Design and install irrigation systems policy

This policy provides direction and information for plumbers, apprentices, and contractors regarding the designing of domestic irrigation systems.

Irrigation plans

An irrigation plan must include complete coverage of the area to be irrigated. If a system does not provide complete coverage of the area to be irrigated, it must be noted on the irrigation plan. You must use PEER Construction approved graph paper when drawing up an irrigation plan.

All irrigation plans must be drawn to scale on approved graph paper and include, at a minimum:

• all major physical features and the boundaries of the areas to be watered
• any objects that could be in the way of the irrigation system, such as buildings, trees, sheds, or areas that must be avoided
• location and type of controller and sensor (such as rain, moisture, wind, flow, or freeze)
• the scale used
• location, type, and size of each of the following:
  • water source, such as a water meter and point(s) of connection
  • backflow prevention device
  • water emission device, including, but not limited to, spray heads, rotary sprinkler heads, quick couplers, bubblers, pipe runs, drip, or micro sprays
  • valves, including, but not limited to, zone valves, master valves, and isolation valves.

Designing efficient and sustainable irrigation systems

When designing an efficient and sustainable irrigation system, plumbers must:

• know the soil condition, types of plants, flow rate and water pressure
• conserve and protect water resources and the environment
• ensure the serviced components meet the irrigation design specifications, manufacturer’s specifications, and any regulations
• ensure the amount of water applied is appropriate to the plants needs and soil properties
• make sure water is applied effectively and uniformly
• ensure water is applied to the plant root zone without wastage through runoff, deep drainage and other water loss sources such as wind drift and evaporation
• ensure the timing of water application suits the plant and weather conditions.

Runoff control

The irrigation plan should ensure:

• a drainage system is in place so any runoff can be drained
• erosion caused by irrigation runoff should be minimised
• systems as rain monitors/gauges are in place, so that if a specified amount of rain has fallen, the irrigation system will not operate, and the risk of surface runoff will be reduced.

Design and installation requirements

The minimum requirements for design and installation are:

• No irrigation design or installation shall require the use of any component, including the water meter, in a way which exceeds the manufacturer’s published performance limitations for the component.
• The maximum spacing between emission devices must not exceed the manufacturer’s published radius or spacing of the device(s). The radius or spacing is determined by referring to the manufacturer’s published specifications for a specific emission device at a specific operating pressure.
• For water pressure, emission devices must be installed to operate at the minimum and not above the maximum sprinkler head pressure as published by the manufacturer for the nozzle and head spacing that is used. Methods to achieve the water pressure requirements include, but are not limited to, flow control valves, a pressure regulator, or pressure compensating spray heads.
• Irrigation systems shall have separate zones based on plant material type, microclimate factors, topographic features, soil conditions, and hydrological requirements.
• Zones must be designed and installed so all the emission devices in that zone irrigate at the same precipitation rate.
• Irrigation systems shall not spray water over surfaces made of concrete, asphalt, brick, wood, stones set with mortar, or any other impervious material, such as, but not limited to, walls, fences, sidewalks, streets, etc.
• When provided, a master valve shall be installed on the discharge side of the backflow prevention device on all new installations.
• All new automatically controlled irrigation systems must include sensors or other technology designed to inhibit or interrupt operation of the irrigation system during periods of moisture or rainfall. Rain or moisture shut-off technology must be installed according to the manufacturer’s published recommendations.
• All new irrigation systems must include an isolation valve between the water meter and the backflow prevention device.
• Piping in all irrigation systems must be installed according to the manufacturer’s published specifications for depth coverage of piping.
• Electrical wiring that connects any electrical components of an irrigation system must be sized according to the manufacturer’s recommendation.

Design approval

Apprentices must send drawing sketches and/or design plans to their supervisor for approval.

Documentation

Any adjustments made during the commissioning process such as pump speed, impeller trim etc, should be recorded in operating and maintenance manuals for future information.

A Certificate of Compliance must be completed in accordance with legislative requirements and sent to the Office of the Technical Regulator (OTR) within 7 days of job completion (when applicable).