Sporting complex water harvesting at a regional sporting venue



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Example of Promotion of Public Viewing




4.8 Project Issues

Groundwater

An unforeseen issue identified at the geotechnical investigation stage was the significant level of groundwater present under the playing surface. Previous geotechnical investigation undertaken when sports lighting was installed revealed no such groundwater problem.


Over the life of the project ground water monitoring showed a correlation between rainfall received and height of groundwater. That late 2010 and 2011 were La Nina years would appear to be responsible for a significant increase in groundwater. The presence of water through the old tip site necessitated the quality testing of the water present due to contamination concerns. Results showed that though some contamination was present, the water meet the levels allowed for irrigating. As a risk management measure Council treated all groundwater as contaminated water and not suitable for capturing for irrigation nor suitable for disposal into the trade waste/ sewage system under licence. The groundwater was transported to Whylandra waste depot.
The layout of the original tank design was to be across the full extent of the playing surface. This was no longer viable due to the lack of support provided by the saturated garbage and gravel layers. The design team then worked on a layout that moved the tank to cover only a third of the playing surface and have a deeper profile so it was able to sit on a clean rock base. This was the ultimate design adopted by Council and approved by the Commonwealth.
The groundwater also necessitated extra works in order to undertake excavation and tank construction. Council constructed an evaporation dam on site to which groundwater was pumped. Due to the wet season evaporation was minimal so Council was required to transport water from Apex Oval to Council’s Whylandra waste depot.

Weather

Above average rainfall created several months delay to the project completion date when compared to the original timetable. Indeed the intensity of one storm led to significant disruption to the construction of the modular tank.



Material cost increase

Another significant issue for the project was the increase in costs since the grant application was submitted. There was a substantial increase in the cost of a modular tank system from the industry based estimates that informed the original budget in the grant application.




Figure 7: Construction of the water holding dam.

Figure 8: The pumping of water out of the excavation site. The tanker would take this water directly to Whylandra Waste Depot.

4.9 Work Health & Safety Considerations

Council, being a local government authority has a strong focus on work health and safety with well established and reviewed systems in place. These systems were incorporated into the project.


During the development of the design investigation took place into the level of contamination of the old waste material. This was analysed both by groundwater sampling (as discussed previously) and air monitoring.
Air monitoring revealed no elevated levels of dust i.e. no risk from asbestos. Although results showed no asbestos in the air the site was treated as potentially contaminated with asbestos and so all staff and contractors working with old waste material had to be licensed to work with asbestos.
The waste was transported in sealed trucks to an isolated site at the Whylandra waste depot and treated as asbestos contaminated. Due to the extensive water-logging of the site it was not necessary to water down the old waste material.
All contractors had to provide evidence of work health and safety systems that were the equivalent as a minimum to Dubbo City Council’s work health and safety systems. Proof of application was also required throughout the project. This is a standard requirement of Dubbo City Council contract documentation.
Heat over the summer period in Dubbo would normally have been a significant issue for worker safety – a large bowl type landscape with black plastic would prove very hot. The very mild and wet summer prevented that being an issue requiring management.
The structural strength of the modular tank system was reviewed independently as a quality assurance measure to assess the long term safety of this system. It should be noted there were no issues found. See Section 4.6 Quality Control for more detail.

5 PROJECT ASSESSMENT

5.1 Project Objectives

TABLE 7: Project Objectives Original and Achieved


Objective

Proposed Outcome

Achieved Outcome

Water Harvesting

12ML tank installed

10ML

Use of water

Irrigating public open space

All water irrigates public

open space



Average amount of water

collected annually



42ML

38.8ML

Reduction of pollutants

entering Macquarie River



Installation of GPT to remove

oils, fuels, rubbish and soil/stones



GPT installed that

removes 99% of hydrocarbons and 85% Total Suspended Solids



Promotion of project as part of

water wise practices of Dubbo

City Council


Four public viewings.

Four viewings held with

public access.


Three meetings with regional CMA based groups.
Two engineering professional viewings were held

Offsetting carbon footprint of

the project



Offsetting 16.23 tonnes of

carbon equivalent per annum



Reduction of carbon

emissions by 16.45 tonnes per annum



Cost Effectiveness

Payback period in 43 years

Payback period in 47

years


Water Harvesting

As described previously, the original 12ML tank design was modified to become a 10ML tank. This was to account for the need to reduce the cost of the tank to a lesser cost that was closer to the forecast cost in the project budget. It should be noted that the feasibility study of the tank showed that a tank of between 10ML and 12ML was the most cost effective size. Approval was given by the Commonwealth for the new 10 ML design on 16 August 2011.



Average amount of water collected

The reduction in tank size meant that on average the annual collected amount of water would be 38.8 ML. This is based on modelling using climate data recorded over 50 years.



Reduction of Pollutants

The GPT selected and installed is rated as removing 99% of hydrocarbons and 85% of Total Suspended Solids. The important feature of the selected GPT is its capacity to filter water without going into bypass. See section 4.4 Water Quality Management for more detail.



Promotion of the Project as part of an overall Water Wise education package

Through general public and professional sector tours Council has been able to reinforce to the wider community the importance of water efficiency, water management and stormwater pollution. Approximately 150 people took the opportunity to view the site during construction.



Offsetting carbon footprint of the project

Council has overall reduced the electricity consumption required to irrigate Apex Oval and East Dubbo Sporting Complex. This relates to the lack of need to treat water to potable standard and the pumping required to move the potable supply from the source at the Macquarie River, through the treatment process and ultimately to urban reservoirs.


Council did change strategy in regard to using non-carbon producing electricity. Council has installed a 4kW solar system on the roof of the Apex Oval Grandstand building. This shall, over time, be a more efficient use of Council resources than purchasing ‘Green’ electricity from major suppliers.
The calculation of greenhouse gas emissions for the previous irrigation system at Apex Oval is complicated by the usage of potable water supplied under pressure by Council’s water reticulation system as opposed to direct pumping. However, there is an electricity cost associated with the bulk treatment of the potable water and Council’s Technical Services Division advises that for 2011/12 financial year data the electricity component for treatment and distribution was $0.11c/ KL.
Applying the cost of electricity to the treated potable water and the running time of pumps, the greenhouse gas emission for each scenario for the existing irrigation system at Apex Oval can be calculated as follows:
24.72 MWhrs x 0.976 tonnes per MWhr = 24.13 tonnes of carbon dioxide equivalent
For the stormwater harvesting scheme the carbon dioxide emission was calculated as:

16.78 MWhrs x 0.976 tonnes per MWhr = 16.38 tonnes of carbon dioxide equivalent


The stormwater harvesting and associated irrigation system reduces greenhouse gas emissions by 7.75 tonnes per year.
In addition Council has placed a 4kW solar panel system on the roof of the grandstand to generate power for the Apex Oval facility. It is estimated that the system shall generate 8MW per annum. This has been estimated to reduce the carbon emissions of the facility by 8.7 tonnes.
In summary the Apex Oval Stormwater Harvesting Project including the solar panels has reduced the carbon emissions of the site by 16.45 tonnes per annum.

Cost Effectiveness

The payback period of 47 years relates to the use of captured stormwater and bore water. This is a conservative approach as it recognises in drought there shall be irregular input into the tank from stormwater.


In considering the use of stormwater only versus the use of town-water the cost of potable water exceeds the cost of harvested stormwater in year 33. See Section 5.3 Levelised Cost of Water for further detail.


5.2 Project Duration

From the date of the signing of the funding agreement to the completion of construction the

Apex Oval Stormwater Harvesting project was undertaken over a period of 22 months from

24 January 2011 to November 2012. Actual construction took 14 months from September

2011 to November 2012.
The initial Project Plan timetable was altered significantly due to the need to redesign the tank due to groundwater and due to consistent wet weather. The wet weather included a large storm event that caused damage to the partially installed modular tank. The higher than average rainfall also led to high ground water levels that necessitated the building and creation of an on-site dam to manage the water.
Rain events of significance occurred on the following days:

29th September 2011 (61 mm)

7th October 2011 (30mm)

14th January 2012 (37mm within a very short time frame)
The changes in timelines is reflected in the change in Milestone achievement when compared to the original timetable (Table 8)
TABLE 8: Milestones Proposed and Actual

Milestone

Number

Description of Milestone

Task

Original Milestone Completion Date

Actual Milestone

Completion Date

1.

Agreement executed by the

Recipient and provided to the

Department for execution.


15 January 2011

24 January 2011

2.

Design and Documentation

phase


15 May 2011

12 July 2011

3.

Purchase and delivery of

material and equipment



1 September 2011

20 December 2011

4.

Installation of tank and

stormwater harvesting infrastructure



1 February 2012

1 May 2012

5

Installation and establishment

of playing surface



9 April 2012

17 September 2012


5.3 Levelised Cost of Water

In assessing the benefit of the project in regard to water saving Council used the Levelised Cost of Water method proposed by Fane, Robinson & White (pp 185-192). The following formula was used:

LC is the levelised cost of water (expressed in $/kL), PV (costs) is the present value of costs to the water service provider and consumer over the life cycle of the option at an accepted discount rate and PV (water demand conserved or supplied) is the present value of the projected annual water demands satisfied by a source or conserved over the same period and using the same discount rate.
Ct is the cost (capital and operating) of the option in the year t, Wt is the water demand conserved or supplied or in year t and r is the discount rate. The sum is taken over the same length of time.
For the purposes of the Levelised Cost of water the waste charges which were an in-kind contribution were not accounted for in the above formula. Table 9 (below) shows the levelised cost of water over a 50 year period. Also included is the increase in the price per kL of potable and bore water supplied by Council’s Water Supply Branch to residential customers over time – an annual increase of 4% was used.
The discount rate used in the calculations was r = 0 .07.
Looking at the results for the Apex Oval project, by year 33 of operation the delivery of harvested stormwater is below the cost of potable water. This benefit should also be considered with the life span of the tank infrastructure which has been rated to 100 years.
In regard to the more effective use of bore water and the harvested stormwater, by year 47 of operation the cost of supply is below that of bore water supplied through Council’s Water Supply Branch bore reticulation network.
The payback period of 47 years compares favourably with the original estimated payback period of 43 years considering the increase in costs between the grant application and the completion of the project.
The cost per ML in year 1 of operation is $84,600. By year 50 of operation the cost per ML is

$1,910.




TABLE 9: Levelised Cost of Water compared to estimated cost of potable and bore water

levelised cost for


Bore

levelised

all non



Year





Capital Cost


Operational Cost

Potable cost /Kl

water cost/ KL

Stormwater used KL


Bore water used




cost only stormwater

potable water




1

$ 6,627,723.00

$ 5,000.00

1.64

0.35

38800




39600

170.95

84.60




2




$ 5,200.000

1.71

0.36

38800




39600

79.76

42.33




3




$ 5,408.000

1.77

0.38

38800




39600

49.63

28.25




4




$ 5,624.320

1.84

0.39

38800




39600

34.74

21.20




5




$ 5,849.293

1.92

0.41

38800




39600

25.95

16.98




6




$ 6,083.265

2.00

0.43

38800




39600

28.61

14.16




7




$ 6,326.595

2.08

0.44

38800




39600

24.55

12.15




8




$ 6,579.659

2.16

0.46

38800




39600

21.50

10.64




9




$ 6,842.845

2.24

0.48

38800




39600

19.13

9.47




10




$ 7,116.559

2.33

0.50

38800




39600

17.24

8.53




11




$ 7,401.221

2.43

0.52

38800




39600

15.69

7.76




12




$ 7,697.270

2.52

0.54

38800




39600

14.40

7.12




13




$ 8,005.161

2.63

0.56

38800




39600

13.30

6.58




14




$ 8,325.368

2.73

0.58

38800




39600

12.37

6.12




15




$ 8,658.382

2.84

0.61

38800




39600

11.56

5.72




16




$ 9,004.718

2.95

0.63

38800




39600

10.85

5.37




17




$ 9,364.906

3.07

0.66

38800




39600

10.23

5.06




18




$ 9,739.502

3.19

0.68

38800




39600

9.67

4.79




19




$ 10,129.083

3.32

0.71

38800




39600

9.18

4.54




20

$40,000

$ 10,534.246

3.46

0.74

38800




39600

8.78

4.35




21




$ 10,955.616

3.59

0.77

38800




39600

8.38

4.15




22




$ 11,393.840

3.74

0.80

38800




39600

8.01

3.97




23




$ 11,849.594

3.89

0.83

38800




39600

7.68

3.80




24




$ 12,323.578

4.04

0.86

38800




39600

7.37

3.65




25




$ 12,816.521

4.20

0.90

38800




39600

7.09

3.51




26




$ 13,329.182

4.37

0.93

38800




39600

6.83

3.38




27




$ 13,862.349

4.55

0.97

38800




39600

6.59

3.26




28




$ 14,416.843

4.73

1.01

38800




39600

6.37

3.15




29




$ 14,993.517

4.92

1.05

38800




39600

6.16

3.05




30




$ 15,593.257

5.11

1.09

38800




39600

5.97

2.95




31




$ 16,216.988

5.32

1.14

38800




39600

5.79

2.87




32




$ 16,865.667

5.53

1.18

38800




39600

5.62

2.78




33




$ 17,540.294

5.75

1.23

38800




39600

5.47

2.71




34




$ 18,241.905

5.98

1.28

38800




39600

5.32

2.63




35




$ 18,971.582

6.22

1.33

38800




39600

5.18

2.56




36




$ 19,730.445

6.47

1.38

38800




39600

5.05

2.50




37




$ 20,519.663

6.73

1.44

38800




39600

4.93

2.44




38




$ 21,340.449

7.00

1.49

38800




39600

4.81

2.38




39




$ 22,194.067

7.28

1.55

38800




39600

4.71

2.33




40

$ 50,000.00

$ 23,081.830

7.57

1.62

38800




39600

4.63

2.29




41




$ 24,005.103

7.87

1.68

38800




39600

4.54

2.25




42




$ 24,965.307

8.19

1.75

38800




39600

4.44

2.20




43




$ 25,963.920

8.52

1.82

38800




39600

4.36

2.16




44




$ 27,002.476

8.86

1.89

38800




39600

4.27

2.11




45




$ 28,082.575

9.21

1.97

38800




39600

4.19

2.08




46




$ 29,205.878

9.58

2.04

38800




39600

4.12

2.29




47




$ 30,374.114

9.96

2.13

38800




39600

4.05

2.00




48




$ 31,589.078

10.36

2.21

38800




39600

3.98

1.97




49




$ 32,852.641

10.78

2.30

38800




39600

3.92

1.94




50




$ 34,166.747

11.21

2.39

38800




39600

3.86

1.91

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