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RIVER TORRENS LINEAR PARK, ADELAIDE

 


Adelaide Creates A Great Asset
River Torrens Linear Park

Ted Dexter

originally published landscape australia 4/1997

Since its inception in the late 1970s, the River Torrens Linear Park and Flood
Mitigation Scheme has turned a stinking stormwater drain into a major linear
park of national and international quality.


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HISTORY

The River Torrens and its catchment have played an im­portant role in the history of the Adelaide region since the first human occupation of the area. As one of the most fer­tile and diverse habitats in South Australia, the area was a significant resource to indigenous inhabitants prior to the European colonisation, with the reed beds a major focus for culture and food gathering, particularly during dry periods, much in the same way as 'Yellow Waters' func­tions in Kakadu.

Indeed the traditional Kauma (indigenous Aboriginal) greeting literally translated is 'Hullo! Come and have something to eat'. Unfortunately, the area's very fertility with plentiful food and water led to the downfall of its indigenous Aboriginals prior to European habitation. As disease spread out from Sydney and Melbourne, the Adelaide area became a place of retreat for many Aborigi­nals, who unfortunately brought the new 'white' diseases with them. Subsequently, a large proportion of Adelaide's original residents were dead prior to European settlement in the 1830s and 1840s.

The colony of South Australia was established in 1836 on the banks of the Torrens due to its supply of permanent fresh water. The river dictated the pattern of development of the colony as it provided the main source of fresh water, and the floodplains were fertile. Indeed, Surveyor General Colonel William Light ensured that his surveyors had as many properties as possible with access to the River. These were the sections quickly taken up by the first landholders. The River Torrens was a major water resource for the first colonists, although by 1839 Governor Gawler had prohib­ited the people from bathing, washing clothes or throwing dead animals into the river within one mile of the town. The river became steadily more polluted, with complaints in 1853 of the Torrens being 'discoloured by the blood and refuse from a slaughter house'. In 1874 the pollution of the Torrens from discharge of sewers within the City of Ad­elaide and from sand washing, slaughter houses and industrial works in Hindmarsh and Thebarton rendered the river water as unsuitable for human use.

The River Torrens previously did not discharge to the sea and during periods of high flow flooded to the north through the Port Adelaide area and south to the Patawalonga. In July 1917, a particularly severe flood hit the region and a proposal was prepared to cut a channel through the sandhills to the beach, sort-circuiting the 'reed beds'. Further flooding in 1933 resulted in the construction of the Breakout Creek section of the River Torrens in a channelised form connecting directly to the sea. This was completed in 1937. Being no longer subject to regular flood­ing, the area became a prime residential district.

The years after the Second World War saw the transfor­mation from a rural district to suburbia for much of the Adelaide Plains. With the introduction of sewage, the river maintained a primary function for sewage overflow, stormwater disposal and industrial waste disposal. The rapid urbanisation of the floodplain over the last 40 to 50 years provided an even greater potential for flood devastation due to increased run-off. During the 1950s and 60s a number of proposals were put forward for the River Torrens including piping, converting the corridor to a major highway route and concrete lining with a trapezoidal drain. Most of these proposals were driven by the recognition of the potential devastation or the potential flood damage should the river escape its normal banks.

Coupled with the need to achieve flood mitigation require­ments was a burgeoning understanding of the importance of open space and the potential the River Torrens provided as a linear open space area through suburban Adelaide. Thus was bom the concept of a Linear Park.

BACKGROUND OF THE SCHEME

The project was a joint State and local government ven­ture, with 12 local government areas involved (now 8 Councils). SA Water Corporation (formerly Engineering and Water Supply Department) was responsible for the implementation of the government commitment to the Scheme, with Hassell Pty Ltd as a design consultant. Coun­cils were responsible for the implementation and cost sharing for the construction of the path network, signage, lighting and bridges.

The River Torrens was the subject of two reports which established the basis for the Linear Park and flood mitiga­tion works. In 1979, the River Torrens Study was published and comprised a detailed ecological landscape planning study of the river and environs. Tony McCormick and Christopher Wren were principally responsible for the preparation of this report. The report included descriptions of the influence of cultural and natural systems on the river and its future development, a recreation study, develop­ment plans and guidelines, a staging strategy, cost estimates and management and monitoring guidelines.

In 1980, the River Torrens Flood Mitigation Study was published, which comprised a detailed examination of the flooding history, flood potential, options for and preferred mitigation measures and cost estimates.

Based on these reports, agreement on the combined River Torrens Linear Park and Flood Mitigation Scheme was reached between the Government and the 12 riparian Councils. The Scheme was approved upon the recommen­dation by the Parliamentary Standing Committee on Public Works in 1981. At the same time this was being undertaken, the proposals for the O-Bahn Busway were being prepared and integrated with the River Torrens Linear Park Study. The Linear Park Study incorporated a light rail transporta­tion route. This was subsequently successfully modified to a guided bus route (O-Bahn).

Both the State Government and local government made commitments for the construction of the Scheme as follows. State Government:

  • Acquire all necessary land;
  • Modify Kangaroo Creek Dam to mitigate the catchment flows
  • Carry out all flood mitigation works in the urban areasof Adelaide; and
  • Construct the basic Linear Park

Local government:

  • Assume responsibility for landscape maintenance;
  • Construct the pedestrian/ bicycle trail system; and
  • Develop other passive and recreational facilities as appropriate to their resources.

Funding has been provided by the South Australian Gov­ernment and by riparian Councils. During the Scheme, assistance for flood mitigation works has been provided by the Commonwealth Government through the Federal Water Resources Assistance Programme.

Construction of the Linear Park works from Hackney Road to O G Road, Klemzig, was undertaken by the North­East Busway Authority and provided an integrated pedestrian and cycle network to connect to the Linear Park, in addition to flood mitigation and Linear Park development works.

THE LINEAR PARK

The River Torrens Linear Park and Flood Mitigation Scheme
is quite unique and remarkable in many ways, since it:

  • is a major conservation and recreation project at local and regional levels, involving 30 km of the River Torrens from the Adelaide Hills to the coast bisecting the Adelaide metropolitan area;
  • involves innovative low cost flood mitigation measures which, in addition to reducing potential major flood problems, restore the existing man-modified river to what will appear to be a natural water-way;
  • reverses the years of abuse that poor adjacent development and exploitation of the river's resources has caused; and
  • demonstrates considerable vision on behalf of the Government and Councils in creating a resource which, as it matures, will provide enjoyment for future generations.

The completion of the River Torrens Scheme provides protection for urban areas from floods up to an estimated 1 in 200 year mitigated event, as well as linking the coast to the foothills with a recreational area comprising natu­ral and more formal park facilities for active and passive recreation.

 

Figure 1:
Drawing to demonstrate the functioning of the wetlands built within flood plain area.


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FLOOD MITIGATION

The project set the standard as a co-ordinated scheme in­volving a Linear Park and flood mitigation component. The environmental / social benefits are associated with the Lin­ear Park works, while the direct financial benefits are derived from the flood mitigation aspects.

The standard of protection at which net benefits would be maximised was determined by comparing the costs and benefits of flood mitigation schemes for various standards of protection. This analysis indicated that the maximum net benefit occurred for a standard of protection equiva­lent to the completed mitigation with a flood recurrence interval of 200 years or less. For a standard of protection equal to a 1 in 200 year return period, the gross benefit was $19.3 million in 1979 values. The optimal solution involved structural measures in the rural catchment (to Kangaroo Creek Dam) and in the eastern and western reaches of the urban catchment to increase capacity.

DEVELOPMENT STANDARDS

The design consultant for the project is Hassell Pty Ltd. The concept design was prepared for approval in 1979 and details were finalised prior to commencement of construction for each stage. The finalisation of these details involved an extensive community consultation period, to develop a close working relationship and sense of ownership with adjoining landholders and potential park users.Hassell prepared the concept designs, final designs and detailed design documen­tation, and assisted with contract implementation and solving a number of problems requiring specialist expertise.

The proposal was to re-establish an as near as possible representation of the native vegetation that would have occurred within the river corridor. Notwithstanding this, there are a small number of socially important stands of exotic vegetation which have been retained. Generally, it has been necessary to remove all noxious weeds and pest plants such as Desert Ash, Lombardy Poplar, common Olive and Almond Leaf Willow which also contribute to flooding problems.

Major earthworks were necessary throughout the Scheme to:

  • increase the channel capacity and create levees to accommodate a channel capacity of 410 cubic metres per second which was estimated to be the 1 in 200 year return period flood;
  • facilitate maintenance and access;
  • reduce active erosion which is endangering properties;
  • ensure positive drainage of all areas of the Linear Park to the river;
  • accommodate trails and paths; and
  • incorporate wetland areas as appropriate, to treat stormwater from adjoining suburban areas (particularly low flows).

The planting is designed to:

  • conform with flood mitigation requirements;
  • stabilise steep banks to reduce erosion;
  • provide wildlife habitats;
  • screen unsightly features and emphasise existing significant features, and
  • restore the riverine character by using indigenous plant species.


INTEGRATING EXISTING RESERVES

Many isolated areas of the River Torrens banks were de­veloped and 'beautified' as council reserves before the project started, but in most cases the remaining areas were neglected and degraded, and often within private owner­ship. This has necessitated major work to achieve an acceptable environment. Also, considerable acquisition of private land was required where title boundaries ran to the centre of the river.

Old sand washing plants were removed, rubbish tips filled and old irrigation systems removed.

In many cases, the earthworks meant relocating existing stormwater outlets and developing a range of less envi­ronmentally intrusive solutions than the generally used mass concrete aprons and headwalls.

Hundreds of thousands of Australian native riverine trees and shrubs that would have been found adjacent to the Torrens have been used throughout the Scheme.

Figure 2:
Illustrative drawings explain the functioning of the river works.


ENVIRONMENTAL SENSITIVITY

The River Torrens flows through the oldest suburbs of metropolitan Adelaide and in fact through the city itself, thus any work on or around the river is done in the public eye.

The project was constructed in stages, with each stage being handed over to the respective council at the conclu­sion of the maintenance period, normally three to six months.

It has been recognised throughout the design and con­struction that to attempt the development of an environmentally sustainable habitat in an urban area which has suffered virtually complete destruction is difficult and would require a lengthy period. To this end, the first stage of planting included major upper canopy plants, with sub­sequent plantings of lower canopy and reintroduction of a range of different plant species as conditions improve. This work is progressively occurring as conditions change and must be constantly reviewed and refined.

Following on from the development of the River Torrens Linear Park has been the preparation of the Torrens Comprehensive Catchment Water Management Plan dealing with the entire catchment of the Torrens, and therefore having the potential of a greater impact on the environ­mental improvement of the water course. The Catchment Plan has been prepared by Hassell and focuses on a broad range of changes in what is a very diverse catchment.

One of the major outputs of the study has been the implementation of a range of community driven projects, with adjoining residents grouping together to form friends of different sections (for example, Friends of the Billabong, and the Our Patch Programme) to progressively reintroduce the range of plants and animals that would have been found within the catchment water course.

CONSTRUCTION

Construction commenced in January 1982, with the initial efforts focusing on flood mitigation components and OBahn works. The project has been progressively delayed, mainly due to financial constraints in successive State budgets; however, all State Governments, of whatever party, have avowed their commitment to complete the works. Previous completion dates included the South Australian Sesquicentenary 1986 and the Australian Bicentenary 1988. However, the final budget allowances and actual construc­tion of the works were completed at the end of September 1997, with final handover to Councils in 1998.

PROJECT MANAGEMENT

Necessarily in a project of this nature, a broad range of per­sonnel and staff have been involved. The interesting aspect of the project is that Hassell has maintained a high level continuity of management throughout the project.

John Simons' significant and major contributions must be acknowledged for his fundamental input into the genesis and development of this park. John's responsibilities over the years included:

  • Manager of Corridor Development for the North-East Busway project;
  • Project Manager for the River Torrens Linear Park between Hackney Road and OG Road, Klemzig;
  • Chairman of the River Torrens Committee from 1968 to 1987

Project managers from Engineering & Water Supply De­partment (SA Water) were:

  • Robert Bock to December 1982
  • Ian Pedler to June 1983
  • David Farwell to December 1993
  • Brian Little to December 1994
  • Panurgem (David Farwell) and Hassell to December 1997.

Hassell project management staff include:

  • Tony McCormick - report preparation to July 1980
  • Christopher Wren - report preparation and project management to 1988
  • Ted Dexter - design documentation and project management from 1981 to October 1997.

Over the years numerous Hassell staff have worked on the River Torrens Linear Park and should all be commended for their individual contributions and confidently feel a strong sense of ownership for their contributions to this major facility.

EVOLUTION OF DESIGN

A project envisaged in the 1960s, with a concept developed in the 70s and construction undertaken in the 80s and 90s, must necessarily undergo a range of changes in response to the changes in social needs and behaviour. An example of this includes the path network. The bicycle and pedes­trian network is a dual-use path and upon consultation with cycle groups was originally envisaged to be used only as a recreational cycle trail. The increased use of bicycles, roller-bladers, roller-skaters and other forms of wheeled personal transport have meant that the path and its design standards have had to be constantly upgraded. This has necessitated detail design reviews and consultation with user groups and those authorities responsible for maintaining path networks.

A number of user surveys have also been undertaken to establish who is really using the Linear Park and their re­action to the Linear Park. Most valued improvements include:

  • improved landscaping appearance;
  • walking and cycle paths;
  • better and safer access;
  • cleanliness;
  • provision of wildlife habitat; and
  • enhanced ability to use the park for recreation and play.

The concerns include:

  • conflict between cyclists and pedestrians;
  • safety and lighting;
  • signage and publicity;
  • landscape maintenance; and
  • lack of continuous access.

The positive comments about the Linear Park exceed negative comments in a ratio of 2.3 to 1.

Interestingly, the recreation trends indicate that most people using the park walk, and more than 50% of users are over 40 years of age. Over 20% of all users are over 60 years of age. The use periods are normally between 30 minutes and an hour, with the main reasons for using or visiting the Linear Park listed as:

  • walking;
  • living nearby;
  • cycling;
  • relaxing;
  • enjoying nature;
  • running / jogging;
  • picnics / barbecues;
  • children's play.

Another area of ongoing refinement has been the incor­poration of wetlands, with a number of permanent wetlands being established adjacent to the river to treat the stormwater low flows prior to their discharge into the River Torrens proper.

RECOGNITION

The River Torrens is registered on the Australian Heritage Commissions Register of National Estate in recognition of its historic, cultural and environmental values. The River Torrens Linear Park Scheme has been the recipient of numerous awards,including those from the Australian Institute of Landscape Architects for a study in the category of infrastructure and as a project. The Linear Park extracts positive responses throughout Adelaide. From living next to a stinking stormwater drain, people are now adjacent to a major park providing connection through the city with grade­separated cycle and pedestrian connections at all intersections, and a primarily passive recreation park of national and international quality.

FUTURE

The completed River Torrens Linear Park and Mitigation Scheme is an outstanding asset in terms of flood protec­tion and a continuous recreation and habitat zone covering over 30 km bisecting the Adelaide metropolitan area. The Scheme has cost $34 million since its inception in the late 1970s and has been delivered within the budget estimates approved by Cabinet in 1984. With the completion of the works the responsibility for maintenance and mana cement of the Linear Park, including the River Torrens clannel, will be transferred from SA Water to DENR (Department of Environment and Natural Resources). Currently a main­tenance manual and audit report is being prepared for SA Water by Hassell for the purposes of this handover of re­sponsibilities to DENR.

The future of the Linear Park will, like its construction, become dependent on establishing clear guidelines and having the strength, forthrightness and dedication to co­operation to ensure its continued implementation. Having been involved in the Linear Park for nearly 17 years, I am looking forward to watching it further grow and develop and revisiting it in 40 years to see the exciting new direc­tions it will have taken over this period.

Many thanks to all who have worked on the Linear Park and particularly to David Farwell for his contribution to its construction and input to this article.

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