It disposes of ash waters from Yallourn Energy, Hazelwood Power, Loy Yang B and Loy Yang A Power Stations.

Ash water is a highly saline wastewater resulting from the use of low quality water to transport ash residue away from the power stations. These waste waters are then collected at Loy Yang. They are carefully monitored and pumped out to Bass Strait via the SWOP at McGauran's Beach.

As with other discharge sites the SWOP operates under strict EPA licence conditions.

The SWOP System from Loy Yang to the Ocean Outfall is owned and operated under the Agreement by Gippsland Water.

The System delivering Saline Waste from Yallourn and Hazelwood is Owned and operated under Agreement by Hazelwood Power.

Loy Yang Power and IPM Operation & Maintenance Loy Yang deliver Ash Slurry to inlet chutes located on the Western Embankment of the Ash Pond.

The Ash Pond is normally operated between RL 139 and 140 with the SWOP System normally operating three weeks of each month. The Ash Pond has provision for the emergency storage of 90 days of saline waste. (The present capacity with the current ash volume is approximately 120 days.)

Saline waste is disposed under the EPA Licence EW000449/1 held by Gippsland Water to discharge waste into waters situated at McGaurans Beach Bass Strait.

Continuous online monitoring of pH, turbidity and electrical conductivity is carried out at the Ash Pond Pump Station. The pumps automatically shut down if the licence limits of 25 for turbidity or 10.5 for pH are exceeded.

The allowable dicharge limit for the licence is 34.7 ML per day of pump operation. Presently the pumps operate at between 34.0 and 34.6 ML per day.

Samples and tests for water quality, heavy metals, toxicity, coastal biological and underwater surveillance are carried out as required under the licence by Gippsland Water.

The following agreements are current for the SWOP system:

• EPA Licence EW000449/1 held by Gippsland Water.
• Saline Waste Management Agreement dated 21 March 1996 between Loy Yang Power and Hazelwood Power Corporation.
• Saline Waste Management Agreement dated 21 March 1996 between Hazelwood Power Corporation and Yallourn Energy Limited.
• Miscellaneous Services Agreement Part 5 and Part 6 between State Electricity Commission of Victoria and Loy Yang B Power Station Pty Ltd/Mission Energy Australia Pty Ltd.
• SWOP Construction, Operation and Maintenance Agreement dated 22 March 1979 between Latrobe Valley Water and Sewerage Board and the State Electricity Commission of Victoria.
• SWOP Finance Agreement dated 22 March 1979 between Latrobe Valley Water and Sewerage Board and the State Electricity Commission of Victoria.

The Ash Pond has an Acid Disposal site setup along the Northern Embankment for delivery of spent sulphuric acid from ICI's chlorine processing plant. This assists in reducing the pH level of the Ash Pond.

Chemical waste from the Loy Yang Power and IPM Operation & Maintenance Loy Yang Water Demineralistation Plants isdeposited into the Ash Pond in separate locations the Ash Disposal Pipelines.