Sunwater has worked with St George irrigators to help save a potential 27,000 megalitres of water while essential repair works at EJ Beardmore Dam are being completed.
Construction of a temporary enclosure, known as a coffer dam, was completed today and is now ready to store further inflows.
Executive General Manager Sunwater Operations Colin Bendall said the coffer dam, which was built by Sunwater with the support of local water users, was a short-term storage solution that in the event of further rainfall, could help save up to 16,000 megalitres of additional water for local irrigation.
Mr Bendall said the capacity of the coffer dam was in addition to the 11,000 megalitres already saved within three private offstream storage systems, that had been reserved during the dam drawn down, increasing the total potential storage capacity to 27,000 megalitres.
In February 2019, Sunwater advised repair works at EJ Beardmore Dam were essential to ensure the safety and integrity of the dam structure and would commence in April 2019.
The work commenced in late May, after inflows from significant rainfall across the dam’s catchment caused a 30-day delay. The dam’s water levels were then drawn down to EL 199.00m AHD (or 5,249 megalitres), releasing the excess flows downstream to enable safe commencement of the works.
Mr Bendall said Sunwater had been working closely with Mallawa Irrigation and other customers to minimise any interim impacts.
“We understand any interruption to water supply, even a short one, can be concerning for growers,” he said.
“To support them, we have been working together to save some of the scheme’s water, despite having to retain the dam at the reduced level.
“In the end, we have created a customised solution that has enabled the works to be completed, while securing some additional storage capacity for our customers.”
Mr Bendall praised the efforts of Sunwater’s southern region staff who have worked tirelessly to mitigate water losses while ensuring the works were prioritised.
He also thanked Mallawa Irrigation and the other irrigation customers for their cooperation, as well as those who have supported local water users by storing water offstream.
Mr Bendall said although some irrigator representative organisations had raised concerns about the volumes of water released, Sunwater’s number one priority had always been to maintain the integrity of the dam.
“We understand that customers would have liked more of the April inflow stored and that other stakeholders would have liked to see more water released into the downstream riverine environment,” he said. “However, in undertaking this project, Sunwater has attempted to balance the needs of our customers and other stakeholder’s interests with our overarching priority – to achieve a stable dam structure and ensure the long-term security of the region’s water supply.”
“The solution is a culmination of intensive effort by Sunwater, Mallawa Irrigation, private storage owners as well as the Department of Natural Resources, Mines and Energy,” he said.
Dam Safety regulatory requirements and the need to prevent any further delay of the essential works had necessitated the release of inflows at a higher rate than regular environmental releases.
EJ Beardmore dam will remain at the revised level for a total period of eight to 12 weeks, weather permitting, and until the essential works are completed.
In the event of further rainfall that cannot be stored by the coffer dam during the construction period, Sunwater is authorised to release water downstream.
Activities completed for the EJ Beardmore Dam works to-date include: construction of the downstream coffer dam; dewatering of the channel; installation of the groundwater dewatering system; demolition of the existing concrete outlet; foundation excavation and reinforcement for the new structure.
For more information:
Levels and volumes stored in the offstream storage and coffer dam will available on Sunwater’s website at https://storagelevels.sunwater.com.au/win/reports/win_storages.htm
Sunwater Media Team
Phone: +61 7 3120 0047