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Waiomu flood protection scheme design report

TR 2013/43
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Report: TR 2013/43

Author: Megan Wood (Wainui Consulting Limited)

About this report

The purpose of this Design Report is to provide a summary of the Waiomu flood protection scheme, including the rationale behind the scheme development, the agreed levels of service, the design details, as built information, the operation and maintenance requirements associated with the scheme, the flood hazard and residual risk of the scheme and the scheme review requirements.

The Design Report includes the following sections:

  • Catchment overview
  • Hydrological assessment
  • Hydraulic model development
  • Flood protection scheme
  • Agreed levels of service
  • Operation and maintenance
  • Flood hazard assessment
  • Residual flood risk
  • Planning controls, and
  • Scheme review.

Read or download the report

Waiomu flood protection scheme design report [PDF, 6 MB]

Contents
  Executive summary iii
1 Introduction 1
1.1 Background 1
1.2 Scope of report 1
2 Catchment overview 2
2.1 Catchment description 2
2.2 Waiomu Stream 3
2.3 Flood history 4
2.4 Flood hazards 6
3 Hydrological assessment 8
3.1 Technical information 8
3.2 Catchment characteristics 9
3.3 Rainfall 9
3.4 Flow estimates 10
3.5 Hydrograph 11
4 Hydraulic model development 12
4.1 Model inputs 12
4.2 Model validation 12
4.3 Model assumptions and limitations 13
5 Flood protection scheme 15
5.1 Long term vision 15
5.2 Scheme development 15
5.3 Design details 19
6 Future works 28
6.1 Proposed scheme upgrade 28
6.2 Priority works 29
6.3 SH25 Bridge upgrade 30
6.4 Sale of remaining council owned land 30
7 Agreed levels of service 33
8 Operation and maintenance 34
9 Flood hazard assessment 36
9.1 River flood hazard classification 36
9.2 River flood hazard map 37
10 Residual flood risk 40
11 Planning controls 41
11.1 General 41
11.2 No. 12 Waiomu Valley Road 41
11.3 No. 18A Waiomu Valley Road 42
12 Scheme review 44
13 References 45
  Appendix 1: Spillway design 46
  Appendix 2: Fill levels along floodway boundary 49
  Appendix 3: Bund design details 53
  Appendix 4: Erosion protection design details 57
Appendix 5: Trotter Avenye existing drainage 66
Appendix 6: Building platform levels 68
Appendix 7: As-built survey 69