Harvest Scientific Services

Wastewater Modelling and Design

 

The Firm has conducted numerous wastewater assessments and reports over the last two decades. Clients have included single residential allotments through to large scale residential and commercial developments including factory sites, multi-residential subdivisions and retirement villages and hostels.

Wastewater assessments require a detailed site investigation to be conducted inclusive of soil test work to establish the capacity of a development site to accept wastewater. In most cases, consideration is given to the scale of the development, the likely volumes of wastewater generated and the site constraints (eg: soil characteristics, topographic features and site drainage conditions). 

Reports are prepared referencing the Environment & Health Protection Guidelines, the AS/NZS Standard 1547:2000 and the local council’s approvals policy for new installations of On-site Management Systems.

The majority of sites are assessed on the basis that all wastewater  flows will be treated onsite with an Aerated Wastewater Treatment System (AWTS), with effluent being disposed of onsite via one of the following methods:

• Surface-spray
• Surface-drip
• Sub-surface effluent irrigation

New developments generally require an evaluation of any existing on-site treatment systems. Our experience has indicated that most existing on-site systems (principally trench systems) older than 30 years show evidence of failure. In such cases, the older system needs to be decommissioned and replaced by a modern AWTS sewage management system.

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