Darlington, Perth Hills
Decentralised Wastewater Treatment
About this Project
Darlington is semi-rural suburb located on the Darling Scarp and has limited access to sewage infrastructure. This property is one of many in the area that requires on site waste water treatment.
Our part in this project was to design and install a secondary treatment system (STS) to process all water from the home and allow safe dispersal elsewhere on the property.
As a certified installer and servicer of decentralised waste water treatment systems, we have specific skills and knowledge to produce safe and effective waste water systems such as this.
- Council Approvals
- Commissioning & Handover
In Western Australia, local councils must approve the design of a secondary treatment system before it can be installed. This is to ensure safety standards are adherred to on a local level.
The design we proposed implemented a FujiClean CE-1500EX unit that has a daily flow rate of 1500 litres. This was based off the average water consumption of a classic large Australian home with numerous occupants. The FujiClean CE-1500EX is more than adequate for this flow rate of this home.
Our design included effluent dispersal areas with a combined area of 150 square metres. We completed a localised Site-and-Soil Evaluation (SSE) to assess soil permeability, depth-to-groundwater, slope and aspect of the site.
The Shire of Mundaring approved our application to install the secondary-treatment-system and we promptly began the installation process.
There were two parts to this installation;
- The STS unit
- Subsurface drip irrigation
The FujiClean unit is relatively large, with a working capacity of 4,359 litres it is designed to be semi-submerged underground where it is out of sight and out of mind. An excavator was used to create a hole 2800mm long, 1800mm wide and approximately 2280mm deep.
There is a very specific checklist of actions that need to be completed during the installation to ensure the system can be commissioned and used.
These are the general items for installations but there are extra requirements that change between areas and local councils.
- Sand bedding
- Depth from sand bed to natural ground level no greater than 2270mm
- Motor box base is secure
- Fill all chambers to 4,000 litres
- Backfill around tank with clean fill or 5-7mm crushed blue metal.
There are two effluent dispersal areas that cover a total of 150 square metres which we calculated as the correct dispersal area given soil permeability and daily flow rate of the unit.
Effluent dispersal areas are characterised by lilac drip, we used Netafim’s Lilac Tiran subsurface irrigation. Effluent has a high nitrate content that is good for the lawn on the top dispersal area as well as the orchard below.
Comissioning & Handover
Earth & Water completed a FujiClean Commissioning Certificate that confirms that all the components have been checked and are functional.
The same certificate was sent to the Health Officer at the Shire of Mundaring where they maintain records about secondary treatment systems in their area.
All residential decentralised waste water treatment systems must be serviced every three months. Although the FujiClean CE-1500EX has a structural warranty of 15 years, it is important to be vigilant when there is a risk of contamination.
These are a few of the components that are checked prior to signing off a commissioning certificate:
- Air blower
- Aeration tank diffusers
- Effluent transfer chamber
- Alarm warning systems
A routine service for a FujiClean STS is $198 for the Perth Metro given there are no issues. Routine services catch problems before they get out of hand. A certified service technician will check
- Effluent clarity
- Sludge and scum levels
- Each filtration chamber for foaming and aeration
- Effluent dispersal area
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