Rural Earthmoving in the Sydney Drinking Water Catchment A Sydney Catchment Authority Current Recommended Practice Publication Rural Earthmoving in the Sydney Drinking Water Catchment ISBN: 978-0-9874680-2-4 Published by the Sydney Catchment Authority (SCA) Penrith, February 2014 © State of New South Wales through the SCA Acknowledgements This current recommended practice ‘Rural Earthmoving in the Sydney Drinking Water Catchment’ has been developed by Alison Kniha and Jim Caddey of the Sydney Catchment Authority with the cooperation and endorsement of the NSW Soil Conservation Service. Unless otherwise stated and referenced, all information in this manual is material sourced from the ‘Earth Movers Training Course’ manuals (Soil Conservation Service, 1991). Disclaimer The Sydney Catchment Authority has made all reasonable efforts to ensure that the contents of this manual are accurate, suitable and complete however it does not warrant its accuracy, suitability or completeness. To the extent permitted by law the Sydney Catchment Authority excludes any liability including any liability for negligence and shall not be accountable for any loss or damage suffered arising from or in relation to the use of the information contained in this manual. Copyright Note © State of New South Wales through the Sydney Catchment Authority, 2014. You may copy, distribute, display, download or otherwise freely deal with this work for any purpose, provided that you attribute the Sydney Catchment Authority as the owner. However, you must obtain permission if you wish to (1) charge others for access to the work (other than at cost), (2) include the work in advertising or a product for sale, or (3) modify the work. Contents Summary ........................................................................................................................................................vi 1. Rural Earthmoving in the Sydney Drinking Water Catchment ............................................ 1 1.1 Introduction .......................................................................................................................................2 1.2 The drinking water catchment ...............................................................................................4 1.3 Requirements of State Environmental Planning Policy (Sydney Drinking Water Catchment) 2011......................................................................6 1.4 Other approvals and legislation.............................................................................................7 1.4.1 Native vegetation and state protected land .................................................7 1.4.2 Controlled activities ......................................................................................................8 1.5 The Soil Conservation Service.................................................................................................8 2. Erosion Control and Design Principles ...................................... 9 2.1 Types of soil erosion and causes ........................................................................................10 2.1.1 Sheet erosion .................................................................................................................10 2.1.2 Rill and gully erosion .................................................................................................11 2.1.3 Streambank erosion ...................................................................................................12 2.1.4 Tunnel erosion ...............................................................................................................13 2.1.5 Scalding .............................................................................................................................13 2.2 Erosion control and design principles ............................................................................14 2.2.1 Land capability ..............................................................................................................14 2.2.2 Farm tracks and other farm improvements ................................................14 2.2.3 Structural works for erosion control.................................................................15 2.2.4 Design principles for structural works ............................................................15 3. Farm Dams .................................................................................... 19 3.1 Approvals and licences ............................................................................................................21 3.2 Types of dams ................................................................................................................................21 3.2.1 Gully (embankment) dams ....................................................................................22 3.2.2 Hillside dams ..................................................................................................................23 3.3 Dam components .......................................................................................................................23 3.3.1 The excavation ..............................................................................................................24 3.3.2 The embankment ........................................................................................................24 3.3.3 The outlet channel or spillway ............................................................................25 3.3.4 Cut-off trenches ............................................................................................................25 3.4 Farm dam planning ....................................................................................................................26 3.4.1 Site selection ..................................................................................................................26 3.4.2 Dam shape .......................................................................................................................29 3.4.3 Soil sampling and testing .......................................................................................29 3.4.4 Soil profiles in excavations .....................................................................................33 3.4.5 Soil placement ...............................................................................................................34 3.4.6 Soil compaction ...........................................................................................................36 3.4.7 Topsoil .................................................................................................................................36 Rural Earthmoving in the Sydney Drinking Water Catchment i 3.5 Dam specifications ......................................................................................................................37 3.5.1 Batter grades...................................................................................................................37 3.5.2 Dam dimensions ..........................................................................................................37 3.6 Farm dam construction............................................................................................................41 3.6.1 Construction techniques ........................................................................................41 3.6.2 Steps in construction ................................................................................................41 3.6.3 Construction of a gully dam .................................................................................43 3.7 Pipes in earthworks .....................................................................................................................45 3.7.1 Primary outlets ..............................................................................................................46 3.7.2 Spillway protection .....................................................................................................47 3.7.3 Trickle pipes ....................................................................................................................47 3.7.4 Location of pipes in earthworks .........................................................................48 3.7.5 Farm dams and detention structures..............................................................48 3.7.6 Banks and outlets ........................................................................................................49 3.8 Embankment failure ...................................................................................................................49 3.8.1 Tunnel failure ..................................................................................................................49 3.8.2 Overtopping ...................................................................................................................52 3.8.3 Embankment and foundation collapse .........................................................52 3.9 Maintenance ...................................................................................................................................52 4. Contour and Graded Banks ....................................................... 55 4.1 Function of banks ........................................................................................................................56 4.2 Types of banks ...............................................................................................................................57