“Mangrove Creek Dam is safe” Council

Mangrove Creek DamMangrove Creek Dam

Mangrove Creek Dam is safe and has not been deemed unsafe by the Dam Safety Committee, according to the Central Coast Council.

“Due to a change in the design standards for how the maximum probable flood levels are calculated, it was necessary to limit the capacity of the dam to 80 per cent to ensure the Dam would not be damaged if a flood of that level was to occur,” a media statement from Central Coast Council said. “At the 80 per cent level the maximum probable flood can be safely passed over the spillway,” the statement said. According to Council, the NSW Dam Safety Committee agreed with this course of action.

“This is not an unusual situation – many dams in NSW, such as Warragamba Dam and Jindabyne Dam have required upgrades to meet new flood capacity requirements. “The NSW Dam Safety Committee agreed with the Councils at the time that an 80% cap on the dam capacity should be in place until the flood capacity could be upgraded. “This upgrade has not yet been undertaken. “Council has operating guidelines for Mangrove Creek Dam and the Central Coast water supply system. “Storage levels at all dams are monitored daily and water transfers into Mangrove Creek Dam managed accordingly.

“At Mangrove Creek Dam’s current storage level of approx. 75 per cent, a further 10,000 ML would be required to reach 80 per cent. “That’s the equivalent of Mardi Dam plus half of Mooney Mooney Dam. “The catchment of Mangrove Creek Dam itself is quite small, with the dam predominantly filled by pumping from Mardi Dam. “As such, Council has a high degree of control on the water levels in the dam.” Any upgrade or increase in the height of the dam wall would be funded by the Council thought its water prices, the statement said. “Our 2012 pricing submission to the NSW Independent Pricing and Regulatory Tribunal (IPART) included pre-construction and construction costs to rectify the capacity of the spillway.

“IPART did not believe that the expenditure was required in the current price path and as a consequence the costs were rejected in the calculation of Central Coast water prices. “We are considering our options for the next IPART pricing submission, which is due to be made in September 2017 for the period commencing July 1, 2018. “Central Coast Council has a dedicated team working to ensure we can meet the water supply needs of our growing population. “Council is currently working with Hunter Water and the Department of Primary Industries: Water, to ensure potential interregional solutions are appropriately considered to obtain maximum benefit from the available water resources on the Central Coast and Lower Hunter.

“Regional solutions are possible because of the pipeline link between the Hunter and Central Coast urban water systems. “Any decision to upgrade Mangrove Creek Dam needs to take into consideration this longer term water resource planning.

“There are a number of options being considered to upgrade Mangrove Creek Dam, ranging from approximately $7 million to $75 million. “These include: upgrading the existing spillway; raising the dam wall to increase storage capacity by 40,000 ML; or, raising the dam wall to increase storage capacity by 80,000 ML.

“Each would overcome the current spillway deficiency, but would provide different yield benefits. “Water that cannot be stored in Mardi Dam or transferred to Mangrove Creek Dam will not be harvested. “This water flows into the Tuggerah Lakes System. “Note that at 80 per cent full, the dam has more than sufficient water to service the current Central Coast population. “The Mardi to Mangrove Link pipeline has made a signifi cant contribution to the Central Coast’s water storage.

“The total volume pumped to Mangrove Creek Dam since transfers first commenced in late 2011 is 44,055 ML, this represents 23 per cent of the total storage capacity of Mangrove Creek Dam. “Without the pipeline, the Central Coast water supply would be much less secure than it is now. “A total of 3,430 million litres has been transferred via the Mardi to Mangrove Pipeline Link this year. “Council continues to work with Hunter Water and the Department of Primary Industries: Water to ensure potential interregional solutions are appropriately considered to obtain maximum benefit from the available water resources on the Central Coast and Lower Hunter.”

Media statement, Sep 22, 2016 Central Coast Council media Jackie Pearson, journalist

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