19 September 2018
Viability of Rainwater Harvesting Techniques
for Johannesburg City Parks and Zoo
R. Schmidt, R.P. Verger, K. Scott &
H. Nemavhandu
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Presentation Outline
• Introduction
• South African Guidelines
• Harvesting Techniques
• Case Studies
South African Water Context
• In South Africa water is a scarce commodity.
• Available water resources are under stress.
• Certain areas are frequently declared as drought areas
by government .
• General pressure on water resources could result in
future water restrictions.
• Irrigation of gardens and parks could be seen as a
wasteful extravagance that cannot be afforded.
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Project Introduction
JCPZ wanted to investigate systems that use water
sources such as rainfall and stormwater runoff as an
asset rather than a problem.
There were 27 JCPZ facilities across 7 regions:
• Depots
• Parks
• Zoo
• Nurseries
• Cemeteries
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Project Introduction
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Introduction to WSUD and SuDS
Water Sensitive Urban Design - WSUD
• Focuses on the integration of surface water
runoff/stormwater into the urban water cycle.
• Allows cities to become more resilient to the
pressures on ageing and expensive water
infrastructure
Sustainable (Urban) Drainage Systems – SuDS
• Practical affordable alternatives to stormwater
management
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South African Guidelines
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The Urban Water Cycle
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Due to urbanisation, the urban water cycle has changed
and there is an increase in the runoff generated from
catchment areas.
JCPZ Project
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Rooftop Rainwater Harvesting
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Rainwater harvesting is a process of capturing rainwater
for re-use in a different system instead of letting the
rainwater enter the stormwater system
In-Field Stormwater Harvesting
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In-field stormwater harvesting is used to slow down
runoff to ensure maximum infiltration into the ground
and recharge.
Stormwater Harvesting Techniques
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Underground stormwater harvesting captures
stormwater runoff in underground tank that is stored
for re-use
Case Studies
Five (5) facilities were chosen to demonstrate the
different techniques proposed throughout the
project.
A viability analysis for each proposed rooftop and
underground stormwater harvesting technique was
completed.
Accumulative total cost over the life of the rooftop
rainwater harvesting system was calculated and
compared to the calculated accumulative water
savings over life of system.
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Example 1
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Section Description Amount VAT 14% Total (Incl. VAT)
A Section A: Springfield Depot R 105 890.00 R 14 824.60 R 120 714.60
B Section B: Springfield Street Trees R 48 687.00 R 6 816.18 R 55 503.18
C Section C: Pioneer Park R 32 251.00 R 4 515.14 R 36 766.14
D Section D: Joubert Park R 22 181.00 R 3 105.34 R 25 286.34
E Section E: Metro Park R 22 181.00 R 3 105.34 R 25 286.34
Region F - Total R 231 190.00 R 263 556.60
Preliminary Cost Estimate and Viability
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6 Storage Tanks
Greenhouse Structure
Section Description Amount VAT 14% Total (Incl. VAT)
A Section A: Marks Park Depot R 73 760.00 R 10 326.40 R 84 086.40
B Section B: Zoo Lake Training Centre
R 79 266.50 R 11 097.31 R 90 363.81
C Section C: Johannesburg Zoo R 60 290.00 R 8 440.60 R 68 730.60
D Section D: Westpark Cemetery R 55 525.50 R 7 773.57 R 63 299.07
Region B - Total R 268 842.00 R 306 479.88
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Preliminary Cost Estimate and Viability
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1 Storage Tank
Ablution Structure
Section Description Amount VAT 14% Total (Incl. VAT)
A Section A: Klipspruit Depot R 38 302.50 R 5 362.35 R 43 664.85
B Section B: Orlando West Park R 22 181.00 R 3 105.34 R 25 286.34
C Section C: Petrus Molefe Prescient R 22 181.00 R 3 105.34 R 25 286.34
D Section D: Thokoza Park R 57 783.00 R 8 089.62 R 65 872.62
E Section E: Diepkloof Extreme Park R 22 181.00 R 3 105.34 R 25 286.34
Region D - Total R 194 987.50 R 221 433.60
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Preliminary Cost Estimate and Viability
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Preliminary Cost Estimate and Viability
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Section Description Amount VAT 14% Total (Incl. VAT)
A Section A: Johannesburg Zoo R 1 830 171.2 R 256 223.968 R 2 086 395.168
Region B - Total R 1 830 171.2 R 2 086 395.168
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2 Underground
Storage Tanks
Preliminary Cost Estimate and Viability
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Section Description Amount VAT 14% Total (Incl. VAT)
A Section A: Huddle Park Nursery R 1 166 592.99 R163 323.02 R1 329 916.01
Region E - Total R 1 166 592.99 R1 329 916.01
Conclusions
• Rooftop rainwater harvesting, stormwater harvesting
and in-field harvesting was found to be viable
interventions that JCPZ facilities could implement.
• These interventions promote conservation and reuse
of water in the broader community.
• WSUD and SuDS provides an integrated approach that
is moving away from the conventional stormwater
management systems.
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Recommendations
Integration of rainwater harvesting and water
conservation philosophies into city-wide Stormwater
Runoff Control Plans.
Techniques should be considered in future
developments.
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Thank You