Land Application Areas
  • Last updated:
  • 22 Jul 2016

The land application area (LAA) is an important part of the on-site sewerage facility (OSF). It disposes or re-uses the wastewater generated within the property. This water must remain within the property boundary. There are a few simple measures that can be undertaken to ensure that your LAA is working effectively.

Trenches

Trench based systems utilise primary treated wastewater that has not been chlorinated. The water will contain high levels of bacteria and potential pathogenic organisms. To avoid human and animal contact, the wastewater disposal happens below the soil surface. Reasons for these systems to fail include:

  • solids from the septic tank or primary chamber carry over to the trenches and block the pores of the soil. This can prevent the effluent from being absorbed into the soil and cause the trenches to overflow
  • tree roots block pipes and trenches
  • overgrown LAAs prevent sun and wind from transpiring excess moisture
  • out of level trenches not working to full capacity due to soil settlement. This can result in trenches overflowing at any low point.

Surface irrigation

Surface irrigation systems distribute secondary quality chlorinated effluent over grassed or gardened LAAs to re-use the wastewater. Reasons for these systems to fail include:

  • failing treatment plant resulting in poor water quality
  • sprinklers not being moved or rotated
  • no chlorine in the system
  • sprinklers too close to neighbouring properties
  • blocked filter, if fitted
  • poor drainage in the top layer of soil resulting in ponding in the LAA.

Sub surface irrigation

Sub surface irrigation systems distribute secondary quality chlorinated effluent to the LAA via a network of small bore piping. The piping has drippers spaced regularly to spread the effluent over the LAA. Reasons for these systems to fail include:

  • small particles flowing from the treatment plant can block the drippers in the small bore pipework
  • blocked or damaged indexing valve can cause incorrect dosing to the LAA
  • blocked filter
  • poor drainage in the top layer of soil resulting in ponding in the LAA.

For a comprehensive guide refer to council's land application areas fact sheet[399KB].