| AIM OF THIS DOCUMENT This document gives a brief outline of the EPA's Guidelines
for the utilisation of treated effluent by irrigation. The Guidelines were released by the EPA in March 1995 for
public comment for four months. The Guidelines are now being revised based on
comments received during this period. WHAT ARE THE GUIDELINES FOR? The Guidelines cover the beneficial use by irrigation of a
wide range of rural and industrial effluents, including secondary treated sewage effluent.
They supersede the following guidelines produced by the former State Pollution Control
Commission:
Best management practices The concepts outlined in the Guidelines are intended to
encourage people to use best management practices in the planning, design, construction
and ongoing operation and management of effluent irrigation systems, to benefit the
environment. Best management practices are those approaches that have been
developed to prevent or minimise water pollution at source, or as close to the source as
practicable. They include those practices that are found to be the best ways of preventing
or reducing the amount of pollution from nonpoint sources to a level compatible with
water quality goals. Any approach that differs from that outlined in the Guidelines
may be acceptable, provided that the resulting scheme is ecologically sustainable and
satisfies the requirements of the EPA and other statutory authorities. WHAT IS THE BROAD POLICY OF THE GUIDELINES? The traditional approach to disposing of wastewaters has been to
apply them on land, using the land as a cheap means of treating (or 'renovating') the
wastewaters. The Guidelines represent a conceptual shift towards accepting treated
wastewater as a resource available for use, rather than a waste that needs to be disposed
of. They aim to help designers and operators optimise the value of effluent in an
agronomic system that is ecologically sustainable. However, do not assume that irrigation of treated effluents is
always the best solution for the environment. Every effluent irrigation proposal should be
compared with alternative discharge and use options on the basis of environmental, social
and economic costs and benefits. The EPA's wastewater management policy is to encourage the use of
effluent where it is safe and practicable to do so, and where it provides the best
environmental outcome. In cases where wastewater cannot be used this way, the EPA
recommends that alternative methods be used to return effluents to the water cycle in an
environmentally and socially responsible way. ENVIRONMENTAL AIMS OF A GOOD EFFLUENT IRRIGATION SYSTEM The EPA has established the following environmental performance
objectives for using wastewaters by irrigation.
THE NEED FOR ONGOING MONITORING There must be sustainability in an irrigation system. Managers
may need a program of ongoing monitoring and progressive modification to correct any
design flaws and deficiencies, to adjust the system as more complete information on the
site becomes available, and to accommodate any changes in operational methods over time. THE COMPUTER MODEL Included with the Guidelines is an irrigation computer
program. The computer model has been developed to estimate the minimum effluent storage
and land area needed for effluent irrigation schemes, based on historical climatic
information and proposed site nutrient and organic loadings. The irrigation model is
userinteractive and gives users data they can use to help work out what design criteria
they need for an effluent irrigation scheme that is ecologically sustainable. THE NEED TO SEEK FURTHER HELP The Guidelines are an environmental guide; they are not a
design and operations manual. Technical and scientific problems associated with using
effluent can be complex and often need the integrated efforts of several disciplines in
science and engineering. Accordingly, designers and operators may need to get advice from
specialist consultants and from Government authorities such as NSW Agriculture, the
Department of Land and Water Conservation, NSW Health and State Forests of NSW. In
particular, they may need advice from NSW Agriculture on appropriate irrigation techniques
and management practices for specific plants and soil types. SUMMARY It is important to use best management practices for effluent
irrigation systems. The Guidelines are designed to help industry function in
an ecologically sustainable way and to meet its obligations under the environment
protection legislation administered by the EPA. They are only educational and
advisory,they are not a binding legal document. FURTHER INFORMATION If you need more information about the Guidelines or about
effluent irrigation, contact your nearest office of the EPA. Branches are listed in the
front of this manual. FURTHER READING From EPA Australia |