Australian Water Management Review Vol. 1 2014 | Page 102

Typical mode of operation for Stormwater
harvesting scheme (Figure 1):
a.

b.
c.

d.

e.
f.

Designated volume of run off from the
catchment (1) is diverted by the diversion
structure (2) installed on the existing
drainage system
The diverted run off is screened to remove
gross pollutants and coarse sediment (3)
Screened run off gravitates into the buffer
storage (4); the aim of the buffer storage
is to level out the variance in the incoming
flows and optimize the operational
parameters of the pump that supplies water
to the treatment component
Water from the buffer tank is transferred/
pumped (5) into the treatment component
e.g. wetland/bio retention (6) were the
required quality of product water is achieved
Treated water is transferred to the clear
water storage typically via a pump (7)

1.0 Environmental Considerations
• Flora & Fauna
• Heritage & Cultural
• LCA (Land Capability assessment)
• Environmental Risks Assessment
2.0 Planning/Approvals
• Statutory & land acquisition, planning zone,
dam permit
• Diversion and water use licenses from water
authorities
• Other utilities (e.g. electricity,
communication )
3.0 Public Consultation
4.0 Site Investigations
• Geotechnical
• Services and Surveying
• Water quality sampling and flow monitoring
• Others

The treated water is stored in the Clear
Water storage (8) for intended use; in many
of the schemes involving irrigational use
of product water a relatively large storage
is required due to the temporal difference
between the rainfall (collection) and
irrigation (usage)

5.0 Detail Design of Stormwater harvesting
scheme

g.

Product water is distributed to the end users
via a system of pump(s) and lilac pipes (9)

• Raw water storage (open dam or
underground tanks)

h.

Distribution process typically includes the
disinfection of product water (10) e.g. with
the on line UV system

• Water treatment

i.

Fit for purpose water is delivered to the end
users (11)

Planning, Design, Construction and Operational
Considerations
While it is beyond the scope of this article
to discuss the particular detail of stormwater
harvesting schemes, a few general comments
based on practical experience should prove useful
for stakeholders contemplating a stormwater
harvesting scheme.
The tasks/disciplines required for the successful
delivery of a stormwater harvesting scheme are
diverse and would typically include the following:
96 | Australian water man age m e nt re v ie w

Typical Components:
• Diversion works incl. primary screens
• Raw water transfer infrastructure
• In line detention

• Clear water storage
• Distribution infrastructure
Tasks/Disciplines involved:
• Hydraulics design (diversion rates,
detention and storage volumes, intake/outlet
structures, pipes, pumps)
• Mechanical (pipes, pumps, tanks)
• Structural engineering (soil mechanics/
retaining structures, dams, concrete
structures, pits, pump stations)
• Civil structures (open storages, access
roads, drainage, waste disposal)
• Electrical engineering (extension of
services, switchboards)

• Process treatment part 1 – natural systems
(e.g. wetlands, bio filtration)
• Process treatment part 2 – conventional
(e.g. media filtration, UV)
• Instrumentation & Controls (e.g. SCADA)
6.0 Landscape architecture (some projects)
7.0 Irrigation design (some projects)
8.0 Estimation of Construction Costs/QS
9.0 Project management, reporting and QA
10.0 Construction Management
11.0 Commissioning and scheme validation
12.0 Post Commissioning scheme performance
assessment, audit and reporting
13.0 Operation & Maintenance
Development of stormwater harvesting practice
The robust engineering basis for the planning,
design, construction, operation and maintenance
of urban stormwater harvesting is yet to be
developed. This is because it is a relatively new
engineering concept, despite being used in some
form or another in various places around the
world for centuries.
In the absence of the established design basis
for stormwater harvesting – designers of these
schemes frequently resort to the approaches
borrowed from the more traditional disciplines
such as municipal drainage and water sensitive
urban design (WSUD). A number of leading
Australian stormwater professional have
commented on this issue e.g. Hatt, Deletic,
Fletcher wrote in their article ‘Integrated treatment
and recycling of stormwater: a review of Australian
practice’ Journal of Environmental Management,
vol.79, issue 1, April 2006:
“Existing stormwater recycling practice is far ahead of
research, in that there are no technologies designed
specifically for stormwater recycling. Instead,
technologies designed for general stormwater
pollution control are frequently utilized, which do
not guarantee the necessary reliability of treatment.
Performance modelling for evaluation purposes
also needs further research, so that industry can
objectively assess alternative approaches.”