Wastewater Treatment Systems

Routine maintenance

Schools manage their inspection and maintenance activities by first familiarising themselves with their system and referring to their permits or licences. The Environment Protection Regulations 2021 (Vic) provide more specific requirements for the management of on-site wastewater management systems (OWMS) with flow rates not exceeding 5,000 litres on any day, including older legacy systems.

Under the Regulations, schools with OWMS must take reasonable steps to:

• operate the system so it does not pose a risk to human health or the environment
• maintain the system in good working order, including older legacy systems that may not meet current standards
• check for signs the system may be failing or is not in good working order
• respond to any system failures.

Permits and licences identify the system specific inspection and maintenance activities that are necessary to ensure the OWMS is safe for use. Refer to the permits and licenses chapter for further information.

Schools use the Asset Information Management System (AIMS) to manage their OWMS maintenance and preventative measures by activating their annual contracts OWMS routine maintenance tasks. Activation of routine maintenance tasks in AIMS automates the creation of reoccurring work orders that are used to manage on-site wastewater systems.

The routine maintenance tasks available for school use in AIMS are:

• AC2.1 – On-site Wastewater Management Systems – Septic Tank (Annually)
• AC2.2 – On-site Wastewater Management Systems – Tank and Treatment (Quarterly)
• AC2.3 – On-site Wastewater Management Systems – Emptying/Desludge.

A school will only need to activate either AC2.1 or AC2.2. All schools with OWMS must activate AC2.3. The Environment Protection Regulations 2021 (Vic) also require schools to:

• keep maintenance service records and provide them to their local council on request
• provide information to occupiers on how to correctly operate and maintain the system
• notify their local council of signs of failure or that the system is not in good working order.

Additionally, schools must ensure that system inspection reports, water quality testing results (if required), LGA defect notifications, and maintenance activities are documented and recorded in AIMS, with records kept for a minimum of 2 years. Schools that are not yet using AIMS should continue to keep local records until AIMS is available.

If your school is yet to be inducted to AIMS, maintenance tasks should be scheduled into the school’s maintenance calendar.

Refer to the AIMS and OWMS quick reference guide on the Resources tab for more information on activating routine maintenance tasks and record keeping in AIMS.

Inspection and maintenance activities

Schools must undertake regular inspection and maintenance activities to keep their OWMS safe for use. This means annually for primary systems and quarterly for secondary systems. Schools must:

• review permits and licenses to ensure they are valid and not expired
• inspect the conditions of septic tanks and treatment plants
• inspect drainage for evidence of blockages/overflow
• inspect the conditions of distribution pit/s and absorption trenches/fields
• inspect tank covers and screens to ensure they are intact
• take flow meter reading (if installed)
• check and confirm system allowances (system type and size) are still fit-for-purpose based on school population size (loading)
• check sludge levels
• perform tests and checks as per EPA 891.4 or equivalent (that is, biochemical oxygen demand (BOD), E.coli, suspended solids) and take action if required
• identify defects, provide defect notification to LGA, and keep record of notification
• schedule and arrange desludging (every 3 years) or when required using an EPA accredited waste management consigner.

Inspection and maintenance works should be carried out by a Victorian Building Authority (VBA) registered plumber or suitably experienced service providers, depending on the works required.

Schools are required to keep records of system maintenance, inspections, and water quality test results for at least 2 years.

Desludging/pump out

To keep your septic system treating sewage efficiently, the tank needs to be pumped every 3 years or once deemed required by inspection by an EPA accredited waste management consigner. The pumping-out/desludging is to be conducted by an EPA accredited waste management consigner specialised with on-site wastewater management systems. More information about accredited waste consigners is available on the EPA website.

The bottom of the septic tank accumulates sludge as the septic system is used. Tank efficiency reduces with an increasing sludge level and solids are more likely to escape into the absorption area. When sludge accumulates too long there is no settling, causing sewage to go directly to the soil absorption area. This results in less sewage being treated.

It is important to know that the soil absorption field will not malfunction immediately if a tank is not pumped out. However, the septic tank is no longer protecting the soil absorption field from solids.

It is possible that the soil in the absorption field will need to be replaced if the tank is neglected for a long time.

After pumping out, tanks must not be washed out or disinfected. They should be refilled with water to reduce odours and ensure stability of plumbing fixtures. A small residue of sludge will always remain and will assist in the immediate re-establishment of bacterial action in the tank.

Schools should keep a record of their septic tank pump-outs and notify the local council that a pump-out was undertaken in accordance with the council permit.

Treatment testing

For complex secondary systems, effluent quality tests (to be carried out by a qualified plumbing or wastewater engineer), are required at the frequency required by the permit or licence to ensure the treatment plant is performing within limits. Performance limits depend on the effluent end use.

• Primary simple systems do not have a specific water quality standard.
• For effluent disposed by surface irrigation, the EPA advanced secondary effluent standard (10/10/10) applies. Samples are to be analysed for:
  • biochemical oxygen demand (BOD) – less than 10mg/L BOD
  • total suspended solids (TSS) – less than 10mg/L TSS
  • E.coli bacteria – less than 10 Escherichia coli cfu/100.

Other analysis may need to be conducted depending on the system and treatments used such as chlorine analyses. Schools should refer to their LGA permit or EPA license for full water quality testing requirements.

Testing samples for analysis must be conducted to a laboratory accredited by the National Association of Testing Authorities (NATA).