Catchment Sensitive Farming: Practical Tips

Practical Tip: Sediment ponds

Sediment ponds vary in size depending on the estimated volume of field run-off that needs to be contained for sufficient time to allow sediment to fall out of suspension.

For relatively small scale operations where most of the soil is excavated and where constructed above-ground embankments are not needed, the work should include the following:-

  • Excavate soil to an appropriate depth. 
  • The soil used from the excavation may be used to create gently sloping banks. 
  • Spread excess soil thinly across land away from the excavated pond area.

For larger scale operations, you should take advice from a qualified soil and water engineer. The work may include the following:-

  • Excavate top soil and an appropriate depth of subsoil. Stack them separately.
  • Construct embankments with subsoil, making sure they are properly compacted to provide a stable structure. 
  • Install an outflow pipe at a suitable location 750 mm below the top of the embankment to provide a freeboard. You may need to provide protection (e.g. stone pitching, slabs or concrete spillway) around the outflow to avoid damaging the receiving ditch. 
  • Spread top soil to the embankments and its outside slopes to allow vegetation to grow to help stabilise slopes and prevent erosion. A grass seed mix of 25 g/mē is suitable.

Please note that although sediment ponds will help to intercept surface run-off they should only be used when other management practices have failed to control the risk of erosion.

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