medium, H: High, E: Extreme



Table 8.4 Edgecumbe Stand Alone Short Listed Options – Further Possible Risk Mitigation Measures for the Short Listed Options

Option 1 – Conveyance of Edgecumbe Raw Sewage to Kawerau WWTP Option 4 – Conveyance of Edgecumbe oxidation pond treated

wastewater to Whakatāne ocean outfall Option 5 Conveyance of Edgecumbe raw sewage to Whakatāne WWTP

NO Source /

Well-being Hazard Threat Risk

Likelihood Rating

Consequence Rating

Current Risk Further Risk

Mitigation Measures Possible

Likelihood Rating

Consequence Rating

Current Risk

Further Risk Mitigation Measures

Possible

Likelihood Rating

Consequence Rating

Current Risk


Possible

Env Natural Environment - Receiving the Discharge

1 Fails to meet “maintain and enhance” the water quality body. Expected Improvement not achieved in the receiving environment

Moderate Severe High

Work with Regional Council on Tarawera

Plan and future consents. Flexibility in WWTP for upgrades

Unlikely Severe Medium Flexibility in

Edgecumbe WWTP upgrade

Unlikely Severe Medium Flexibility in WWTP to

upgrade

2 Unexpected other contaminant issues, e.g. micro-organisms

Possible Minor Medium Flexibility in WWTP for

upgrades Unlikely Severe Medium

Flexibility in Edgecumbe WWTP

upgrade Unlikely Severe Medium

Flexibility in Whakatāne WWTP to

upgrade

3 Soils become saturated in land application Unlikely Severe Medium Maintain large area of rapid infiltration beds

appropriately

NA NA NA NA NA NA NA NA

4 Contaminant break through inland application Possible Severe High

Flexibility in WWTP for upgrades and also maintain large land

area

NA NA NA NA

NA NA NA NA

5 Long term sustainability not achieved Possible Severe High


area

Unlikely Medium Low


and to upgrade/lengthen Whakatāne outfall

Unlikely Medium Low

Flexibility in Whakatāne WWTP and

to upgrade/lengthen outfall

6 Unexpected effects on ecology including wild food Unlikely Severe Medium


area

Unlikely Severe Medium


and to upgrade/lengthen Whakatāne outfall


Flexibility in Whakatāne WWTP and

to upgrade/lengthen outfall

Existing Infrastructure

1 Unexpected problems in using existing infrastructure


Pre-treatment of raw sewage prior to

entering Kawerau WWTP

Unlikely Minor Low

Flexibility in operating Edgecumbe oxidation pond and Whakatāne

ocean outfall

Possible Minor Medium Upgrade oxidation

pond at Whakatāne

2 Greater costs/difficulties than expected from future upgrades of existing infrastructure to meet new consents and/or WWTP upgrades


Thorough investigations prior to future consents and

obtaining appropriate consents

Possible Minor Medium


ocean outfall

Possible Minor Medium Flexibility in

Whakatāne oxidation pond upgrade

Ec Economic - Capital, Operating, Community

1 Capital cost: Unexpectedly higher than estimates/reviews

Possible Severe High Thorough site

investigations and appropriate design


Appropriate investigation and

design and securing sufficient land

Possible Severe High



2 Operating cost: Unexpectedly significantly higher than estimates/reviews e.g. power cost increase; chemical usage

Possible Severe High Appropriate long term

agreement with Kawerau DC



design and operating flexibility




3 Population/demand increase over design capacity Possible Major Extreme

Flexibility in design and particularly pumping

rate for as far as practical







4 Population/demand decrease over design capacity Possible Minor Medium

Having appropriate septicity and odour

management in conveyance

Possible Insignificant Low





T Technical/Construction

1 Septicity/Corrosion of infrastructure greater than expected.


Appropriate design and operation of the total

conveyance system to Kawerau WWTP


Appropriate design and operation of the

Edgecumbe oxidation pond and conveyance

system, use of Whakatāne Maturation

pond

Possible Minor Medium Appropriate design and operation of the Matatā

conveyance system

2 Climate change impacts - peak and prolonged wet weather and dry periods

Unlikely Severe Medium Ensure sealed LPS

system to minimise wet weather flows

Possible

Ensure adequate storage at Edgecumbe

oxidation pond Ensure appropriate

operation of Whakatāne ocean

outfall


Ensure appropriate upgrade of Whakatāne

oxidation ponds and ocean outfall operation





NO Source /


Likelihood Rating

Consequence Rating



Likelihood Rating

Consequence Rating

Current Risk


Possible

Likelihood Rating

Consequence Rating

Current Risk


Possible

3 Equipment and System not as proven and as reliable as thought. Predicted treatment/reduction not achieved

Unlikely Severe Low

Select appropriate systems and ensure Kawerau WWTP can

accept LPS raw sewage

Unlikely Minor Low Appropriate upgrade of Edgecumbe oxidation

pond Unlikely Minor Low

Appropriate upgrade Whakatāne oxidation

ponds

4 Future flexibility for capacity changes and changed consent conditions


Long conveyance system needs careful

design with future flexibility. Kawerau

WWTP to be assessed for future flexibility


Ensure flexibility in Whakatāne and

Edgecumbe WWTP and Whakatāne ocean

outfall


Ensure future flexibility to upgrade Whakatāne

oxidation ponds and ocean outfall operation

5 Unexpected Geotechnical risks (instability, water tables, etc.)

Possible Severe High Thorough

investigation, route selection and design

Possible Minor Medium Thorough



Thorough investigation, route

selection and design

6 Available power supply Possible Severe High Thorough







7 Insufficient construction corridor in roads Possible Minor Medium Thorough







OP Operating and Maintenance

1 Septicity and odour nuisance and corrosion: Unexpectedly more difficult to mitigate

Possible Major Extreme Appropriate design and

operation Unlikely Minor Low

Appropriate Edgecumbe oxidation pond treatment and

conveyance

Possible Severe High Appropriate design and

operation

2 Technical and Operational: Operational Resilience - unexpected critical failure to key elements of solution e.g. power failure at pump stations, WWTP


operation of long conveyance system


Appropriate design and operation and

contingency plan including more storage

at Edgecumbe oxidation pond


Appropriate design and operation of Matatā

conveyance and upgraded Whakatāne

WWTP

3 Natural hazard risks, e.g. earthquakes, floods, landslips, coastal zones etc



selection, design and resilient engineering


Appropriate investigation design, resilient engineering

and contingency planning




PC Planning, Consenting, Approvals

1 Land for treatment and disposal: Unexpectedly more difficult to find, purchase, and secure long term leases and consents

NA NA NA NA NA NA NA NA NA NA NA NA

2

Resource consents: Unexpectedly more difficult to obtain. Conveyance mains alignment and pump stations, unexpectedly more difficulty to get approval

Possible Severe High Applies to future

Kawerau DC consent also


Maximise advantage of using existing

Whakatāne outfall consent and

Edgecumbe oxidation pond consent for

treatment (not discharge) as far as

possible



Whakatāne consent as far as possible

3 More stringent future Tarawera Catchment Management Plan requirements than anticipated

Possible Severe High Full involvement with Regional Council at time of plan review


PH/S/CE Public Health/Social/Community Environment

1 Resistance to treatment and disposal facilities near/on private property

Unlikely Severe Medium Consultation and appropriate siting


Effective consultation and appropriate

consent conditions, but these are existing treatment facilities

Unlikely Minor Low


consent conditions

2 Public Health: Unexpectedly risks/ high impact e.g. micro-organisms not treated effectively


Based on current WWTP experience.

UV disinfection could be reinstalled


3 Unexpected noise effects from facilities on individual properties

Unlikely Severe Medium Appropriate siting and

design operation Possible Severe High

WWTP design and operation with effective

disinfection Unlikely Severe Medium


disinfection

4 Public Health nuisance from any overflows/breakdowns

Possible Severe Medium Appropriate siting and design operation and contingency planning


Possible Severe Medium

Appropriate siting and design operation and contingency planning

MC Maori Cultural – WDC to Advise TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD

O Other





NO Source /


Likelihood Rating

Consequence Rating



Likelihood Rating

Consequence Rating

Current Risk


Possible

Likelihood Rating

Consequence Rating

Current Risk


Possible

1 Unexpected difficulties as WDC do not have ownership of the Kawerau District Council wastewater infrastructure


Ensure effective long term agreement

between WDC and KDC


2 Other ??? TBD TBD TBD TBD TBD TBD TBD

TBD TBD TBD TBD TBD

Notes This table identifies additional procedures and approaches that could be adopted to reduce the risk category generally a llowed for in the options conceptual development to date and allowed for in the indicative cost estimates. Such further risk mitigation matters can be expected to have additional cost implications. En - Environmental Ec - Economic T - Technical OP – Operating and Maintenance PC – Planning, Consenting, Approvals PH/S/CE – Public Health/Social/Community Environment MC Maori Culture – WDC to Advise O - Other NA Not Applicable TBD – To Be Determined

Risk Colour Coding as follows: Low Grey Medium Yellow High Blue Extreme Red

Refer Table 7.1 likelihood scale classification Table 7.2 consequence style classification Table 7.3 Risk Classification



Table 8.4 Edgecumbe Stand Alone Short Listed Options – Further Possible Risk Mitigation Measures for the Short Listed Options

Option 8 Upgrade of existing Edgecumbe oxidation ponds and Land Application at Thornton Dunes

Option 12 – Upgrade of existing Edgecumbe oxidation ponds and Rangitaiki river discharge

NO Source /


Likelihood Rating

Consequence Rating

Current Risk


Possible

Likelihood Rating

Consequence Rating

Current Risk


Possible



Possible Severe High Flexibility in WWTP for upgrades to maintain ground water quality

Possible Severe High Flexibility in WWTP for

upgrades


Possible Severe High Flexibility in WWTP’s

for upgrades Unlikely Minor Medium

Flexibility in WWTP for upgrades

3 Soils become saturated in land application Possible Severe High Reserve land in application area

NA NA NA NA

4 Contaminant break through inland application Possible Severe High

Flexibility in WWTP for upgrades.

Reserve land in application area

NA NA NA NA

5 Long term sustainability not achieved Possible Severe High




Future flexibility in upgrades – greater river dilution and

dispersion

6 Unexpected effects on ecology including wild food Unlikely Minor Low



Unlikely Minor Low Flexibility in WWTP for

upgrades



Unlikely Severe Medium Flexibility in WWTP for

upgrades Unlikely Severe Medium



Possible Minor Medium Flexibility in WWTP for upgrades



dispersion








design








3 Population/demand increase over design capacity Possible Severe High

Flexibility in design and particularly pumping conveyance and in having a generous

reserve area and land application

Possible Severe High Flexibility in WWTP

design

4 Population/demand decrease over design capacity Possible Minor Medium

Having appropriate flexibility in WWTP;s

and conveyance systems and land application area

Possible Minor Medium Flexibility in WWTP

design



Unlikely Minor Low

Appropriate design and operation of the Matatā

WWTP and Edgecumbe oxidation

pond

Possible Minor Low

Appropriate design and operation of the to River conveyance

system



Ensure adequate variable storage at

Edgecumbe oxidation pond and adequate

land application area





Unlikely Minor Low

Ensure appropriate upgrade design of Matatā WWTP and


Unlikely Minor Medium

Ensure appropriate upgrade of Edgecumbe

oxidation pond plus additional (WWTP)

treatment processes


Possible Minor Medium Ensure flexibility to upgrade WWTP.

Ensure spare capacity Possible Minor Medium

Ensure flexibility to upgrade WWTP



Option 8 Upgrade of existing Edgecumbe oxidation ponds and Land Application at Thornton Dunes

Option 12 – Upgrade of existing Edgecumbe oxidation ponds and Rangitaiki river discharge

NO Source /


Likelihood Rating

Consequence Rating

Current Risk


Possible

Likelihood Rating

Consequence Rating

Current Risk


Possible

in land treatment system







6 Available power supply Possible Minor Medium Thorough





7 Insufficient construction corridor in roads Unlikely Minor Low Route investigations,

lay in carriage if necessary

Unlikely Minor Low

Route investigations, lay in carriageway if

necessary

O Operating and Maintenance


Unlikely Minor Low Appropriate design and

operation Unlikely Minor Low

Appropriate design and operation

2 Technical and Operational: Operational Resilience - unexpected critical failure to key elements of solution e.g. power failure at pump stations



conveyance and upgraded WWTP


Appropriate design and operation of upgraded

WWTP and conveyance line






Appropriate design and operation upgraded

WWTP




Thorough investigations of the use of WDC coastal

reserve

NA NA NA NA

2




reserve


Thorough investigation and consultation and working with Regional

Council







consent conditions, but these are existing treatment facilities


Consultation and appropriate siting but WWT at Edgecumbe Oxidation Pond site

maybe extended a little


Possible Minor Medium WWTP design and

operation with effective disinfection



disinfection



design operation Unlikely Minor Low

Appropriate siting and design operation


Possible Severe Medium Appropriate siting and design, operation and contingency planning


Appropriate siting and design, operation and contingency planning

C Maori Cultural – WDC to Advise TBD TBD TBD TBD TBD TBD TBD TBD

O Other



2 Other ??? TBD TBD TBD TBD TBD TBD TBD TBD

Notes This table identifies additional procedures and approaches that could be adopted to reduce the risk category generally allowe d for in the options conceptual development to date and allowed for in the indicative cost estimates. Such further risk mitigation matters can be expected to have additional cos t implications. En - Environmental Ec - Economic T - Technical OP – Operating and Maintenance PC – Planning, Consenting, Approvals PH/S/CE – Public Health/Social/Community Environment MC Maori Culture – WDC to Advise O - Other NA Not Applicable TBD – To Be Determined





Table 8.5 Combined Edgecumbe and Matatā Schemes Short Listed Options – Further Possible Risk Mitigation Measures for the Short Listed Options

At Kawerau Land 1 (KL1) At Edgecumbe River 3 (ER3) At Thornton Land 2 (TL2)

NO Source /


Likelihood Rating

Consequence Rating

Current Risk

Further Risk Mitigation Measures Possible

Likelihood Rating

Consequence Rating

Current Risk


Possible

Likelihood Rating

Consequence Rating

Current Risk





Work with Regional Council on Tarawera Plan

and future consents. Flexibility in WWTP for

upgrades

Possible Severe High Flexibility in WWTP

for upgrades Possible Severe High

Flexibility in WWTP for upgrades to maintain ground water quality


Possible Minor Medium Flexibility in WWTP for

upgrades Unlikely Minor Medium


Possible Severe High Flexibility in WWTP’s for

upgrades

3 Soils become saturated in land application Unlikely Severe Medium Maintain large area of rapid infiltration beds

appropriately NA NA NA NA Possible Severe High Reserve land in application

area

4 Contaminant break through inland application Possible Severe High Flexibility in WWTP for

upgrades and also maintain large land area

NA NA NA NA Possible Severe High



5 Long term sustainability not achieved Possible Severe High Flexibility in WWTP for




dispersion




6 Unexpected effects on ecology including wild food

Unlikely Severe Medium Flexibility in WWTP for


Unlikely Minor Low Flexibility in WWTP

for upgrades Unlikely Minor Low





Moderate Severe High Pre-treatment of raw

sewage prior to entering Kawerau WWTP


Flexibility in WWTP for upgrades including

odour management for Matatā inflow

Unlikely Severe Medium Flexibility in WWTP’s for

upgrades



Thorough investigations prior to future consents

and obtaining appropriate consents



dispersion

Possible Minor Medium Flexibility in WWTP’s for upgrades



Possible Severe High Thorough site

investigations and appropriate design

Possible Minor Medium Appropriate

investigation and design


Appropriate investigation and design and securing

sufficient land


Possible Severe High Appropriate long term

agreement with Kawerau DC





Appropriate investigation and design and operating

flexibility

3 Subsidies: DoH acceptance/approval not obtained for Matatā

TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD

4 Population/demand increase over design capacity

Possible Major Extreme Flexibility in design and

particularly pumping rate for as far as practical


Flexibility in WWTP design and

particularly pumping rates for Matatā as far

as practical



conveyance and in having a generous reserve area

and land application

5 Population/demand decrease over design capacity



management in conveyance



management in Matatā conveyance


Having appropriate flexibility in WWTP;s and

conveyance systems




Appropriate design and operation of the total

conveyance system to Kawerau WWTP


Appropriate design and operation of the Matatā conveyance

system

Unlikely Minor Low

Appropriate design and operation of the Matatā WWTP and Edgecumbe

oxidation pond


Unlikely Severe Medium Ensure sealed LPS

system to minimise wet weather flows





Ensure adequate variable storage at Edgecumbe

oxidation pond and adequate land application

area


Unlikely Severe Low

Select appropriate systems and ensure Kawerau WWTP can

accept LPS raw sewage

Unlikely Minor Medium

Ensure appropriate upgrade of

Edgecumbe oxidation pond plus additional (WWTP) treatment

processes

Unlikely Minor Low

Ensure appropriate upgrade design of Matatā WWTP and Edgecumbe

oxidation ponds



At Kawerau Land 1 (KL1) At Edgecumbe River 3 (ER3) At Thornton Land 2 (TL2)

NO Source /


Likelihood Rating

Consequence Rating

Current Risk


Likelihood Rating

Consequence Rating

Current Risk


Possible

Likelihood Rating

Consequence Rating

Current Risk




Long conveyance system needs careful design with future flexibility. Kawerau WWTP to be assessed for

future flexibility

Possible Minor Medium Ensure flexibility to

upgrade WWTP Possible Minor Medium

Ensure flexibility to upgrade WWTP. Ensure

spare capacity in land treatment system


Possible Severe High Thorough investigation,

route selection and design



Possible Minor Medium Thorough investigation,


6 Available power supply Possible Severe High Thorough investigation,






7 Insufficient construction corridor in roads Possible Minor Medium Thorough investigation,


Unlikely Minor Low

Based on Greig Road route. Higher risk for state highway route

option

Unlikely Minor Low Route investigations, lay in

carriage if necessary



Possible Major Extreme Appropriate design and

operation Possible Severe High



operation

2

Technical and Operational: Operational Resilience - unexpected critical failure to key elements of solution e.g. power failure at pump stations, WWTP


operation of long conveyance system


Appropriate design and operation of

Matatā conveyance and upgraded WWTP





Moderate Severe High Thorough investigation, route selection, design

and resilient engineering Possible Severe High


Matatā conveyance and upgraded WWTP






NA NA NA NA NA NA NA NA Possible Severe High


reserve

2


Possible Severe High Applies to future Kawerau

DC consent also Possible Severe High

Thorough investigation and consultation and

working with Regional Council



reserve


Possible Severe High Full involvement with

Regional Council at time of plan review






Possible Severe High Consultation and appropriate siting



Based on current WWTP experience. UV

disinfection could be reinstalled





disinfection



design operation Unlikely Minor Low

Appropriate siting and design operation


design operation



Possible Minor Medium Appropriate siting and design operation and contingency planning



C Maori Cultural – WDC to Advise TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD

O Other



Ensure effective long term agreement between

WDC and KDC NA NA NA NA NA NA NA NA

2 Other ??? TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD

Notes

This table identifies additional procedures and approaches that could be adopted to reduce the risk category generally allowe d for in the options conceptual development to date and allowed for in the indicative cost estimates. Such further risk mitigation matters can be expected to have additional cost implications. En - Environmental Ec - Economic T - Technical OP – Operating and Maintenance PC – Planning, Consenting, Approvals PH/S/CE – Public Health/Social/Community Environment MC Maori Culture – WDC to Advise O - Other NA Not Applicable TBD – To Be Determined





Table 8.5 Combined Edgecumbe and Matatā Schemes Short Listed Options – Further Possible Risk Mitigation Measures for the Short Listed Options

At Thornton Land 3 (TL3) At Whakatāne Ocean 1 (WO1) At Whakatāne Ocean 5 (WO5)

NO Source /


Likelihood Rating

Consequence Rating

Current Risk


Likelihood Rating

Consequence Rating

Current Risk


Possible

Likelihood Rating

Consequence Rating

Current Risk




Possible Severe High Flexibility in WWTP to


Flexibility in WWTP to upgrade

Unlikely Severe Medium Flexibility in Edgecumbe

WWTP upgrade


Possible Severe High Flexibility in WWTP Unlikely Severe Medium Flexibility in WWTP to


Flexibility in Edgecumbe WWTP upgrade

3 Soils become saturated in land application Possible Severe High Reserve land application

area NA NA NA NA NA NA NA NA

4 Contaminant break through inland application Possible Severe High Flexibility in WWTP NA NA NA NA NA NA NA NA

5 Long term sustainability not achieved Possible Severe High Flexibility in WWTP

Unlikely Medium Low

Flexibility in Whakatāne WWTP

and to upgrade Lengthen outfall

Unlikely Medium Low

Flexibility in Edgecumbe WWTP to upgrade Lengthen outfall

6 Unexpected effects on ecology including wild food

Unlikely Severe Medium Flexibility in WWTP

Reserve land application area


Flexibility in Whakatāne WWTP

and to upgrade Lengthen outfall


Flexibility in Edgecumbe WWTP to upgrade Lengthen outfall



Unlikely Minor Low Only uses Edgecumbe

oxidation ponds Possible Minor Medium

Upgrade oxidation pond at Whakatāne

Unlikely Minor Low


ocean outfall


Possible Minor Medium Flexibility in Edgecumbe

WWTP upgrade Possible Minor Medium

Flexibility in Whakatāne oxidation

pond upgrade Possible Minor Medium


ocean outfall



Possible Severe High Appropriate investigation and design and securing

sufficient land Possible Severe High




Appropriate investigation and design and securing

sufficient land


Unlikely Severe Medium Appropriate investigation and design and operating

flexibility Possible Severe High




Appropriate investigation and design and operating

flexibility

3 Subsidies: DoH acceptance/approval not obtained for Matatā

TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD

4 Population/demand increase over design capacity



conveyance and in having a generous reserve area

and land application


Flexibility in design and particularly

pumping rate for as far as practical


Flexibility in design and particularly pumping rate

for as far as practical

5 Population/demand decrease over design capacity

Possible Minor Medium Having appropriate

flexibility in WWTP;s and conveyance systems

Flexibility in design and particularly

pumping rate for as far as practical

Possible Insignificant Low

Flexibility in design and particularly pumping rate

for as far as practical



Possible Severe High Appropriate design and operation of the Matatā

conveyance system Possible Severe High

Appropriate design and operation of the

Matatā and Edgecumbe raw

sewage conveyance system

Possible Minor Medium Appropriate design and operation of the Matatā

conveyance system



Ensure adequate variable storage at Edgecumbe

oxidation pond and adequate land application

area


Ensure appropriate upgrade of

Whakatāne oxidation ponds and ocean outfall operation

Possible

Ensure adequate storage at Edgecumbe oxidation

pond Ensure appropriate

operation of Whakatāne ocean outfall


Unlikely Minor Medium Ensure adequate variable

storage at Edgecumbe oxidation pond

Unlikely Minor Low Appropriate upgrade Whakatāne oxidation

ponds Unlikely Minor Low

Appropriate upgrade of Edgecumbe oxidation

pond



Ensure flexibility to upgrade WWTP. Ensure

spare capacity in land treatment system

Possible Minor Medium Ensure future

flexibility to upgrade Whakatāne oxidation


Ensure flexibility in WWTP and Whakatāne and

Edgecumbe ocean outfall



At Thornton Land 3 (TL3) At Whakatāne Ocean 1 (WO1) At Whakatāne Ocean 5 (WO5)

NO Source /


Likelihood Rating

Consequence Rating

Current Risk


Likelihood Rating

Consequence Rating

Current Risk


Possible

Likelihood Rating

Consequence Rating

Current Risk


ponds and ocean outfall operation








6 Available power supply Possible Minor Medium Thorough investigation,






7 Insufficient construction corridor in roads Unlikely Minor Low

Based on Greig Road route. Higher risk for state highway route

option








operation Possible Severe High


Unlikely Minor Low

Appropriate Edgecumbe oxidation pond treatment

and conveyance

2

Technical and Operational: Operational Resilience - unexpected critical failure to key elements of solution e.g. power failure at pump stations






Matatā conveyance and upgraded

Whakatāne WWTP


Appropriate design and operation and contingency

plan including more storage at Edgecumbe

oxidation pond



operation of Matatā conveyance and WWTP





Appropriate investigation design, resilient engineering and

contingency planning



Possible Severe High Thorough investigations

of the use of WDC coastal reserve


2



Thorough investigation and effective consultation and appropriate resource

consent conditions



Whakatāne consent as far as possible


Maximise advantage of using existing Whakatāne

outfall consent and Edgecumbe oxidation

pond consent for treatment (not discharge) as far as

possible





Possible Severe High Consultation and appropriate siting

Unlikely Minor Low


consent conditions, but these are existing

treatment facilities


Effective consultation and appropriate consent

conditions







design operation Unlikely Severe Medium

WWTP design and operation with

effective disinfection Possible Severe High


disinfection


Possible Severe Medium Appropriate siting and design operation and

contingency plan Possible Severe Medium




C Maori Cultural – WDC to Advise TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD

O Other



2 Other ??? TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD

TBD

Notes

This table identifies additional procedures and approaches that could be adopted to reduce the risk category gener ally allowed for in the options conceptual development to date and allowed for in the indicative cost estimates. Such further risk mitigation matters can be expected to have additional cost implications. En - Environmental Ec - Economic T - Technical OP – Operating and Maintenance PC – Planning, Consenting, Approvals PH/S/CE – Public Health/Social/Community Environment MC Maori Culture – WDC to Advise O - Other NA Not Applicable TBD – To Be Determined

Risk Colour Coding as follows: Low Grey Medium Yellow High Blue Extreme Red Refer Table 7.1 likelihood scale classification Table 7.2 consequence style classification Table 7.3 Risk Classification



9 Tāneatua and Te Teko Options

9.1 Tāneatua

Tāneatua is located on the Whakatāne River approximately 15km from Whakatāne. The WWTP is

located to the west of the town and is currently authorised to discharge wastewater to the Whakatāne

River as described in Section 2.12 until 1 October 2026.

WDC currently monitors the volumes of treated wastewater discharged to the Whakatāne River which

varies between 50 and 150 m3/day. Microbiological samples are collected upstream and downstream of

the discharge every two months.

WDC Officers note that during summer there are times when there is no observable discharge from the

WWTP itself. It is likely at these times that a combination of treated wastewater seeping through the

base of the ponds, along with low inflow volumes and high levels of evapotranspiration, lead to this

occurrence.

Any future discharge to water consent sought would be treated as a discretionary activity and would

need to be assessed against the ‘potable water’ classification of the Whakatāne River in the Regional

Land and Water Plan. Given this, should a direct to water discharge continue to be preferred in the

future, additional treatment including possible disinfection, may be required.

However, although no site investigations have been undertaken, the area surrounding Tāneatua

appears to have well drained soils, and this along with the relatively low volumes of wastewater

requiring treatment, means that a local land based treatment and disposal system may be appropriate.

A number of site specific investigations/assessments are recommended ahead of expiry of the existing

Tāneatua discharge consent including:

Develop an outline programme of works for the resource consent application ahead of the

current consent expiry date;

Review of the existing monitoring programme to determine appropriateness of inform any future

resource consent application;

Assess the effects of the existing discharge on the water quality and ecology of the Whakatāne

River, guided by the relevant BOPRC planning framework (particularly the potable water

classification of the Whakatāne River) and the NPS-FM;

Investigate the feasibility of a local land application/treatment option;

Investigate the feasibility of conveying raw sewage to the Whakatāne oxidation ponds and also

the option of Tāneatua oxidation pond treated wastewater to the Whakatāne ocean outfall or the

Whakatāne maturation pond(s); and

Reflecting on the overall WDC Wastewater Strategy and considering a future option that is

compatible with that going into the future e.g. standalone schemes or regional (conveyance)

type schemes.

9.2 Te Teko Options

A number of investigations have been undertaken to potential wastewater treatment and disposal

options for the currently unsewered township of Te Teko.

Harrison and Grierson (2009) both oxidation pond and package WWTP options including discharge

scenarios to the Rangitaiki River, land disposal to the Rangitaiki Plains, spray irrigation to forestry and

land disposal to the Te Teko golf course.



The preferred option for treatment and disposal was an appropriate and robust package WWTP with

disposal to the golf course, as compared to the other systems assessed whilst still producing high

quality effluent.

This Report has not assessed Te Teko in any further detail at this stage. It is noted that the combined

Matatā and Edgecumbe option KL1 standalone or the Edgewater Option 1, which both convey raw

sewage to Kawerau, passes through Te Teko. If either of these options were progressed Te Teko could

be connected to this conveyance line at a later date. Alternatively, wastewater sourced from Te Teko

could be conveyed to Edgecumbe for either storage, treatment or conveyance for treatment and

discharged elsewhere (e.g. Whakatāne WWTP) in one of those Edgecumbe options.



10 Conclusions and Next Steps

10.1 Conclusions

10.1.1 Edgecumbe Standalone Options

A large number of options have been considered for the future treatment, conveyance and disposal of wastewater sourced from Edgecumbe. Taking into account a range of considerat ions including cost, the ranking of the top three options were:

1. Option 4 – Oxidation Pond Wastewater to Whakatāne WWTP Ocean Outfall;

2. Option 5 – Raw Sewage to Whakatāne WWTP; and

3. Option 8A – Upgraded Oxidation Ponds and Land Application at Whakatāne Airport.

Options 4 and 5 propose the conveyance of either wastewater treated in the oxidation ponds at Edgecumbe or raw sewage to Whakatāne WWTP. Both options utilise the existing infrastructure at the Edgecumbe and Whakatāne WWTP’s, and would require a condition change to the existing resource consent for the discharge of treated wastewater from the Whakatāne WWTP, or a new consent to be applied for.

Land application at the Whakatāne Airport also ranks highly, and may be possible to combine with a future treatment option at the Whakatāne WWTP, where land application of treated wastewater from the Whakatāne ponds may be possible in the future.

10.1.2 Matatā/Edgecumbe Combined Options

Similar to the Edgecumbe standalone options considered above, a wide range of future treatment, conveyance and disposal options were considered for a combined Matatā and Edgecumbe wastewater scheme. Taking into account a range of considerations including cost, the ranking of the top three options were:

1. Option WO5 – Conveyance of Matatā raw sewage to Edgecumbe oxidation ponds. Edgecumbe

oxidation ponds treated wastewater for joint Whakatāne Ocean Outfall discharge

2. Option WO1 – Conveyance of Matatā raw sewage to Thornton and Edgecumbe raw sewage to

Thornton – then combined to Whakatāne WWTP and Ocean Outfall Discharge; and

3. Option TL3A - Conveyance of Matatā raw sewage to Edgecumbe. Joint treatment at

Edgecumbe oxidation ponds and conveyance to land application at the Whakatāne Airport.

Similar to the Edgecumbe standalone options, the conveyance of treated wastewater to Whakatāne in option WO5 has a number of advantages over the conveyance of raw sewage in WO1. Land application at Whakatāne airport also ranks highly and should be included in further considerations.

10.1.3 Taneatua and Te Teko

A number of site specific investigations/assessments are recommended ahead of expiry of the existing

Tāneatua discharge consent including:

Develop an outline programme of works for the resource consent application ahead of the

current consent expiry date;

Review of the existing monitoring programme to determine appropriateness of inform any future

resource consent application;

Assess the effects of the existing discharge on the water quality and ecology of the Whakatāne

River, guided by the relevant BOPRC planning framework (particularly the potable water

classification of the Whakatāne River) and the NPS-FM;

Investigate the feasibility of a local land application/treatment option;



Investigate the feasibility of conveying raw sewage to the Whakatāne oxidation ponds and also

the option of Tāneatua oxidation pond treated wastewater to the Whakatāne ocean outfall or the

Whakatāne maturation pond(s); and

Reflecting on the overall WDC Wastewater Strategy and considering a future option that is

compatible with that going into the future e.g. standalone schemes or regional (conveyance)

type schemes.

No specific actions have been identified for Te Teko, although it remains a possibility that future wastewater treatment options include conveyance of wastewater to the existing Edgecumbe oxidation ponds for treatment, and either conveyance or discharge.

10.2 Next Steps

It is recommended that the following options are taken forward for consultation as the Project progresses:

Edgecumbe standalone:

Options 4, 5 and 8A.

Combined Matatā/Edgecumbe options:

Options WO1, WO5, TL3A.



11 Acknowledgements Terry Long and Paul Futter – Bay of Plenty Regional Council

Whakatāne District Council Officers



12 References Whakatāne District Council

Wastewater Contract 15-069 Work Stream 2a and Variation for2b: MWH Compilation of Reference Documents

1. Appendix A#2 Electro Care Technologies Ltd Edgecumbe Sewers 3 – 5

Electrical Report

2. Appendix B#2 Edgecumbe Wastewater Reticulation Repairs – Pumping

Station (Feb 2011 -May 2011

3. Appendix C Rainfall Figures - Thornton Rain Gauge 23042011 – 30042011

4. Appendix D Plans#2

5. AWT Cost Estimate Report - April 2013

6. AWT Matatā Wastewater Servicing Peer Review – Oct 2011

7. AWT Whakatāne & Ohope Wastewater Treatment Ponds – Capacity

Review October 2010 – Final

8. Bay of Plenty Regional Council Resource Consent Application and Consent No. 62659 for

Whakatāne Air Discharge Permit

9. Bay of Plenty Regional Council Rights in Respect of Natural Water (for Whakatāne Consent

No 02 0368 granted 28 July 1978 & Edgecumbe Effluent

Discharges – Edgecumbe Consent No. 02 0702 granted 1 May

1980 – both expire 1/10/2026)

10. Bay of Plenty Regional Council Workbook for Edgecumbe Oxidation Pond Discharge to

Omeheu Canal – 1998 to 2015

11. Bay of Plenty Regional Council Workbook for Whakatāne Oxidation Pond Discharge to the

Bay of Plenty Marine Environment – 2000 to 2015

12. Bay of Plenty Regional Council Operative Regional Policy Statement

Regional Water & Land Plan

Regional Plan for Tarawera River Catchment

Regional Coastal Environment Plan

13. CPG Matatā Wastewater Treatment Scheme Review – Nov 2011

14. Appendix A#2 Electro Care Technologies Ltd Edgecumbe Sewers 3 – 5

Electrical Report

15. Harrison Grierson Detailed Design Report (A421400) Feb 2014

16. Harrison & Grierson First Time sewerage for the community of Matatā Preliminary

Design Report Dec 2009

17. Harrison Grierson Wastewater Scheme for the Towns of Edgecumbe, Matatā and

Te Teko Options Report Sept 2004

18. Iwi Environmental Management Yet to be determined.

19. Plans & Settlement Acts



20. MWH Review of the Whakatāne District Sewage Treatment and

Disposal Schemes Jan 2002

21. MWH Wastewater Review and Options Study for Edgecumbe

Wastewater Treatment and Disposal – Proposal 15-069 May

2012

22. MWH Edgecumbe: Options for Upgrading Wastewater Treatment

and Disposal 2002 (show as 2014 on cover)

23. MWH, URS, WDC Matatā Wastewater Scheme – Resource Consents and

Notices of Requirement Assessment of Effects on the

Environment - November 2013

Support Documents

1 Matatā Wastewater Scheme – Consultation Strategy

2 Natural Hazards, Constraints and Risk Assessment

3 Flowrates and Mass Land Assessment for Determination of Land Disposal Field Requirements

4 Alternatives Assessment Information

5 Matatā Wastewater Scheme – Wastewater Land Application Groundwater Assessment

6 Matatā Wastewater Scheme – Receiving Water Quality, Ecological and Public health Risk Assessment

7 Ecological Assessment of Potential Sites for the Proposed Matatā Wastewat4er Treatment Plant and Disposal Filed – Amended following Selection of the Disposal Field Site

8 Assessment of Landscape and Visual Effects for the Proposed Matatā Wastewater Treatment Plant

9 Draft Restoration and Enhancement Plan for the Mitigation and Management of the Proposed Matatā Wastewater Treatment Disposal Field and Adjacent Dunelands

10 Consultation Records

24. MWH Matatā Review of Design Flows Final 03.03.14

25. NZ Government NPS for Freshwater Management 2014

NZ Coastal Policy Statement 2010

Local Government Act 2002

NZ Government Treasury Report Guidelines 30 Year Infrastructure Strategies

Reserve Act 1977

26. Opus Technical Memo Whakatāne WWTP Mill Rd Abattoir Loading

March 2015

27. Opus Wastewater Treatment and Management Options for

Edgecumbe and Matatā – 15 July 2013

28. Opus WDC Contract 12/001 – Edgecumbe Wastewater Upgrade –

Preliminary Design Report – Jan 2012



29. Opus Whakatāne Wastewater Treatment Plant – Optimisation

Report – Nov 2011

30. Opus Edgecumbe Reticulation Preliminary Design Report – Oct

2011 plus Appendices Plans A2, B2, C & D

31. Opus Whakatāne District Wastewater Treatment Ponds: Desludging

Requirements May 2010

32. Opus Edgecumbe Ponds Wastewater Discharge – Effects on the

Omeheu Canal Water Quality – 2009

33. Opus Edgecumbe Wastewater Treatment – Design Report – June

2007??

34. Opus Whakatāne Wastewater Treatment Plant – Optimisation

Report – Nov 2007

35. Opus Whakatāne and Ohope Ocean Outfall Condition Survey Date

??

36. URS (Letter) Matatā Wastewater Scheme – High level Cost

Estimate Review – 7 March 2014

37. URS R004 - Matatā WWTP flowrate and mass load Assessment

Memo Rpt20130614 Final - June 2013

38. Whakatāne District Council Long Term Plan 2015-2025

39. Whakatāne District Council 15-069 Professional Services for Wastewater Review &

Options – Study for Edgecumbe Wastewater Treatment &

Disposal – June 2015

40. Whakatāne District Council Draft Infrastructure Strategy 2015 – 45 (vA821419)

41. Whakatāne District Council 2013/2014 Wastewater Asset Management Plan

42. Whakatāne District Council Matatā Options Strategic Review and Edgecumbe Options

Part 5

43. Whakatāne District Council Sustainability Strategy 2010-2015

44. Whakatāne District Council Operative & Proposed District Plan

45. Whakatāne District Council LIDAR Information



13 Glossary of Terms and Abbreviations

Activated Carbon Filters A bed of activated Carbon through which foul air is passed to remove odour compounds

Actiflo Refer Section 2.8 of Report – a treatment process for clarifying wastewater and removing phosphorus.

ADF Average daily volume/flow in mᶟ/day

ADWF Average dry weather flow in mᶟ/day

AECOM (URS)

Consultants involved in the Matatā standalone options investigations – Formally URS Consultants.

AEE Assessment of Effects on the Environment for Matatā Consents and Designations dated December 2013

Best Practicable Option (BPO)

In terms of the Resource Management Act 1991 – “in relation to a discharge of contaminant or an emission of noise, means the best method for preventing or minimizing the adverse effects on the environment having regard, among other things, to: The nature of the discharge or emission and the sensitivity of the receiving environment to adverse effects; The financial implications, and the effects on the environment, of that option when compared with others options; and The current state of technical knowledge and the likelihood that the option can be successfully applied.”

Biochemical Oxygen Demand (BOD, cBOD5)

Carbonaceous biochemical oxygen demand (cBOD5) measured as 5 day standard test. It is a measure of organic matter or organic strength of the water, reported as the mass of oxygen consumed per L of water (mg/L). A quicker measure of the organic strength is COD, which is measured through chemical oxygen. The COD in urban wastewater is roughly twice the BOD.

Biofilters, Biotrickling Filters Refer Section 2.6 & 1.2 of this Report - odour control treatment processes

BoPRC Bay of Plenty Regional Council, also referenced to as the Regional Council

BPTRC = TMCP Bay of Plenty Regional Plan for Tarawera River Catchment

Conveyance Terminology Refer to Section 2.6 of this Report

DWF Dry Weather Daily Flow

EDG Edgecumbe

Effluent Treated Wastewater (effluent is considered an outdated word)

Engineering Resilience The material selection, design and generation of infrastructure to add resistance/future proofing against natural hazards and other unexpected events



Faecal Coliform (FC)

Faecal coliform (FC) are bacteria. Their presence may indicate that the water has been contaminated with faecal material from of humans or other animals. Like E.coli this bacteria is used as an indicator micro-organism for pathogenic (germ) micro-organisms.

GIS Geographic Information System

Grinder Pumps Small pumps that are housed in factory made pump stations that grind the raw sewage up for collection and conveyance

H&G Harrison and Grierson – Consultants

HDPE High Density Polyethylene Pipe as used for estimating in the

Conveyance options

KDC Kawerau District Council

L Land Application of Treated Wastewater

LAF Land Application Field as previously applied to the earlier Matatā Wastewater Consenting project

LGA Local Government Act 2002

LPS Low Pressure Wastewater Collection System (LPS) involving grinder pumps on each individual serviced property.

LTP Whakatāne District Councils Long Term Plan 2015 - 2025

M Matatā

MBBR Refer Section 2.8 of this Report. A treatment process for removing organic matter and nutrients particularly Nitrogen

MCA Multi criteria Assessment – a decision making tool to compare evaluation criteria and options

mg/L Milligrams per litre is a concentration measure of a contaminant in liquid, is the same as mg/L is the same as g/m3 and is in effect the same as parts per million (ppm)

MWH Consultants undertaking this contract 15-069 project

NA or N/A Not Applicable

No/100mL Number of micro-organisms per 100 ml of sample

NPS - FM National Policy Statement on Freshwater Management 2014

NPV Net Present Value – The estimated costs of capital and annual operating costs taken on a 20 year basis (refer Section 4.1 of this Report)

NZCPS New Zealand Coastal Policy Statement 2010

O Whakatāne Ocean Outfall (as the discharge point)

O&M Operating and Maintenance

Option Same as “alternatives” in terms of RMA definitions

Opus Consultants



OPW Oxidation Pond Treated Wastewater

Oxidation Ponds A natural pond type of wastewater treatment as presently used at Edgecumbe and Whakatāne. The treatment capacity can be increased by addition of mechanical aerators

PE

Population equivalents – Determine by dividing the ADWF (average daily wastewater volume by the average per capita production of wastewater (at 225 litres per head per day) to determine the number of PE’s. Can also be calculated on a BOD or other contaminant basis especially if there is a significant trade waste discharge included

Peaking Factor The increase of a PWWF from an ADWF or other determined lower flow e.g. ADF

PS Pump Station

PWWF Peak wet weather flow in L/sec or mᶟ/day

Q&A Questions and Answers

Retention Time The time the raw sewage or treated wastewater is retained in the conveyance system or a treatment process (refer to section 2.6 of this Report)

RIB’s Rapid Infiltration Basis – rapid land soakage beds at KDC’s WWTP

Rising Main A conveyance main where the raw sewage or treated wastewater is pumped (Refer to Section 2.6 of this Report)

Risk Assessment Categories

As set out in Section 7 of this Report

RMA Resource Management Act, 1991

Rohe Maori boundary, district, region, territory, area, border (of land)

Septicity Where raw sewage or partly treated sewage goes septic (sour) through anaerobic decomposition and emits hydrogen sulphide and other odourous gases (refer to Section 2.6 of this Report)

Suspended Solids SS = TSS Suspended Solids equals Total Suspended Solids (SS=TSS)

T Thornton

TBD To Be Determined

TMCP = BPTRC Bay of Plenty Regional Plan for Tawerau River Catchment

TN Total Nitrogen

URS Consultants who are involved in the Matatā standalone investigations – now AECOM

USEPA United States of America, Environmental Protection Agency

WWTP Wastewater Treatment Plant

√ Option confirmed for the Long List



X Option Parked – option not included in confirmed long list but could be reconsidered later if required



Edgecumbe Oxidation Ponds Flow Balancing Technical Memorandum



Whakatāne Oxidation Ponds – Capacity Assessment Technical Memorandum



Legal Advice on Regional Plan for the Tarawera River Catchment



Edgecumbe Standalone Options – Long List Assessment



Edgecumbe Standalone Options – Short List Route Alignments



Matatā and Edgecumbe Combined Options – Long List Assessment



Matatā and Edgecumbe Combined Options – Short List Route Alignments



Conveyance Capital and Annual Operating and Maintenance Costs



Treatment and Disposal / Discharge Capital and Annual Operating and Maintenance Costs



Net Present Value Estimated Costs



Actiflo® and MBBR Treatment Processes Supplier Information