Eco Trench Wastewater Systems

What is an Eco Trench?

An Eco Trench is an on site wastewater management system and one of the most reliable, compact and efficient systems available to receive treated wastewater. Ideal for smaller sections, and a great option on properties with high ground water levels.

Eco Trenches comprises four key components: The wastewater source fixtures and activities which can affect the quantity and quality of the wastewater to; the treatment plant, a dosing system and a land application system or dispersal field.

There are a number of different types of land application systems, one of which is the EcoTrench. This page offers a brief explanation and description of the Eco Trench.

If you would like more information about how an Eco Trench might work for you, get in touch with us today for an assessment.

How does an Eco Trench Work?

The idea of the EcoTrench was developed by ecoEng when working in the Cook Islands in 2006. A small but effective land application system was required to disperse septic tank effluent. It was originally called the Banana Trench.

The Eco Trench has been developed by ecoEng as a low footprint post treatment land application system (LAS) option for the sustainable and effective on-site management of domestic wastewater.

The Eco Trench is designed to maximise site risk mitigation through treatment and optimising beneficial water balance. One of the more expensive LAS option to install, it is specifically designed for sites with limiting available land area and for sites with high groundwater.

To date there have been about 50 Eco Trenches installed in the Canterbury region. The Eco Trench receives treated domestic wastewater treated to secondary effluent standard. The actual size and dimensions of the EcoTrench is to be designed for the site’s specific conditions and will depend on things such as the design volume to be managed each day, influent quality to the EcoTrench; particularly BOD5 and possibly the land area available for the EcoTrench.

Schematic illustration of an Eco Trench wastewater system layout

The EcoTrench is designed to optimise the on site management of as much of the pre-treated wastewater as is acceptable, safe and compliant, before storage and final off site cartage, or, where permissible, off site discharge. It relies on several processes for the management of the treated effluent.

  • Efficient degradation and stabilisation of remaining effluent organics (BOD) by the humus ecology located on top of the sand column.
  • Sand (2A sand or equivalent filter sand) filtration to remove pathogens.
  • Evapotranspiration from the sloping surface of the ecoTrench.
  • Buffering storage within base gravel pores.
  • Soakage to ground at the base of the ecoTrench.
  • Prevention of surface ponding by the installation of under drainage should the hydraulic capacity of the soakage bed base be exceeded.
  • Shedding of rainfall by mounding.
  • Water balance componentsPerimeter or up slope interceptor field drains to optimise the water balance for wastewater soakage.