2.11 Irrigation for Landscaping
General Criteria. An irrigation system (if required) will provide water to plants only when needed. Drip irrigation should be considered where appropriate. Care will be taken so that water can be conserved through the use of a properly designed irrigation system.
Non-potable water should be used as a source for the irrigation system when it is available.
Reliable performance must be a prime goal in the design of irrigation systems. Materials will be durable and relatively maintenance free. Irrigation systems will be most successful in the long run if local design practices are followed and locally available materials are used.
Allow for expansion of the irrigation system, both in area and in flow rate, so the system can be adjusted as plants mature.
Metering. Irrigation water should be metered separately from domestic water to avoid expensive user sewage fees.
Zoning. Irrigation systems shall be zoned so different areas can be watered at different times. Avoid mixing different head or nozzle types (such as a spray head and a bubbler) on the same station. Different types of vegetation, such as turf and shrub areas, should also not be placed on the same station.
Application Rates. The system shall be designed to minimize surface run-off. In heavy clay soils, a low application rate may be required. Overspray onto paved surfaces should be avoided.
Controls. Irrigation controls should be easily understood by maintenance personnel. The designer should coordinate with the building manager as to the appropriate controls. Provide automatic controls to allow for scheduling of watering times for late night and early morning to reduce water losses due to evaporation.
Rain sensors or soil moisture sensors are essential to prevent unnecessary watering. Freeze sensors should be provided for systems in cold climates.
Maintenance Considerations. All major components shall be installed in protected, accessible locations. Controllers and remote sensing stations should be placed in vandal-proof enclosures. Above-ground components, such as backflow preventers, shall be placed in unobtrusive locations and protected from freezing.
Quick coupling valves should be of two-piece body design and installed throughout the system to allow for hosing down areas and to permit easy access to a source of water. Locate drain valves to permit periodic draining of the system.