Denmark water supply upgrade

Project goal:

We are working to improve the supply of water to the town of Denmark and investigating long-term water supply options.

Delivery date:

2017-18

Management of brackish water

Denmark experienced its second driest year on record in 2014, which impacted inflow to the town's main drinking water source, Quickup Dam. We have put in place plans to help secure the town's water supplies.

Portable desalination units have been installed at Denmark Water Treatment Plant for use when the town's secondary source, Denmark River, has high salinity levels. To date, the portable desalination units have not been required. However, they will allow greater flexibility in using the two sources for supply purposes.

Brackish (salty) water is a by-product of desalination procedures. The water is about half as salty as seawater so therefore needs to be managed and disposed of appropriately. 

We have systematically followed steps in analysing possible disposal options that focus on local solutions which have positive economic, social and environmental outcomes. Currently, we're exploring the following disposal options:

New technology

This option will concentrate the brackish water up to eight times at our treatment plant, significantly reducing the volume requiring disposal. The remaining brackish water will then be trucked to our Timewell Road storage pond, which will act as an evaporation point.

In April 2017 Water Corporation invited organisations to submit a proposal outlining a sustainable solution for managing the disposal of brackish water from the desalination units, should they be required. We will involve further community consultation, should any of the proposals be pursued.

Ocean disposal around Denmark

This option would involve tankering brackish water to possible beach locations. The water would be released into the ocean through a small above-ground pipeline.

Denmark River - not viable at this stage

This option would release the brackish water downstream of the Denmark Dam directly from the Denmark Water Treatment Plant. At this stage, the disposal option may not be viable as a year-round solution as there will be a requirement to further dilute the brackish water.

Existing Albany tree farm - not viable at this stage

Brackish water would be transported to Albany and stored at the Water Corporation’s Timewell Road Wastewater Treatment Plant pond. Gradually it would be blended onto the tree farm. At this stage, this option would only be viable during certain times of the year and only for a limited time.

We thank the Denmark community and other affected stakeholders for their cooperation and patience while this essential work is carried out and for their ongoing water conservation efforts.

Quickup and Denmark River Dam levels

In June 2016, Denmark received an above average rainfall of 147mm, higher than the 2015 average rainfall of 84mm.

Since June 2016, we have been pumping water from Denmark River Dam to Quickup Dam to increase water storage.  Our pump back strategy has played a significant role in ensuring Quickup Dam can continue to supply water to Denmark. 

There has been a considerable improvement in the water levels at Quickup Dam and Denmark River Dam which continue to run much higher than 2016. We hope the pump-back strategy continues to have a positive impact on the dam levels.

Longer-term water supply options & drilling investigations

In March 2016, we commenced aerial investigations to locate potential groundwater sources around Denmark.

The survey used magnetic signals to identify rock formations below the ground likely to store groundwater. The final report identified 40 target sites for potential groundwater investigation. Ground-based geophysical surveys were performed in January 2017 to refine the target areas into 15 specific locations for the planned drilling investigations.

In July and August 2017, work was carried out to drill five of the locations. Two of the locations identified significant water flow, however, the water returned a high salinity count and may not be useful. We are currently waiting for a full report from the consultant.

Due to wet ground conditions, investigations of the remaining locations has been postponed until the warmer months between November 2017 and January 2018.

We will continue to engage with the community, regulators and other stakeholders as our investigations continue. 

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Contact us

  • Regional Engagement and Communications Officer Kate Duff, Email: kate.duff@watercorporation.com.au, Phone: (08) 98424252
  • Project Manager Rob Kneebone, Email: rob.kneebone@watercorporation.com.au , Phone: (08) 9420 2810
  • Community Engagement Officer Larissa Stanley, Email: larissa.stanley@watercorporation.com.au, Phone: (08) 9420 2789

Frequently asked questions

Below are answers to a number of frequently asked questions surrounding the project.

 

What is the climate outlook?

Over the next 30 years, the south west of WA is expected to experience further declines in rainfall due to climate change. The Lower Great Southern has a projected decline in rainfall of up to 40%. This will have a significant impact on water availability for households, business and industry, local government, mining, agriculture and the environment.

How does Denmark and Albany’s current rainfall compare to previous years?

Since 1975 average rainfall has declined by 9% in Denmark and 8% in Albany. Denmark experienced its second driest year on record in 2014 and 2015 has followed a similar pattern with 23% less rain than the long-term average. Albany had similar results with 38% less rainfall than the long term average and 30% less rainfall in 2014, making it the second driest and third driest years respectively. 

How has rainfall decline affected local water sources?

The decline in rainfall in the Great Southern Region has resulted in a decline in the amount of river flow. For the Denmark area, the decline in rainfall has shown a 36% decline in average flows for Denmark River flow (on which the Denmark River Dam is located) for the period 1983–1990 compared to the period 2001–15.

Water Corporation used the climate change outlook to predict the impact on the runoff for the Quickup and Denmark Rivers and to understand the future reductions in riverflow. For 2030 the rainfall is predicted to decrease by 8–11%. This will  equate to a reduction of river flow by 25% to 31% and by 2050 rainfall is predicted to decrease by 14–20%  which will equate to a reduction in river flow by 44% to 54%.

The Quickup River (on which the Quickup Dam is located) has not shown the same average annual river flow reductions. This is most likely due to the different catchment sizes. The Denmark River catchment is ten times bigger than Quickup River catchment so is more prone to variability in the rainfall.

 

 

What is the annual water demand in Denmark? What is the projected water demand in the next 5–10 years?

The average Denmark source demand across 2010–15 was 560 million litres per year. For 2015, 540 million litres has been taken from the Quickup and Denmark River Dams which is 3.6% below in the average 2010–14 demand. The highest demand recorded for Denmark was 626 million litres in 2010 and was likely attributed to the drier year and prior to water efficiencies being introduced such as Stage 5 restrictions in December 2014.

By 2020 source demand is projected to be 600 million litres per year and by 2025 demand is projected to increase to 665 million litres per year. This is assuming the 2.1% growth rate on water demand continues which is what has occurred within Denmark from 2010–14.

Will water tanks become mandatory?

We cannot mandate measures such as the installation of water tanks in all new residential or commercial buildings. However, we support the use of rainwater tanks that are plumbed in for non-drinking purposes such as toilet flushing and clothes washing. WA Department of Health does not recommend people use rainwater for drinking or food preparation, unless it is adequately treated. 

Denmark Rainwater Reward Program began on 1 December 2015 giving Denmark residents a chance to claim significant financial rebates on the cost of new or existing rainwater tanks. We encourage residents to check eligibility against the criteria and consider implementing this water efficiency measure.

What are the current water sources for Denmark?

Denmark Dam was constructed in 1961 and was the original dam supplying water to Denmark. Due to increasing salinity and contamination in Denmark River, Quickup Dam was built in 1988 to supply Denmark with better quality water. Since it was built, Quickup Dam has been the sole supply for Denmark due to its better water quality. Denmark Dam has been used occasionally during periods of low runoff into Quickup to supplement Denmark town’s water supply. Water quality is managed by the Department of Water (DoW). DoW has implemented a number of issues in the catchment. For example, to help with salinity runoff into the Denmark River, appropriate plant and tree species were planted in large, heavily-cleared upper catchment areas.

In 2015, we commenced a project that will allow Denmark Dam to be used on a more permanent basis. Pipework installed in 2015 will allow water to be pumped from the Denmark Dam to Quickup Dam to ensure there is sufficient water to supply Denmark. 

What is the volume of each dam?

Quickup Dam has the capacity to hold 1,089 million litres and Denmark River Dam has the capacity to hold 451 million litres.   

Will mixing water from Denmark River and Quickup Dam impact the environment?

The Department of Fisheries determined the potential for fish pathogens to be transferred in the water from the Denmark River Dam to Quickup Dam. Therefore, the Department requested that the water be treated for pathogen removal. The water from Denmark Dam to Quickup Dam will be transferred via a new ultrafiltration plant, due to be operational by mid-2016. The new ultrafiltration system will have the capacity to produce more treated water.

Has Water Corporation considered recycling wastewater from the Denmark Wastewater Treatment Plant (WWTP)?

Through the Royalties for Regions grants, we have received $15 million funding to develop a water recycling scheme to recycle treated wastewater from the Denmark WWTP through a new pipeline for use in irrigation. Pipeline routes are being investigated for the transfer of the recycled treated wastewater. Our goal is to recycle 30% of wastewater by 2030. We are currently in discussions with various stakeholders regarding possible reuse options for the treated wastewater from the Denmark WWTP. 

Are new water sources being investigated?

We have engaged a contractor to conduct aerial surveying in the Denmark, Walpole and Two People’s Bay areas in February and March 2016. This geophysical investigation was to obtain sub-surface images of the area. This information will enable an assessment of the area for possible future groundwater investigations. Aerial surveying is routine in the early stages of exploring water supply sources. Should further investigations be required on land, we will obtain all necessary approvals and inform the community of the next stage of the investigation.

Why might Denmark need these units?

During the year salinity levels in the Denmark River vary, depending on the season and the amount of water flow in the river. During times when salinity levels are higher, the water needs to be treated in order to supplement the town’s drinking water supply. Portable desalination units can be used to ensure the water quality meets Australian Drinking Water Guidelines (ADWG).

Water Corporation is yet to operate the portable desalination units.

What is brackish water?

This desalination process produces rejected brackish (slightly salty) water as a by-product that consists of the salts naturally found in the Denmark River. The treatment process also uses a small amount of standard water treatment chemicals, including anti-scalant, which are approved by the Department of Health for use in drinking water.

Total dissolved solids (TDS) are made up of inorganic salts (calcium, magnesium, potassium, sodium, bicarbonates, chlorides, and sulphates) and small amounts of organic matter dissolved in water.

How will the desalination units operate, if required?

The desalination units are located at the Denmark Water Treatment Plant, adjacent to the Denmark River Dam. The treatment plant consists of 3 reverse osmosis (RO) units. The number of units required for operation is dependant upon different factors. The number of RO units operating will depend on the amount of water needed to supply Denmark. So, in low supply time, only 2 RO units will be needed, and in high demand times all 3 RO units will run. At full production of all 3 units, the units can produce up to 95% of treated water required to supply Denmark.

How long will Water Corporation run the desalination units?

The desalination units will run for as long as required to ensure Denmark’s drinking water meets (ADWG). Water Corporation aims to minimise the need to run the desalination units by using a combination of Quickup Dam and Denmark Dam water.

How much does it cost to run the desalination units?

It is estimated that it will cost around $1,000–2,000 per day depending on how the units are being operated. Water Corporation always aims for cost efficiencies.

How much energy do they require?

The average operating energy for running all 3 RO’s is 50.5 kilowatts per hour. This is about the same energy for a family-sized refrigerator to run for a week (https://www.keysenergy.com/appliances.php).  

Where else are desalination units used in WA and how is  brackish water disposed of?

Portable desalination units are used all over WA for both seawater and brackish water including Hopetown, Leonora, Gascoyne Junction and Yalgoo. The brackish water is disposed of by ocean outfall, evaporation ponds, infiltration and is reused for mining operations.

How much brackish water will be produced during treatment?

It is estimated the amount of brackish water could be up to 60–100 thousand litres a day. The amount of water produced will vary depending upon the salinity level in Quickup Dam and how much water is required to supply the down. The comparative volume of brackish water disposed of each day is about the volume of a large backyard swimming pool.

How did Water Corporation develop the options to manage brackish water? 

This brackish (salty) water produced as a by-product from desalination needs to be managed and disposed of appropriately.

We systematically followed steps in analysing the possible options. These included:

  • Desktop review of brackish water disposal within WA, Australia and globally by other utilities and the private sector.
  • Selection criteria based on environmental, social and economic factors were applied across all options.
  • Community feedback to help us in this process and to identify new options.
  • Additional scientific investigation into available disposal options. 

We are looking at a number of options for the management of brackish water from the desalination units. These options will focus around a more local solution that has good economic, social and environmental outcomes.

New technology
This option will concentrate the brackish water up to eight times at our treatment plant, significantly reducing the volume requiring disposal. The remaining brackish water will then be trucked to our Timewell Road storage pond, which will act as an evaporation point.

Ocean disposal around Denmark 
This option would involve tankering brackish water to possible beach locations and releasing the water to the ocean through a small above-ground pipeline.

Denmark River – not viable at this stage
This option would release the brackish water downstream of the Denmark Dam directly from the Denmark Water Treatment Plant. At this stage, the disposal option may not be viable as a year round solution as there will be a requirement to further dilute the brackish water.

Existing Albany tree farm – not viable at this stage
Brackish water would be tankered to Albany and stored at our Timewell Road Wastewater Treatment Plant pond and gradually blended onto the tree farm. At this stage, this option would only be viable during certain times of the year and only for a limited time. 

Could a pipeline be built from the Water Treatment Plant to the ocean?

Currently, no pipeline route is being considered due to the distance from the water treatment plant to the ocean and the cost of constructing a pipeline for a waste that may only be produced a few times a year. However, if it is looked at, all factors will be taken into consideration including cost, time, approvals and design. 

Can the brackish water be used for public and private swimming pools?

There are examples of brackish water being used in swimming pools. However, salinity levels need careful monitoring because the same water is recirculated and treated on a continuous basis. Salt residual accumulating over time can be costly to reduce and remove.   

Has recycling the brackish water through private business use been considered?

We will consider ideas regarding how private businesses may use brackish water and is open to hearing further suggestions for possible disposal locations. 

Can brackish water be used for fighting fires?

The quantity of brackish water may not meet demands as it will only be produced if reverse osmosis (RO) are in use and the cost of storage provides a considerable challenge for the end-user. We are always open to options for private use of the brackish water.      

Will Perkin’s Beach be considered as a disposal option?

We will no longer pursue Perkin’s Beach as an option.

How will brackish water impact nearby waterways and vegetation?

Environmental studies are being conducted to consider potential impacts to waterways such as Lake Powell and local creeks. Similarly, potential impact on local vegetable crops and blue gum plantations is being examined. 

Can brackish water be used on plants?

Water quality restricts the possible usages of the brackish water. There are some plants that can tolerate higher salinity water but application on plants would need to be considered on a case-by-case basis.  

Who is responsible for water quality issues (such as salinity) in the Denmark River catchment?

The Department of Water is responsible for managing salinity issues in the Denmark River Catchment and has already undertaken a considerable amount of work to date. This is documented in their reports titled Denmark River Water Resource Recovery Plan (2011) and Salinity Situation Statement Denmark River (2004).  Large areas of the heavily-cleared upper catchment areas of the Denmark River were planted with appropriate plant and tree species to help with salinity runoff into the river. The Department has also improved water quality by excluding animal access in areas of the catchment.

How will plant and animal species be affected by brackish water disposal?

Environmental studies will investigate the impact of brackish water disposal on all marine animal and plant life and on river fauna, in particular the black bream and cobbler. The studies will help determine the viability of disposal options.

When will Water Corporation make a decision on the option/options?

At the community information sessions last year and earlier this year, we explored several options for managing the brackish water from the Reverse Osmosis (RO) units in Denmark (should they ever be required).

The final reports from the two environmental studies that were carried out confirmed that neither option (discharging the brackish water downstream of Denmark River Dam or into storage ponds and then blending with the treated waste water and discharged onto the Albany Tree Farm) is viable at this stage for the timeframes and volumes required.
To ensure we find a solution, we have started other investigations. One of the most promising of these involves new technology, which will concentrate the brackish water up to eight times at our treatment plant, significantly reducing the volume requiring disposal.

The remaining brackish water will then be trucked to our Timewell Road storage pond, which will act as an evaporation point. This process will significantly reduce transport costs and provide an environmentally friendly solution to managing the brackish water. We are proposing to run a trial of this technology in Denmark in January 2017.

In parallel with this, we are continuing to explore other disposal options. All of these options still require extensive investigations and will involve further community consultation if they are pursued.

We are considering another round of community information sessions later this year to update you on local water management strategies for moving into the summer period.  

Will my water bill be affected by the use of desalination?

Tariffs are set by the State Government each financial year. Every 2 months we read your meter and send you a bill for your water use and service charges. The service charges ensure we can always supply you with clean and safe drinking water and take away your wastewater and dispose of it in a socially and environmentally friendly way. We would not expect an increase in customers' water bills which are directly related to the reverse osmosis (RO) units. An operations budget would cover the costs and be built into future years' operations.

Community information sessions

Below you can find the presentations and materials from our community information sessions regarding medium and longer term water plans for Albany and Denmark.

Community presentations Denmark and Albany April 2016

Community presentation Denmark 25 November 2015

Preliminary options for brackish water management in Albany and Denmark map

Conceptual selection criteria analysis of all options for brackish water management

We have also received the final reports from the two environmental studies that were carried out to determine the possibility of discharging the brackish water downstream of Denmark River Dam or into storage ponds and then blending with the treated waste water and discharged onto the Albany Tree Farm.

Media releases

Licence amendments allow management of brackish water from Denmark if required

Water efficiency important in Denmark’s drying climate

New pipeline linking Denmark dam's complete

Securing Denmark's future water supply: environmental assessments

Water recycling scheme a boost for Denmark

Work starts to boost Denmark's water supply