Stormwater Inflow Reduction Project

Share on Facebook Share on Twitter Share on Linkedin Email this link
Stormwater inflow reduction, keeping stormwater out of the sewer

Coffs Harbour City Council is initiating a Stormwater Inflow Reduction Project to reduce the volume of stormwater entering the sewerage network across our Local Government Area. Stormwater inflow can be difficult to detect as it is not always obvious where the problem is occurring

What is stormwater inflow?

Stormwater inflow is where stormwater is able to enter the sewer system directly. The cause is illegal downpipe connections from homes and other buildings, low or damaged gully traps and damaged or uncovered manholes.

What problems does this cause?

The sewer system is designed to receive domestic sewage from residential and commercial properties. A small amount of storm water entry is unavoidable however, excessive inflow places significant strain on the sewer system and can lead to environmental spills, public health risks and push pump stations and treatment plant operations to capacity.

By reducing storm water inflow into the sewer, Council can continue to provide a cost effective service to residents. If nothing is done about this problem, it will lead to increased operating costs and expensive capacity upgrades, the costs of which are ultimately borne by the ratepayer.

What is Council doing?

Council is embarking on a program of visual inspections and smoke and dye testing of the sewerage system in residential, commercial and industrial areas across the Local Government Area. This testing is to identify sources of stormwater inflow from homes, commercial and public buildings and to have them rectified or repaired.

It is a long term project and it will take a number of years to complete testing and inspection of all suburbs and sewer connected areas.

What does this mean for you?

Once testing commences in your area, if connected to sewer, then your home or premises will be subject to testing and inspection.

You will be given lots of notice ahead of the day of testing. Notifications will be by mail to your address a few weeks in advance and a letter box drop the day prior to testing. Notifications will also be posted on Council’s social media platforms (Facebook and Twitter), in Council’s e-newsletters and on this webpage.

The testing involves pumping a non-toxic smoke (similar to that from fog machines used in theatres and performing arts) into the sewer main and observing where smoke escapes from the system. If smoke escapes from a roof gutter for example, it means there is an illegal cross connection between the roof gutter and the sewer.

Testing inspectors will require access to your property to conduct a visual inspection of external plumbing and drainage systems, inspectors will not need to enter your house.

Dye testing may also be undertaken where required to confirm that stormwater is connected to sewer. This involves a small volume of non-toxic dye being mixed with water and poured into your roof gutter or other suspected cross connection. If the dye is observed entering the sewer, the presence of a stormwater cross connection has been confirmed.

The Police and Fire Service will be notified ahead of all testing to avoid instances of false alarm.

For more information on the testing methods, please see the FAQs on this website.

How can you help?

Council understands that current owners or occupants may not be aware that rainwater from the property is entering the sewage system. Previous owners or residents might have improperly or illegally connected rainwater pipes to the sewer network.

There are some simple things you can do to ensure your property doesn’t contribute to stormwater inflow such as:

  • Check that downpipes discharge to ground or to the street. Observe where water flows. If no point of discharge can be found, there might be an illegal connection
  • Inspect the area around the gully trap or overflow relief gully to ensure stormwater can flow away. Check this during a rain event and if water builds up around it then adjust the landscaping or remove the obstacle (refer to FAQs on this page for more details and further information).

Your understanding of the issues associated with stormwater inflow and your willingness to be part of the solution is appreciated and will benefit everyone who uses this service, whilst also benefiting the local waterways and natural environment.

Coffs Harbour City Council is initiating a Stormwater Inflow Reduction Project to reduce the volume of stormwater entering the sewerage network across our Local Government Area. Stormwater inflow can be difficult to detect as it is not always obvious where the problem is occurring

What is stormwater inflow?

Stormwater inflow is where stormwater is able to enter the sewer system directly. The cause is illegal downpipe connections from homes and other buildings, low or damaged gully traps and damaged or uncovered manholes.

What problems does this cause?

The sewer system is designed to receive domestic sewage from residential and commercial properties. A small amount of storm water entry is unavoidable however, excessive inflow places significant strain on the sewer system and can lead to environmental spills, public health risks and push pump stations and treatment plant operations to capacity.

By reducing storm water inflow into the sewer, Council can continue to provide a cost effective service to residents. If nothing is done about this problem, it will lead to increased operating costs and expensive capacity upgrades, the costs of which are ultimately borne by the ratepayer.

What is Council doing?

Council is embarking on a program of visual inspections and smoke and dye testing of the sewerage system in residential, commercial and industrial areas across the Local Government Area. This testing is to identify sources of stormwater inflow from homes, commercial and public buildings and to have them rectified or repaired.

It is a long term project and it will take a number of years to complete testing and inspection of all suburbs and sewer connected areas.

What does this mean for you?

Once testing commences in your area, if connected to sewer, then your home or premises will be subject to testing and inspection.

You will be given lots of notice ahead of the day of testing. Notifications will be by mail to your address a few weeks in advance and a letter box drop the day prior to testing. Notifications will also be posted on Council’s social media platforms (Facebook and Twitter), in Council’s e-newsletters and on this webpage.

The testing involves pumping a non-toxic smoke (similar to that from fog machines used in theatres and performing arts) into the sewer main and observing where smoke escapes from the system. If smoke escapes from a roof gutter for example, it means there is an illegal cross connection between the roof gutter and the sewer.

Testing inspectors will require access to your property to conduct a visual inspection of external plumbing and drainage systems, inspectors will not need to enter your house.

Dye testing may also be undertaken where required to confirm that stormwater is connected to sewer. This involves a small volume of non-toxic dye being mixed with water and poured into your roof gutter or other suspected cross connection. If the dye is observed entering the sewer, the presence of a stormwater cross connection has been confirmed.

The Police and Fire Service will be notified ahead of all testing to avoid instances of false alarm.

For more information on the testing methods, please see the FAQs on this website.

How can you help?

Council understands that current owners or occupants may not be aware that rainwater from the property is entering the sewage system. Previous owners or residents might have improperly or illegally connected rainwater pipes to the sewer network.

There are some simple things you can do to ensure your property doesn’t contribute to stormwater inflow such as:

  • Check that downpipes discharge to ground or to the street. Observe where water flows. If no point of discharge can be found, there might be an illegal connection
  • Inspect the area around the gully trap or overflow relief gully to ensure stormwater can flow away. Check this during a rain event and if water builds up around it then adjust the landscaping or remove the obstacle (refer to FAQs on this page for more details and further information).

Your understanding of the issues associated with stormwater inflow and your willingness to be part of the solution is appreciated and will benefit everyone who uses this service, whilst also benefiting the local waterways and natural environment.