2.8 Design Guideline Water Storage Tank (Ground) · Goulburn Valley Water 2.8 Water Storage Tank (Ground) - Design Guideline 4 Component Description: 1. Tank All ground level tanks

2.8

Design Guideline

Water Storage Tank (Ground)

Goulburn Valley Water

2.8 Water Storage Tank (Ground) - Design Guideline

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Table of Contents

Description: .................................................................................................................................................. 3

Objective: ...................................................................................................................................................... 3

Risk:…. ......................................................................................................................................................... 3

Reference Documents: ................................................................................................................................. 3

Component Description: ............................................................................................................................. 4

1. Tank ................................................................................................................................................... 4

2. Storage Volume ................................................................................................................................. 4

3. SCADA and Monitoring .................................................................................................................... 4

4. Inlet and Outlet Mains ....................................................................................................................... 4

5. Sample Point ...................................................................................................................................... 5

6. Site ..................................................................................................................................................... 5

7. Perimeter fence and Gate ................................................................................................................... 6

8. Access Track ...................................................................................................................................... 6

9. Scour .................................................................................................................................................. 6

10. Overflow ............................................................................................................................................ 6

11. Pipework ............................................................................................................................................ 7

12. Steel Lined Tank ................................................................................................................................ 7

13. Roof.................................................................................................................................................... 7

14. Roof Access Hatch and Work Platform ............................................................................................. 8

15. Reference Markings ........................................................................................................................... 8

16. Metallurgy .......................................................................................................................................... 8

17. Tank Access ....................................................................................................................................... 9

18. Tank Finish ........................................................................................................................................ 9

19. Design Life......................................................................................................................................... 9

Photos. ......................................................................................................................................................... 10

Schematic Plan ........................................................................................................................................... 12



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Description:

The water supply storage tank is a component of the reticulation system that provides 8 hour

minimum reserve storage at peak day plus an allowance for diurnal fluctuations and is positioned on

a suitable elevated parcel of land.

Objective:

To provide emergency storage (8 hour minimum) and a consistent satisfactory water supply pressure

to customers.

The tank and associated pipework is to be designed to withstand a bush fire event and provide a

secure water supply.

Risk:

This Guideline may identify some risks and provides guidance in mitigating these risks. However a

further site specific assessment and/or HAZOP are required to address other risks.

Reference Documents:

Water Supply System Assessment Board Report – February 2007

WSAA – MRWA – Water Supply Code of Australia

GVW Supplement to the WSAA – MRWA – Water Supply Code of Australia - Version 1.0, WSA

03-2002 (Water Code)

GVW Product Manual

GVW Development and Construction Manual

Design Manual – Water Supply Booster Pump Station (To be prepared)

GVW Standard Specification for Switchboards

GVW Building Aesthetics – Design Manual

AS/NZ 4020 Products for use in contact with drinking water



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Component Description:

1. Tank

All ground level tanks are to be constructed in a fire proof material, such as pre-cast or cast in-

situ concrete, bolted steel or welded steel.

All materials and coatings used shall be in accordance with AS/NZ 4020 Products for use in

contact with drinking water.

All tanks are to be constructed so that they are resistant to fire.

All are to include a manhole entry at the top and are to be fitted with a suitable access ladder

and landing to enable safe and secure access for cleaning and maintenance purposes (refer

Tank access hatch and work platform design guideline for details).

2. Storage Volume

The minimum storage volume to provide satisfactory emergency storage is to be 200 KL.

If due to the remote nature of a site or other limitation, such as available space, etc, the target

volume of 200 KL could be reduced to provide an economical and efficient solution. Please

note, 200KL is still the nominal storage volume.

3. SCADA and Monitoring

Low level and high level alarms (floats) are to be installed within the tank to generate alarm

signals. A pressure sensor is also to be installed to monitor water volumes in the tank and will

be used to control inflow to the tank. There is to be a telemetry (radio) link between the supply

pumps and storage tank.

Cable is not preferred when the distance between the booster pumps and the storage tank is

greater than 100m.

The preferred arrangement is for the water level in the storage tank to be relayed to the supply

pump station, which displays all information on the pump station switchboard and is connected

to SCADA.

4. Inlet and Outlet Mains

The preference is for a dedicated inlet water supply main from the supply pumps to the storage

tank, with a separate outlet main connecting to the reticulation system.

If these mains are constructed within private land then an easement or reserve is to be created

over the mains in favour of GVW.

Interconnection between inlet/outlet pipes is required to allow the tank to be bypassed for

maintenance when the tank being constructed is the lone tank on site. If there is more than one



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tank on the site then the design must allow for the new tank to operate independent of the

existing tanks.

Separate inlet and outlet to the tank must be provided and it is preferred that they be located

on opposite sides of the tank minimise short circuiting and promote mixing. In any case where

this is not possible alternative measures to ensure that short circuiting does not occur must be

taken. This may involve vertical separation or directional nozzles.

The inlet shall be designed to prevent sediment disturbance during filling periods.

The outlet screen shall be designed to prevent sediment collection and be accessible for diver

vacuum cleaning.

5. Sample Point

To enable samples to be taken to monitor the quality of the water in the storage tank, a

standard tap is to be fitted to the outlet from the tank within the tank site perimeter fence.

The preferred arrangement is for the tap to be fixed to a post, facing sideways with appropriate

threading to enable standard fittings to be installed when sampling.

6. Site

The storage tank site is to be located within a reserve in favour of the Goulburn Valley Region

Water Corporation.

A storage tank site is to be selected that provides sufficient elevation to provide suitable design

water pressure, access, stable base, space for future tank (if required) and area for

maintenance purposes. Advice is to be sought from Goulburn Valley Water’s Planning and

Project Development Section.

The site is not to be encumbered by existing or proposed overhead power lines and is to provide

satisfactory coverage for monitoring and control via SCADA.

The surrounding area of tank site is to be covered with a minimum of 100mm compacted

crushed rock or similar approved material to provide an all weather access to the site. Good

drainage must be provided.

The layout of the storage tank and other features must ensure that the available space for

maintenance purposes is maximised.

A minimum of 2 metre clearance between all assets and the reserve title boundary must be

achieved where possible.

It is recommended that trees are no closer to the Tank than a distance equal to 1½ times their

mature height. This distance should be increased where rows or groups of trees are planted.



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7. Perimeter fence and Gate

The site perimeter is to be fenced with a 1.80m high chain mesh security fencing around the

complete site boundary.

A minimum 3m wide chain mesh security hinged double gate with padlock keyed is to be

provided a the entrance to GVW system. The gates are to be hinged so that they open out

completely and can be secured back against the perimeter fence when required.

Minimize aesthetic issues for neighbouring properties and the general public. This may require

perimeter buffering planting or screens and should be investigated with Council and local

residents.

NOTE: Additional land will be required to be provided for the reserve if screen plantings are

required.

8. Access Track

The site must be accessible by vehicles (light truck and two wheel drive) by means of an all

weather road. The minimum width of the access is 3 metre wide and sufficient space is to be

provided for a light truck vehicle to turn and for at least 1 parking space.

The access track is to be constructed so that it is accessible by a light truck or small two-wheel

drive vehicle under all weather conditions.

If the access track is created over private land, then a carriageway easement in favour of GVW

is to be created over the track and any parking/turning areas required.

Turning space should be provided inside the tank site with at least one parking area outside the

perimeter fence.

9. Scour

The tank is to be fitted with a scour valve and pipe that enables the tank to be drained as

required. The scour is to drain from the floor of tank and is to be at the lowest point. The design

of the scour point is to consider the need to ‘drain and sweep’ the tank and for vacuum

cleaning by divers. The scour point is not to have a permanent mesh cover as access is

required for cleaning and for use by divers while cleaning the tank.

The scour pipe is to discharge clear of the tank site, preferably into a stormwater system.

Discharge from the scour is to be directed so that it does not cause scouring, damage or future

legal problems.

10. Overflow

The tank is to be fitted with an overflow pipe that is designed to accept the ultimate inlet flow.



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The overflow pipe is to discharge clear of the tank site, preferably into a stormwater system.

Discharge from the overflow is to be directed so that it does not cause scouring or future legal

issues.

A single overflow/scour pipe will be accepted.

11. Pipework

All pipework in the vicinity of the tanks that is above ground shall preferably be DICL. If stainless

steel or other metallic materials are utilised then insulation joints are required.

All exposed ductile pipe and fittings inside the tank must have all ductile surfaces epoxy coated.

All above ground pipework is to be designed to be able to withstand a bushfire event.

All below ground pipe work within the tank site, under the access road or parking areas, must

be DICL material or equivalent.

12. Steel Lined Tank

If a steel lined tank is proposed the following is to be provided:

Cost of installing an alternative concrete tank;

Life of liner and costs of installing liner to provide minimum of 50 year service life;

Procedure or method of taking the tank off line for repair/replacement of the liner; and

Inclusion of fittings, pipework and second tank (if required) to enable the tank to be taken

off line.

If a liner is installed then consideration needs to be given to the amount of loose material and

wrinkles. These provide stress points in the liner and areas for entrapment of sedimentation

and make it hard for cleaning purposes.

13. Roof

All tanks are to include a roof. The roof is to be designed to restrict contamination from entering

the tank even during heavy storm events. The design is to allow for adequate ventilation of the

tank and is to take into consideration the high water level and overflow of the tank and ensure

the roof does not come into contact with the water in the tank.

The roof is to be constructed from material considered appropriate for the environment and

designed to provide a minimum 25 year life without maintenance.

No internal gutters are to be used and the roof is to be designed so that the natural fall of water

is away from the centre of the tank.

No gutters are to be included on the tank and the roof is to extend past the wall of the tank and

flashed to prevent water entering the tank. Appropriate ground level drainage and landscaping



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is to be provided to collect the rain water and divert it away from the base of the tank and not

allow water to pool near the base of the tank.

Appropriate methods are to be used to ensure birds and other vermin cannot enter through the

roof and the design is to reduce areas for bird to construct a nest or roost.

Any manholes or access points through the roof are to be designed and flashed to prevent rain

water entering the tank (refer Tank access hatch and work platform design guideline).

Roof supports if required are to be made from stainless steel and insulated top and bottom

from other materials.

14. Roof Access Hatch and Work Platform

For tank roof access hatch and work platform requirements refer to GVW Design Guideline -

Tank roof access hatch and work platform

15. Reference Markings

Reference markings are to be provided on the internal and external walls of tanks greater than

200KL.

All reference markings are to be a minimum of 300mm in height and painted in a durable

coating appropriate for the environment and the suitable for the tank wall or coating type. The

colour of the reference marking is to be in high contrast to the tank wall or coating.

The reference markings are to be in the form of an analogue clock format with the following

markings at a minimum; 3, 6, 9 & 12. More reference markings may be needed on larger tanks.

Reference marking 6 is to represent the main ladder access point into the tank.

External reference markings are to be located around the tank in the centre of the tank height.

Internal tank markings are to be located in two locations, 500mm from the top and floor of the

tank walls. On tanks walls <2m in height this can be replaced with one marking 1m from the

floor.

All valves associated with the tank are to be clearly labelled (i.e. “inlet’, “outlet” etc.)

16. Metallurgy

Consideration shall be given to the metallurgy for materials used, with no galvanised material

below the water line.

Consideration shall be given to providing cathodic protection of the steel components of the

tank.

Refer to GVW Design Guideline – Avoiding dissimilar metal corrosion



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17. Tank Access

Access ladders are required at a minimum and are to be made to Australian Standards.

Internal ladders are to be vertical and made of stainless steel (SS) or Fibre Reinforced Plastic

(FRP). If ladders are made from SS then consideration shall be given to metallurgy and the need

for electrical insulation of the ladder.

External ladders are to be designed to prevent unauthorised access and are to be lockable.

18. Tank Finish

Concrete Tank

Where a concrete tank is installed any exposed surfaces shall at a minimum have a class 3

surface finish.

No external or internal paint or coating is required for concrete tanks, except for reference

markings.

Steel tanks

Where a steel tank is installed (bolted or welded) the contractor shall ensure that the steel is

protected from corrosion and provide a guaranteed minimum design life.

External coating of the tank shall be Pale Eucalypt or similar.

19. Design Life

The following design life parameters are to be met:

Tank skeleton 80 years

Roof structural members 50 years

Tank liner 50 years

If these parameters cannot be met then additional information regarding the actual design life

and additional costs associated with maintenance/replacement of components is to be

provided.



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Photos



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Version No. Date Description Prepared by: Approved by:

1.0 Sep 2009 Original draft issue Steven Nash N.A.

1.1 Nov 2009 Amended Final Document

(Changed to accept BA comments)

Steven Nash Bruce Anderson

1.2 Jan 2010 Steel Line Tank condition included Steven Nash Bruce Anderson

1.3 March 2010 Steel tank liner life of 50 years and replacement

liner included

Steven Nash Bruce Anderson

1.4 Sept 2010 Revised Format Jeff Block

1.5 Oct 2010 FRP ladders included and electrical insulation of

SS ladders

Adam Glasson Bruce Anderson

1.6 Nov 2010 Amended draft issue Daniel Flanagan Bruce Anderson

1.7 Sep 2011 Added AS 4020 reference for all materials and

coatings

Adam Glasson Steven Nash

1.8 Feb 2012 Added references to design guidelines, tank roof

access hatch and work platform and avoiding

dissimilar metal corrosion

Adam Glasson

1.9 Feb 2012 Made changes to roof requirements including

flashing etc & added photos

Adam Glasson Bruce Anderson

1.10 Sept 2012 New numbering and front page design Adam Glasson Michael Welk

1.11 June 2013 Added risk section Adam Glasson Michael Welk



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Schematic Plan