Environment Canterbury Backflow Requirements Backflow prevention is the prevention of backflow (a reversal of the normal direction of flow in a pipe) of unwanted and undesirable flow of non-potable water or other toxic substances. (Natural Resources Regional Plan) Presenter – Colin Bird Agenda • Statutory requirements • Consent conditions • Selection of backflow prevention devices (BFP’s) • Procedures for installing Chemigation valves Statutory Requirements • Canterbury Natural Resources Regional Plan Chapter 4 Water Quality – Policy WQL 9 Prevent the entry of hazardous contaminants to groundwater – Policy WQL 11 Avoid contamination of groundwater via bores or excavations Policy WQL9 Prevent the entry of hazardous contaminants to groundwater • (3) Prohibit the discharge of the following contaminants into groundwater via a bore, excavation, storage tank or other mean: • (a) hazardous substances and hazardous wastes, except where the discharge occurs during the remediation of contaminated land or it is required as part of a groundwater investigation, provided the discharge does not result in any significant adverse effects on groundwater quality; • (b) wastes from industrial or trade processes, excluding heated water or cleanfill material; • (c) human sewage effluent; or • (d) animal effluent from a collection system Policy WQL 11 Avoid contamination of groundwater via bores or excavations • (3) Groundwater bores and water infiltration galleries are to be constructed and maintained so that contaminants are prevented from entering a bore or gallery from the land surface, or from backflow of water down the bore, or down the side of the bore casing or gallery, in accordance with the following: • (a) when an application is made for a resource consent to take water from an existing bore or gallery, the applicant will be required to demonstrate that there are effective measures in place to prevent contaminants entering the bore or gallery; • (c) any bore or gallery used to take groundwater and located within: a Community Drinking Water Protection Zone; the Christchurch Groundwater Protection Zone 1 …….; or a site where an activity listed in Schedule WQL3 is occurring, shall have effective measures in place to prevent contaminants from entering the bore or gallery within 3 years of the relevant provisions of the NRRP becoming operative. Next step in meeting NRRP policy • Whilst the NRRP has a requirement for backflow prevention it is silent on how that is to be achieved. • Environment Canterbury introduced conditions into their resource consents requiring backflow prevention devices. Early Resource Consent Conditions (a) (b) The irrigation system used to distribute diluted dairy effluent must not be hydraulically connected to surface or ground water unless an effective backflow prevention device, approved by Canterbury Regional Council, is installed and operated within the pump outlet plumbing or within the mainline to prevent the backflow of diluted dairy effluent into the water source. The backflow prevention device shall be tested at the time of commissioning the installation and annually thereafter by a suitably qualified or certified person in accordance with Canterbury Regional Council approved test methods relative to the device used. A test report shall be provided to the Canterbury Regional Council Attention: RMG Compliance and Enforcement Manager within two weeks of each inspection. 2nd Generation Resource Consent Conditions • (a) The irrigation system used in association with taking water from bore [ ] shall not be used to distribute effluent, fertiliser or any other added contaminant, unless a reduced pressure zone backflow preventer is installed within the pump outlet plumbing or within the mainline to prevent the backflow of water into the bore. • (b) The backflow preventer shall be tested within one month of its installation and annually thereafter by a suitably qualified person. A test report shall be provided to the Canterbury Regional Council within two weeks of each inspection. Changing Times • Expanding growth of the dairy industry – more cows, more effluent. • Irrigation efficiency targets to be met • Shift in irrigation methods towards lateral/centre pivots • Farm Environmental Plans (FEP’s) with nitrate levels Q. How best to dispose of all this effluent? • More effluent storage required • Effluent irrigators – labour intensive, time consuming and generally inefficient • Solution – distribute the effluent through existing irrigation infrastructure. • Problem – contamination of the primary irrigation water source. Selecting an appropriate BFP device. • Initially the only BFP device authorised for use was a Reduced Pressure Zone (RPZ) valve or an Air Gap. • Was this the most practical device to be used in an agricultural environment? • Where the source of contamination is a high risk or the water source supplies potable water for community water schemes or is located in a community drinking water supply protection zone then an Air Gap or RPZ device must be installed. • Where the water source is for agricultural purposes a testable Chemigation valve may be used. 3rd Generation Resource Consent Conditions • • (a) If the irrigation system used to distribute water taken in terms of this permit is used to distribute effluent, fertiliser or any other added contaminant, a backflow preventer manufactured in accordance with AS 2845.1 (1998) or the American Society of Sanitary Engineers standards shall be installed within the pump outlet plumbing or within the mainline, to prevent the backflow of water into the bore. (b) The backflow preventer shall be tested to the standard set out in AS 2845.3 (1993) or an equivalent method within one month of its installation and annually thereafter by a suitably qualified person. A test report shall be provided to the Canterbury Regional Council, Attention: RMA Compliance and Enforcement Manager, within two weeks of each inspection. Environment Canterbury’s requirements for the use of Chemigation valves