Stormwater Soakage and Groundwater Recharge in the ...

1 Stormwater Soakage and Groundwater Recharge in the Auckland Region Guideline Document 2021/007 Version 1. Stormwater Soakage AND Groundwater Recharge IN THE AUCKLAND REGION i Stormwater Soakage and Groundwater Recharge in the Auckland Region 2021. Auckland Council Guideline document GD2021/007. ISSN 2230-4541 (Print). ISSN 2230-455X (Online). ISBN 978-1-99-100228-0 (Print). ISBN 978-1-99-100229-7 (PDF). Reviewed and recommended for publication by: Name: Branko Veljanovski Position: Head of Engineering Design and Asset Management Approved for publication by: Name: Paul Klinac Position: General Manager, Technical Services Recommended citation: Montakhab, A.

2 , Cunningham, A., & Roberts, R. (2021). Stormwater Soakage and Groundwater Recharge in the Auckland region. Auckland Council guideline document GD2021/007. 2021 Auckland Council Auckland Council disclaims any liability whatsoever in connection with any action taken in reliance of this document for any error, deficiency, flaw or omission contained in it. This publication is provided strictly subject to Auckland Council's copyright and other intellectual property rights (if any) in the publication. Users of the publication may only access, reproduce and use the publication, in a secure digital medium or hard copy, for responsible genuine non-commercial purposes relating to personal or public service, provided that the publication is only ever accurately reproduced and proper attribution of its source, publication date and authorship is attached to any use or reproduction.

3 This publication must not be used in any way for any commercial purpose without the prior written consent of Auckland Council. The use of this publication for professional training purposes, regardless whether payable or free of charge, also requires Auckland Council's prior written consent. Auckland Council does not give any warranty whatsoever, including without limitation, as to the availability, accuracy, completeness, currency or reliability of the information or data (including third party data) made available via the publication and expressly disclaim (to the maximum extent permitted in law) all liability for any damage or loss resulting from your use of, or reliance on the publication or the information and data provided via the publication.

4 The publication, information, and data contained within it are provided on an "as is" basis. Stormwater Soakage AND Groundwater Recharge IN THE AUCKLAND REGION ii Acknowledgements This document was prepared with technical input from Auckland Council and industry experts including, but not limited to the following individuals: Authors Dr Amir Montakhab, Amelia Cunningham, and Ross Roberts Contributors Project management: Dr Amir Montakhab Technical content: Glenn Broadbent, Scott Paton, Jason Ng, Phillip Johansen, Kura Taraare, Daniel Reeves, Rajinesh Kumar, Inthan Azoor, Dean Yee, and Andrew Irvine.

5 Editorial: Janet MacKinnon A preliminary review of the draft document has been carried out by Water New Zealand. The feedback from the following individuals has been incorporated: Sian France, Ann Williams, Michael Hannah, Peter Mitchell, Alan Pattle, and Glenn Richmond. Thanks are also extended to industry professionals who contributed to this document including, but not limited to, Roger Seyb, Kevin Jonathan, Ian Shaw, Noel Roberts, Tania Shaw, and Gerald Strayton. Special thanks are also extended to following people who contributed to this work: Bastogne-Zhiyuan Lu, Paige Harris, Ally Bodmer, Mathew Chandran and Zihao Lin.

6 Thanks also to Auckland Council staff, both past and present, and industry experts who contributed to the development of the guideline. This document is based on Auckland Council's Technical Report 40. (TR2013/40) Stormwater Disposal via Soakage in the Auckland Region, (Auckland Council, 2013). The project team acknowledges the work undertaken by many individuals and organisations over the years to provide technical content for this document. Stormwater Soakage AND Groundwater Recharge IN THE AUCKLAND REGION iii Preface What is the purpose of this document? This guideline document, Stormwater Soakage and Groundwater Recharge in the Auckland Region (Guideline Document 2021/007 or GD07) provides detailed design guidance for Soakage and Groundwater Recharge devices in Auckland.

7 It is aligned with Auckland Unitary Plan requirements to achieve a resilient and sustainable outcome utilising the principles of water sensitive design. The focus is on the design of Soakage devices that either: Manage the impact of Stormwater quantity by disposing of Stormwater to the ground (primary Stormwater systems), or Recharge Groundwater in peat soil to avoid drawdown-induced settlement ( Groundwater Recharge systems). GD07 is an update of Technical Report 2013/040 - Stormwater Disposal via Soakage in the Auckland Region, and will supersede that document once it is included in the Auckland Council Stormwater Code of Practice.

8 It aims to provide user-friendly technical design guidance for developers, designers and regulators based on current best practice specific to the requirements of the Auckland Unitary Plan. GD07 has been prepared for use in the Auckland region. While many of the principles are universal and can be used elsewhere, the technical specifications have been developed for the geology, geography, climate, receiving environments and context of Auckland. Auckland Council, therefore, disclaims any responsibility for the use of GD07 outside of the Auckland region. What new inclusions and approaches are in this guideline document?

9 The key new approaches in this document, relative to Technical Report 2013/40 Stormwater disposal via Soakage in the Auckland region (Auckland Council, 2013), are: Alignment with the requirements of the Auckland Unitary Plan (Auckland Council, 2018). Alignment with the NZ Ground Investigation Specification (Ministry of Business, Innovation and Employment & New Zealand Geotechnical Society, 2017). Alignment with the Auckland Council Stormwater Code of Practice The Inclusion of climate change and best practice design guidance for Soakage devices Additional guidance on other device design considerations such as safety in design.

10 How was this guideline document developed? A comprehensive review of national and international Soakage management and control guidelines was carried out to identify current best practice procedures and guidelines. This was accompanied by analysis which identified gaps and issues within currently used guideline documents, including: Technical Report 2013/040 Stormwater Disposal via Soakage in the Auckland Region (Auckland Council, 2013). Auckland City Council's Soakage Design Manual 2003 (Auckland City Council, 2003). Papakura District Council Development Code (Papakura District Council, 2010).