Amended soil mounds

Amended soil mounds

Amended soil mound

An amended soil mound in the Blue Mountains.

Amended soil mound diagram

Cross section of an amended soil mound.

Amended soil mounds use specially modified soil to remove extra nutrients (phosphorus and nitrogen) and microorganisms from the effluent. Effluent is pumped or flows by gravity into the mound where nutrients are removed as the effluent moves through the soil.

Septic tanks are the most common treatment system used with amended soil mounds, but they may also be combined with composting toilets, biological filter systems and aerated wastewater treatment systems (standard and advanced).

Common problems with amended soil mounds are:

  • installing mounds on too steeply sloping sites or deep enough to connect with groundwater
  • building the mound too flat, so that rainfall doesn't run off but is absorbed in the mound
  • inadequate stormwater diversion drains, causing the mound to become saturated
  • mound too small for amount of effluent (hydraulic load).


Tuesday 12 November
1,214,619 ML
2,596,150 ML
9,129 ML
1,305 ML
-13,833 ML
Tuesday 12 November