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A fresh look at dual reticulation
June 2014
A fresh look at dual reticulationAn assessment of the performance and ongoing viability of dual reticulation schemes on the Gold Coast, the assessment utilises the Australian Water Recycling Centre of Excellence’s Total Economic Value Framework.
Irrigation Australia National Conference
Presented by: Kathy Baker
Executive Coordinator Integrated Water Cycle Planning
Gold Coast Water
June 2014
Slide 3
Background
Prior to 2006, GCW owned and operated its bulk water supply assets
Pimpama Coomera Waterfuture Master Plan (including Class A+ recycled water) adopted in 2004
By 2056, Class A+ predicted to contribute 20ML out of 366ML
Millennium drought effecting South East Qld
10 years since adoption – appropriate to review and consider the current and future costs and benefits
Slide 4
Map…
Slide 5
Map…
Slide 6
Map…
Class A+ Uses:Outdoor – garden irrigation, car washing
Indoor - toilet flushing
Fire fighting
Slide 7
Current situation
Class A+ to 6000 properties in the Pimpama Coomera region
Use 0.5% (0.8 ML/day) City’s total water demand
10 ML/day is supplied by Class B/C recycled water schemes
Class A+ usage rate much less then expected
Only 8 ML/day expected in 50 years (2.4%)
152
325
8
0.8
0
50
100
150
200
250
300
350
Now In 50 years
Ave
rage
Day
Dem
and
(ML/
day)
Total Class A+ Recycled Water Demand
Total City Potable Water Demand
Slide 8
Key changes since adoptionIssues Assumptions/Outcomes
DroughtMillennium drought broke and water use behaviours have changed significantly in SEQ
Bulk water State Government took ownership
Population projections Growth rates have slowed from those projected for the PIP.
Environmental discharge No Pimpama River release.
Outdoor water useGeneral outdoor water use has decreased by 65% compared with original assumptions.
Household recycled water demand
Actual recycled water demand per household is currently 75% less than that assumed for original demand projections.
Scheme capital costsWOL (50yrs) capital costs for Class A+ recycled water, approx. double original estimate in the PCWF Master Plan.
Scheme operating costsWOL O & M costs of Class A+ treatment & distribution system approx. 10 times greater than originally estimated.
Slide 9
Issues
Cross-connections – complicated pipework on-lot and off-lot
Household audits
Slide 10
Value and viability assessments
Not financially viable - cancelled future expansion of DR into the Stapylton, Yatala and Cabbage Tree Point areas
Detailed Value Assessment of Pimpama Coomera
Total economic value of recycling
– financial, environmental and social factors
Australian Water Recycling Centre of Excellence
Slide 11
End of dual reticulation for City of Gold Coast
Council resolved in December 2013 to discontinue implementation of dual reticulation on the Gold Coast due to:
High cost of operating and maintaining the scheme High cost of constructing new capital infrastructure Low demand usage Negative net “value” (costs outweigh benefits) Significant regulatory monitoring and reporting requirements Risk of cross connections
Estimated to save rate payers $3 million/year or $114 million over 40 years (in 2013 dollars)
Slide 12
Transition Plan to decommission Class A+ supply
Potable water to be supplied via both potable and recycled water networks
Initially operated as discreet systems (no mixing)
Class C return main from Pimpama STP to Coombabah STP
‘Switch over’ estimated to occur by December 2016
Slide 13
Existing Recycled Water SchemeExisting Recycled Water Scheme
- Northern Supply Scheme
- Southern Supply Scheme
Class B/C
- Approximately 50 fixed customers
- Some 400 Recycled Water Carrier Customers
- Total reuse for the past 5 years ranges from 16.5% - 20.3%
- Total irrigated area approximately 1700ha
- Irrigation of Sporting Fields, Council owned Parks, Schools, Nurseries, STP wash-down, Municipal Irrigation and Industrial / Commercial Use
Recycled Water Reuse vs Rainfall
0
10
20
30
40
50
60
2000-2001
2001-2002
2002-2003
2003-2004
2004-2005
2007-2008
2008-2009
2009-2010
2010-2011
2011-2012
Financial Year
Volu
me
of R
ecyc
led
Wat
er (M
L)
0
500
1000
1500
2000
2500
Rain
fall
(mm
)
Recycled Water Leaving WWTP
Volume of Recycled Water Reuse (ML)
Rainfall (mm)
Recycled Water Reuse Target
Slide 14
Where to from here? Release
-Seaway-Ocean?
Local Opportunities
- Identified further open space irrigation
Additional treatment Class C to Class A+
- Jupiter’s Casino
- Potential Commonwealth Games venues
Slide 15
Where to from here? Potential Northern Recycled Water Scheme
PO Box 5042 Gold Coast MC QLD 9729P 1300 GOLDCOASTE [email protected] cityofgoldcoast.com.au