Wastewater

Prior to the commissioning of the Westport Wastewater Treatment Plant foul sewage and stormwater were often discharged to the same pipe which was then discharged to the receiving waterways. This stormwater infiltration now causes significant loadings on the plants during wet weather, with sometimes as much as ten times more flow entering the plants than during normal dry weather flow.

As some areas of Westport experience a considerable backup of sewage/stormwater during moderate to heavy rainfall, Council are investigating where stormwater infiltration can be removed. This may include the separation of stormwater at various residential properties.

Council would appreciate any efforts by property owners to separate stormwater from foul sewage lines on their properties, particularly in areas where problems exist. If you require advice please contact Council 0800 807 239.

The purpose of smoke testing is to identify areas within the wastewater network that need attention. Council is undertaking a smoke testing programme in Westport. This programme will be undertaken by WestReef Services staff at various manhole locations around the network.

Smoke testing involves forcing a dense, non-toxic and odourless smoke into the wastewater (sewer) system at a manhole. The smoke fills the main sewer pipe and any connected pipes, and follows the path of any breaks in pipework to the ground surface. Smoke testing staff monitor where smoke escapes the system.

Please refer to our guide to smoke testing (PDF 239.84KB) and what it means for you for some FAQs to access more information on this project.

If you are living in an area that is not connected to the wastewater network, you will have a septic system connected to your house. 

These private septic systems may include pumps or mechanical components (macerators) which need to be regularly serviced to remain effective. This also applies to your tank which requires regular maintenance.

If you own a rural property, your septic tank or other onsite septic systems need to comply to your resource consent from the West Coast Regional Council. It is your responsibility to ensure that your septic system complies to the guidelines in your resource consent.

Septic systems and tanks require regular maintenance to work effectively with a clean being recommended every three to five years.

What is relining? 

Relining is a trenchless method to maintain aged wastewater pipes or fix broken pipes within a wastewater network.

How does it work?  

The work is carried out by specialised contractors who first clean the wastewater pipes then use a robotic camera to re check that the pipe is suitable for relining. This footage is also used to locate the position of household connections. The relining sleeve is then blown through the pipe and cured with UV. Lateral sections (the pipe section from the main wastewater pipe to the property boundary) are cut out and relined or replaced with conventional pipe. 

Relined wastewater pipes have a very similar diameter to the original wastewater pipe. The relining membrane is thin (for works on Adderley St the lining will be 3.7mm thick) the wastewater pipe material is very smooth with few joints, the flow is essentially the same as the original earthenware pipe would have been when new.

The result is a pipe with an equivalent strength to the same PVC/PE pipe which would be used and installed through an open trench. You can read more in the RelineNZ technical Information or on the RelineNZ website.  

What are the benefits?  

Relining is significantly faster and removes the need for open trenching. In places where the wastewater pipes are very deep, open trenching becomes an expensive and slow process, due to requirements such as shoring and dewatering.

Shoring is the placement of barriers to prevent collapse of trenches more than 1.5m deep to protect workers. Dewatering involves pumping the groundwater out of trenches so that the level the pipe needs to be laid at is not submerged and to stabilise the sides of the trench.

For difficult locations relining is more environmentally friendly, time efficient, less expensive and has less impact on residents.

Why is it used ? 

Council relines wastewater pipes in certain areas to strengthen sections in deep, difficult and time sensitive locations. For these locations relining is the method that is more environmentally friendly, time efficient, less expensive and has less impact on residents. It has been used in parts of Westport and Reefton.  

Where are we at?

The relining in parts of Reefton is currently on pause, due to the pre-relign investigations showing an unmapped bend in the main pipe.

This bend would require a manhole installation to ensure proper sewer flow and relining.

Due to this, Council is re-costing and reviewing the religning of the Reefton pipes including the new information in the upgrade.

The investigative CCTV footage shows that some pipes that were planned to be religned, need to be replaced due to their poor condition. Currently more investigation is on its way, since the footage could not capture the state of the full length of the pipe due to debris in the line and the bend.

The Westport relining is currently under way with the relining expected to finish late August and lateral replacement starting shortly after. 

There is some weather dependency to finish the project, since contractors need four days of fine weather – especially considering the interconnected nature of the Westport stormwater and wastewater network.

Very little interruption to businesses is expected during the relining work. Impacted business owner will be contacted by WestReef Services Ltd. WestReef. who is managing this part of the project,  regarding the timing of works and any interruptions.