Home » Services & Infrastructure » Infrastructure » Water & sewer » Major projects
The township of Yamba and the neighbouring communities of Angourie and Wooloweyah are located on the North Coast of NSW on the mouth of the Clarence River and are serviced by a centralised gravity sewerage system that transports raw sewage to the Yamba Sewage Treatment Plant (STP).
| About the project | News update | Outcomes | Progress | Publications | More information | Construction Updates | Glossary |
Construction of the Yamba Sewerage Augmentation was completed in June 2016.
Download this diagram of the ebb-tide pipeline.
The Sewage Treatment Plant (STP) was constructed in 1973 and has since undergone four augmentations.
in 2016 the Yamba STP was upgraded from 7,400 EP to 16,200 EP to provide capacity for predicted population growth in the catchment and holiday flows. Treatment quality was improved to increase beneficial reuse on sporting fields, while recycled water unable to be reused is released to the environment via an ebb-tide release. Prior to May 2016, environmental release was to woodlands/wetlands to the South and West of the STP and the excess water was causing degradation of the vegetation.
Clarence Valley Council is keen to ensure all raw sewage produced now and in the future is adequately treated to a standard suitable for re-use or for safe release into the environment. Council also aims to develop more sustainable opportunities for the re-use of recycled water in the area.
The Yamba Sewerage Augmentation Project was devised by Clarence Valley Council in close consultation with the Yamba Water Recycling Management Committee (YWRMC) consultation group and State agencies. The project consists of:
Consultants WorleyParsons undertook detailed design for the Yamba Sewerage Project.
| Back to Top |
The $43.3 million Yamba Sewerage Augmentation was constructed in two contract packages - a Sewage Treatment Plant (STP) package and a reticulation and ebb-tide release contract. The STP tender was awarded to Haslin Constructions in January 2014 and was completed in November 2015. The reticulation and ebb-tide release package was awarded to Ledonne Constructions in January 2015, and was completed in May 2016. The project was completed 14% under its pre-construciton budget of $50.4 million. The NSW State Government provided 5.2% financial assistance under the Country Towns Water Supply and Sewerage Scheme.
Investigations are being undertaken to:
Following negotiations with stakeholders, a single under water corridor was approved by Council in September 2014 for the Yamba and Iluka recycled water pipelines, and is adjacent to the Country Energy power line upgrade between Yamba and Iluka. A Review of Environmental Factors (REF) to assess environmental impacts of the construction and operation of the ebb-tide release was approved by Council in September 2014. The ebb-tide release has operated since May 2016.
The YWRMC was a community committee which provided feedback to Council through all stages of the project. The committee, which represented a wide range of local community interests, was established in 1999 by Council to assist and advise Council throughout the life of this upgrading phase. The Committee's final meeting was held in August 2016, where Council formally thanked all members for their work in developing the Yamba Seweage Augmentation.
The YWRMC developed an occasional newsletter known as Water Cycle which updated Yamba residents on progress with the sewerage augmentation.
The Yamba Sewerage Augmentation represented an effective partnership of government agencies, local government, contractor and the community.
| Back To Top |
Augmentation = improvement and making larger. The Yamba Sewerage System is improving the level of treatment at the Sewage Treatment Plant to produce the highest quality recycled water possible and to increase its capacity from 7,400 EP to 17,200 EP. It is also extending the network of pipes and pumps to maximise reuse of recycled water with irrigation; and enable environmental release of excess recycled water not able to be reused during wet weather.
Coffer dam = A temporary structure which will be built in the river to protect the divers who are constructing the ebb-tide diffuser. This will allow them to work on the diffuser despite underwater currents. It will also ensure that the material which makes up the riverbed will be contained within the structure when the drill hole “breaks through” the bed of the river and not create a cloud of dirty water. The coffer dam will be constructed using sheet piles which will extend from above the water surface to the bed of the river and will be dismantled when the ebb-tide diffuser construction is completed
Collection pit = an underground tank upstream of a sewer pump station into which rising mains discharge. When raw sewage sits in rising mains for some time, it can become high in sulphides due to natural chemical reactions. The sulphides can cause corrosion of concrete manholes and odour problems. Air is extracted from the collection pit using forced ventilation to reduce odours. Part of the Yamba sewerage augmentation includes extending existing rising mains to a collection pit upstream of the pump station in Park Avenue so that the rising mains no longer discharge into manholes in the network. This will reduce both corrosion and odour problems in the pipe network.
Ebb-tide release = flow of excess recycled water into the river on the outgoing tide. Recycled water that can’t be reused (eg., in wet weather when no irrigation needed) will be released through a diffusing structure on the bed of the Clarence River, on the north side of the shipping channel. Recycled water will only be released on an ebb (outgoing) tide, with the release ceasing in sufficient time so that all recycled water will reach the ocean before the tide turns.
EP = equivalent persons. This is a measure of theoretical sewage load of an ‘average person’, including both flow (volume of water) and nutrients (amount of bacteria, chemicals, etc). The sewerage system has residential and non-residential uses, so a common measurement is needed to express the need for and supply of sewerage infrastructure. In other words, the sewerage system serves individual people in domestic houses and units, as well as in restaurants, hotels and other places; and it also serves local industries (eg., sewage from the industrial estate). The sewage produced by all these parts of our community are translated into the measure of “equivalent persons” (EPs). For example, the new improved STP will provide treatment for 17,200 EP; 11,000 EP being for the local residential population and 6,200 EP for tourism and other non-residential uses.
HDD = horizontal directional drilling = a steerable, trenchless method of installing underground pipes. A surface-launched drilling rig is used to drill underground in a shallow arc along a prescribed bore path. HDD is being used to drill a borehole under the bed of beneath the Clarence River to the ebb-tide release point. A pilot hole will be drilled first, then reamed (enlarged), and finally the recycled water pipeline will be inserted. The HDD Launch Site, where the drilling rig is situated, is on Yamba Rd almost opposite the marina. It is surrounded by a series of shipping containers that form part of a noise abatement strategy (reducing the impact of drilling noise on surrounding residents).
Hydrostatic testing = pressurising the pipeline to a specified pressure and maintaining the pressure for a set amount of time. It is how we determine if there are any leaks in the pipeline.
Manhole audits = Manholes are the large concrete discs that allow workers access to the sewerage system. They are not watertight, so in extremely wet weather, especially when water pools or ponds in over the manhole, stormwater can enter the sewerage system. This increases the volume of sewage that needs to be treated at the STP, increasing the need for infrastructure (pumps and pipes), energy use and the amount of recycled water needing to be used or released into the environment. An analysis (audit) of existing manholes in areas where stormwater is known to pond is being undertaken to determine whether the lids can be replaced with sealed and “locked” manholes, which prevents stormwater inflow.
ORG/drainage audits = ORG stands for “overflow relief gully” which is sometimes known as a “yard gully”. An ORG is a critical part of the sewerage system as it prevents sewage from flooding houses. ORGs are a drain-like fitting located in the ground outside a house, usually near the laundry area, and are at a lower level than the house floor. They are designed to overflow sewage onto the ground outside the house (rather than inside the house) if there is a plumbing blockage or excessive rain water in the sewerage network. Large houses with a few bathrooms may have more than one overflow relief gully. In extremely wet weather, if water ponds in people’s backyards the stormwater can flow back into the sewerage system through the ORG. This increases the volume of sewage that needs to be treated at the STP, increasing the need for infrastructure (pumps and pipes), energy use and the amount of recycled water needing to be used or released into the environment. Council is inspecting ORGs in areas where ponding is known to occur to see if the existing ORGs can be replaced with special ORGs which have a one way valve, which will release sewage but not let stormwater enter the system.
PE pipe = polyethylene pipe (most people call this “poly-pipe”). The sizes of polypipe used in this project range from about 90mm to 375mm diameter on the inside of the pipe. It is welded together with a special PE melting welder (not your average arc-welder used for metal!).
Potable water = the town water supply that is of such a high quality it can be used for all purposes including drinking.
Reaming = enlarging the pilot hole to the diameter required for the ebb-tide release pipeline. The pilot hole is enlarged using a series of reamers as the process may take several stages to reach the desired diameter and maintain borehole integrity. Drilling fluids are used to remove cuttings and stablise the borehole.
Recycled water = Wastewater that has been treated to a standard sufficient to enable it to be reused for a particular purpose (eg., watering sportsfields, public parks and golfcourses; agricultural irrigation; household uses such as toilet flushing, car washing and watering gardens). Using recycled water helps us use our drinking water supplies more efficiently.
Recycled water main = large pipe carrying recycled water from the Sewage Treatment Plant to place of reuse (eg., golfcourse, sportsfields) or environmental release (diffuser for ebb-tide release). Mains range from 100mm to 375mm in diameter and are made from either PVC or polyethylene (PE)
Sewage = what flows from our toilets, bathrooms, kitchens and laundries into the sewerage system.
Sewerage = the infrastructure which transports and treats sewage (including pumps, pipes, Sewage Treatment Plant).
Sewer rising main = a pressurized pipe that transports raw sewage from a sewer pump station to either a manhole or a collection pit.
Sewer pump station = electrically powered pumps which pump raw sewage through rising mains from underground storage called a “well”. The pumps automatically operate based on the depth of sewage in the well, and there is a minimum of two pumps per well in case one pump fails and to provide greater pumping capacity during wet weather. The pump stations have electrical controls above ground, and an alarm if the level in the well gets too high so Council is alerted that there is a problem. Because Yamba is very flat, the sewage from some areas travels through two pump stations before reaching the Sewage Treatment Plant.
Steel casing = lining the first 75 metres of the pilot hole being drilled under the Clarence River. As part of the horizontal directional drilling (HDD) of the ebb-tide release pipeline, the initial section of the pilot hole needs to be lined with steel so that soft soil and sediment does not collapse into the hole. The steel will remain in place while the drilling occurs and the pipeline inserted through it. It will then be removed.
Underboring = using trenchless technology to lay pipework (eg., along Angourie Rd). Rather than digging trenches, laying pipes and refilling the trenches with soil, a ‘short drill’ is being used to create a horizontal hole in the ground through which pipework is inserted. This minimizes disruption to the surrounding environment and infrastructure such as roads, footpaths, stormwater pipes and telecommunication wiring.
Clarence Valley Council welcomes your comments and feedback regarding the Yamba Sewerage Scheme Augmentation Project. If you wish to comment on the Project please contact Council's Water Cycle section.