Ord River Dam

Historic Engineering MarkerCommemorative Plaque

Unveiling Ceremony

Kununurra - Western Australia

Saturday, 28th August 2004Ord River Dam

Proudly presented by

On the abutment of Ord River Dam site during inspectionsby selected tenderers. Photograph (looking upstream) fromBrisbane "Courier Mail" of Monday, August 12 1968

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C O O O

HIS

TO

RIC

EN

GIN

EER

ING

MA

RK

ER

Ord

Riv

er

Da

m

The P

ublic W

ork

s D

epart

ment

of

Weste

rn A

ustr

alia w

ith

Contr

acto

r D

ravo P

ty L

td c

om

ple

ted t

his

dam

in 1

972.

It o

pened u

p 7

6 0

00 h

ecta

res o

f la

nd f

or

irrigate

d a

griculture

and c

hanged t

he e

conom

ic a

nd s

ocia

l str

uctu

re o

f th

ere

gio

n.

The r

ockfill d

am

is 6

8 m

etr

es h

igh a

nd 3

55 m

etr

es

long a

nd o

rigin

ally im

pounded 5

.8 m

illion m

egalitr

es o

fw

ate

r, t

hen t

he larg

est

reserv

oir in A

ustr

alia.

In 1

996 t

he

spillw

ay w

as r

ais

ed 6

metr

es,

alm

ost

doubling its

capacity.

Constr

uction e

ngin

eers

were

challenged b

y e

norm

ous

annual floods a

nd t

he s

ite’s

rem

ote

ness.

The

Insti

tuti

on o

f E

ng

ine

ers

Austr

alia

and

W

ate

r C

orp

ora

tion o

f W

este

rn A

ustr

alia

, 2004

Program

Welcome

Mr Ken Kelsall AM HonFIEAust CPEngFormer Chairman, WA DivisionEngineers Australia

History

Mr Tony Moulds MIEAust CPEngChairman, Engineering Heritage PanelEngineers Australia, WA Division

Unveiling of the Commemorative Plaque

Hon. Nick Griffiths MLCMinister for Government Enterprises

Acceptance of the Commemorative Plaque

Mr Jim Brown FIEAust CPEngGeneral ManagerWater Corporation

Morning Tea

5 2

A g

roup a

t th

e s

ignin

g o

f th

e C

ontr

act

on D

ecem

ber

16 1

968

Left

to R

ight:

Fra

nk K

eet

Secre

tary

and D

irecto

r D

ravo P

ty L

td;

Ken K

els

all

Constr

uction E

ngin

eer

P.W

.D.; D

on M

unro

Chie

f Engin

eer

P.W

.D.; G

uy R

eid

Pro

ject

Manager

Dra

vo P

ty L

td;

John P

ark

er

Directo

r of

Engin

eering P

.W.D

.;G

eorg

e M

arley M

anagin

g D

irecto

r D

ravo P

ty L

td.

The Ord River Dam is of national significance -

o the dam and its associated irrigation scheme changed the economic and socialstructure of the region by establishing a new agricultural industry and a new townwith modern facilities in the midst of a community of sparsely populated cattlestations and a small port town.

o the Ord River Scheme has been a landmark in the development of WesternAustralia’s north and, in putting the East Kimberley "on the map" for mostAustralians, has inaugurated a flourishing tourist industry in the region.

o the dam is a fine example of rock-fill dam technology and its design incorporatedseveral innovative features, which included:-

o the staging of the works to permit one wet season’s river flows to passover the partially completed works and the provision of special measuresto protect the works from these flows; and

o accommodation of the very large estimated peak flood flow by raising theheight of the dam to above maximum flood level and providing a smallcapacity spillway which would gradually release wet season floodwatersduring the dry season.

o the Ord Scheme has been an important research centre for the development oftropical agriculture and the Ord River Regeneration Reserve has provided valuableinformation on the regeneration of overgrazed pastoral country.

o the establishment of the Ord irrigation scheme followed in the continuum of twoimportant Australian historical themes, "peopling the north" and "testing the land"and, like earlier examples, commercial success on the Ord has been hard won overmore than twenty five years.

o the development of Kununurra as the Ord Scheme’s service centre served as animportant model for the establishment of subsequent modern mining towns in thestate’s north-west.

o the 30 megawatt hydro-electricpower station built at the dam in 1996was the first in the state to beprivately constructed to providepower to the state power authority.

o the Scheme has historic associationswith prominent persons involved inits development, in particular:

Sir Russell DumasSir Charles CourtSir John ParkerDonald Munro

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A Brief History

In the 1940s investigations were made into various sites for the main dam on the OrdRiver but, as the magnitude of the wet season discharges of the river became apparent,provision of adequate spillway capacity in the narrow gorge became a problem. Depthto foundation rock was also greater than expected. A submission to the CommonwealthGovernment for funding in 1956 for the whole scheme was unsuccessful but a fivemillion pounds grant for northern development was offered by Canberra. In the sameyear Kimberley Research Station reported favourably about the establishment ofirrigated agriculture and the Hawke State Government decided to develop Stage One ofthe scheme (the diversion dam, preparation of the irrigation area and the building ofKununurra) under the grant. Stage One was completed in 1963.

A rockfill dam with a thin impervious core was found to be more economical for themain dam than the type of mass concrete dam that had been proposed originally. It wasinitially planned to provide for a huge volume of the design flood level by means of aconcrete-lined spillway cut through a saddle just downstream of the right abutment ofthe dam. An innovative alternative was found to be more economical. The spillway wasrelocated by cutting through rock at a saddle 8 km North-East of the dam. The height ofthe dam was raised so that it would be able to store major floodwaters and release themgradually over the spillway during the dry season.

The Commonwealth decided to provide a grant for the construction of the main dam in1967 and the contractor for the works. Dravo Pty Ltd commenced work in April 1969.As work could not be carried out on the dam during the wet season the work wasprogrammed to be carried out during three dry seasons (from April to November). Workwas completed in 1971.

Commercial success of tropicalagriculture and horticulture has beenhard won on the Ord. In 1974growing of the main crop, cotton,had to be suspended due to theincreased resistance of the heliothismoth to insecticides.During the1980s the growing of low-pricedfield crops, such as sorghum,ceased to be viable. In the 1990s ahighly diversified pattern ofhorticulture and agriculture provedto be more resilient and profitable,especially those targeting nichemarkets during the southernwinters.

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