Construction and Establishment Guidelines: Swales, Bioretention Systems and Wetlands Version 1.1, April 2010

Transcription

1 Construction and Establishment Guidelines: Swales, Bioretention Systems and Wetlands Version 1.1, April 2010 Water by Design is a program of the South East Queensland Healthy Waterways Partnership

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3 Construction and Establishment Guidelines: Swales, Bioretention Systems and Wetlands Version 1.1, April 2010 Construction and Establishment Guidelines: Water by Design Swales, is a Bioretention program of the Systems South East and Queensland Wetlands Healthy Waterways Partnership 1

4 South East Queensland Healthy Waterways Partnership 2009 This work may be reproduced in whole or part for study or training purposes subject to inclusion of an acknowledgment of the source and no commercial usage or sale. Reproduction for the purposes other than those named above requires the permission of the South East Queensland Healthy Waterways Partnership office. Requests and enquires concerning reproduction rights should be forwarded to ISBN Version 1.1, April 2010 This report should be cited as: Water by Design, 2010, Construction and Establishment Guidelines: Swales, Bioretention Systems and Wetlands, South East Queensland Healthy Waterways Partnership, Brisbane. Disclaimer The material contained in this publication is produced for general information only. It is not intended as professional advice on specific applications. It is the responsibility of the user to determine the suitability and appropriateness of the material contained in this publication to specific applications. No person should act or fail to act on the basis of any material contained in this publication without first obtaining specific independent professional advice. The South East Queensland Healthy Waterways Partnership (SEQHWP) expressly disclaim all and any liability to any person in respect of anything done by any such person in reliance, whether in whole or in part, on this publication. The information contained in this publication does not necessarily represent the views of the funding partners. Acknowledgements The were developed by the Water by Design program of the South East Queensland Healthy Waterways Partnership, with financial assistance from the State of Queensland acting through the Department of Environment and Resource Management. Authoring Team: The guidelines were authored by Shaun Leinster (DesignFlow) and Robin Allison (DesignFlow) with significant input provided by Damian McCann (Australian Wetlands). A number of government and industry stakeholders provided valuable input to the development of the guidelines. The principal review of the guidelines was undertaken by Geoff Hunter (J Wyndam Prince) with reviews also by (in alphabetical order) Jeff Byrne (Gary Dean Constructions), Peter Curley (Environmental Protection Agency), Alan Hoban (Water by Design program, SEQHWP), Greg Jenkyns (Shadforths Civil Contractors), Leon Rowlands (Sunshine Coast Regional Council), Nick Sommes (Ecodynamics), Steve Tracey (Sunshine Coast Regional Council) and landscape assessment staff at Sunshine Coast Regional Council. Scott Paten (Brisbane City Council) and Grant Witherridge (Catchments and Creeks) also provided input to the guidelines. Project Manager: Sarah Jones (Water by Design program, SEQHWP). Editor: Justine Gannon (Proof etc). The photos contained in these guidelines are credited to (as indicated by the number in the bottom right hand corner of each photo): 1. Shaun Leinster (DesignFlow, EDAW Ecological Engineering) 2. Andrew O Neill (DesignFlow) 3. Alan Hoban (Water by Design, EDAW Ecological Engineering) 4. Sally Boer (EDAW Ecological Engineering) 5. Robin Allison (DesignFlow, EDAW Ecological Engineering) 6. Peter Breen (EDAW Ecological Engineering) 7. Geoff Hunter (J Wyndham Prince) Sections of these guidelines are drawn from the Water Sensitive Urban Design Technical Design Guidelines for South East Queensland (SEQHWP, 2006). Water by Design welcomes feedback on the guidelines which can be directed to info@waterbydesign.com.au

5 Water by Design Water by Design was established in 2005 and is a program of the South East Queensland Healthy Waterways Partnership. Water by Design builds capacity of the water and urban development sectors to help successfully implement sustainable urban water management. Sustainable management of the urban water cycle supports sustainable development, including protection of the natural water cycle. South East Queensland Healthy Waterways Partnership South East Queensland Healthy Waterways Partnership is a collaboration between government, industry, researchers and the community. The Partnership was created in The partners work together to improve catchment management and waterway health in Moreton Bay and the rivers of South East Queensland between Noosa and the Queensland-New South Wales border. The Partnership also manages the Ecosystem Health Monitoring Program (EHMP), which produces an annual report card on the health of the region s waterways, estuaries and bays. Further information on the SEQ Healthy Waterways Partnership and the Water by Design Program, is available from and This document is available for download from Sign-off Forms Each section of this document contains sample sign-off forms. A set of editable sign-off forms is available from

6 CONTENTS 1 INTRODUCTION Background and context of the guidelines Scope and structure of the guidelines Audience How to use the guidelines How to enforce the guidelines Evolution of the guidelines SWALES Swales Roles and responsibilities Timing Civil considerations and specifications Ordering materials Tolerances Flush kerbs Landscape considerations and specifications Topsoil specification and installation Plant types and density Plant procurement Mulching Planting procedure Watering Measuring success Managing sediment during the building phase Development phases Staged construction and establishment methods Option 1: Surface protection with temporary vegetation Option 2: Surface protection with permanent vegetation Step-by-step sequence Options 1 and Civil construction Stage 2 Building phase protection Landscape establishment Potential failure and rectification Certification Compliance Civil and landscape contracts Contracts Ownership and handover Sign-Off Forms BIORETENTION SYSTEMS Bioretention Systems Roles and Responsibilities Timing Civil considerations and specifications Ordering materials Tolerances Hydraulic structures

7 3.4.4 Bioretention system liners Under-drainage Installing and compacting bioretention media Construction issues with large bioretention systems Services Coarse sediment capture Maintenance access Bioretention media specification and certification Filter media Transition layer Drainage layer Saturated zones Certification and chain of custody Compliance testing (for on-maintenance or off-maintenance) Landscape considerations and specifications Planting Plant procurement Preparing filter media Mulching Planting procedure Watering Measures of successfully established plants Managing sediment during the building phase Managing sediment Development phases Staged construction and establishment methods Option 1: Surface protection Option 2: Bypass flows and early establishment of vegetation Option 3: Sediment basin and bioretention function Option 4: Leave as sediment basin Step-by-step sequence Options 1, 2 and Stage 1 Civil construction Stage 2 Building phase protection Stage 3 Landscape establishment Step-by-step sequence Option Stage 1 Civil construction Stage 2 Building phase protection Stage 3 Civil construction and landscape establishment Potential failure and rectification Certification Compliance Civil and landscape contracts Contracts Ownership and handover Sign-Off Forms

8 4 CONSTRUCTED WETLANDS Constructed Wetlands Roles and responsibilities Timing Civil considerations and specifications Controlling erosion and sediment during the construction phase Hydraulic structures Impervious liner Earthworks and trimming Tolerances Maintenance access Landscape considerations and specifications Topsoil Plant types and density Plant procurement Timing of planting Planting procedure Water level control Watering Weed control Bird protection Measuring success Managing sediment during the building phase Managing sediment Development phases Staged construction and establishment methods Option 1: Bypass flows and early establishment of vegetation Option 2: Leave as sediment basin Step-by-step sequence Option Stage 1 Civil works Stage 2 Building phase protection and Stage 3 Landscape Establishment Stage 3 Landscape establishment (inlet zone only) Step-by-step sequence Option Stage 1 Civil works Stage 2 Building phase protection Stage 3 Civil works and landscape establishment Potential failure and rectification Certification Compliance Civil and landscape contracts

9 Contracts Ownership and handover Sign-Off Forms REFERENCES

10 ONE INTRODUCTION

11 1.1 Background and context of the guidelines Water Sensitive Urban Design (WSUD) is a design philosophy that integrates land and water planning and management into urban design. WSUD is based on the idea that urban development and redevelopment must address the sustainability of water, integrating it into the built form at the earliest stage of the decision -making process. WSUD systems take a number of forms focusing on demand management, wastewater minimisation and stormwater management. Various tools and guidelines are available, or are in preparation, to assist in planning, designing and implementing WSUD in Queensland. Figure 1.1 illustrates these tools and how they can be used in the context of a typical urban development process. Figure 1.1: WSUD tools and guidelines in press or available from Experience shows that the critical periods in the life of WSUD vegetated stormwater management systems are the construction and establishment phases. The timing and approach to these systems must be carefully considered to ensure successful establishment and long-term performance.wsud is a relatively new concept for contractors, site inspectors and compliance officers responsible for construction and establishment. Industry stakeholders have highlighted that a major barrier to the successful implementation of WSUD, and in particular vegetated stormwater management systems, is a lack of appropriate guidelines and protocols for constructing and establishing WSUD. The Construction and Establishment Guidelines: Swales, Bioretention Systems and Wetlands focus on vegetated stormwater management systems. Concept Design Guidelines MUSIC Modelling Guidelines Stormwater Harvesting Guidelines Technical Design Guidelines Deemed to Comply Solutions & Sample Site Layouts Standard Drawings Construction and Establishment Guidelines Asset Management Resources including Guidelines Available 2009 Available

12 1.2 Scope and structure of the guidelines The Water Sensitive Urban Design Construction and Establishment Guidelines provide a suite of resources to facilitate the successful delivery of vegetated stormwater management systems. The guidelines specifically address swales (chapter 2), bioretention systems (chapter 3) and constructed wetlands (chapter 4) because these systems are the most commonly applied stormwater management measures in Queensland. Table 1.1 provides an explanation of each of these management measures. Each chapter has a similar structure to help users negotiate the information. Each chapter is generally split into the following parts, as described further in Table 1.2: Methodologies - staged construction and establishment methods - step-by-step construction and establishment guidance - potential failure and rectification Certification and compliance - certification requirements - compliance requirements - civil works and landscape contract requirements - sign-off forms, including inspection and as constructed drawing requirements. Considerations and specifications - civil works and landscape specifications - construction and establishment considerations - civil works and landscape design advice Table 1.1: Management measures addressed in the guidelines CHAPTER MANAGEMENT MEASURE DESCRIPTION 2 Swales Vegetated swales are small vegetated depressions in the landscape used to convey stormwater in lieu of, or in conjunction with, underground pipe drainage systems. Swales convey stormwater flows along gentle slopes, disconnect impervious areas from downstream waterways and remove coarse and medium sediments. They are commonly combined with bioretention systems or trenches to increase the removal of pollutants. 3 Bioretention systems Bioretention systems are vegetated soil profiles of sandy loam, sand and gravel layers that capture stormwater on the surface. They treat stormwater as it percolates through the soil layers. Pollutants are removed by filtration and by the biological uptake of nutrients. Bioretention systems are now common stormwater treatment devices in new urban developments in South East Queensland. Successful construction and allowing adequate time for the systems to establish is critical to their long-term performance. 4 Constructed wetlands Constructed wetlands are shallow, vegetated water bodies that remove pollutants from stormwater by enhanced sedimentation, fine filtration and biological uptake. Constructed wetlands are a combination of soil, aquatic vegetation and stormwater. Construction and establishment can present challenges. 10

13 Table 1.2: Structure of each chapter SUB-SECTION Swales, bioretention systems and constructed wetlands Roles and responsibilities Timing Civil works considerations and specifications Landscape considerations and specifications Managing sediment during the building phase Staged construction and establishment methods Stage 1 Civil works construction Stage 2 Building phase protection Stage 3 Landscape establishment Potential failure and rectification Certification Regulation and compliance Civil and landscape contractual issues Sign-Off Forms (addendums) DESCRIPTION Describes the function of swales, bioretention systems and constructed wetlands within the concept of WSUD. Describes the roles of stakeholders in the construction, establishment and certification of vegetated stormwater management systems. Summarises the issues that influence the timing of construction and establishment of swales, bioretention systems and constructed wetlands. Outlines issues that must be considered when preparing and completing landscape works and planting. This section can be referred to for specifications from landscape drawings rather than generating a specification document. Outlines issues that must be considered when preparing and completing landscape works and planting. This section can be referred to for specifications from landscape drawings rather than generating a specification document. Describes problems associated with sediment during the building phase and how these problems can influence construction and establishment of vegetated systems. Summarises the need for staged construction and establishment of vegetated stormwater management. Provides a step-by-step construction sequence with detailed descriptions and photos. This section can be laminated and used as an on-site reference during construction. Provides a step-by-step sequence for protecting systems during the building phase. A number of options are given for bioretention systems. This section can be laminated and used as an on-site reference during construction. Provides a step-by-step sequence for establishing landscapes with detailed descriptions and photos. This section can be laminated and used as an on-site reference during construction. Outlines system failures as a result of poor construction and establishment. Actions to rectify system failures are described. Provides guidance on certification requirements. Provides guidance on how local authorities can reference and mandate these guidelines and details potential compliance processes. Briefly outlines how best practice construction and establishment requirements can be written into civil and landscape contracts. Provides Sign-Off Forms to guide construction, establishment, certification and compliance. The sign-off forms can be used within contracts, to guide day-to-day construction and establishment, and to inform certification and compliance. 11

14 The contents of the guidelines are tailored for Queensland, but can be easily applied to areas outside Queensland. The guidelines do not cover the asset handover process or the ongoing management of WSUD systems. Water by Design is developing resources to address these issues through the WSUD Asset Handover Guidelines and WSUD Asset Maintenance Manual to be published in Although these guidelines provide the relevant specifications critical for correctly functioning vegetated stormwater management systems, the Water Sensitive Urban Design Technical Guidelines for South East Queensland (SEQHWP, 2006) should also be consulted for design advice. 1.3 Audience These guidelines are intended for professionals responsible for on-the-ground delivery of vegetated stormwater management systems including: WSUD specialists landscape architects civil engineers site inspectors civil contractors landscape contractors local government compliance officers. The guidelines particularly support site inspectors, civil contractors, landscape contractors and compliance officers. These people are responsible for implementing WSUD and may not be aware of the issues associated with delivery. The guidelines are based on practical, on-ground experience. 1.4 How to use the guidelines The guidelines provide a single reference point for the construction and landscape sectors to help deliver vegetated stormwater management systems. Table 1.2 provides a description of sub-sections in each chapter and how they should be used. The considerations and specifications sections of the guidelines outline issues and specifications that must be taken into account when preparing and completing civil works. These sections can be referred to for specifications directly from engineering and landscape drawings rather than generating a specification document. The Sign-Off Forms (addendums to the guidelines) are the basis for construction and establishment, certification and compliance. They should be used within contracts, to guide the day-to-day construction and establishment of the vegetated systems, and to inform certification and compliance. The other sections of the guidelines should be used as a reference. The sections on civil works construction, building phase protection and landscape establishment provide comprehensive step-by-step guidelines. These sections can be laminated and used as an on-site reference during construction. Although written primarily to support the construction and establishment of vegetated stormwater systems that will ultimately be owned by local authorities, the guidelines can also be used to support the delivery of systems that will be privately owned and managed. 1.5 How to enforce the guidelines Local authorities have two ways of mandating the construction and establishment specifications and the methods outlined in these guidelines. Firstly, planning schemes can be amended to refer to these guidelines, specifying the preferred construction method to be applied within a specific local government area. The second approach is to condition a preferred construction method with Development Approvals. Conditions within Development Approvals need to refer to: the preferred staged construction and establishment method certification of constructed systems using the Construction and Establishment Sign-Off Forms triggers for on-maintenance and off-maintenance. Water by Design is assisting local authorities in South East Queensland to develop a set of Development Approval Conditions that can be used to support the methods, certification and compliance recommendations provided in these guidelines. 12

15 1.6 Evolution of the guidelines The Construction and Establishment Guidelines: Swales, Bioretention Systems and Wetlands provide design advice that is not contained in existing guidelines and resources. They will be updated during 2010 and the design information contained in the guidelines will be incorporated into the Water Sensitive Urban Design Technical Design Guidelines for South East Queensland. Future versions of these guidelines may be developed to include construction and establishment guidance for other stormwater management systems including sedimentation basins, infiltration measures, sand filters and stormwater harvesting. Users of the Construction and Establishment Guidelines: Swales, Bioretention Systems and Wetlands are encouraged to provide feedback on this document to Feedback will be considered in future updates of the guidelines. 13