Capture of 12,000m2 dairy shed, loafing pad, feed storage, feed pad and holding yard dairy effluent. Solids removal via twin drying beds with weeping walls constructed on a floating foundation, 10,000m3 lined effluent irrigation storage pond and automated effluent irrigation pumping system achieving 50m3/hr (50,000 L/hr) at 3.5mm/hr application rate.



AgResearch Tokanui had an existing dairy shed with an under-performing dairy effluent system. Their storage capacity was approximately half of the required size, the effluent irrigation capacity was not sufficient and there were multiple challenges with solids from the feed pad and the two pond system that was in place.

There were many challenges. The existing ponds were in the only location that gravity could be achieved. The new system had to be constructed in the same location of the existing system at the same time as keeping the existing system operational. The subsurface ground conditions were excessively soft, there was no space for the required 10,000m3 pond via gravity and the surrounding areas were of challenging contour. The effluent irrigation area had a large elevation variation and many different soil types. The existing irrigation pipeline and application system infrastructure was to be utilised even though additional capacity was required.


Design Specifics:

  • 66m x 12m x 1.8m 200mm thick 40MPA pre-cast concrete weeping wall system.
  • 10,000m3 pond at 4.5m depth with 2:1 internal batters. Constructed on slope, 5m wide crest with up to 7m high external embankment and 4:1 batter slope. No carted fill required.
  • 1.5mm HDPE pond lining, geotextile underlay, Tenax tendrain drainage and leak detection system via gravity plus sub-liner gas ventilation system.
  • 37.5kW Grundfos shore mounted centrifugal water irrigation pump with self-cleaning suction screen.
  • Irrigation pump VSD (Variable Speed Drive), PLC and touch screen for complete control, three irrigation pressure set points for varying areas of the farm, automatic fresh water priming on start-up, automatic flood wash tank fill, touch screen effluent area selection with either multiple pipeline irrigation or single on demand.
  • Full Effluent Management Plan, Engineering Design, As-builts, Staff Training and support.
  • Full project designed, supplied, constructed, signed off and serviced by AgFirst Engineering. 


AgFirst Engineering is interested in helping you ensure you maximise your dairy effluent value and provide an easy to manage system. Get in contact with us or call on 0800 118 111.