Desalination units at the Denmark Water Treatment Plant
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. To date, we've explored the following disposal options:
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. Submissions needed to demonstrate a key focus on disposal options that offered a local solution which have positive economic, social and environmental outcomes.
All proposals have since been reviewed and of the nine applications received, three have been shortlisted for further consideration. We thank all applicants for their contribution during this investigation stage.
To date, the desalination units have not be used, and with water storage at its current levels, we do not anticipate they will be required for the coming year.
Given the current dam levels, we will revisit the shortlisted proposal in winter 2018.
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
Following the winter and spring rains in 2017, we are pleased to report there is sufficient capacity in Quickup Dam to meet demand this summer. In October 2017 the dam overflowed for a second year in a row and with current conditions, we anticipate satisfactory dam levels for the coming summer months.
Quickup Dam continues as the primary drinking water source for Denmark, and is supplemented with water from the Denmark River Dam, when required. Our pump back strategy (we have been pumping water from Denmark River Dam to Quickup Dam since June 2016), continues to play a significant role in ensuring Quickup Dam can continue to supply water to Denmark.
While storage is sufficient for this summer, it is still important the Denmark community keeps up the good work to save water and follows the two-day a week sprinkler roster.
Investigations for a long term water supply - Groundwater source
In January 2017 we completed a number of ground based geophysical surveys as part of our search for a long term groundwater source. The surveys refined 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 (salty water) count and is not useful.
Due to wet ground conditions, the remaining locations were postposed and we aim to recommence the drilling investigations in March 2018.
All findings will assist us in our investigations to confirm the presence and quality of groundwater and a long term water supply for the town of Denmark.
We will continue to engage with the community, regulators and other stakeholders as our investigations continue.