Sydney Water Operational Audit 2011/2 - IPART - NSW Government

Clause Requirement Grade
Reason
Audit Questions Evidence Cited Audit Observations
deliver drinking water to an excellent standard to its customers. Sydney
Water achieved full compliance with 9 out of the 10 audited sub-classes with
high compliance awarded to the remaining sub class.
On-going action - Sydney Water developed models to calculate Ct values
under various operating conditions for each WTP in 2003-04. These models
are currently being reviewed and updated where necessary to deal with site
changes.
Real time variation of Ct and associated log inactivation of Giardia at each
WTP is currently being reviewed. A trial involving trending an instantaneous
Ct value on SCADA is being planned for one of the WTPs. A discussion
paper to determine the use of Ct within Sydney Water is currently being
drafted.
This has been developed for a WTP and will be rolled out to others shortly.
The risk management training strategy has been implemented and all
operational users have been trained. The supplementary e-Learning tool has
been developed with YouTube quick bites to refresh users. These will be
rolled out over 2012-13.
Ongoing action - By midway through the course of this Five-Year plan,
Sydney Water intends to summarise its existing critical control point
information into one document.
This information is currently captured in the BWSA, DWQEMP, SCADA and
control systems as well as SOPs. The current range of systems and
documents contain water quality targets, operational limits and control
actions. Work on summarising the critical control points started in 2011-12.
North Richmond WTP was used as the trial plant.
A template is currently being finalised and once completed will be used to
capture the same information across all other WTPs.
SWC and Woronora Ongoing action - Due to accelerated loss of
disinfection residual in the Woronora Delivery System in 2011 a new
operating protocol for disinfection at Woronora WTP was implemented to
improve residual maintenance in the distribution network. Prechlorination of
the raw water was trialled at first and then an increase in the final chlorine
set point target at the WTP. These measures were found to prevent the loss
of disinfectant residual in the distribution network.
With the Desalination Plant shutting down the total blend of water supplied
will change with increased water from Prospect WTP. A review of the
operating regime will be completed in 2012-13 to further optimise levels of
disinfectant throughout the distribution network, particularly in higher risk
GHD | Report for Independent Pricing and Regulatory Tribunal - Operational Audit of Sydney Water Corporation, 23/14602 | 49