Title AS/NZS 3500.3.2:1998 National plumbing and drainage - Stormwater drainage Acceptable solutions Licensee Licensed to LUU MINH LUAN on 26 Feb 2002 Conditions of use This is a licensed electronic copy of a document where copyright is owned or managed by Standards Australia International Your licence is a single user licence and the document may not be stored, transferred or otherwise distributed on a network You may also make one paper copy of this document if required Web Check-up AS/NZS 3500.3.2:1998 National plumbing and drainage Building Code of Australia primary referenced Standard Licensed to LUU MINH LUAN on 26 Feb 2002 Single user licence only Storage, distribution or use on network prohibited Australian/New Zealand Standard™ Part 3.2: Stormwater drainage— Acceptable solutions AS/NZS 3500.3.2:1998 This Joint Australian/New Zealand Standard was prepared by Joint Technical Committee WS/20, Stormwater It was approved on behalf of the Council of Standards Australia on May 1998 and on behalf of the Council of Standards New Zealand on 15 May 1998 It was published on June 1998 Licensed to LUU MINH LUAN on 26 Feb 2002 Single user licence only Storage, distribution or use on network prohibited The following interests are represented on Committee WS/20: Association of Consulting Engineers, Australia Association of Hydraulic Services Consultants, Australia Australasian Institute of Chartered Loss Adjusters Australian Aluminium Council Australian Chamber of Commerce and Industry Australian Chamber of Manufactures Bureau of Meteorology (Australia) Department of Land and Water Conservation, N.S.W Department of Local Government and Planning, Qld Local Government Office, Tas Master Builders Australia Master Plumbers and Mechanical Services Association of Australia Master Plumbers Australia New Zealand Local Government Association New Zealand Manufacturers Federation New Zealand Water and Wastes Association Plastics and Chemical Industries Association (Australia) Plastics Institute of New Zealand Plumbing Industry Board, Victoria Royal Melbourne Institute of Technology University of Technology, Sydney Department of Administrative Services - Australia Review of Standards To keep abreast of progress in industry, Joint Australian/ New Zealand Standards are subject to periodic review and are kept up to date by the issue of amendments or new editions as necessary It is important therefore that Standards users ensure that they are in possession of the latest edition, and any amendments thereto Full details of all Joint Standards and related publications will be found in the Standards Australia and Standards New Zealand Catalogue of Publications; this information is supplemented each month by the magazines ‘The Australian Standard’ and ‘Standards New Zealand’, which subscribing members receive, and which give details of new publications, new editions and amendments, and of withdrawn Standards Suggestions for improvements to Joint Standards, addressed to the head office of either Standards Australia or Standards New Zealand, are welcomed Notification of any inaccuracy or ambiguity found in a Joint Australian/New Zealand Standard should be made without delay in order that the matter may be investigated and appropriate action taken This Standard was issued in draft form for comment as DR 96171 AS/NZS 3500.3.2:1998 Licensed to LUU MINH LUAN on 26 Feb 2002 Single user licence only Storage, distribution or use on network prohibited Australian/New Zealand Standard™ National plumbing and drainage Part 3.2: Stormwater drainage— Acceptable solutions Originated in Australia in part as part of AS CS3 — 1931 Previous editions AS 2180 — 1986 and AS 3500.3 — 1990 AS 2180 — 1986 and AS 3500.3 — 1990 jointly revised, amalgamated and redesignated in part as AS 3500.3.2:1998 Incorporating: Amdt 1—1998 Published jointly by: Standards Australia The Crescent, Homebush NSW 2140 Australia Standards New Zealand Level 10, Radio New Zealand House, 155 The Terrace, Wellington 6001 New Zealand ISBN 7337 1984 AS/NZS 3500.3.2:1998 PREFACE This Standard was prepared by the Joint Standards Australia/Standards New Zealand Committee WS/20, Stormwater, to supersede AS 2180 — 1986, Metal rainwater goods — Selection and installation, and AS 3500.3 — 1990, National Plumbing and Drainage Code, Part 3: Stormwater drainage This Standard is part of a series, as follows: AS 3500.3.1 Part 3.1: Stormwater drainage — Performance requirements AS/NZS 3500.3.2 Part 3.2: Stormwater drainage — Acceptable solutions (this Standard) Stormwater drainage — Methods for verification (Part 3.3) is in the course of preparation The objective of this Standard is to provide installers with acceptable solutions for materials and products and design and installation of stormwater drainage systems These solutions are not intended to exclude the use of other solutions This edition sets out acceptable solutions for the following: (a) Roof drainage systems: Licensed to LUU MINH LUAN on 26 Feb 2002 Single user licence only Storage, distribution or use on network prohibited (i) A general method for design incorporating recent Australian research on the following: (A) Eaves gutter systems — procedures similar to those of AS 2180 — 1986 but with significant decreases in the ratios for the effective cross-sectional area of eave gutter to vertical downpipes (B) Box gutter systems — procedures similar to those in AS 2180 — 1986 with additional procedures for sump/side overflow and sump/high-capacity overflow devices (C) Valley gutters — procedures based on research published in 1988 by Martin and Tilley (see Paragraph A2) (ii) Installation, based on modifications and additions to AS 2180 — 1986 (b) Surface drainage systems: (i) Nominal and general methods for design (ii) Installation, based on modifications and additions to AS 3500.3 — 1990 (c) Subsoil drainage systems design and installation, based on modifications and additions to AS 3500.3 — 1990 The advantage of the roof drainage general method is the relative simplicity of its application Continuing analysis of available experimental data is expected to result in new procedures for the design of — (a) valley gutters; and (b) eaves gutters with bends at various gradients for a wide range of cross-sections, sizes and depth to width ratios of 1:0.4 to 1:3.0 Statements expressed in mandatory terms in notes to figures and tables are deemed to be requirements of this Standard The terms ‘normative’ and ‘informative’ have been used in this Standard to define the application of the appendix to which they apply A ‘normative’ appendix is an integral part of a Standard, whereas an ‘informative’ appendix is only for information and guidance AS/NZS 3500.3.2:1998 CONTENTS Licensed to LUU MINH LUAN on 26 Feb 2002 Single user licence only Storage, distribution or use on network prohibited Page SECTION SCOPE AND GENERAL 1.1 SCOPE AND APPLICATION 1.2 REFERENCED DOCUMENTS 1.3 DEFINITIONS 1.4 NOTATION 1.5 STORMWATER DRAINAGE INSTALLATION PLANS 1.6 IDENTIFICATION 1.7 PROTECTION OF WORKS 1.8 POSITION AND MANNER OF DISCHARGE 6 11 11 11 12 SECTION MATERIALS AND PRODUCTS 2.1 SCOPE OF SECTION 2.2 SELECTION AND USE 2.3 ROOF DRAINAGE SYSTEM 2.4 STORMWATER DRAINS (NON-PRESSURE) 2.5 RISING MAINS (PRESSURE) 2.6 SUBSOIL DRAINS 2.7 JOINTS 2.8 VALVES 2.9 CONCRETE AND MORTAR 2.10 EMBEDMENT MATERIAL 2.11 TRENCH FILL 2.12 MISCELLANEOUS 2.13 FILTERS FOR SUBSOIL DRAINS 2.14 RE-USE 13 13 13 14 15 15 15 16 16 17 17 17 18 18 SECTION ROOF DRAINAGE SYSTEMS— DESIGN 3.1 SCOPE OF SECTION 3.2 GENERAL METHOD 3.3 METEOROLOGICAL CRITERIA 3.4 CATCHMENT AREA 3.5 EAVES-GUTTER SYSTEMS 3.6 VALLEY GUTTERS 3.7 BOX GUTTER SYSTEMS 3.8 SOAKERS 19 19 19 20 24 29 30 31 SECTION ROOF DRAINAGE SYSTEMS—INSTALLATIONS 4.1 SCOPE OF SECTION 4.2 TRANSPORT, HANDLING AND STORAGE 4.3 THERMAL VARIATION 4.4 CORROSION 4.5 INSTALLATION AND TESTING 4.6 INSPECTION AND CLEANING 4.7 ALTERATIONS AND DISCONNECTION 4.8 EAVES GUTTERS 38 38 38 38 39 42 42 42 AS/NZS 3500.3.2:1998 Page Licensed to LUU MINH LUAN on 26 Feb 2002 Single user licence only Storage, distribution or use on network prohibited 4.9 4.10 4.11 4.12 4.13 4.14 4.15 4.16 BOX GUTTERS VALLEY GUTTERS DOWNPIPES OVERFLOW DEVICES OR MEASURES JOINTS FOR METAL COMPONENTS JOINTS FOR PVC COMPONENTS JOINTS FOR OTHER COMPONENTS SUPPORT SYSTEMS 42 43 43 43 44 45 45 47 SECTION SURFACE DRAINAGE SYSTEMS—DESIGN 5.1 SCOPE OF SECTION 5.2 DESIGN METHODS 5.3 LAYOUT 5.4 NOMINAL METHOD 5.5 GENERAL METHOD 49 49 49 51 51 SECTION SUBSOIL DRAINAGE SYSTEMS—DESIGN 6.1 SCOPE OF SECTION 6.2 PURPOSE 6.3 TYPES 6.4 LAYOUT 6.5 DESIGN CONSIDERATIONS 62 62 62 64 65 SECTION SURFACE AND SUBSOIL DRAINAGE SYSTEMS—INSTALLATION 7.1 SCOPE OF SECTION 7.2 GENERAL REQUIREMENTS 7.3 SITE STORMWATER DRAINS 7.4 SUBSOIL DRAINS 67 67 71 74 SECTION SURFACE AND SUBSOIL DRAINAGE SYSTEMS—ANCILLARIES 8.1 SCOPE OF SECTION 8.2 PAVED SURFACES 8.3 POINT(S) OF CONNECTION 8.4 REFLUX VALVES 8.5 INSPECTION OPENINGS 8.6 STORMWATER PITS, INLET PITS AND ARRESTERS 8.7 SURCHARGE OUTLETS 8.8 JUNCTIONS 8.9 JUMP-UPS 8.10 ANCHOR BLOCKS 8.11 ON-SITE STORMWATER DETENTION (OSD) SYSTEMS 77 77 77 77 78 78 84 84 85 85 87 SECTION PUMPED SYSTEMS 9.1 SCOPE OF SECTION 9.2 GENERAL 9.3 WET WELLS 9.4 PUMPS 9.5 RISING MAINS 9.6 ELECTRICAL CONNECTION 90 90 90 91 91 91 AS/NZS 3500.3.2:1998 Page Licensed to LUU MINH LUAN on 26 Feb 2002 Single user licence only Storage, distribution or use on network prohibited SECTION 10 TESTING 10.1 SCOPE OF SECTION 10.2 DOWNPIPES AND DRAINS WITHIN 10.3 TEST CRITERIA 10.4 PROCEDURE OR UNDER BUILDINGS APPENDICES A REFERENCED AND RELATED DOCUMENTS B SITE MIXED CONCRETE FOR MINOR WORKS C STORMWATER DRAINAGE INSTALLATION PLANS D GUIDELINES FOR RAINFALL INTENSITIES E RAINFALL INTENSITIES FOR AUSTRALIA—FIVE MINUTES DURATION F RAINFALL INTENSITIES FOR NEW ZEALAND—10 MINUTES DURATION G EXAMPLES OF ACCEPTABLE OVERFLOW MEASURES FOR EAVES GUTTERS H GENERAL METHOD FOR DESIGN OF EAVES GUTTER SYSTEMS— EXAMPLE I BOX GUTTER SYSTEMS GENERAL METHOD, DESIGN GRAPHS AND ILLUSTRATIONS J BOX GUTTER SYSTEMS GENERAL METHOD, EXAMPLES K SURFACE DRAINAGE SYSTEMS—NOMINAL AND GENERAL METHODS, EXAMPLES L EXAMPLE CALCULATION—PUMPED SYSTEM © Copyright 92 92 92 93 94 98 99 101 102 118 123 126 131 140 150 160 STANDARDS AUSTRALIA / STANDARDS NEW ZEALAND Users of Standards are reminded that copyright subsists in all Standards Australia and Standards New Zealand publications and software Except where the Copyright Act allows and except where provided for below no publications or software produced by Standards Australia or Standards New Zealand may be reproduced, stored in a retrieval system in any form or transmitted by any means without prior permission in writing from Standards Australia or Standards New Zealand Permission may be conditional on an appropriate royalty payment Australian requests for permission and information on commercial software royalties should be directed to the head office of Standards Australia New Zealand requests should be directed to Standards New Zealand Up to 10 percent of the technical content pages of a Standard may be copied for use exclusively in-house by purchasers of the Standard without payment of a royalty or advice to Standards Australia or Standards New Zealand Inclusion of copyright material in computer software programs is also permitted without royalty payment provided such programs are used exclusively in-house by the creators of the programs Care should be taken to ensure that material used is from the current edition of the Standard and that it is updated whenever the Standard is amended or revised The number and date of the Standard should therefore be clearly identified The use of material in print form or in computer software programs to be used commercially, with or without payment, or in commercial contracts is subject to the payment of a royalty This policy may be varied by Standards Australia or Standards New Zealand at any time AS/NZS 3500.3.2:1998 STANDARDS AUSTRALIA / STANDARDS NEW ZEALAND Australian / New Zealand Standard National plumbing and drainage Part 3.2: Stormwater drainage — Acceptable solutions S E C T I O N 1.1 S C O P E A N D G E N E R A L SCOPE AND APPLICATION Licensed to LUU MINH LUAN on 26 Feb 2002 Single user licence only Storage, distribution or use on network prohibited 1.1.1 Scope This Standard specifies acceptable solutions for materials and products, and design and installation of roof drainage systems, surface drainage systems and subsoil drainage systems to the point(s) of connection to the external stormwater drainage network 1.1.2 Application This Standard will be referenced in the Building Code of Australia by way of BCA Amendment to be published by July 1998, thereby superseding the previous editions, AS 2180 — 1986 and AS 3500.3 — 1990, which will be withdrawn 12 months from the date of publication of this edition 1.2 REFERENCED DOCUMENTS listed in Appendix A The documents referred to in this Standard are 1.3 DEFINITIONS For the purpose of this Standard, and unless otherwise stated, the definitions referenced in the following Standards apply: (a) For terms relating to Part 3, as given in AS/NZS 3500.0 (b) For terms relating to buried flexible pipes, concrete pipes and vitrified clay pipes, as given in AS/NZS 2566.1, AS 3725 and AS 4060, respectively For other terms, the definitions below apply 1.3.1 Average recurrence interval (ARI) — the expected or average interval between events of a rainfall intensity of a given magnitude being exceeded NOTE: The ARI is an average value based on statistical analysis The actual time between exceedances will vary 1.3.2 Box gutter — graded channel, generally of rectangular shape, for the conveyance of rainwater, located within the building Includes a gutter adjacent to a wall or parapet (See Figures I5, I7.) 1.3.3 Eaves gutter — channel, for the conveyance of rainwater, located along the eaves of a roof external to the fascia line A concealed eaves gutter is located inside the fascia line and can also be called an internal eaves gutter 1.3.4 External stormwater drainage network — a network that collects and conveys stormwater from individual properties NOTE: The network includes easement or inter-allotment drains, and street and trunk drainage systems 1.3.5 Freeboard — the specified minimum vertical distance between the calculated and actual depths for a gutter, site stormwater channel or the like COPYRIGHT AS/NZS 3500.3.2:1998 1.3.6 Inert catchment — a rainwater collection area whose dominant material has little or no effect on the chemical composition of rainwater draining from it Such materials include acrylic, fibreglass, aluminium/zinc alloy-coated steel, glass, glazed tiles, unplasticized polyvinyl chloride and pre-painted metal 1.3.7 Inlet pit — a chamber fitted with side, grate or combination entry to permit the collection and ingress of stormwater to a site stormwater drain (see Clauses 1.3.12, 1.3.18 and 1.3.24) 1.3.8 Main internal drain — a drain that collects stormwater from two or more site stormwater drains within a property and — (a) has a diameter greater than DN 300; or (b) drains stormwater from a roadway or accessway serving a number of buildings located on one property 1.3.9 Major storm — a storm due to rainfall events of rare occurrence which can cause stormwater flows in excess of the capacity of the surface drainage system and hence overflows along overland flow paths Licensed to LUU MINH LUAN on 26 Feb 2002 Single user licence only Storage, distribution or use on network prohibited NOTE: In Australia an ARI of 100 years (see the chapter on urban stormwater drainage in ARR87) and in New Zealand an ARI of 50 years, are commonly adopted for a major storm 1.3.10 Minor storm — a storm due to rainfall events for which the surface drainage system is designed NOTE: The selected ARI for a minor storm will depend on the level of nuisance and damage likely to be caused by overflows due to rainfall events of a greater ARI, or failure of the surface drainage system or stormwater drainage network 1.3.11 Network utility operator — the operator of the external stormwater drainage network 1.3.12 On-grade pit — an inlet pit located on a slope where stormwater that is not readily admitted bypasses the inlet 1.3.13 On-site stormwater detention (OSD) tank — a tank for the temporary storage of stormwater to reduce the peak flow to the stormwater drainage network 1.3.14 Overflow device — a device for use with the roof drainage system to safely divert flow in the event of a blockage 1.3.15 Permanent ponding — occurs along the sole of eaves and box gutters when free water is evident for more than three days after the cessation of flow 1.3.16 Point of connection — the point provided for the connection of a site stormwater drain to the stormwater drainage network NOTE: Where a property is more than 90 m from an external stormwater drainage network, the network utility operator may permit an alternative point of connection 1.3.17 Rainhead — a collector of rainwater, generally of rectangular shape, at the end of a box gutter and external to a building, connected to an external downpipe (see Figure I2) It has a similar function to a sump (see Clause 1.3.26) 1.3.18 Sag pit — an inlet pit located in a depression where stormwater ponds over the inlet due to restricted entry 1.3.19 Site stormwater drain or channel — a conduit, generally buried, or an artificial open channel for the conveyance of stormwater to the point of connection to the external stormwater drainage network or to a main internal drain 1.3.20 Soaker — a purpose made channel or flashing located along the intersection of a roof with the upper edge of a chimney or similar roof penetration COPYRIGHT 147 J4 EXAMPLE 3: BOX GUTTERS, DEVICES AND DOWNPIPES AS/NZS 3500.3.2:1998 SUMP/HIGH-CAPACITY OVERFLOW J4.1 Problem A sump/high-capacity overflow device is to be fitted to the outlet of 5.0 m long and 3.8 m long box gutters with gradients of 1:200 and sole widths of 600 mm Inflow from the catchment area of the roof is at the rate of 1.7 L/s/m Determine the size of the box gutters and the sump/high-capacity overflow device including the normal and overflow vertical downpipes Licensed to LUU MINH LUAN on 26 Feb 2002 Single user licence only Storage, distribution or use on network prohibited To assist the understanding of this example the application of Figures I4, I6(a) and I8 is shown in Figure J5 (a) Determination of values for l oc FIGURE I4 DESIGN GRAPH FOR SUMP FIGURE I6 DESIGN GRAPH FOR SUMP/SIDE OVERFLOW DEVICE (a) Application of Figure I4 (b) Application of Figure I6(a) (The figures above have been reproduced in reduced size for the purpose of this example only Use Figures in Appendix I when designing or checking components of box gutter systems.) FIGURE J5 (in part) EXAMPLE — APPLICATIONS OF FIGURES I4, I6(a) AND I8 COPYRIGHT Licensed to LUU MINH LUAN on 26 Feb 2002 Single user licence only Storage, distribution or use on network prohibited AS/NZS 3500.3.2:1998 FIGURE I8 148 DESIGN GRAPH FOR SUMP/HIGH-CAPACITY OVERFLOW DEVICE (c) Application of Figure I8 (The figure above has been reproduced in reduced size for the purpose of this example only Use Figures in Appendix I when designing or checking components of box gutter systems.) FIGURE J5 (in part) EXAMPLE — APPLICATIONS OF FIGURES I4, I6(a) AND I8 TABLE J1 DATA FOR EXAMPLE Item Box gutter (a) (b) Length Design flow Depth of box gutter with discharge to rainhead (ha) from Figure I1 m L/s mm mm Width w bg 5.0 3.8 8.5* 6.5 (1.7 x 5.0) (1.7 x 3.8) 105 98 600 600 Sump 0.6 (see Figure I7) 1.0 (1.7 x 0.6) — — Totals 9.4 16.0† — — * Largest design flow from any one box gutter † Total design flow from each box gutter and section of roofing COPYRIGHT 149 AS/NZS 3500.3.2:1998 J4.2 Calculation The calculation below illustrates the application of the procedure shown in Figure 3.11 Each step designation (for example (b)) has a corresponding letter in the flowchart Proceed as follows: (a) From Table 3.1, select 100 years ARI for Australia, and 50 years ARI for New Zealand, for box gutters with a normal factor of safety Licensed to LUU MINH LUAN on 26 Feb 2002 Single user licence only Storage, distribution or use on network prohibited (b) to (g) The procedure for the determination of the catchment areas and design flows is illustrated in Appendix J, Examples and The procedure for the determination of the minimum depth of box gutter (ha) for free flow conditions is the same as for a box gutter served by a rainhead shown in Example Table J1 summarizes the results of these procedures for a selected width of box gutter (w bg) = 600 mm (h) Is the total design flow through the outlet >16 L/s? No Go to Step (i) (i) Select 1:200 gradient of box gutters Go to Step (j) (j) Total design flow = 16 L/s From Figure I4, for a 150 mm diameter downpipe, the depth of sump (hs) = 217 mm Adopt 220 mm (k) Qmax = 8.5 L/s for any box gutter Width of box gutter = 600 mm From Figure I6(a), loc = 27 mm (l) If the downpipe ceases to function because of a blockage, the water level at the ends of the box gutters will increase to discharge the design flow across the overflow weirs From Table J1, the largest flow in any box gutter is Q = 8.5 L/s From Figure I8, for Q = 8.5 L/s and wbg = 600 mm, the minimum height of the box gutter above the top of the overflow weirs (h t) = 83 mm (m) The depth of box gutter has to be sufficient to contain the flow under overflow conditions without overtopping Usually, the minimum total depth of gutter (dbg) required for this condition is more than the minimum total depth of gutter (h a) required when there are no blockages But for wide gutters this is not always the case, partly because of different levels of freeboard incorporated in the graphs From Step (g) (shown on summary Table J1), = 105 mm From (l), h t = 83 mm From (k), loc = 27 mm ht + loc = 110 mm Is ha(105)