Recycle pits

Recycle pits — Key Considerations

Select from the tabs below

• Overview
• Key Considerations
• Planning and design
• Construction and operation
• Links and references

What makes a good recycle pit?

• Sized to capture all irrigation tailwater from a production area – with sufficient volume in the recycle pit to capture the tailwater from a complete irrigation event (and/or the first flush of stormwater).
• A bypass system to allow high flows to bypass the recycling pit with minimal mixing during high flow events.
• Impermeable base and walls to ensure that water is stored without losses to groundwater.
• Adequate capacity is maintained to capture the next event, by reusing water on-farm as soon as possible after the irrigation or rainfall event.
• Sufficient pumping capacity. Pumps and pipelines must be appropriately sized and located to allow rapid and efficient reuse of the water. Possibly solar to reduce electricity costs.

Treatment processes

Suitability and limitations

Recycle pits are generally used in areas where surface furrow irrigation results in tailwater run-off. This is primarily in irrigated sugarcane and broadacre cotton and grain crops[3][2] in the Burdekin, Fitzroy and Burnett Mary regions. Recycle pits are also used, although are not as widespread, in other regions such as the Mackay Whitsundays.

Approximately 15-20% of the irrigation water applied to sugarcane is lost as run-off[4]. By capturing and reusing this run-off, recycle pits have the potential to significantly reduce the losses of sediments, nutrients and pesticides to downstream waterways. They need to be operated correctly in order to improve water quality. That is, to ensure water is rapidly re-used on the farm and sufficient capacity is maintained in the recycle pit to capture all irrigation tailwater, without overflowing to downstream waterways[1].

Recycle pits can be a cost-effective way to improve water quality and ensure water security. An economic assessment of recycle pits in the lower Burdekin suggests that the combined savings in irrigation water and fertiliser, would allow the farm to recoup the construction costs of recycle pits within four years[5].

The actual cost-effectiveness of recycle pit will vary for each individual site. The cost-effectiveness needs to be considered relative to other treatment systems or management intervention options. Refer to cost considerations for more information.

References

1. ^ Rickert, A & Kenniff, J (2018), Recycle pit data review: Summary report, Burdekin Bowen Integrated Floodplain Management Advisory Committee, Ayr.
2. ^ Rose, M, Crossan, A, Kennedy, I, Chapman, V & Spanswick, S (2006), Wetlands and water storages on cotton farms.
3. ^ Shannon, E & McShane, T (2013), Options for tailwater capture and reuse in the Barratta catchment: A scoping study, FarmAcist and BBIFMAC, Ayr.
4. ^ Sugar Research Australia (2020), 'A new horizon for irrigation in the Lower Burdekin', Lower Burdekin irrigation Extension Action Plan Project, Queensland Government Reef Water Quality Program.
5. ^ Waltham, N, Canning, A, Smart, J, Hasan, S, Curwen, G & Waterhouse, J (2020), 'Scoping land conversion options for high DIN risk, low-lying sugarcane, to alternative use for water quality improvement in Dry Tropics catchments', Report to the National Environmental Science Programme, p. 303, Cairns.

Last updated: 10 June 2022