PCDI Irrigation

It is commonly required on heavy clay soils where soakage is limited, and it is important that the treated water is spread evenly.

• PCDI has small emitters allowing a limited flow, this forces the liquid to distribute across the entire field rather than pooling in one area.
• Due to the fine emitters, the treatment plant must treat to secondary level and the lines regularly cleaned.
• The PCDI lines can be of varying lengths and run across contour to a certain degree, giving much more flexibility to the layout and shape of the irrigation area.
• At the end of the lines are flush taps, that allow the flushing out of any contaminants that might build up over time, it is best done with clean water. At the end of the main feed line is the end flush tap. It is similar to other flush taps, but some systems will have a hose fitting for back flushing properties.
• If your irrigation is buried, the flush taps will be found under purple flush boxes. These have a purple lid and sit flat to the ground to allow the area to be mowed.

This is a favourite of ours, as it is the most robust irrigation system available. Using larger 25mm distribution laterals with drilled holes, it is much less prone to blockage and crushing. These larger orifices are covered with a unique and innovative ‘squirt guard’ designed and developed by Waterflow. These systems do require a rectangular area and must run level with the contour, which can limit options of where they can be placed onsite.

• Lines of equal length are laid 1-1.5m apart (spacing is dependent on council regulations) on a level contour and they can either be covered with mulch or buried in the topsoil.
• The laterals are fed from a manifold at the head of the field, ensuring an even distribution across the field.
• At the end of the laterals are flush taps, that allow the flushing out of any contaminants that might build up over time.
• The size and number of the holes is calculated by our design technicians for each project. Innovative squirt guards developed here at WaterFlow, clip over each hole to spread the effluent.
• Larger laterals and orifice sizes mean robustness and less prone to blockages.

LPED Field Calculator

They use higher loading rates than irrigation systems and can reduce your discharge area by up to 50% or more in suitable soils.

These are the most robust LAS systems utilising the earths natural ability to soak up discharge water, using large holes in the dispersal pipes rather than small orifices (like irrigation types), meaning there is virtually no maintenance required and much less chance of blockages over time. Of course, along with the benefits, these systems do have a higher initial investment because of the machinery and materials required to install them.

These beds are normally between 0.5 – 3.0m wide and 0.45m deep and are filled with drainage metal, in which the effluent is discharged using a low-pressure distribution system. The bed is formed with a slight mound and densely planted, across the entire bed, to maximise evapotranspiration and achieve great hydraulic absorption, especially in clay bound soils. These LAS’s can be loaded at a much higher rates than irrigation types, thus reducing the land application area quite significantly in a lot of applications.

Across soakage bed does not require mounding like an ETS bed and can be just grassed, so can have less visual impact on the property, though it is important to remember that these are only suitable in well-draining soils. With these beds being normally between 0.5 – 3.0m wide (though can be wider in some jurisdictions) and 0.45m deep, they can typically sustain higher loading rates, which in turn minimises area required and site impact.

There are a few variations to these, such as sand trenches and deep trenches. Conventional soakage trenches are not so commonly used and depend on council regulations as to their use. If you’re unsure, then get in touch with us early on in your project and we can help you.

Raised mounds are ideal if there is an elevated water table or a flood prone area, where it is necessary to lift the height of the discharge.

Since these require resource consent and aren’t a permitted activity under any council in New Zealand, boreholes are only used on small sites with very limited options for discharge.

We're here to help, get in touch with us to Get a Free Site Assessment as early into your project as you can, and we can recommend the best land application system for your site or property.