Delivering on Water Quality in the Cassowary Coast - The CCRC journey to eliminate boil water events

Abstract

The Cassowary Coast Regional Council has four water supply schemes but only the Innisfail scheme that draws its water from the Johnstone River has a full water treatment process. The Nyleta, Tully and Cardwell supply schemes are solely run of creek and have no treatment other than course filtration and chlorination. This presentation describes the challenges of supplying water to significant communities including tourist areas all year round with no treatment and when the region is subject to annual rainfall totals between 3 and 4 m. When Council received approval for its first DWQMP in 2013, Council was gradually implementing major improvements to its SCADA and turbidity analysis equipment that was monitoring flows from its creek supply sources. From this time, Council was able to see real time the impact of major rainfall events and all of sudden, the communities of Tully, Mission Beach and Cardwell and many other smaller communities were having up to 20 boil water alerts being imposed. Water staff dreaded the prospect of any major rainfall as it inevitably triggered boil water. After heavy rain, normally pristine clear creeks would run dirty and chlorination systems were deemed ineffective. Over the past 6 years Council has been working progressively to construct systems of SCADA, turbidity monitoring and control valves at our intakes which now allow us to shut down the intakes once the creeks are at turbidity critical control limits. Once the intakes are shut, we are able to draw clean supply from new reservoirs (2 schemes) or by starting a bore (Cardwell). The intake reservoir of our Nyleta system has only limited storage capacity but we are able to keep it recharged by drawing from a new underbed sand filtered intake that allows water with quite high turbidity to be cleaned sufficiently so it can be used for normal consumption. The improvements undertaken for each scheme are cost effective solutions that have allowed Council to now deliver water all year round and without any boil water alerts. This presentation will provide details on the different infrastructure and technology solutions CCRC has implemented for each supply scheme to achieve this outcome. Details will be provided on our SCADA and controls, the engineering challenges with some of our new reservoirs, the innovation of our underbed intake and the role of bore water