Two Rocks

In 2000, the Water Corporation installed a new calgon dosing facility at the Two Rocks Water Treatment Plant as part of an extensive programme of works which the water utility has been pursuing throughout its facilities in Western Australia. The development and implementation of the calgon technology is being done in conjunction with Hydramet, under a licensing agreement with the Water Corporation.

The total investment for the area involved around AU$500 million between 1998 and 2002.

CALGON WATER TREATMENT PLANT

The addition of low concentrations of calgon, sodium hexametaphosphate (NaPO3)6, improves potable water quality in hard water areas. The chemical is added to the water supply at low concentrations to inhibit scale formation when hard water is heated. This approach provides most of the customer benefits of full softening, but at a fraction of the cost, by reducing the effect of scaling problems experienced in domestic hot water systems and electrical appliances. However, it has no effect in aiding the lathering of hard water.

The Corporation has refined the use of calgon over a number of years, having developed a standardised batching and dosing plant and obtained a patent on the dissolving apparatus. They are currently extending the use of this treatment to more than 20 of their sites across Western Australia.

Calgon is a registered food additive which has been approved by Australia’s National Health and Medical Research Council. The decision to add calgon to the water supply was only taken after the local residents had been surveyed and had shown support.

Construction began in May 2000 and was finished later in the same year. The project’s progress was held up for a time by a land dispute which led to the dosing facility being built as a portable, skid mounted unit and temporarily located at the Two Rocks tank site, where the ownership of the land was less contentious. However, the Calgon Plant is now fully functional and performing to specification.

MEDIA ATTENTION

At the time of the calgon plant installation, a number of allegations were made in the Australian media against the nearby Two Rocks wastewater treatment plant regarding unacceptable level of odours. During the run-up to local elections there were attempts to tie odour problems in the coastal area with the wastewater plant but it was subsequently shown that the smell was coming from rotting seaweed on a nearby beach. A groundwater sampling programme undertaken at the same time also established that the wastewater treatment plant was operating in accordance with Department of Environmental Protection (DEP) requirements.

A number of other issues, including the suggestion of illegal discharges of wastewater and calls for extra site security, erupted out of the debate over the claims being made but ultimately they have also come to nothing.

The wastewater treatment plant and the calgon treatment plant are entirely separate.