Download A fresh look at dual reticulation

A fresh look at dual reticulation
June 2014
A fresh look at dual reticulation
An 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:
June 2014
Kathy Baker
Executive Coordinator Integrated Water Cycle Planning
Gold Coast Water
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 3
Map…
Slide 4
Map…
Slide 5
Map…
Class A+ Uses:
 Outdoor – garden irrigation,
car washing
 Indoor - toilet flushing
 Fire fighting
Slide 6
Current situation
 Class A+ to 6000 properties in
the Pimpama Coomera region
350
8
300
 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
Average Day Demand (ML/day)
Total Class A+ Recycled Water Demand
250
Total City Potable Water Demand
200
0.8
150
325
100
152
50
0
 Only 8 ML/day expected in 50
years (2.4%)
Now
In 50 years
Slide 7
Key changes since adoption
Issues
Assumptions/Outcomes
Drought
Millennium 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 use
General 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 costs
WOL (50yrs) capital costs for Class A+ recycled water, approx. double
original estimate in the PCWF Master Plan.
Scheme operating costs
WOL O & M costs of Class A+ treatment & distribution system approx. 10
times greater than originally estimated.
Slide 8
Issues
 Cross-connections –
complicated pipework
on-lot and off-lot
 Household audits
Slide 9
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 10
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 11
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 12
Existing Recycled Water Scheme
Existing Recycled Water Scheme
Recycled Water Reuse vs Rainfall
- Northern Supply Scheme
2500
- Southern Supply Scheme
50
Class B/C
40
- Approximately 50 fixed customers
2000
1500
Rainfall (mm)
Volume of Recycled Water (ML)
60
Recycled Water Leaving WWTP
of Recycled Water Reuse (ML)
- Some 400 Recycled Water Carrier Volume
Customers
30
Rainfall (mm)
- Total reuse for the past1000
5 years ranges
from
16.5%
20.3%
Recycled
Water
Reuse -Target
20
- Total irrigated area approximately
1700ha
500
10
0
20002001
20012002
20022003
20032004
20042005
20072008
Financial Year
- Irrigation of Sporting Fields, Council owned Parks, Schools,
0
Nurseries, STP wash-down,
Municipal Irrigation and Industrial /
2008- 2009- 2010- 2011Commercial Use
2009
2010
2011
2012
Slide 13
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 14
Where to from here?
Potential
Northern
Recycled
Water
Scheme
Slide 15
PO Box 5042
Gold Coast MC
QLD 9729
P 1300 GOLDCOAST
E [email protected]
W cityofgoldcoast.com.au