HOBART CITY COUNCIL
DEVELOPMENT AND ENVIRONMENTAL SERVICES DIVISION
RIDGEWAY
LOCAL AREA PLANNING
PROVISIONS
BACKGROUND DOCUMENTATION VOL 1
DRAFT FOR PUBLIC COMMENT – OCTOBER 2002
At its meeting on 28 October 2002 Council approved the release of the draft Ridgeway Local Area Planning Provisions for public comment. The Local Area Planning Provisions comprise 2 documents. Volume 1 (Background Document) contains supporting information on the physical environment, community views, infrastructure and constraints and hazards. Volume 2 (Local Area Planning Provisions) provides the framework for the future planning, development and management of the study area and recommends a number of actions for implementation. Council is inviting public comments on the draft document prior to making any decision on its recommendations. Comments on the Plan should be sent to: General Manager Hobart City Council GPO Box 503E Hobart Tas 7001 by Monday 16th December 2002
For further information please contact James McIlhenny (Senior Development Planner) on (03) 62382891
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CONTENTS 1. BACKGROUND ...... 6 1.1 INTRODUCTION ...... 6 1.2 APPROACH ...... 6 1.3 EXISTING PLANNING FRAMEWORK ...... 7 1.3.1 City of Hobart Planning Scheme 1982...... 7 1.3.2 Land Use Planning and Approvals Act 1993 ...... 7 1.3.3 State Policies...... 8 1.3.4 Local Government (Building and Miscellaneous Provisions) Act 1993...... 8 1.3.5 Kingborough Planning Scheme 1988...... 8 1.4 INFORMATION SOURCES ...... 8 2. NATURAL AND CULTURAL VALUES AND HAZARDS ...... 10 2.1 PHYSICAL FEATURES ...... 10 2.1.1 Landform ...... 10 2.1.2 Catchments...... 10 2.1.3 Climate...... 10 2.1.4 Geology and Soils...... 10 2.2 HAZARDS...... 10 2.2.1 Land Slip...... 11 2.2.2 Soil Erosion...... 11 2.2.3 Flooding...... 11 2.2.4 Water Quality...... 11 2.2.5 Bushfire...... 12 2.3 BIOLOGICAL FEATURES...... 12 2.3.1 Flora...... 12 2.3.2 Fauna...... 13 2.4 CULTURAL FEATURES...... 14 2.4.1 Aboriginal Heritage ...... 14 2.4.2 European Heritage ...... 15 2.5 VISUAL AND CULTURAL LANDSCAPE VALUES...... 15 2.5.1 Visual Landscape...... 15 2.5.2 Cultural Landscape ...... 16 3. DEMOGRAPHIC PROFILE ...... 18 3.1 POPULATION ...... 18 3.2 HOUSING ...... 18 3.3 SOCIO ECONOMIC PROFILE...... 18 2 October 2002 Ridgeway Local Area Planning Provisions - Background Documentation ______3.3.1 Australian Born Persons ...... 18 3.3.2 Age Distribution ...... 18 3.3.3 Income ...... 19 3.3.4 Employment / Occupation & Qualifications ...... 19 3.3.5 Journey to Work ...... 19 3.3.6 Summary...... 19 4. LAND USE AND INFRASTRUCTURE...... 20 4.1 DEVELOPMENT PATTERN AND LAND TENURE...... 20 4.2 LAND USE AND DEVELOPMENT POTENTIAL ...... 20 4.2.1 Potential for Agricultural/Horticultural Land Use...... 20 4.3 INFRASTRUCTURE...... 21 4.3.1 Roads ...... 21 4.3.2 Water...... 22 4.3.3 Stormwater...... 22 4.3.4 Waste Disposal ...... 22 4.3.5 Electricity and Communications...... 23 4.3.6 Recreation, Open Space and Fire Trails ...... 23 4.3.7 Commercial/Community Facilities...... 24 5. COMMUNITY VALUES AND ISSUES...... 26 5.1 INTRODUCTION ...... 26 5.2 HOUSEHOLD SURVEY...... 26 5.3 COMMUNITY WORKSHOP...... 29 5.3.1 Natural Environment ...... 29 5.3.2 Community Facilities and Services ...... 29 5.3.3. Cultural Heritage and Landscape...... 30 5.3.4. Development Issues ...... 30 6. SITE ASSESSMENT...... 33 6.1 INTRODUCTION ...... 33 6.2 SECTORS...... 33 6.2.1 Property Along Dunns Creek ...... 33 6.2.2 West Ridgeway...... 34 6.2.3 Central Ridgeway ...... 34 6.2.4 East Ridgeway ...... 35 6.2.5 Southern Outlet...... 36 7. ENVIRONMENTAL AND PLANNING ISSUES...... 37 7.1 ENVIRONMENTAL ISSUES ...... 37 3 October 2002 Ridgeway Local Area Planning Provisions - Background Documentation ______7.2 DEVELOPMENT AND INFRASTRUCTURE ISSUES ...... 37 7.3 COMMUNITY FACILITY AND SERVICES ISSUES...... 37 7.4 PLANNING SCHEME ISSUES ...... 37 7.4.1 Rural B Zone - Precinct 44A ...... 38 7.4.2 Rural C Zone - Precincts 43E and 44B...... 38 7.4.3 Planning Scheme Generally...... 38 7.5 REGIONAL IMPLICATIONS...... 39 7.6 IMPLICATIONS FOR FUTURE PLANNING ...... 39
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MAPS
Map 1 - Study Area Map 2 - Planning Scheme Zones and Precincts Map 3 - Plant Communities Map 4 - Significant Faunal Habitats Map 5 - Visual Character Units Map 6 - Visual Absorption Capability Map 7 - Land Tenure Map 8 - Site Analysis Sectors
APPENDICIES
A Bibliography B Elton D (1997) Ridgeway Catchment Mapping, Habitats and Hazards C North A (1997). Botanical Survey of Hobart Bushland - Stage 2 Ridgeway D Brereton R (2000) Ridgeway Local Area Plan - Fauna and Habitat Overview E Extract from 208 Network (1994), Mt Wellington: Mountain Park Resource Inventory, F Complete Agricultural Consulting Services (2000), Ridgeway Area - Land Capability Assessment G B Ridder, (1998) Septic Tank Survey - Method | Discussion | Conclusions unpublished report for the Hobart City Council
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1. BACKGROUND
1.1 INTRODUCTION
This Local Area Planning Provisions document is one of a number that have been prepared for the suburbs on the bushland fringes of Hobart. They have been prepared in recognition of the importance of these areas in terms of their conservation, environmental management and landscape values and their sensitivity to the impacts of development.
In March 2000 Council endorsed the project brief for the preparation of a Local Area Plan for Ridgeway. The primary objective of the project was to prepare a Plan that integrates all of the ecological, social, cultural, economic and strategic elements that determine the existing and future development pattern in the Study Area.
The key outcomes expected from this project were as follows: • An environmental inventory and capability assessment of the Study Area, based on an integrated assessment of its environment, catchments and resources. • The identification of possible future pressures for development in the context of both the overall city wide and regional patterns of growth and infrastructure provision. • An integrated resource assessment and land use planning framework for the Study Area. This framework should define the desired nature and character of the area and the related performance criteria for its environmentally sustainable development and management. • Appropriate provisions for City of Hobart Planning Scheme or other recommended statutory planning instruments.
The primary Study Area is shown on Map 1 and incorporates the area within the City of Hobart south of Ridgeway Park and east of Summerleas Road with the north eastern boundary being the Southern Outlet.
This report provides the background information collected in Stage 1 (Analysis and Background Documentation) of the Local Area Planning Provisions process. This chapter outlines the existing planning context, the approach taken and information sources used.
1.2 APPROACH
The preparation of the Local Area Planning Provisions involves the following process: a) Analysis and documentation of all relevant background information on environmental, social, economic and cultural issues in order to gain a strategic insight into the underlying values of the Study Area. b) A strategic overview of the Study Area in terms of its relationship with the rest of the City and the region. c) Community consultation to identify issues and community values for consideration when developing future directions. d) Formulating clear guidelines on the type, form and location of new development. e) Developing a framework for managing development and use in accordance with the objectives of the Resource Management and Planning System.
This report deals primarily with the contents of a) to c) and provides the background to the formulation of the Local Area Planning Provisions. These will recommend strategic directions for the future of the area which will be used as the basis for an extensive program of community and public consultation on the relevant issues identified in the analysis. Fig. 1 sets out the process for the development of the Local Area Planning Provisions.
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1.3 EXISTING PLANNING FRAMEWORK
1.3.1 City of Hobart Planning Scheme 1982
The Study Area is contained within Precincts 43E, 44A and 44B of the City of Hobart Planning Scheme 1982 and is zoned either Rural B or Rural C (Map 2). The intent of these Precincts as described in the Statement of Desired Future Characters is to protect the existing rural and bushland character while providing for rural activities and the development of single dwellings on large lots.
Within Precincts 43E and 44B the minimum subdivision lot size is 4ha and within Precinct 44A it is 2ha. Further subdivision is discouraged in Precinct 44B.
The only permitted uses in Table A1 of the Scheme are a house and passive recreation. There are 2 use groups in the Rural B zone (IV-domestic business, XIV-light industry, warehouse, saleyard) and 1 in the Rural C zone (IV-domestic business) which may be allowed at the discretion of Council. Bed and breakfast accommodation, self contained visitor accommodation and backpacker accommodation are also discretionary uses in both zones. All other use groups are prohibited.
Land in the Rural B and C Zones is subject to the provisions of the Bushland Management Schedule in the City of Hobart Planning Scheme 1982 where proposed use or development is to be located within an existing bushland habitat. The primary objective of this Schedule is to protect the environmental values of bushland and it requires the preparation of a Development and Environmental Management Plan for all use and development.
Schedule I Clearing of Land in the City of Hobart Planning Scheme 1982 also applies throughout the area. This Schedule requires approval to be obtained for the removal of vegetation where it involves an area of land greater than 500m2 on any one lot within 2 consecutive years or any significant tree listed in the appendix to the Schedule.
1.3.2 Land Use Planning and Approvals Act 1993
The Land Use Planning and Approvals Act 1993 sets out the objectives of the Resource Management and Planning System of Tasmania along with the planning process. The outcomes of the Local Area Planning Provisions will need to demonstrate compliance with the Resource Management and Planning System (RMPS) of Tasmania and the following objectives set out in Schedule 1 of the Land Use Planning and Approvals Act 1993:
“1(a) to promote the sustainable development of natural and physical resources and the maintenance of ecological processes and genetic diversity; and (b) to provide for the fair, orderly and sustainable use and development of air, land and water; and (c) to encourage public involvement in resource management and planning; and (d) to facilitate economic development in accordance with the objectives set out in paragraphs (a), (b) and (c); and (e) to promote the sharing of responsibility for resource management and planning between the different spheres of Government, the community and industry in the State.
In clause 1(a), "sustainable development" means managing the use, development and protection of natural and physical resources in a way, or at a rate, which enables people and communities to provide for their social, economic and cultural well-being and for their health and safety while - (a) sustaining the potential of natural and physical resources to meet the reasonably foreseeable needs of future generations; and (b) safeguarding the life-supporting capacity of air, water, soil and ecosystems; and (c) avoiding, remedying or mitigating any adverse effects of activities on the environment”.
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1.3.3 State Policies
The RMPS also enables the State Government to prepare State Policies which are to be implemented through local planning schemes. The only State policies currently in operation are the State Policy on Water Quality Management and the State Policy on the Protection of Agricultural Land.
1.3.4 Local Government (Building and Miscellaneous Provisions) Act 1993
Part 3 of the Local Government (Building and Miscellaneous Provisions) Act 1993 provides for the regulation of the subdivision of land. It states the circumstances in which a Council must not or may refuse an application for subdivision. It also provides for the provision of public open space or a cash payment for open space purposes upon the approval of subdivisions.
1.3.5 Kingborough Planning Scheme 1988
Land adjoining the municipal boundary in the Kingborough Council area is zoned Rural B under the provisions of the Kingborough Planning Scheme 1988. The intent of the Rural B zone is to retain land for predominantly agricultural and landscape protection purposes. The minimum subdivision lot size in this zone is 20ha. Uses allowed in the zone include house, holiday flat, tourist operation, rural industry and passive recreation. The Kingborough Council has recently prepared a new planning scheme for its Municipality which has yet to be finally approved by the Resource Planning and Development Commission.
1.4 INFORMATION SOURCES
The information presented in this report has been obtained from a number of sources including past reports, literature review, Council files and maps, site investigations, surveys, consultants reports, ABS Census data and community consultation.
A list of references consulted is provided in Appendix A. The various consultants reports are attached as appendices with the exception of the cultural heritage report by Sheridan G (2000) which will be made available as a separate document.
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RIDGEWAY LOCAL AREA PLANNING PROVISIONS – PROCESS
Resource Community Regional / Legislative Analysis Consultation State Policy Analysis Framework & Objectives Stage 1 Objectives
Values, Issues & Opportunities
Strategies and Objectives
· Landscape & Environmental Improvement · Infrastructure Stage 2 · Access & Traffic Management Public Consultation · Planning and Development
LOCAL AREA PLANNING PROVISIONS
Statutory Instrument – Works Management Planning Scheme: Program · On Ground Stage 3 · Zones · Design Management · Use Classes · Implementation · Education · Standards · Financing · Enforcement · Codes · Encouragement · Design Guidelines · Evaluation · Research Ridgeway Local Area Planning Provisions - Background Documentation ______
2. NATURAL AND CULTURAL VALUES AND HAZARDS
This Chapter provides a brief summary of the physical, biological and cultural features of the Study Area as well as the natural hazards affecting development.
2.1 PHYSICAL FEATURES The following is a summary of the physical features of relevance to the future development of the Study Area. A more detailed description can be found in the report (see Appendix B) Ridgeway Habitat and Hazard Mapping (1997) by D Elton.
2.1.1 Landform
The land within the Study Area is generally steep and comprised of a series of ridges and gullies, with the flatter areas found on the ridges and a plateau area in Ridgeway itself. The steeper slopes and gullies are still largely in native vegetation.
2.1.2 Catchments
The Ridgeway study area is part of the Browns River catchment and contains the upper tributaries of a series of creeks that eventually all flow into Browns River. Each of these systems has a series of small permanent or intermittent tributary creeks. The tributary defining the Southern Outlet, Vincents Rivulet, partly follows a complex fault system.
2.1.3 Climate
The nearest weather stations are at Fern Tree and the Waterworks, which report 1160mm and 834mm of rainfall as long term annual averages, and it is not unrealistic to assume a value somewhere between these two figures for Ridgeway. Rainfall is relatively evenly spread throughout the year. Prevailing winds are from the west and north west.
The elevation of Ridgeway, 350m at the junction of Hall and Bramble Streets, ensures that the temperature will be at least a couple of degrees below that in the City. Frosts are common throughout the winter and early spring period.
Those parts of the Study Area with a southerly aspect have decreased sunshine hours due to topographic shading, particularly in winter. In Hobart, daily sunshine hours average 7.9 in summer and 3.6 in winter. Specific figures are not available for Ridgeway however the hours of sunshine are likely to be less due to the elevation and proximity of Mount Wellington to the west.
2.1.4 Geology and Soils
Most of the Ridgeway area is composed of Jurassic dolerite which forms the various ridge landforms and underlies the plateau section in the centre of the Study Area.
Podzolic Soils on Dolerite (PSD) comprise the predominant soil type, with a shallow clay loam-loam top soil over a yellow brown/gravelly clay. The PSD’s are interspersed with small areas of brown loam- sandy loam particularly in the eastern sector.
2.2 HAZARDS The analysis of the physical features of the Study Area highlight a number of environmental hazards that may place limitations on the location and form of development. Each of these are outlined below.
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2.2.1 Land Slip
The potential for land slip is dependent on slope, geology, level of sub-surface moisture, and vegetation cover. From the landform analysis in the Ridgeway Habitat and Hazard Mapping report, D Elton (1997), (see Appendix B) most of the Study Area consists of gentle (5-12o) or mid-slopes (12- 20°) which can generally be built on safely.
The Elton (1997) report recommended that all development on slopes over 12 degrees be supported by a geo-technical assessment submitted with the development application. More recently Council has developed procedures which adopt a 15 degree threshold for areas of dolerite geology and 10 degrees for triassic sedimentary.
Given the geology and gradient, most of the Study Area could potentially be developed from a slope stability perspective, subject to geo-technical assessment. Existing Council procedures have been developed which address these issues. The Elton (1997) report recommends that creek gullies be reserved from development for their inherent risk of flood and earth movement, and importance in maintaining creek stability and water quality.
2.2.2 Soil Erosion
Soil erosion is an important consideration because excessive soil loss from an area constitutes a serious environmental impact and increased soil levels in waterways diminishes water quality and amenity.
As described in the report by Complete Agricultural Consulting Services (2000) Ridgeway Area Land Capability Assessment (Appendix C), most of the land area falls within the Department of Primary Industry and Fisheries (DPIF) Chimney Pot Hill System No.34962. It is stated in the DPIF Land Systems of Tasmania Region 6 Report (p197) "The land system is not particularly prone to erosion, although sheet, rill, and gully erosion problems sometimes occur on the crests and slopes following disturbance."
Evidence of rill/small gully erosion is noticeable adjacent to tracks and fire trails. Where drains have been established on steep slopes beside roads significant erosion occurs. Tunnel erosion is evident adjacent to Proctors Road.
In this medium-high rainfall area any disturbance of existing vegetation is likely to result in some erosion problems.
Any development needs to be undertaken with the appropriate sediment control structures in place and stormwater needs to be managed in accordance with best management practices. The length and number of driveways on steep slopes also need to be minimised.
2.2.3 Flooding
With most of the area covered in vegetation and relatively small water catchments, houses in Ridgeway rarely if ever experience flooding. This situation also stems from the low level of stormwater runoff due to low development densities. High water flows could be expected at times of significant rainfall alongside the creeks in the Study Area and it is important that forest cover on the steep upper slopes be retained in their natural state to buffer any storm generated runoff. One dwelling on Old Proctors Road may be in a flood risk zone.
2.2.4 Water Quality
The quality of downstream water, particularly in the hours immediately after a storm, provides a good indicator of the sensitivity of upstream development. Ridgeway is drained by Dunns Creek to the south and Vincents Rivulet to the east, both of which subsequently drain into Browns River which then discharges into the River Derwent at Kingston Beach.
In the past five years, Kingborough Council has recorded high levels of faecal contamination in the lower section of Browns River. It has been demonstrated that this is primarily due to the impact of stormwater and leaky sewers in the residential suburbs of Kingston.
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Although areas like Ridgeway and Fern Tree have not been identified as contributing to the Browns River problem, there is the potential that future development could change this.
A decline in water quality can be expected following modification of the riparian system or the input of pollutants. Around Ridgeway modification of the riparian system has been minimal, with all of the upper watershed (recharge) zones still functional and little development having taken place in the gullies.
2.2.5 Bushfire
The destruction wrought by the 1967 bushfires in Ridgeway, and the more recent "near-miss" in January 1998, indicate that Ridgeway is at risk from bushfire, particularly those dwellings which are in close proximity to vegetation. During the major bushfires in 1967 very few structures around Ridgeway survived intact.
Bushfire in the Hobart area is invariably induced by human activity, either accidental or deliberate. Ridgeway is a settlement surrounded by bush, which is in turn surrounded by the outlying suburbs of Hobart and Kingston. Combustible material and sources of ignition are in abundance. Under these circumstances, regular bushfire is inevitable, with the risk of property damage only reduced through sensible bushfire hazard minimisation practices.
The Tasmanian Fire Service defines areas of high fire hazard as being over 15° in slope and covered with vegetation. A significant part of the Study Area fits this classification.
Planning Note No. 11 - Bushfire Hazard Minimisation Planning, (1997), Land Use Planning Review Panel states that land identified as being either moderate or high bushfire hazard should ideally not be used for land uses which would present a potential risk to life or property.
It also states that any developments in medium or high risk areas should comply with measures to reduce fire risk, such as those found in Planning Conditions and Guidelines for Subdivision in Bushfire Prone Areas, Tasmania Fire Service (1995). The impact of the extent of clearing or other bushfire fuel management on landscape and conservation values does however need to be carefully considered.
More detailed guidelines are currently being prepared by a regional committee comprising representatives from local government, the Tasmania Fire Service and the Housing Industry Association (Guidelines for Development in Bushfire Prone Areas for Tasmania, Draft 2002, Bushfire Planning Group). The outcomes from this will be considered for incorporation into the Local Area Planning Provisions.
A draft Ridgeway Park/Waterworks Reserve Fire Management Plan has recently been prepared by AVK Environmental Management and IFERM P/L (June 2002) on behalf of the Hobart City Council. One of the principle objectives of this Plan is to minimise the risk of wildfires starting in the Park and damaging built assets on and surrounding the Park. It is also an objective of the Plan to inform residents adjacent to the park about fire safety issues and measures to protect themselves and their property.
2.3 BIOLOGICAL FEATURES
2.3.1 Flora
Generally, the slopes in the Ridgeway area are covered by forest and woodland although the canopy has been opened up near settlements or on hard stony ground. The dolerite soils are covered by associations of White Peppermint, Bluegum and Stringybark forest/woodlands with heath, sedges and some shrubby areas. Broadleaf and Fern communities occur along the creek lines in the wetter gullies protected from fire, while other areas have an understorey of bracken.
A botanical survey of the area has been undertaken by A J North & Associates, the results of which can be found in Appendix C - Botanical Survey of Hobart Bushland - Stage 2 Ridgeway A North (1997).
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The survey found several plant species of conservation significance including Danthonia procera, Gahnia rodwayi, Olearia rodwayi and Allocasuarinia duncanii all of which are listed as rare under the Threatened Species Protection Act 1995.
Two plant communities ( Grassy White Gum Woodland and Sedgey Black Gum Forest) were considered in critical need for further conservation. Several plant communities were also identified as having important conservation priority. The location and significance of the plant communities identified is shown on Map 3.
2.3.2 Fauna
A detailed assessment of the fauna values within the Study area is provided in Appendix D - Ridgeway Local Area Plan - Fauna and Habitat Overview, (2000) R Brereton. Map 4 shows the location of significant faunal habitats.
The assessment found that there are a large number of species of conservation significance which have been recorded from the Ridgeway area. Most of the significant faunal species are associated with the wet forest and wet gully habitats.
Tables 1 and 2 below list threatened and significant fauna in the Study Area and their likely habitats. In Table 1 the “status” column refers to their listing in the Tasmanian Threatened Species Protection Act 1995 or the Commonwealth Endangered Species Act 1992. In Table 2 it refers to their listing by the Tasmanian Vertebrate and Invertebrate Advisory Committees 1994. If their status is not shown it indicates that their status has not yet been determined by those Committees.
Table 1. Threatened fauna Species Common name Status Habitat Tas/Nat
Perameles gunnii Eastern Barred -/V Occurs in grassy forests and grasslands (both Bandicoot native and introduced). It also utilises gardens in urban areas and is vulnerable to predation by cats and dogs.
Accipiter Grey Goshawk R/- A pair is known to breed in the Fern Tree- novaehollandiae Ridgeway area. Nests are usually located in Acacia melanoxylon in riparian habitats (Brereton & Mooney 1993).
Lathamus discolor Swift Parrot E/E Known to breed in Ridgeway area. Nests in hollows in old growth eucalypts (Brown 1989, Brereton 1997a). Recorded foraging in flowering Eucalyptus globulus and E. obliqua in the study area.
Lissotes menalcas Mt. Mangana stag V/- Lives in decaying logs in wet forest. beetle
Fraus latistria Broad-striped Ghost R/- Recorded from E. pulchella grassy woodland at Moth Ridgeway (Nielsen & Kristensen 1989).
Key: E - Endangered, V - Vulnerable, R - Rare, M - Requires monitoring, K - Unknown risk status.
Table 2. Significant species Species Common name Status Habitat
Ornithorhynchus Platypus Although widespread in permanent waterways anatinus across Tasmania, there is concern that it is disappearing from waterways in catchments that have been altered by land management practices
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Isoodon obesulus Southern brown Occurs in grassy and shrubby dry forests. It is bandicoot uncommon in the study area and is vulnerable to predation by cats and dogs.
Potorous tridactylus Long-nosed Potoroo It is associated with dense vegetation and is generally uncommon in the Hobart area and is restricted to the wetter habitats in the study area.
Bettongia gaimardi Tasmanian bettong M Extinct on the mainland and has a patchy distribution in Tasmania. It is restricted to dry forests in the study area.
Cercartetus lepidus Little Pygmy-possum M This species has a restricted distribution on the Australian mainland and is uncommon in Tasmania.
Accipiter cirrhocephalus Collard Sparrowhawk Forest dependant species which is rare in the Hobart area.
Neophema Blue-winged Parrot This species is uncommon in southern chrysostoma Tasmania and is known to breed in Ridgeway area. Nests in hollows in old growth eucalypts.
Aegotheles cristatus Australian Owlet K Inhabits dry forests where it as an apparently Nightjar rare species.
Sericornis magnus Scrubtit Endemic species which is rare in the Hobart area. It is a wet forest specialist, usually associated with dense ferny gullies. Restricted to Dunns Creek.
Petroica rodinogaster Pink robin Wet forest specialist which is rare in the Hobart area. It is restricted to wet forests and rainforests.
Pachycephala olivacea Olive Whistler Wet forest specialist which is rare in the Hobart area. It is associated with dense shrubby understoreys.
Zoothera dauma Bassian Thrush Wet forest specialist which is rare in the Hobart area. It is restricted to closed wet forests and rainforests.
Tympanocryptis Mountain Dragon K Occurs in dry forests. diemensis
Allocharopa sp. snail Newly discovered species endemic to south- east Tasmania. Occurs in the Wellington Range and Huon/Channel area (Kevin Bonham pers. comm.).
The assessment also recommends measures to maintain the faunal values within the area. These include the protection of significant habitats from development, controls over vegetation removal and fire management planning which considers the need to maintain faunal habitats.
2.4 CULTURAL FEATURES
2.4.1 Aboriginal Heritage
Prior to European settlement, the Ridgeway area was probably visited by Aborigines on hunting expeditions. It may have been "developed" by native people in the sense of being regularly burnt to maintain open grasslands in the place of closed forests. Such grassland provided Aborigines with well stocked and easily traversed terrain for hunting.
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The Ridgeway Park, Hobart - Cultural Heritage Survey and Assessment (1998) A. McConnell et. al., identified two rock shelters in the vicinity of Gentle Annie Falls which were probably used by Aborigines, as well as two pieces of flaked stone on the banks of Sandy Bay Rivulet. Although all three sites are outside the Study Area, they suggest that Aboriginal sites may exist inside the boundaries of the Ridgeway Study Area.
Although no detailed studies of Aboriginal archaeology or heritage have been conducted within the Study Area, investigations undertaken for the Mt Wellington: Mountain Park Resource Inventory, (1994) 208 Network, (See Appendix E) indicate that the history of Aboriginal occupation and use of the Mt Wellington foothills was likely to be significant.
Aboriginal sites and evidence of occupation are important for the information they provide about Aboriginal lifestyles and culture and are consequently valued by the Tasmanian Aboriginal community. Areas of potential archaeological sensitivity were identified as:
• sandstone rock shelters; • undisturbed banks of major creeks; • historical and unsealed tracks; and • level to gently sloping areas facing north or south east.
One of these areas of potential archaeological sensitivity was identified within the Ridgeway Study Area.
Aboriginal sites are protected from damage or disturbance by the Aboriginal Relics Act 1975.
2.4.2 European Heritage
The report by G Sheridan (2000) History, Landscape and Planning in Ridgeway, describes in detail the historical evolution of the Ridgeway area since European settlement. It identifies several themes in the development of Ridgeway commencing with rural land grants in the early 1800’s, followed by the development of roads and transport and then followed by early settlers and tourism. The development of Ridgeway has been overshadowed by the 1967 bush fires which destroyed many of buildings in the area and much of the historic fabric.
The report by G Sheridan (2000) identified four places of heritage significance that are recommended for protection in the Local Area Planning Provisions. These are as follows: • Line of Pinus radiata, Hall Street • 32 Hall Street - Tagg family home • 25-27 Bramble Street - Originally Jack Finn’s cottage • 29 Bramble Street - The Tea House
2.5 VISUAL AND CULTURAL LANDSCAPE VALUES
2.5.1 Visual Landscape
The report by D Elton (1997) Ridgeway Habitat and Hazards Mapping (Appendix A) includes a visual analysis of the landscape and its sensitivity to further development and change.
The assessment divides the area into visual character units (See Map 5) and describes the character of each unit in terms of its landscape, development pattern and visual prominence. It then goes on to suggest possible visual character objectives which are a strategic statement of intent for each unit based on viewing opportunities, regional significance and perceived community values. Examples of standards to achieve the objectives are also given. These are to be further refined during the preparation of the Local Area Planning Provisions and in the light of the cultural landscape assessment by consultant, G Sheridan. The visual character units, objectives and standards are summarised in the table below:
Table 2.5 Visual Character Visual Character Objective Visual Performance Standard Unit (example only) Rural To minimise the visual intrusion of Development to be of a scale and colour 15 October 2002 Ridgeway Local Area Planning Provisions - Background Documentation ______
suburban style housing in a in harmony with the scale and natural predominately rural landscape and to colours of the site. preserve the regional skyline. Rural Residential To minimise the visual intrusion of Development to be of a scale and colour Ridge ridgeline development and preserve in harmony with the scale and natural the regional skyline. colours of the site.
Rural Cluster To maintain cluster development with Developments must conform to a unified high visual amenity by developing a character style, with complimentary character style. treatment of design, colour and scale. (The character style for the cluster to be decided by community consultation)
Rural Isolated To ensure isolated developments do Development to be kept below the tree not predominate the rural landscape. line and in a style and colour that harmonizes with the scale and natural colours of the site. Tree clearance to be a minimum to meet fire requirements.
Road Corridor To enhance and maintain the scale Maintain existing alignments, natural and rural character of the roadways. road edges and drainage features (e.g. grassed swales) To protect the viewshed from the Southern Outlet. Development to be kept to a minimum and to be of a scale and colour in harmony with the scale and natural colours of the site
Forest Ridge To protect the remaining ridgelines in Development to be generally avoided on forest cover and ensure any the remaining ridges or to meet specific development is visually unobtrusive. performance criteria.(e.g. minimal clearance of vegetation and development to be kept below the tree line and in a style and colour that harmonizes with the natural colours of the area)
Forest Slope To maintain the forest cover of the Development not to be encouraged on slopes. steep forested slopes or to meet specific performance criteria. (e.g. minimal clearance of vegetation and development to be kept below the tree line and in a style and colour that harmonizes with the natural colours of the area)
2.5.2 Cultural Landscape
The report by G Sheridan (2000) History, landscape and Planning in Ridgeway, details the historical evolution of the Ridgeway landscape since European settlement and identifies aspects of that landscape which have cultural value. Sheridan (2000) considers that Ridgeway has significant landscape values due to the natural bushland character, the sense of enclosure and isolation and it can be seen from distant viewing points at both lower and higher elevations.
Sheridan (2000) has also carried out an assessment of the visual absorption capability (VAC) of the landscape character units identified by Elton (1997). The VAC is a tool used in landscape evaluation to measure the ability of the landscape to visually absorb alterations. Areas with a low VAC are extremely visually sensitive to change whereas areas with a high VAC can absorb change in that new landscape elements will not vastly alter the existing landscape picture. A VAC sensitivity scale of 1 to 10 is used, 1 is low VAC - extremely sensitive to change and 10 is high VAC - change can easily be absorbed.
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The VAC rating of each of the areas described by Sheridan(2000) are shown on Map 6. The VAC assessment has shown that most of the area has a similar rating of 3/4. Some areas, particularly those along heavily vegetated gullies and ridges, are extremely sensitive and will not accept change without a reduction of the present landscape qualities. Other areas, such as around Tagg and Hall Streets, have a greater ability to absorb change however that change needs to be managed to preserve the character of Ridgeway. The Local Area Planning Provisions will develop policies to assist in the protection of the landscape qualities identified.
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3. DEMOGRAPHIC PROFILE
This Chapter provides details of the population, housing and a socio-economic profile of the residents within the Census Collectors District (6050805) in which Study Area is located. The Census Collectors District also contains properties in Turnip Fields Road which is outside the Study Area. The data was obtained from ABS Census data 1991 and 1996.
3.1 POPULATION
The population of the Census Collectors District within which the Ridgeway Study Area is located was at the 1991 Census 217 and at the 1996 Census 245. This is an increase in the population of 28 or about 2 percent per year. In the same period the whole City of Hobart population actually decreased by approximately one percent.
3.2 HOUSING
The number of dwellings in the Ridgeway area in recent years has been increasing at a lower rate than the rest of Hobart. There were 86 dwellings in 1991 and 92 in 1996. This represents an increase of 6.5%. In the same period Hobart experienced a growth rate in the number of dwellings of 9.5%. 93% of dwellings are separate houses.
The number of persons per dwelling in the Ridgeway area increased from 2.5 in 1991 to about 2.7 in 1996. Over the same period the dwelling occupancy rate for the City of Hobart fell from 2.32 people per household to 2.2. This is largely due to Ridgeway having a higher proportion of families with children than other parts of Hobart.
At the 1996 Census 83.8% of dwellings in Ridgeway were owned or being purchased. There are a relatively small number (approximately 15) of rental properties in the area. By comparison Hobart has 59% of separate houses being purchased and 31% in rental occupation.
3.3 SOCIO ECONOMIC PROFILE
3.3.1 Australian Born Persons
Ridgeway has had an increase in the number of Australian born persons between 1991 and 1996 of approximately 8% from 77% to 85% (13 persons). The Hobart area has had an increase of 5% over the same period. There does not appear to be any particular ethnic groups living in the Ridgeway area. The majority of the overseas born population living in Ridgeway were born in the United Kingdom or the Netherlands.
Table 3.1 Australian Born Persons Location 1991 1996 Change Ridgeway 77% 85% +8% Hobart 74% 79% +5%
3.3.2 Age Distribution
The age distribution for the area shows up 3 age groups which differ to the Hobart area age distribution. These are summarised in Table 3.2 below.
30% of the population in Ridgeway is contained in the 0-19 years age group compared to Hobart which has 24% in this age group. 65% are in the 20-64 year old age group compared to Hobart overall having 57%. This would indicate a slightly higher proportion of established families with dependent children living at home.
There is a significant decrease in numbers after 64 years of age. In 1996 the population of Ridgeway over 64 was 4% of the population while in the Hobart area the population over 64 was about 19%. 18 October 2002 Ridgeway Local Area Planning Provisions - Background Documentation ______
Table 3.2 Age Groups in 1996 0-19 years 20-64 years over 64 years Ridgeway 30% 65% 4% Hobart 24% 57% 19% Difference 6% 8% 15%
3.3.3 Income
The individual incomes within Ridgeway are generally similar to those in the Hobart area. Table 3.3 below compares the proportion in certain income groups in Ridgeway and Hobart.
Table 3.3 Ridgeway - Annual Individual Income Income($) Ridgeway(%) Hobart (%) 0-8,000 23 26 8,001-20,000 37 32 20,001-35,000 23 22 35,001-52,000 10 12 52,000+ 7 8
3.3.4 Employment / Occupation & Qualifications
The most common industries of employment of people living in Ridgeway are Government Administration, Health/Community Services and Property/Business Services which employ 17% of the workforce.
In 1996 Ridgeway had 12% of the population with a degree or higher qualification compared to the rest of Hobart had which had 18% of its population with a degree or higher qualification. 4.5% were qualified tradespersons compared to 6% in Hobart.
3.3.5 Journey to Work
At the 1996 census there were a total of 107 employed persons living in the Ridgeway area. The principle method of travel to work was by car (as driver) with 71% using this form of transport. 3.7% traveled in a car as a passenger, 3% rode a bicycle and 7.5% caught the bus. On the day of the Census 3% worked at home and 6.5% did not go to work. The vast majority traveled to work within the City of Hobart.
3.3.6 Summary
In summary, Ridgeway has had an average increase in population of about 2% per annum over the 5 year period between 1991 and 1996 with the total increasing from 217 in 1991 to 245 in 1996. It has a higher proportion of established families with children living at home and relatively few in the over 64 years age group.
The population has a higher than normal percentage purchasing their dwellings. The socio-economic profile of the residents does not indicate the need for any special services or facilities to provide for the needs of particular social or ethnic groups in the community.
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4. LAND USE AND INFRASTRUCTURE
4.1 DEVELOPMENT PATTERN AND LAND TENURE
The development pattern of land in Ridgeway is a reflection of its physical characteristics such as topography and vegetation and a number of historical factors related to land grants, subdivision, agriculture and tourism. The historical development of the area is described in detail in the report by G Sheridan (2000), History, Landscape and Planning in Ridgeway.
Development of land for residential purposes has occurred mainly in the form of development along the established grid pattern roads such as Hall and Bramble Streets in Ridgeway. Lot sizes in these areas are typically between 1000m2 and 1ha.
Outside of the main areas subdivided for residential purposes are rural lots mostly between 1 and 10 ha in size. Very few lots in the area are greater than 10ha in size with the largest being about 42ha.
Map 7 shows the land tenure pattern within the Study Area. With the exception of 2 lots, all of the land in the area is privately owned. The largest area of publicly owned land is a 4.8ha parcel of Crown land at the western end of James Street.
4.2 LAND USE AND DEVELOPMENT POTENTIAL
The pattern of land use in the Study Area reflects the land tenure and development pattern outlined above. The predominant use in the area is residential with 61% of lots containing a dwelling. 34% of properties are vacant and 5% are used for other purposes. Other land uses include bushland, open space/recreation, rural activities, public utilities and a plant nursery. There are no significant commercial or industrial activities providing employment in the area .
Rural activities are limited in the Study Area and are largely confined to domestic agricultural activities on larger lots. Agricultural use and potential are discussed in more detail in 4.2.1. Most of the steeper areas are undeveloped and contain significant vegetation cover.
The Rural C (Precincts 43B&E) Zone under the City of Hobart Planning Scheme 1982 has a minimum lot size of 4ha. In this zone only 5 privately owned lots have subdivision potential with the theoretical maximum number of lots being 25 (see Table 4.1). Much of this land is too steep or has other environmental factors which would preclude its subdivision into 4ha sized lots.
In the Rural B Zone the minimum lot size is 2ha. Eight lots in this zone have subdivision potential with the theoretical maximum number of lots being 26. Again some of this land could not be subdivided due to difficult access or other environmental constraints.
Table 4.1 Zone and lot potential ZONE MIN. LOT SIZE LOTS WITH MAX NUMBER SUBDIVISION OF LOTS POTENTIAL POSSIBLE Rural B 2ha 8 26 Rural C 4ha 5 25 Total 12 51
4.2.1 Potential for Agricultural/Horticultural Land Use
An assessment of the land capability for agricultural - horticultural use in the Ridgeway area was undertaken in June 2000 by Mr F W Walker of Complete Agricultural Consulting Services. (see report - Appendix F)
The purpose of the assessment was to ascertain the presence of prime or significant agricultural land within the Ridgeway area and to identify potential agricultural or horticultural enterprises that maybe undertaken on a sustainable basis.
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The assessment was undertaken as Council is required to ensure that the planning scheme is consistent with the provisions of any State Policy. It was therefore necessary to assess if Ridgeway has any ‘prime’ or ‘significant’ agricultural land in terms of the State Policy on the Protection of Agricultural Land 2000.
In undertaking the assessment the agricultural potential of all the land forms that make up the Study Area were reviewed and conclusions made based on the principles that apply to Land Classification, as outlined in the Noble K. E. (1992). Land Capability Survey of Tasmania, Land Capability Handbook, Dept of Primary Industry, Tasmania.
The Land Capability Assessment revealed that the Study Area comprises Class 4 to Class 7 Land with the majority of the land being a composite of Class 6 and 7 (see Map in Appendix F). A summary of the class definitions is as follows: (A full description can be found in Appendix F)
Class 1 - Multiple use land suited to intensive cropping and grazing. Class 2 - Land suitable for intensive cropping and grazing with minor limitations that can be readily overcome by management and minor conservation practices. Class 3 - Land suitable for intensive cropping and grazing, but with more pronounced limitations than for Class 2. Class 4 - Land marginally suitable for cropping because of severe limitations. The land is well suited to intensive grazing. Class 5 - Land with slight to moderate limitations to pastoral use. Class 6 - Land marginally suited for grazing because of severe limitations. Class 7 - Land with very severe to extreme limitations which make it unsuitable for agricultural use.
The Land Capability Assessment found that the topography and the south-south west aspect of much of the land, the shallow stony soils and a lengthy cold winter period with frosts experienced into late spring are the most significant matters that limit the primary industry enterprises that can be undertaken on a sustainable basis.
4.3 INFRASTRUCTURE
The infrastructure of the Study Area has been examined with regard to roads, water, stormwater and waste disposal and in particular the constraints to development associated with each of these.
4.3.1 Roads
The principal means of access to Ridgeway from Hobart is via Huon and Chimney Pot Hill Roads or Waterworks and Ridgeway Roads.
The main arterial road serving the Study Area is Huon Road which starts at the end of Davey Street in South Hobart and continues through Fern Tree to join with the Huon Highway at Sandfly. This road carries about 2390 vehicles per day north of Strickland Avenue. The junction of Chimney Pot Hill and Huon Roads is about 600m south of Jacksons Bend on Huon Road.
All other roads in the area are minor access roads mostly servicing residential properties. The roads in the area have adequate capacity to cater for the anticipated traffic volumes now and in the future.
A number of issues relating to roads in the area have been identified by the community during the preparation of this report. These are as follows: • Sight distance problems due to regrowth in Ridgeway Road. • Roads narrow, poorly signposted and require more maintenance. • 80KM speed limit too high, threat to wildlife and public safety. • Narrow point in road in Tagg Street between Hall Street and junction of Chimney Pot Hill and Ridgeway Roads. • School bus turning circle at corner of Hall and Bramble Streets in poor repair • Give way road sign required at junction of Chimney Pot Hill and Ridgeway Roads. 21 October 2002 Ridgeway Local Area Planning Provisions - Background Documentation ______
There are also a number of unused road reserves in the area. These were defined in the 1800’s with no consideration for the local topography. They tend to run perpendicular to the contour and may be environmentally damaging if ever developed as roads.
4.3.2 Water
The water supply to Ridgeway comes from the Mount Wellington North West Bay system. Water from this system flows into the pump station at Stephenson Place and is pumped to the reservoir known as Fern Tree Reservoir which has an access from Pillinger Drive. The reservoir capacity is 4.5ML which is adequate to serve 750 dwellings. There are currently 273 dwellings in the area serviced by the reservoir which includes Fern Tree and Ridgeway. With only limited potential for further subdivision in the area, the reservoir has adequate capacity to cater for the expected future demand.
Ridgeway is supplied with water from the Fern Tree Reservoir via a pressure control station. There are several residences outside the central area of Ridgeway which do not have a reticulated water supply and rely on tank water or other on-site storage for domestic purposes and fire protection.
4.3.3 Stormwater
Stormwater in Ridgeway is not reticulated, with most water from rooftops being directed either to on- site absorption trenches or onto the ground. Road runoff is generally directed to overland flow paths which discharge eventually to waterways.
This situation seems to function effectively, with few complaints relating to nuisance caused by runoff, and few apparent problems with erosion. It is advisable however to manage stormwater in a fashion which encouraged detention and infiltration. This would enable contaminants to be captured and decomposed, rather than discharged into the drainage system. These processes can be achieved through the use of structures such as grassed swale drains and small-scale stormwater basins / sediment traps.
Construction sites also need to be suitably protected to ensure that sediment-laden runoff does not enter the stormwater system when it rains.
4.3.4 Waste Disposal
All of the dwellings at Ridgeway presently utilise septic tanks and absorption trenches for onsite sewage treatment. It is possible that some septic systems in Ridgeway are not operating effectively, yet no evidence is available to suggest that effluent is being discharged into the drainage system in quantities which would constitute a widespread public health risk or environmental harm.
Three factors which serve to minimise the risk of contamination from dwellings in Ridgeway are: • Low development densities which generally result in houses being surrounded by a vegetative buffer. This helps to ensure that polluted run-off is absorbed into the soil instead of washing directly into a watercourse. • Ridgeway (around Hall St) is relatively flat, and so run-off during rainy periods will generally experience longer detention times, providing greater opportunity for breakdown of pollutants by soil micro-organisms. This process is enhanced by the number of farm dams found around Ridgeway. Each serves to capture polluted stormwater and remove nutrients and bacteria. • The stormwater system is not reticulated, with most of the run-off from roads being eventually infiltrated into the soil rather than quickly transported into waterways. It would be unwise however, to suggest that the water flowing from the Ridgeway area is potable without confirmation through extensive water quality monitoring. It would be unrealistic not to expect the occasional input of domestic pollutants from a settlement like Ridgeway.
Agriculture also contributes to the levels of faecal material found in waterways. This impact would be minimised in Ridgeway by the probability that much of the faecal material is absorbed into the soil and broken down, for similar reasons to those described above. In any event, animal faecal material is 22 October 2002 Ridgeway Local Area Planning Provisions - Background Documentation ______generally considered to be of lower health risk than human faeces as it contains fewer human pathogens.
It is unlikely that sewerage mains will be extended to Ridgeway in the foreseeable future. For this reason, any dwellings built on land which is unsuitable for absorption trenches will have to make use of alternative systems to the septic tank. Land considered unsuitable is generally either steep or close to a watercourse.
With no industry in the Study Area, pollutants are limited to runoff from houses and roads, and faecal contaminants from septic systems. Septic system performance is dependent on good maintenance and the following design factors: a) Need as much sunlight on trenches as possible. b) Trenches should be a long distance from creeks and stormwater drains. c) Trenches should be on deeper soils / gentle slopes. d) Trenches should be of sufficient length, up to 50m.
Contamination from septic systems is broken down if exposed to soil organisms for sufficient time, and so the most desirable method of stormwater retention / transport is in grassed swales which allow the contaminated water to infiltrate into the soil.
The use of septic tanks in Ridgeway and other parts of the City have been investigated and discussed in the report Septic Tank Survey - Method | Discussion | Conclusions, (1998) B Ridder, ( unpublished report for the Hobart City Council - see Appendix G).
One of the main conclusions from this report was that most people using septic systems in the Hobart municipality are generally satisfied with the situation and would not wish to be connected to the sewerage system. Given that most problems with septic systems could be solved through better management by residents, it seems that connecting the area to sewerage mains would be unnecessary, not to mention unpopular with the community.
The lack of a reticulated sewerage system is one constraint to more intensive development in the Ridgeway area. The high rainfall, steep land in parts and dolerite based soils provide a difficult environment for the efficient operation of septic tanks. Relatively large land areas are required to allow for the on-site absorption or spray irrigation of septic tank effluent.
4.3.5 Electricity and Communications
There is one major electricity transmission line within the Study Area which runs in a north - south direction close to the western end of Hall and James Streets. Transend Networks Pty Ltd have no current plans to develop additional major electricity transmission lines in the area.
Aurora Energy has advised that the existing electricity distribution network within the area is adequate for existing and anticipated future development and could be upgraded if the need arises. The electricity supply does not pose any particular constraints to future development.
Telstra have also advised that they would respond to demand for telecommunications facilities as required and that there is adequate exchange capacity for the area. Some individual properties may require additional cabling to be installed before a telephone connection can be provided. No major telecommunications facilities such as mobile phone towers are planned at present. Major facilities are located nearby on Chimney Pot Hill and at the summit of Mount Wellington.
4.3.6 Recreation, Open Space and Fire Trails
Ridgeway is well served by open space available for a variety of recreational activities. There are significant areas of public open space in nearby Ridgeway and Wellington Parks. Within these 2 Parks there are extensive areas of open space and opportunities for recreation.
The City of Hobart Open Space Study (1997) Acer Wargon Chapman, published by the Hobart City Council, undertook a strategic analysis of open space within the City and made recommendations for open space acquisitions. No areas in Ridgeway were identified for acquisition in this Study or the more recent City of Hobart Open Space Strategy endorsed by Council in 2000.
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The most significant walking track running through the area is the Pipeline Track which runs from the Waterworks Reservoirs in South Hobart, through Ridgeway and past Neika to near the start of the North West Bay River.
There is a network of fire trails in the Ridgeway area which link to trails in the south and east in the Municipality of Kingborough. There is limited opportunity for the establishment of new trails due to the steep terrain.
Horse riding trails are not officially designated in the area, several tracks and fire trails however are used informally for this purpose. The need for a link for horse riders between the Southern Outlet and Ridgeway Park has been identified. This may need to cross private land in the north eastern corner of the Study Area and would be subject to discussions with the landowners affected.
4.3.7 Commercial/Community Facilities
Being a relatively small community there are no commercial or community facilities in the immediate area apart from a plant nursery. Residents of the Study Area are dependent on commercial and community facilities provided in other areas for services such as schools, health, child care and retail shopping.
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25 October 2002 Ridgeway Local Area Planning Provisions - Background Documentation ______
5. COMMUNITY VALUES AND ISSUES
5.1 INTRODUCTION
This Chapter outlines the views expressed by the local community about the future planning direction and issues for the Ridgeway area. These views were ascertained by a survey sent to all households within the Study Area in April 2000 and a workshop held with the community in December 2000.
5.2 HOUSEHOLD SURVEY
A survey form along with a pamphlet explaining the preparation of the Local Area Planning Provisions was delivered to all households in the Study Area. The survey had a response rate of 72% which is an extremely good response for this type of survey. (A similar survey for the South Hobart Local Area Plan had a response rate of 28%). The responses to each of the questions on the survey are summarised below:
1. How long have you lived in the suburb of Ridgeway?
Table 5.1 Length of Residence of Respondents Years % of respondents Under 2 years 6 2 - 5 years 33 6-10 years 24 11- 20 years 22 over 20 years 16
Table 5.1 shows that many of the residents have lived in the area for a relatively short period of time with 63% of respondents having lived in the area for 10 years or less. 38% have lived in the area for more than 10 years.
2. Why did you choose to live in Ridgeway?
Table 5.2 Reasons for Living in Ridgeway Reason % of respondents Natural bushland / rural setting 97 Access and convenience to city 89 Affordable land/housing 67 Views 43 Safe area 30 Always lived there 11 Close to family 11 Climate 5 Other 40
Table 5.2 shows that a high number (97%) of respondents chose to live in Ridgeway because of the natural bushland / rural setting. The location of Ridgeway being close to the city also was another reason given by many for living in the area. Other reasons included privacy, community spirit, access to walking tracks, few houses and large building blocks.
3. What are the three best aspects about living in Ridgeway?
Table 5.3 Best Aspect of Living in Ridgeway Reason % of respondents Access to city 78 Rural setting and lifestyle 76 Quietness, space and privacy 76 Views 22 Safe from crime 16 Sense of community spirit 16 26 October 2002 Ridgeway Local Area Planning Provisions - Background Documentation ______
Low cost of land and housing 8 Zoning to prevent ‘suburbia’ - large blocks 11 Clean air and environment 6
The majority of the respondents repeated many of the reasons given above in Table 5.2 as the best aspects of living in Ridgeway. One aspect mentioned in this section which was not reflected in Question 2, was the quietness, space and privacy, 76% of the respondents replied that this was one of the three best aspects of living in Ridgeway.
The rural setting and lifestyle and access and convenience to the city are the major reasons people like living in Ridgeway.
4. What are the three worst aspects about living in Ridgeway?
Table 5.4 Worst Aspects of Living in Ridgeway Reason % of respondents Lack of adequate public transport 41 Weather/climate 38 Road condition 30 Bushfire danger 22 Possibility of ‘suburbia’ due to continued 19 development Animal pests (rabbits and possums in vegetable 11 gardens) Noise from businesses (woodcutting) 5 No local store 5 Septic tanks 8 Lack of parks and reserves 5
Several reasons are highlighted as the worst aspects of living in Ridgeway with no one reason being particularly outstanding. Lack of adequate public transport, climate and the condition of roads were identified as the 3 worst aspects of living in Ridgeway.
5. How would you rate the adequacy of local facilities?
Table 5.5 Adequacy of Local Facilities Issue Very Acceptable / Poor Unsure Good(%) appropriate (%) (%) (%) Roads and footpaths 9 58 30 3 Water supply 78 19 0 3 Open spaces and reserves 51 35 14 0 Waste Disposal 49 41 3 8 Recreational opportunities 54 30 8 8 Public transport 3 16 73 8
The majority of local facilities were rated by residents as being very good or acceptable/appropriate. The water supply, waste disposal and open spaces and reserves received the highest approval ratings.
Roads and footpaths and public transport received the second highest “poor” rating (30%). Several respondents were concerned that roads were narrow, poorly sign posted and required more maintenance. 73% of respondents were concerned about the lack of a public bus service.
6. Issues of concern in the future planning of Ridgeway
The following issues were identified as being important or very important by the majority of respondents to the future planning of the Ridgeway area:
Environmental issues: 27 October 2002 Ridgeway Local Area Planning Provisions - Background Documentation ______
• Spread of weeds (gorse and blackberries) into bushland • Bushfire risk • Clearance of bushland • Water quality in creeks • Impact of pets on native animals (especially cats) • Recreational impacts within bushland areas (particularly motorbikes) • Failure of septic tanks
Development issues: • Maintenance of roads (grading and additional gravel) • Design and siting of houses to fit with rural/bush setting • Concern over further subdivision of large vacant land areas
7. Please indicate how you would rate the condition of the local environment in regard to the following aspects:
Table 5.6 Condition of local environment Issue Very good (%) Good (%) Poor (%) Unsure (%) Air quality 89 11 0 0 Water quality in creeks 27 35 5 32 Quality of natural vegetation 25 54 17 3 Street amenity 20 33 43 3 Scenic values and views 57 33 6 3
Most aspects of the local environment were rated as good or very good by respondents. The highest ratings were given to air quality and scenic values/views. The only notable poor rating was given to street amenity, this mainly related to the condition of roads and absence of footpaths. 32% of respondents were unsure about the water quality in the creeks.
8. Please indicate how you would rate the threat to the local environment in regard to the following issues:
Table 5.7 Threats to local environment Issue Major (%) Minor (%) None (%) Unsure (%) Weed invasion 57 41 3 0 Soil erosion 24 59 5 8 Bushfires 81 19 0 0 Water pollution 32 32 8 27 Land and housing development 68 22 8 3 Vegetation and tree removal 57 32 3 8
The bush fire threat is seen by residents as the greatest threat to the local environment. Other significant threats include land and housing development, vegetation removal and weed invasion.
9. Other Issues
Other issues raised in the community survey for consideration included the following:
• The impact of fuel reduction burns on the understory vegetation and small mammals. • Pest control (particularly high numbers of rabbits and possums). • Impact of businesses on bushland (woodcutting). • Air pollution from fires (rubbish incineration) and noise from chainsaws and motorbikes within the area. • Need to underground power cables. • Need to upgrade roads by sign posting of narrow sections of road, concealed intersections and junctions and marking of a solid white centre line. • Development of recreation areas (picnic tables, barbecues, toilet and shelter) along with established horse, bike and walking tracks. • The establishment of historical, cultural and information boards along tracks and in reserves, including maps of walking tracks. • Increased public transport. 28 October 2002 Ridgeway Local Area Planning Provisions - Background Documentation ______
• Bridleways for horses, mountain bikes and walkers. • Establishment of a local store.
5.3 COMMUNITY WORKSHOP
A community workshop was held in December 2000 in order to provide an opportunity for residents to identify problems/threats and issues that need to be considered in the preparation of the Local Area Planning Provisions and also to put forward ideas/opportunities for addressing the issues identified.
People at the workshop were given the opportunity to participate in the following topic groups:
• natural environment • community facilities and services • cultural heritage and landscape • development issues
The outcomes of each group are summarised below:
5.3.1 Natural Environment
Problems/threats and issues to the natural resources/local environment in Ridgeway were identified as: • Bramble Street - Increased traffic if becomes thru road due to subdivision. • General concern about further subdivision particularly around ‘Shamrock Cottage’ in Bramble Street. • Loss of rural atmosphere if more development and subdivision. • Protection of riparian vegetation along Dunns Creek. • Clearing of remnant bushland. • Co-operation with adjacent Councils. • Bushfire threat. • Weed infestation (gorse, pine trees etc.) particularly on property at western end of Hall Street. • Skyline Protection. • Dogs and cat control, cats are a threat to wildlife. • General problems with introduced species; starlings, blackbirds and rabbits. • Burned out cars and rubbish dumped in old quarry. • Trail bike noise especially in “parkland”.
Ideas/opportunities for better managing the natural environment in Ridgeway were identified as: • Protect stand of E. cordata, threatened species on the property at the western end of Hall Street. • Greater utilsation of Ridgeway park oval. • Protect and enhance waterhole at the southern end of Tagg Street. • Encourage native birds through retention of bushland and encourage incentives for planting by residents. • Cat bells or curfew or runs. • More assiduous control by Council of dogs. • Advise residents of suitable boxes for native birds. • Encourage bumble bees by flower planting. • Put in ponds/dams no spraying for frogs. • Keep Ridgeway as Hobarts best kept secret. • Do more to educate land owners about weeds and eradication.
5.3.2 Community Facilities and Services
Problems/threats and issues related to the community facilities and services in Ridgeway were identified as:
29 October 2002 Ridgeway Local Area Planning Provisions - Background Documentation ______
• Public transport - more frequent. • Sewerage connection not desired. • Telephone lines poor. • Want no formed roads or street lights - happy with gravel roads. • Blind corner due to regrowth in Ridgeway Road. • 80KM speed limit too high, threat to wildlife and public safety. • Dangerous narrow point in road in Tagg Street between Hall Street and junction of Chimney Pot Hill and Ridgeway Roads. • School bus turning circle at corner of Hall and Bramble Streets in poor repair • Give way road sign required at junction of Chimney Pot Hill and Ridgeway Roads. • Bus Services - provide more bus turning areas, provide bus shelter and improve timing for school kids from Hobart.
Ideas/opportunities for improving community facilities and services in Ridgeway were identified as: • Identification of bridle, trail bike and walking tracks. • Pedestrian right of ways required from end of Bramble Street to Kingborough Municipality. • Walking tracks to town from Ridgeway Reservoir. • Maintain green verges. • Minority for introduction of some form of public transport. • Council should promote car pooling. • Increase picnic facilities at the ‘triangle’ at the corner of Chimney Pot Hill Road and Ridgeway Road. • Maintain or ensure public access to trails from Southern Outlet to Ridgeway and south to Kingborough Municipality.
5.3.3. Cultural Heritage and Landscape
The problems/threats and issues related to the cultural heritage values in Ridgeway were identified as:
1. Rocky Whelan cave in Kingborough Municipality possibly an Aboriginal site. 2. Lack of identification and acknowledgment of value/presence of heritage sites.
The main idea/opportunity for protecting and managing cultural heritage values in Ridgeway was that items of cultural value, eg. remnants of tea gardens should be protected.
5.3.4. Development Issues
Problems/threats and issues related to development issues and opportunities in Ridgeway were identified as: • Sympathetic design for new housing development including natural materials/colour to blend with the environment. • Minimise land clearing. • Minimum 4ha lots in subdivisions. • Excessive nutrient and water runoff from Nursery. • Like low traffic volumes. • Some houses inappropriate, design better for suburbia. • Scale of new access off end Bramble Street, suggests a lot of Development/Traffic. • Don’t seal Bramble and Hall Street. • Subdivision of rural landscape. • 10ha minimum lot size in Subdivision. • Limit Dog Kennels.
Ideas/opportunities related to development issues in Ridgeway were identified as: • Retain and reinforce rural village character • Could increase population by 20%.
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• Greater discretion to allow the provision of village facilities. Greater uses than are available at present ie low key commercial uses such as: restaurant, gallery and B&B, Springs scale development not appropriate. • Greater scope for cottage industries/contemporary lifestyle uses gallery/retreats. • Min lot 2ha with no discretion. • No sewerage mains/allow new disposal systems and be consistent. • Guidelines for house colour and possibly design.
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32 October 2002 Ridgeway Local Area Planning Provisions - Background Documentation ______
6. SITE ASSESSMENT
6.1 INTRODUCTION
This chapter discusses the development potential of land contained within the study area which has been assessed in regard to the development constraints and issues described in the preceding sections of this report.
6.2 SECTORS
For the purposes of this assessment the area has been divided into a number of sectors based on topographic features or similar characteristics. The location of each sector is identified on Map 8.
6.2.1 Property Along Dunns Creek
The land within this area is predominantly forested and consists of steep slopes bordering Dunns Creek. This area has been divided into 7 sectors which are discussed below:
Sector 1
This large lot is occupied by one house amidst open forest recovering from the January 1998 bushfires. It is geographically isolated from the rest of Ridgeway by Dunns Creek and is accessed from Summerleas Road in Fern Tree. The potential for future development on this lot is limited by the lack of available gently sloping land, the single road access, bushfire risk and high visual impact of any development when viewed from surrounding areas.
Sector 2
Hall Street terminates at a forestry-style gate adjoining a large piece of land dominated by an electricity easement. A narrow strip of bushland runs along the eastern edge of this property. The easement consists of two high voltage power lines running approximately north-south, with a thin line of trees between them. Within the cleared land of the easement can be found the recharge basin of a small tributary of Dunns Creek. A 4WD track through this area is quite boggy at times.
West of the easement and creek, the land is forested and recovering from the January 1998 bushfires. The area is steep and damp, with a view towards the D’Entrecasteaux Channel. Open forest of lower gradient can be found on the ridgeline extending from Chimney Pot Hill down to Dunns Creek. Access to the ridge can be gained from a rough track which runs across the contour from the easement to the ridge. Another track near the northern boundary follows a smaller power easement up over the ridge toward Halls Saddle.
Development on the western side of the ridge would be highly visible from Mount Wellington and Fern Tree. The most suitable area of land for development is found on the northern boundary, where the ridge is reasonably flat, although the visual impact in this area would need to be carefully managed.
Sector 3
The western portion of this lot is traversed by the electricity easement. The land is steep, rocky, and split by a minor drainage line. The aspect of the block is to the south-west and looks across toward the house in Sector 1 and Summerleas Road. Any development on this lot would be of high visual impact (viewed from Mount Wellington and Summerleas Road) as the easement offers no visual screening.
Sector 4
This lot is not developed. It is entirely forested, and predominantly consists of steep, south facing slopes. Any development on this property would be most appropriate in the north-east corner. Development elsewhere on the lot would entail much greater visual impact.
Council road reserves for James Street and Huon Street run along the northern and eastern boundaries of this lot. Originally defined with no consideration for the local topography, these
33 October 2002 Ridgeway Local Area Planning Provisions - Background Documentation ______reserves tend to run perpendicular to the contour, and would be environmentally damaging if ever developed as public roads.
Sector 5
This lot encompasses a heavily forested, south facing gully. A small section of land has been cleared on the northern boundary. Housing on this block would receive limited sunlight, and if close to the creek would experience cold air drainage from higher ground. These factors, in conjunction with the steepness of the land, would hinder the effectiveness of a septic system.
The James Street road reserve runs along the northern boundary of this property. A vegetation community classified as important is found in south-eastern corner of this lot.
Sector 6
This area consists of two lots accessed from Bramble Street. The large, original lot contains one dwelling and is almost entirely forested. The smaller lot also contains one dwelling and is mostly forested. There is some potential for further development on these lots as some relatively flat land remains.
Any development needs to have regard to possible visual impact and minimising duplication of access roads. Development may not be appropriate in proximity to; Dunns Creek, the tributary which crosses over the area, or the classified "important" vegetation community found in the middle of the lot.
Sector 7
This lot predominantly consists of steep, south facing forested slopes. A house is located in the north- east corner, which is the only flat site on the lot. Access is gained via the lot to the north. Both nearby road reserves are poorly positioned, with one passing through a drainage line, and the other going straight up over a steep rocky ridge. The vegetation community in the region of the house has been classified as important.
6.2.2 West Ridgeway
Sector 8
This area consists of land to the east of the high voltage electricity easement, west of Tagg Street and Ridgeway Road, and north of the forested slopes of Dunns Creek. The land is generally quite flat and is predominantly cleared, originally for grazing and horticulture. From a land capability perspective there is potential for future development, either for housing, a return to horticulture, or both.
The small farm dams located to the south of Hall Street are important in ensuring that sewage effluent leaking from septic tanks in Central Ridgeway is detained before entering Dunns Creek. Future development proposals should recognise the need to maintain or increase this detention capacity, particularly if there is further development within West Ridgeway.
The Huon Street road reserve is not presently used as a road, although it may be required for access if any subdivision in Sector 4 occurred in the future.
6.2.3 Central Ridgeway
Sector 9
This area is comprised of a strip of land bounded by Tagg Street/Ridgeway Road to the west, and Bramble Street to the east. The southern boundary coincides with the northern edge of Sector 6.
Residential development exists in this Sector to a much higher average density than elsewhere in Ridgeway. In some respects then, it is likely that the impacts of development are more prevalent in this sector. This is certainly true of sewage disposal, with a greater number of complaints originating from this area in relation to septic tanks than from surrounding areas.
34 October 2002 Ridgeway Local Area Planning Provisions - Background Documentation ______
It has been noted elsewhere that the farm dams found in Sector 8 are important in reducing the impact of escaped sewage effluent from this area. There is also a small dam near the intersection of Bramble Street and the Badgers Hill road which detains possibly contaminated runoff from houses on Bramble Street.
A situation worthy of consideration with regards to fire hazard involves the southern part of this Sector. Dwellings in this area are generally found at the top of the ridge with the steep land to the west remaining under vegetation. Under certain circumstances it is likely that these dwellings would face considerable risk from bushfire.
Clearing of the bush from the southern area would compromise the ecological value of the strip of bushland which traverses the entire slope and increase the visual impact of the area as viewed from Mount Wellington and Chimney Pot Hill.
The construction of access to the lots in the southern part of this sector from Tagg Street would increase the likelihood of erosion, given the steep slopes, and probably require the upgrading of Tagg Street.
The lots in this sector which are to the north of Hall Street are located within the catchment of Vincents Rivulet. Water drains north to enter the Rivulet below Ridgeway Reservoir, before then swinging south toward Kingston and Browns River.
Some of the bushland in this northern section is identified as "important".
6.2.4 East Ridgeway
The land within this area lies immediately to the east of Central Ridgeway described above. Lot sizes are generally quite large, with the dwellings accessed via Hall Street or Bramble Street. The area is drained by one principle creek which is in fairly good condition.
Sector 10
This area consists of mostly low slope land to the east of Central Ridgeway. Development is of a fairly low density, with some clearing on most of the lots for agricultural activities.
The two properties to the north of Hall Street are situated on higher land which drops off steeply to the north, while those to the south of Hall Street are located within a small semi-enclosed basin which drains to the east.
There is potential for development in the latter area, although given the enclosed, yet cleared, nature of the space, any additional dwellings would be readily noticeable. An old farm dam is currently located on the creek flowing from this area, and if any more intense development were to occur, this dam may need to be converted for use as a stormwater detention area.
If the population of Ridgeway were to increase there would be a strong argument for linking Hall Street with the Southern Outlet to provide emergency bushfire access. The two large southern lots in this sector contain vegetation communities which are classified "important".
Sector 11
These two lots are accessed from Hall Street to the north. They occupy land with a south-eastern aspect sloping down to a small, heavily wooded creek. The upper slopes are cleared and support a small number of domestic sheep. A small creek runs through the south of the Sector and the south- eastern corner contains a vegetation community which is classified "important".
35 October 2002 Ridgeway Local Area Planning Provisions - Background Documentation ______
Sector 12
The three properties in this Sector encompass either the ridge or summit of Badgers Hill. A driveway provides access along a Crown road reserve to the central lot, upon which there appear to be two dwellings. Access to the eastern lot is via a right-of-way through Sector 13. A large house has recently been constructed on the western lot, accessed via Bramble Street. A track through this western lot is also used for access to a house in Sector 7, and possibly for properties in neighbouring Kingborough municipality.
There is a recharge basin in the south-west corner of this sector and also a creek running through the north-eastern corner. Nearly all of the bushland in this Sector has been classified "important".
6.2.5 Southern Outlet
Sector 13
This area slopes generally eastward down to the Southern Outlet, with access to most of the lots via Proctors Road. Several small creeks drain the slopes, which form part of the catchment of Vincents Rivulet. The area is important as a visual corridor for the Southern Outlet.
A considerable portion of the area was subdivided into 7 lots in 1995. Development controls for the subdivided lots have been specified as covenants on each title, and include restrictions on tree clearing and construction of large buildings. In addition, the subdivision approval includes reference to a right-of-way for the purpose of horse riding, suggesting that this is an important local recreational issue.
The creek that runs through the northern part of the subdivision is also disturbed immediately upstream by a small concrete weir at the point where a water pipeline crosses. The water pipeline runs from Ridgeway Reservoir through to Kingston, and passes through this Sector roughly parallel to the highway.
Most of the vegetation in this area is classified "important". In addition there are two small areas of bush identified as being "critical".
36 October 2002 Ridgeway Local Area Planning Provisions - Background Documentation ______
7. ENVIRONMENTAL AND PLANNING ISSUES
This Chapter identifies a range of planning issues that affect the sustainable use and management of resources within the Study Area. These issues were identified from the research undertaken in Chapters 1-4 and the values and issues identified by the community as outlined in Chapter 5:
7.1 ENVIRONMENTAL ISSUES
A list of environmental issues within the Study Area has been identified as a result of the community consultation, review of reports, research and fieldwork. These include:
a) problems with introduced weed infestation (gorse and pine trees etc.)and weed control; b) the need for sediment control on construction sites and detention of stormwater in grassed roadside drains ; c) landscape and habitat value which may be vulnerable to future development pressure as most areas of bushland are in private ownership; d) the impact of domestic animals on native fauna and problems with introduced species such as starlings, blackbirds and rabbits; e) the lack of base-line monitoring of environmental resources such as water quality and erosion hazards; f) fire management and bush fire risks throughout the area; and g) difficult environment for the effective operation of septic tanks.
7.2 DEVELOPMENT AND INFRASTRUCTURE ISSUES
The development and infrastructure issues identified within the Study Area included:
a) the capacity for subdivision of larger land parcels which could alter the character of Ridgeway, principally through the removal of remnant vegetation and loss of setting ; b) inappropriate siting and design of houses leading to poor quality appearance, loss of amenity values, limited solar benefits, impacts on view lines and loss of remnant vegetation; c) narrow roads and unsatisfactory intersections in certain locations ; d) lack of a reticulated sewerage system and limitations on the effective operation of septic tank systems; and e) the limitations of vegetation clearing controls for protection/management.
7.3 COMMUNITY FACILITY AND SERVICES ISSUES
The community facility and services issues identified within the Study Area included:
a) concern about the condition of some roads; b) inadequate public transport system ; c) flexibility to allow the establishment of home based cottage industries and other low key commercial uses such as bed and breakfast establishment or gallery; and d) virtually no local commercial facilities and services within the Study Area which increases dependency upon car travel and the limited public transport services.
7.4 PLANNING SCHEME ISSUES
As discussed in Section 1.3 planning control in the Study Area is through the City of Hobart Planning Scheme 1982. This Scheme divides the area into a number of zones and Precincts (see Map 2) each with its own objective and statement of desired future character. The operation of the planning controls in each of these Precincts has been assessed and is described below:
37 October 2002 Ridgeway Local Area Planning Provisions - Background Documentation ______
7.4.1 Rural B Zone - Precinct 44A
The Objective of the Rural B Zone which covers Precinct 44A is to provide for uses suited to broad- acre subdivision consistent with the character of the natural and rural landscape and the proper management of rural enterprises and public utility services.
The Statement of Desired Future Character for Precinct 44A states: “The Precinct is set aside as an area for rural/residential activities. New development should be compatible with the semi-rural character and generally be restricted to single dwellings on large lots. Farming and grazing at a domestic level should be permitted as should leisure and recreational activities such as bushwalking, horse riding and orienteering. In the design of subdivisions provision should be made for a network of fire trails and horse riding trails with a minimum width of 4 metres.”
It is considered that the general intent of this zone has been met and the character of the setting has been maintained. Many of the existing lots are however too small to provide for uses suited to broad- acre subdivision. There are also examples of development which have not been unobtrusively sited or designed to be sympathetic to the landscape setting.
The minimum subdivision lot size of 2ha within this Precinct has acted to protect the character and limits the potential for further subdivision. Only 8 lots have further subdivision potential.
7.4.2 Rural C Zone - Precincts 43E and 44B
The Objective of the Rural C Zone is to retain an area of natural bushland beyond the fringe of urban development, generally with only one detached house per broad-acre allotment. It also states that these Precincts should continue to be dominated by their verdant bushland and within this setting, buildings should be unobtrusively sited and not impinge on the tree dominated skyline. The minimum subdivision size is 4ha.
While much of the land in these Precincts has not been developed due to its steep topography there are examples of housing form, siting and appearance not responding to site constraints and characteristics. The subdivision of land along the Southern Outlet is one example of the subdivision and development pattern not responding to site constraints and characteristics. There are also examples of houses in areas of high bush fire hazard with only one means of access.
Further subdivision within these Precincts has implications for environmental degradation, tree clearing, bush fire hazard and visual amenity. Removal of bush fire hazards often has implications for conservation and landscape values. The 4ha minimum lot size appears too low for this zone as much of the land is too steep or has other environmental constraints which would preclude its subdivision into 4ha sized lots. Although only 5 privately owned lots have subdivision potential, the theoretical maximum number of lots is 25.
7.4.3 Planning Scheme Generally
The Principles of Development Control in the Planning Scheme mention such matters as energy efficiency, environmental pollution, townscape and amenity. However there is no specific requirement to address these matters in an application. With the exception of the Bushland Management Schedule (recently introduced into the Planning Scheme), the existing planning controls do little to support the zone objectives and Statements of Desired Future Character in the Scheme. There are examples of housing form, siting and appearance not responding to site constraints and characteristics. There are also examples of environmental degradation, problems with access to some sites and houses in areas of high bushfire hazard. The subdivision of land along the Southern Outlet is one example of the subdivision and development pattern not responding to site constraints and characteristics.
38 October 2002 Ridgeway Local Area Planning Provisions - Background Documentation ______
These issues will need to be addressed in the Local Area Planning Provisions and the subsequent planning instrument if the objectives of the Land Use Planning and Approvals Act 1993 are to be achieved.
7.5 REGIONAL IMPLICATIONS
Ridgeway has a total population of 245 (1996 Census) which is a very small proportion (0.15 %) of the population of all Hobart suburbs. In terms of population and the provision of land for housing Ridgeway has little regional significance. The availability of land and the physical and environmental constrains to development would suggest that this situation is unlikely to change.
The report by S Hogue (1996), Future Urban Development and Infrastructure Provision in Greater Hobart, Department of Environment and Land Management, identifies significant areas available for residential development in other parts of the region. Many of these areas do not have the constraints to development that are found in the Ridgeway area. In terms of regional land supply for housing there would appear to be little justification in attempting to provide significant areas for residential development in Ridgeway.
7.6 IMPLICATIONS FOR FUTURE PLANNING
The environmental, development and community planning issues will need to be addressed within the formulation of the Local Area Planning Provisions. However some of the issues are outside of the powers and controls available within a Planning Scheme and will need to be tackled through other mechanisms eg. co-ordination between agencies, Council works programs and community initiatives.
The range of planning issues suggests that the Local Area Planning Provisions should be based around the development of a number of objectives for the Study Area that address: • landscape and environmental improvement; • infrastructure; • access and traffic management; • planning and development.
These objectives would then help determine an overall planning framework to guide the future development of the Ridgeway area.
39 October 2002
APPENDIX A BIBLIOGRAPHY
Acer Wargon Chapman (1997), The City of Hobart Open Space Study, Hobart City Council.
AVK Environmental Management & IFERM P/L (2002), draft Fire Management Plan for Ridgeway Park and Waterworks Reserve, unpublished report to Hobart City Council.
Brereton R (2000) Ridgeway Local Area Plan Fauna and Habitat Overview, unpublished report to Hobart City Council.
Complete Agricultural Consulting Services (2000), Ridgeway Area - Land Capability Assessment, unpublished report to Hobart City Council.
Elton D (1997), Ridgeway Catchment Mapping, Habitats and Hazards, unpublished report to Hobart City Council.
Hepper J & de Gryse J (1994), City of Hobart Open Space and Landscape Strategy, Hobart City Council.
Hogue S (1996), Future Urban Development and Infrastructure Provision in Greater Hobart, Department of Environment and Land Management, Hobart
Land Use Planning Review Panel (1997), Planning Note No. 11 - Bushfire Hazard Minimisation Planning, Department of Environment & Land Management, Hobart.
McConnell A et. al., (1998) Ridgeway Park, Hobart - Cultural Heritage Survey and Assessment, Hobart City Council.
North A (1997), Botanical Survey of Hobart Bushland - Stage 2 Ridgeway unpublished report to Hobart City Council.
Ridder B (1998), Septic Tank Survey - Method | Discussion | Conclusions unpublished report to the Hobart City Council
Scripps L (1989), The Pipeline Track Mt. Wellington - Historical Study, Hobart City Council.
Sheridan G (2000), History, Landscape and Planning in Ridgeway, unpublished report to the Hobart City Council.
Tasmania Fire Service (1995), Planning Conditions and Guidelines for Subdivision in Bushfire Prone Areas, Tasmania Fire Service.
208 Network (1994), Mt Wellington: Mountain Park Resource Inventory, Hobart City Council.
HOBART CITY COUNCIL
RIDGEWAY HABITAT AND HAZARD MAPPING David Elton 1997
1.0 SITE DESCRIPTION 1.1 Introduction 2.0 RIVER CATCHMENT MAPPING 2.1 Catchments 2.2 Hydrological regimes 2.3 Hydrographic features 2.4 Disturbance regimes 3.0 HABITATS 3.1 Geological History 3.2 Geomorphic Background 3.3 Habitat Systems 3.4 Soils 3.5 Vegetation 3.6 Fauna 4.0 HAZARDS 4.1 Soil and Slope Hazards 4.2 Fire Hazard 4.3 Flooding Hazard 5.0 VISUAL ANALYSIS 5.1 General Comments 5.2 Methodology 5.3 Visual Character Units 6.0 RECOMMENDATIONS 7.0 GLOSSARY 8.0 REFERENCES Catchment Mapping Habitats and Hazards
1.0 SITE DESCRIPTION
1.1 Introduction
All the tributaries of the Ridgeway study area ultimately flow into Browns River, and these fluvial systems have had a major impact on the creation of the local landscape. The southern boundary of the area is set by Dunns Creek. This runs approximately south-east from the foothills of the Mount Wellington Range, joins Browns River just to the north-west of Firthside, before both enter the Derwent Estuary at Kingston Beach. The study area is some 5 km2 in area and comprises a series of prominent ridges, steep upper and valley side slopes, and the tributary series of often deeply dissected gullies. In general most development is confined to a plateau area in Ridgeway itself, although there are some isolated homesteads in the surrounding clearings and bush. The steeper slopes and gullies are still largely in native vegetation. The study area can be divided into four main Land Form systems separated by the tributary creeks:
⇒ the Ridgeway plateau system ⇒ the Bracken Hill ridge system ⇒ the Hall Street ridge system ⇒ the Chimney Pot Hill-Tolmans Hill ridge system
The primary classification developed in this report is largely geomorphically (i.e. process) based. It is related to the hydro- geological systems and climatic/aspect influences. Ridgeway contains a range of Landscape Ecosystems heterogeneous within themselves but displaying some regional homogeneity as a group. These have been further broken down into Habitats as will be described below.
2.0 RIVER CATCHMENT MAPPING
2.1 Catchments
The Ridgeway study area contains the upper tributaries of a series of creeks that eventually all flow into Browns River. Each of these systems has a series of small permanent or intermittent tributary creeks. The tributary defining the Southern Outlet, Vincents Rivulet, partly follows one of the complex parallel fault systems that define the Derwent graben.
2.2 Hydrological Regimes
Ridgeway is an erosional landscape that is still geomorphologically active, although on a much reduced scale today compared with past erosional events in the geological time scale. The nearest weather stations are at Fern Tree and the Waterworks, which report 1160mm and 834mm as long term annual averages, and it is not unrealistic to assume a value somewhere between these two figures for Ridgeway. It is quite obvious that many creeks in the Hobart region are underfit, deriving their local floodplain from earlier and much wetter periods, but here in the headwater zone the relic terraces and underfit bed cross-sections are less apparent than in the lower reaches of these systems. The largely radial drainage pattern of the study area is a system of permanent and seasonal creeks draining directly to the Derwent Estuary via Browns River, and the study area
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contains the headwaters and re-charge basins of some of these tributary creeks.
Dunns Creek itself flows along the southern boundary of the study area and drops about 110m over 1.8km within this zone. The general stability of the bed of most tributaries in the present day can be partly attributed to the lining of resistant doleritic boulders which have derived from the surrounding hillsides. The study area, like the adjacent Mount Nelson, is composed largely of Jurassic Dolerite bedrock. Through the area the gradients are generally similar for all the tributaries and storms in recent years have slightly damaged the banks of some of the creeks in places, but this is a natural process.
Often deeply incised into the containing slopes with side angles sometimes in excess of 25 degrees, the upper creek beds generally show a slowly degrading process (geologically) which has produced only minor isolated gullying, with ~1m splash pools and heavy bouldered beds common. The resistant doleritic parent material in the upper zones of the small catchments has helped produce a relatively stable long profile. Few areas exhibit advanced erosional features, and then only where tree cover has been removed or there have been temporary bed re-alignments (fallen logs directing flow onto a bank).
2.3 Hydrographic Features
The riparian zones including the local creek bed are marked as elongated polygons on the hydrographic layer. The other hydrographic features in the riparian zone generally include features like floodplains (often relic), wetlands, springs, farm dams, marshes and swamps.
Bogs and marsh systems play a vital part in purifying water by settling any locally generated suspended solids and are usually found in this type of land form at nick points in the long profile; springs at such height can be indicative of regional aquifers. The other main feature identified on the upper slopes are localised recharge zones or basins, topographically discreet areas usually at the head of each tributary. These important basins are the main water table re-charge zones and run-off collection points from the surrounding ridge/slope Habitats. While not all creeks had a distinct basin feature with a steeper gully below them, there still can be seen a zone of re-charge in these headwater areas often demarked by floral species tolerant of higher water tables and/or poor drainage.
All the above mentioned features can be placed in a critical management category, not only because of the fundamental position they play in the geomorphological process or their importance to the health of terrestrial and aquatic organisms, but also their over- riding integrative role in the energy balance of the ecographic model. Any modification of their structure or pristine role usually breaks the balance and stability exhibited by landscape ecosystems and can have deleterious consequences for downstream water quality and quantity. It is important to remember that, like the Fern Tree area and parts of Mount Nelson, Ridgeway contains the headwaters of several tributary systems, and any modification could impact directly on the water quality of Browns River.
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2.4 Disturbance Regimes
The sample of creek lines observed in the field do not display excessive or concentrated fluvial erosional features. This in part has to do with the nature of the well vegetated upper gullies which regulate storm flows, and the more resistant doleritic bed material in some sections which is helping to maintain grade. The generally showery nature and lower annual rainfall of recent times, without the type of heavier storm events experienced in the tropical and sub-tropical systems of Australia, and the small catchment sizes, have not created the conditions that promote continual accelerated riparian erosion processes in this area.
It is important that future housing does not impact on the re-charge basins. This can only have the result of impacting on water quality as the form and function of the basin will be modified. It is to be expected in these cases that stormwater will be increased from all the roofing and hard surfacing, and, with pets and garden fertilisers, nutrient levels will be raised in the local area. This is important because of the role these basins play in aquifer re- charge. There are isolated sections of erosion below some stormwater pipe outlets but this has not led to any overall severe erosion that has been noted. Fortunately most of the upper and steeper catchments are also still largely under native vegetation cover which generally provides good riparian protection. Only on the cleared and very steep slopes immediately to the south of Ridgeway are there some signs of incipient scouring and deepening swirl pools where some revegetation should be considered.
3.0 HABITATS
3.1 Geological History
The oldest rocks in the Hobart region in the study area, the Permian sedimentary deposits, consist of fine sandstone, coarse siltstone and fossiliferous mudstones. In the study area these are found in a small section along the Southern Outlet on the eastern boundary.
The Triassic rocks contain beds of thickly bedded medium to course sandstones and minor mudstone; a small outcrop straddles Dunns Creek in the west of the area. The bulk of Ridgeway is composed of Jurassic dolerite which forms the various ridge landforms and underlies the plateau section in the centre of the study area. The eastern boundary along the Southern Outlet is associated with one of the series of parallel faults that follow the Derwent graben.
Basically the study area is formed of two distinct and six minor valley trough units with associated tributaries, separated by intervening ridges and/or slopes. Dunns Creek and Vincents Rivulet have incised into the underlying Jurassic intrusion and form the southern and eastern boundaries respectively. Four of the more distinct tributaries drain eastward and join Vincents Rivulet within the study area. One of them, the most northerly, flows from the Ridgeway Reservoir which has cut-off the headwaters for this creek. The Reservoir, which is not open to the public, is linked to the regional water supply system and is continually filled from external supply. A small flow (including leaks) maintains a water presence in this creek.
The slightly dipping Permian and Triassic sedimentary beds of the Hobart area were intruded during the Jurassic period with dikes and
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sills of dolerite which now forms the hard resistant capping of study area. Faulting since the Jurassic intrusions has resulted in a fracture along which Vincents Rivulet has carved its valley (part of Southern Outlet). This fault is one of the series of north to north-west trending faults which form part of the Derwent graben and, together with cross faulting, have helped determine parts of the courses of many creeks and some smaller tributaries in the Hobart area. Two more faults merge just to the east of Chimney Pot Hill.
3.2 Geomorphic Background
The structural history of Ridgeway, as derived from the largely doleritic bedrock and the periods of erosional cycles to which it has been subjected, has produced the characteristic form of the study area today. Millions of years of erosion has created the near radial valley-ridge systems of the creeks which are centred around the hard resistant central plateau area of Ridgeway. It is the dolerite capping which has most likely preserved this plateau-like feature where less resistant lithologies would have created a more dissected terrain.
While periods of major faulting during and after the Jurassic have guided the formation of some of the creek lines, here as well as in other parts of Hobart, the close proximity of the ridges to the Creek in certain places has strongly influenced the creation of the steep sided slopes and gradients found in many of the gullies. Wetter cycles have created generally underfit entrenched riparian systems, and on the lower grades, occasional minor relic floodplains and terraces. Doleritic boulders and debris can be found along the various creek beds.
3.3 Habitat Systems
The individual habitats were primarily noted on aerial photographs and in the field during the reconnaissance surveys, and finally demarked on the digital imagery using the MapInfo utility. The time constraints for field work meant that not all Habitat sites were visited individually, although a representative range of types was determined.
As a result of the dominant role that lithology has played in the geomorphic processes a set of unique Habitats has been formed in Ridgeway. These Habitats can be described as Crest features with slopes up to approximately 6°, the adjacent Brow and the relic Bench components with a range of slopes from 6° to 15°, Steep Slopes 20- 25°+, Mid Slopes from 12-20°, Gentle Slopes from 5-12°, and Gullies making up the watercourse feature. Another Habitat is composed of a Leading Ridge feature above 12° and is common at the side of the deeply entrenched gullies, while flatter sites below 12° have been termed Ridges. A Plateau area with slopes from 5-12° has been discerned in the central area and is unique to Ridgeway, and there is one Saddle (5-12°) unit. Two quarries were noted (Artificial) and the Reservoir was put into a separate habitat classification.
These features are partly related to the intrinsic resistance to weathering of the parent materials and/or to the past erosional/depositional cycles. At 1:2,500 all these Habitat features have a minimum size of about 1 hectare in area. The Steep Slope Habitats are in places covered, to a varying degree and in a discontinuous pattern, by layers of locally derived talus and colluvium which has subsequently overlain residual bedrock/soils.
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The result of a complex pattern of past cycles of erosion and deposition, it was not possible at the intensity of field work in this study to map the limits of these deposits.
3.4 Soils
As a general rule the soil landscapes follow the typical cateena sequence described in Davies (1988). Further details on each of the various soil morphologies can be found by reference to Hofto, et al (1991) and the Appendices in this report. However, the doleritic clays show a slightly more uniform thickness from crest to slope bottom and are also generally thin, being about 1m in thickness over weathered bedrock; there is much variation with localised talus deposits especially in the steep sided gullies and in places these deposits will be much thicker. The limited area of Permian and Triassic mantles are generally more true to cateena form, with thin rocky skeletal soils on the crests and grading to deeper deposits (also with colluvium and talus in places) on the lower slopes, but here in Ridgeway only the lower slopes and valley bottoms are exposed. Soil erosion and soil creep on these steep slopes over many millennia have created this morphological setting.
Thus the Habitats generally display a typical regolith based on this morphology, with the higher crest and brow Habitats having thinner profiles with an increasing depth of deposit downslope. Localised areas of gentler gradient in any mid-slope position will tend to have an accumulation of deposits, while the deepest horizons generally tend to be on the lower sections of the slope Habitats, particularly near riparian zones. This tendency has been reinforced by the distribution of the discontinuous and localised horizons of talus and colluvial material.
Soils on the Permian These soils are subject to erosion, some types more than others, and areas cleared of vegetation can display sheet, tunnel and gully erosion. Typically sheet erosion is common on the ridge tops and upper slopes underlain by thin silty sands and gravels; tunnel and subsequent gully erosion is more common on flats and lower slopes, particularly associated with the removal of native vegetation and increased surface and sub-surface flows. Some of the clay subsoils are strongly dispersive and examples of gullies in Hobart have been found 5 metres in depth and 7 metres in width and tens of metres long.
Deeper deposits often occur at the base of steep south and south- east facing slopes and the talus contains angular fragments of bedrock in a sand/silt/clay matrix. These deposits will settle slightly under load and seasonal shrinkage-expansion may cause problems if the water content is changed through development. Instability may also occur where bedrock dip exceeds 10-20o, is steeper then the ground slope angle and dips in the same direction as the slope. Excavation in these areas may cause whole blocks of bedrock to slip out along bedding planes. Seepages from springs flowing from boundaries or discontinuities, like faults, joints or bedding planes, may also exacerbate the dip/slope problem. Excavation of soil and upper rock may allow the erosion of joint fill material increasing the flow of water through any discontinuity.
Soils on the Triassic The Triassic rocks weather irregularly depending on the parent material in each layer. The mudstones are more susceptible to
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weathering and can produce thick layers of clay while the sandstone units general break down to clayey sand, weathering being very variable and often exceeding 2-3m in depth. In areas of extreme fracturing weathering is deeper and differential compaction may result. Exposed crests and ridges typically contain stony, black to brown sands and sandy silts grading to medium plasticity clays down slope. Lower down the slope deposits can vary from podsolised sandy horizons to duplex silty sands over sandy clays and clay. These can be very deep at the base of steep slopes as a result of moisture content and soil creep. From past downslope movements areas below Dolerite can have admixtures of montmorillonite clays which have a high shrink-swell characteristic.
If areas of even mild slope have been cleared of vegetation the soils can be subject to various forms of erosion, including gullying, tunnel gullying and slumping. Some soils have been classified as highly dispersive which has exacerbated the problems although generally gullying is on a smaller scale than on the Permian soils. Springs can occur near clay boundaries, or discontinuities like joints, faults or bedding planes and can be a development hazard.
Soils on the Dolerite The generally thinner deposits of clay soils that develop on this rock type have usually a high plasticity and are expansive. Locally, in protected gullies and slopes, deeper soils (>1-2m) may cause stability problems. For example, on the lower slopes of Mount Nelson, thick unsupported fill has been placed along the Enterprise Road extension into a small valley and this must be considered as creating an unstable situation. On many steeper sites a talus of boulders or boulders in a clay matrix are left as remnants from earlier cycles of erosion. These can be mixed with sedimentary rock and clay deposits as well. Several soil types are exhibited on the dolerite and are more fully detailed in Davies (1988), and Hofto, et al (1991), refer also Appendices in this report. Generally the dolerite soils are not prone to excessive surficial erosion but the colluvial and talus slopes are subject to landslide. An historic landslide in 1960 on the northeast slope of Mount Wellington, above the north western edge of the study area, caused flood waters to break the banks of New Town Creek.
3.5 Vegetation
The vegetation of the Ridgeway area has been recently mapped by Johnson (1994) into a number of different communities and associations. These are available as hard copy maps and Johnson's work has also been digitised onto the HCC GIS data base. Generally, the slopes in this area are covered by forest and woodland although the canopy has been opened up near settlements or on hard stony ground. The dolerite are covered by associations of White Peppermint, Bluegum and Stringybark forest/woodlands with heath, sedges and some shrubby areas. Broadleaf and Fern communities occur along the creek lines in the wetter gullies protected from fire, while other areas have an understorey of bracken.
The history of the area, with perhaps millennia of involvement by Aboriginal tribes moving along the Derwent and more recently its proximity to Hobart City, has given a legacy of fire impact that can be clearly observed in the types and structures of the plant communities (patches). In fact, whether by accident or design fire continues down to this day to be a moderator of the vegetation and has caused arrested disclimax in many habitats.
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Generally, the communities, ex-Johnson, include:
Eucalyptus obliqua shrubby/heathy forest on slopes. Eucalyptus obliqua frequently occurs in association with E. pulchella, E. globulus and some E. viminalis. Eucalyptus pulchella shrubby/heathy woodland and open forest on the dolerite ridges and upper slopes. E. pulchella also occurs with E. globulus and E. viminalis. Heathy/grassy Eucalyptus viminalis woodland with E. pulchella in the drier eastern areas of Ridgeway. Some Allocasuarina forest and woodland on the fringes of the Southern Outlet, often in association with E. pulchella. Some patches of gully scrub with Acacia dealbata forest, ferns and broadleafed species in the more fire protected gullies. Also some minor E. ovata near the Southern Outlet.
The area is predominantly under native vegetation, with few areas of land described as "degraded" in terms of weed invasion or health of vegetation perhaps because of the low scale of housing development and the isolation of the area.
Recently, and after the earlier draft of this report had been finalised, A. North completed Stage 2 of a study of the floristic communities of the HCC areas, North (1997). This has now brought the coverage up to Ridgeway, as well as redefining his earlier work on South Hobart and Lenah Valley. His work differs from that of Johnson in that his mapping units and boundaries are concerned with the floristic composition of the communities rather than their structural description. This is more valuable in that conservation status for the communities can be more easily discerned. He has generated a set of rules to determine the conservation status of the various communities he has described for the study areas.
For a description of A. North’s findings for Ridgeway, see North (1997).
3.6 Fauna
A brief appraisal of fauna conservation status has been included in this report. This work follows on from studies by Dr. R Taylor and included in the South Hobart and Lenah Valley Local Area Strategy Plans (Taylor, 1997). It is clear from work in the Hobart area that a number of species are threatened or important in the local context. However, with the exception of some data around Marlyn Road/Jubilee Road (Douglas et al, 1995) the suburban fringe has not been subjected to intensive trapping and recording studies.
In the absence of hard data on population numbers and diversity, it has been necessary to develop a predictive model as a first level assessment of habitat importance. This approach has been tried elsewhere successfully (Catling and Newsome, 1981), (Elton, 1981).
For Ridgeway, the detailed floristic communities map prepared by A. North, has been used as a basis for predicting the presence or absence of certain faunal species. The assumption here is on the known association of certain species with a particular floristic/structural habitat. This, of course, is only relevant
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where faunal species occupy ranges that are compatible with the size of vegetation patches that are being mapped at this scale. Obviously, some species have larger ranging habitats (raptors) while others occupy sites below the scale of mapping utilised in these studies (invertebrates). The mammals that are at most risk, fortunately, do fit into the scale of mapping boundaries used in this study.
From this basis a methodology has been derived for the major species under threat in the Hobart area. The methodology has been based on the maps produced for South Hobart and Lenah Valley by R. Taylor, and refined in subsequent conversations with him. One of the problems has been the changing nomenclature and boundaries of A. North’s vegetation polygons, however it has been assumed (March 1998) that the floristic communities are relatively fixed now. These boundaries have been digitised into the Council GIS data base, and from the rules generated in the following table it is then possible to rank the polygons into various classes. This has allowed the creation of the Fauna layer in MapInfo.
SUMMARY OF FAUNA HABITATS FOR HCC AREAS
Title After North After Johnson Map Rank Swift Parrot WET-Glob1 Eg/GS/BS/G THREATENED Where blue gums form > Dry-gGLOB Eg/G/S 50% of the canopy WET-GLOB 0100 Eg/BS/F DRY-gPULC Ep-Eg/G DRY-sOV Eov/SD/G Goshawk Wet forest Some GS (A. THREATENED along gullies melanoxylon) particularly with Blackwoods Eo/GS/BS WET-OB0110 Er/GS/BS WET-REG1001 Eg/BS/F WET-GLOB 0100 Bettong DRY-hTEN-mud Et/H/G IMPORTANT Found on poorer soils DRY-hTEN-sand Et/H/G DRY-gAM Ea/G DRY-hAM-sand Ea/H/G Barred Bandicoot DRY-gPULC Ep/G THREATENED Dry grassy forest on DRY-gVIM Ev/G better soils Poorly reserved habitat DRY-shPULC Ep/S POORLY in HCC WET-GLOB Eg/BS/GS/F RESERVED Riparian Zone IMPORTANT Need 30m buffer in bush areas
THREATENED Habitat of rare or threatened species, by law Parks and Wildlife Service must be consulted IMPORTANT Not threatened but of high conservation significance POORLY RESERVED Important habitat at local level and not well represented in HCC reserves
4.0 HAZARDS
4.1 Soil and Slope Hazards
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Because of the high public concern and financial repercussions involved in any potential subdivision slope failure (e.g. the Rosetta landslides), and the concern of liability, this aspect has been treated in a more detailed way in this report. Further material that expands this theme can be found in Appendix E.
In assessing the suitability of any site for further development one of the most critical aspects relates to slope stability. This is a complex issue and covers a range of factors that interrelate in ways that are not always completely understood nor predictable. Slope failure can refer to a range of phenomena variously referred to as rockfalls, slab failure, rock avalanche, slumps, and planar slides in deep-seated rock failures, to a variety of mass wasting processes in soil/regolith mantles and described variously as rotational slumps, debris slides/avalanches/flows, earth and mud flows. Some trigger mechanisms are noted in Appendix B. Surficial soil erosion is more concerned with features like soil creep, tunnel, sheet and gully erosion. In the more ancient landscapes of the Hobart region, where threshold rock slopes have attained some stability, mass movement is today largely displayed in the regolith/soil matrix particularly on the deeper slope deposits of weathered clays and unconsolidated talus or boulder/colluvium beds, and especially where land cover/use has been recently modified.
Soil morphology and hence chemistry is so variable across the landscape, even within short distances, that few site specific recommendations can be given. In such a case as this, and in the absence of more detailed site analyses, slope profiles provide one of the few keys to assessing hazard, in as much that a general analysis of failed slopes with a particular rock/soil type and land cover can be indicative of potential instability elsewhere within a similar defined regional setting. Critical landslip slope angles for a range of rock types, as advised by the Department of Energy and Resources, can be seen in Appendix D. These can then be extrapolated to the different Habitats.
Each type of Habitat is composed of a range of slope angles that help define them as well as other topographic and biogeographic similarities. As such they can be assessed in terms of their slope stability hazard or because of their hydrographic function. From this basis, and in consultation with the needs of the HCC planners, a ranking system of four basic zones has been produced, Potential Development Zones (PDZ), Limited Development Zones (LDZ), Critical Management Zones (CMZ) and Prohibited Development Zones (XDZ).
Quite simply PDZ are areas where, provided all environmental safeguards are observed, further development should pose no threats in terms of environmental sustainability. These areas can be downgraded by the effect of a limiting factor. LDZ are areas where, due to the critical role the Habitat plays in ecosystem dynamics, its buffering properties or both, there are limited opportunities for development; also they are subject to more or less stringent environmental and development controls. CMZ are areas where, due to the critical role the Habitat plays in ecosystem dynamics, its buffering properties or both, housing development is generally prohibited, although passive recreational development may be a possibility; moreover they are subject to stringent environmental controls. XDZ are areas where hydrological functions are critical for maintaining water quality and hence development is prohibited. The limitations determined in this study that govern the capability are either (A) areas of expansive soils, (B) areas of slope instability or (C) the critical hydrological areas (water re-charge or riparian protection).
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The limitations are used in the analysis to determine the development potential for each Habitat. Thus expansive soils, because of their impact on footings, downgrade a PDZ to an LDZ. Once Habitats contain slopes in excess of 12o soil stability issues start to become paramount, in terms of landslip potential or soil creep, and a PDZ containing both (A) and (B) becomes downgraded to a CMZ. If a Habitat contains a hydrological component (a riparian corridor), whether it has (A) or (B), neither or both, it is downgraded to a XDZ and all development is prohibited. The following table expresses these relationships.
HABITATS AND CAPABILITY ANALYSIS
Habitats Average Slope Capability Limitation C Crest 0-6° PDZ P Plateau 5-12° LDZ A S Saddle 5-12° LDZ A BE Bench 6-15° LDZ A BR Brow 6-15° LDZ A SS Steep Slopes 20°+ CMZ A + B MS Mid Slopes 12-20° CMZ A + B GS Gentle Slopes 5-12° LDZ A LR Leading Ridge 12°+ CMZ A + B R Ridge <12° LDZ A A Quarries, etc. Variable XDZ Special RES Reservoir 0 XDZ C V Gullies 6-20°+ XDZ C
KEY PDZ = POTENTIAL DEVELOPMENT ZONE LDZ = LIMITED DEVELOPMENT ZONE CMZ = CRITICAL MANAGEMENT ZONE XDZ = PROHIBITED DEVELOPMENT ZONE LIMITATIONS (A) EXPANSIVE SOILS IF (A) THEN PDZ = LDZ, (B) SOIL INSTABILITY IF (A) + (B) THEN PDZ = CMZ, (C) HYDROLOGICAL IF (C) THEN PDZ = XDZ
No areas were noted during the field work which exhibit the types of more serious problem that can be experienced with the sedimentary regolith. This in part is strongly related to the fact that most of the catchments are in mainly good vegetative growth and urban development is minimal. The steep slopes of this study area will require careful land management if they are to be developed. Some of the creek beds showed minor bank and bed movement, and the worst example was seen near the confluence of Dunns Creek and the creek that drains south from Ridgeway (230464), where some localised, deeper bed and bank scour is occurring.
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4.2 Fire Hazard
Bushfire is a constant risk around the urban fringe where development meets the forest edge and Hobart, like many other Australian cities, has had its fair share of fires and destruction. This risk is related to the susceptibility to fire of the native vegetation and the cycles of summer drought and strong northerly (dry) winds. Unlike other environmental hazards which are largely fixed due to some geological or geomorphic constraint (slope/hydrology), fire hazard is more amenable to manipulation. Strategies for reducing bush fire hazard include fire suppression, fire prevention works designed to support suppression efforts (e.g. the construction of firebreaks and fire access roads), the provision of adequate water supply points and broad-scale fuel reduction burning.
The devastation of major fire outbreaks in Victoria (Ash Wednesday) and the 1994 Sydney bushfires has resulted in a national review of fire control strategies particularly for those areas of high risk at the urban-bush interface. Petris and Potter (1995) in their report on a National Bushfire Strategy listed several objectives and policies that should be pursued to reduce hazards, including policy 2.3: "Develop the application of a GIS to map and identify areas of high fire risk for the introduction of the national standard on buildings in bushfire prone areas. Develop minimum standards for controlling development in these areas"
Partly as a response to these issues, the State Fire Service of Tasmania (TFS) are reviewing several aspects of their management strategies and response to fire hazard, and encouraging local communities to participate in reducing their vulnerability to this hazard and to develop bushfire safety strategies. A significant step in this direction has been taken by the TFS by its publication of planning and design guidelines for local communities, particularly for those on the urban-bush fringe (TFS, 1995). The TFS are also developing a GIS to map areas of fire risk around the State and Mount Nelson will be one of the first areas to be mapped.
The planning guidelines themselves are aimed at local council planning agencies, subdividers and individual householders and illustrate a range of design parameters from whole subdivisions down to individual lots with regard to adequate buffers, site layout, provision of water supply, fire tender access and fuel reduction programs.
In regard to this study and the issue of hazard mapping, the general policy State wide has been to develop Fire Management Area Committees (including a mandatory representative from the local council), one of whose tasks is to produce a Fire Protection Plan for their local area of interest. To help in the preparation of these plans the Committees will initiate risk assessment. Areas of high risk will receive immediate attention with abatement works being the responsibility of individual land owners or managers, possibly in co-operation with local Brigades.
A methodology has been developed by the TFS and passed to the State Land Use Planning Review Panel (LUPRP) for authorisation. It is an assessment which allows the risks to be determined from aerial photographs or orthographic images with some contour information where each zone is assigned a continuing risk ranking made up of
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Slope, Vegetation Type and Area. The assessment procedure is as follows:
LOW for none bushfire prone areas, with bushfire prone areas being designated as having any vegetation over 1 hectare in area or vegetation within 100m of such an area. It excludes grassland on slopes less than 5°. MEDIUM for bushfire prone areas with a slope of 0-14° HIGH for bushfire prone areas with a slope greater than 15°
In general, the LUPRP and individual planning authorities will determine the planning consequences of the above methodology. On case by case issues the fire hazard will be resolved by a more detailed methodology that assesses risk ranking in terms of Slope, Access and Vegetation Type (Static Risk), together with the Fuel Load (Changing Risk) to give a current risk ranking (Total Risk). This more detailed appraisal is to be done by local Brigade members where possible.
4.3 Flooding Hazard
The hydrological hazards are identified on the Hydrographic layer and comprise quite simply the riparian zone, which encompasses the active creek bed and immediate floodplain, and the re-charge basins or zones. For the purposes of this study the riparian zones are considered a prohibited zone for development, while the re-charge areas can be considered critical or limited if a complimentary use can be found for the zone that does not impinge on its functions or cause environmental harm e.g. environmentally designed sports fields.
In the study area the hydrographic layer encompasses the upper catchment features of several creeks contributing to Browns River. Contributing to these main rivulets are several smaller intermittent tributaries, most of them still with a natural cover of native vegetation. As noted above, most streams would be described as "underfit", occupying only part of a larger riparian cross section that has been formed in geologically wetter periods.
Few problems exist in the areas seen during field work. Much of the reason for this has to do with the small catchments and largely native forest cover. It is important that the upper slopes and riparian areas, including the recharge zones, remain in a natural state wherever possible to buffer any storm run-off. Their geomorphic role has to be clearly understood and any development occurring in them must not be allowed to compromise the functions they play in infiltration, storage and re-cycling of water and nutrients. Developments must be able to show they can retain those functions without causing environmental harm.
The catchment in the upper slopes of the Ridgeway area can be expected to collect a reasonable annual total rainfall. The annual rainfall is in the range of 830-1160mm (there is no station at Ridgeway). Catchments with moderately steep long profiles over short lengths (one typical catchment drops about 200 m in 1 km), with reduced upper catchment permeability characteristics (dolerite), and experiencing reasonably high local orographic distribution of annual and storm rainfall volumes, can be expected to have moderately energetic regimes. In such situations the retention of forest cover on these steep upper catchment slopes is
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important to buffer any storm generated runoff. The removal of critical patches of slope and riparian vegetation can aggravate bed stability by excess runoff characteristics with reduced mantle protection, initiating changes that may take decades to stabilise.
Where appropriate hazards can be reduced in already compromised or threatened areas by provision of environmentally designed riparian improvements. Wetlands and artificial bog-flush systems can be constructed, particularly at nick points and in headland areas; smaller scale infiltration \ evaporation beds and trenches can be constructed to handle local stormwater run-off before discharge to a drainage line; the use of tree and shrub species with high rates of transpiration can be encouraged; fertilisers are to be avoided or limited to low rates of slow release types and so on. Well defined buffers of native vegetation should be established to the nearest cultivated garden zone.
Inappropriate development would include high density housing, excessive paddock development, overstocked animal paddocks or large areas of non-absorptive paving in re-charge zones, excessive roofing areas and stormwater collection and piping that discharged directly to a creek. Streams and creek lines should not be modified or crossed wherever possible. However, where approved, any essential roading should be constructed with minimal batters and be immediately revegetated, with adequate diameter culvert capacity and protection measures. Lower down in the floodplain zone meanders play a vital role in stream and river morphology and often they are disturbed and shortened by inappropriate development. By steepening the overall grade active rejuvenation often occurs with consequences for increased upstream bed and bank erosion.
5.0 VISUAL ANALYSIS
As part of this assessment a visual analysis has been undertaken for the study area, to identify features in the study area whose cultural importance, aesthetic qualities or visual prominence are of sufficient importance to the local and regional community that they require particular management strategies. The methodology was developed for the Fern Tree area and is outlined below. Also refer to photographs in rear of report.
It should be stated at this stage that the analysis should be classified as a reconnaissance approach, in line with the other hazard assessments undertaken for the study. A comprehensive analysis, similar to the full treatment given forestry areas under the State Forest Visual Planning Process, is beyond the time and financial constraints of this project. At another time it is recommended that a more comprehensive analysis be undertaken, utilising computer simulation and view fields.
However, the most appropriate starting point for the analysis is the Forestry methodology. This is because it is well accepted both here and on the mainland, it is as objective as this type of study ever can be, and it presents a systematic way of dealing with the landscape that has relevance to planning and, ultimately, the derivation of performance criteria. In that sense, the methodology proposed can be seen as a simplified version of the Forestry program, bearing in mind that their system has been developed for large scale rural landscapes, and not for the more intimate suburban/townscape fabric.
5.1 General Comments
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The study area itself forms a sub-regional unit set against the forested foothills of Mount Wellington, and it is in this context that it forms part of the view fields from areas around Kingston (P13). From here only part of Ridgeway can be seen. The rest of Ridgeway is largely hidden from view from the Eastern shore due to the ridge that runs from Mount Nelson to Bonnet Hill (Albion Heights). The odd house in the plateau area can be seen from the Summerleas Road ridge area in Fern Tree.
The bulk of the study area is in a cover of natural vegetation and composed of steep slopes, ridges and crests. As such it forms an important forested backdrop to the city’s regional setting with the natural areas forming a continuum with the upper slopes of Mount Wellington Park. This setting can be classed as a wilderness view field. The limited development in Ridgeway and along some ridgelines is generally inevident and would be classified as a Contemporary Bushland setting, following Gulson et al (1995). Gulson went further in describing these character zones and set a series of objectives for their management (op.cit. section 6.3.2) and performance criteria for their achievement (section op.cit. 7.3.1). For example, suggesting allowable canopy clearance percentages, and colour/tone contrast limits (op.cit. table 7.2). This approach is justifiable and worthy of further development, but until there is community input to establish character objectives for Ridgeway, the approach will not be expanded on here.
5.2 Methodology
Several basic assumptions have been made in proposing this methodology:
⇒ The broad theme of visual management is to give protection to the inherent visual character of the various landscape components.
⇒ There is an underlying premise that viewers experience the landscape, including any introduced changes to the landscape, within the context of the visual character of the regional landscape which surrounds them.
⇒ There is an inherent conservatism in the way people view a significant/prominent landscape, and unless great care is taken in managing the elements of change, most change is viewed in a negative fashion (e.g. the cable car proposal).
⇒ Surveys indicate rural landscapes, especially with high scenic content (mountains, forests, rivers, etc.) are preferred viewing to urban-style landscapes. There are many complex psychological and light theory reasons for this, but it underscores the reason why such landscapes are highly sought for living in, and as tourist destinations.
For planning purposes it is essential to develop a spatial unit to which planning objectives and controls can be applied. It is therefore proposed to develop a Visual Character Unit (VCU) in keeping with the scale and purpose of the study. Typical examples were recorded as photographs, see (P) below. Obviously in a regional context the whole of Ridgeway can be seen as part of one unit, a steep forested mountain zone of ridges and gullies. But within this broader regional perspective it is possible to break the area down into discrete character units, on the basis of regolith
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characteristics (as per the Habitats), spatial dimension, viewing fields, and the internal arrangement of various visual phenomena (trees/houses/scale/enclosure/colour/etc.).
Having established a range of VCUs that cover the variety of natural and cultural landscape elements in the study area, it is then possible to describe their intrinsic and distinguishing visual characteristics and thus document their Current Visual Character. At the same time an analysis will determine the prominent vista points (P11), both within the study area (along roads, on significant headlands/crests etc.) and outside the area (regionally significant vista points viewing into the study area). These will be marked on the accompanying maps. Photographic records will be established of the VCUs from prominent vista points. These record the units in time and are suitable for defining the key elements of each unit’s visual landscape character.
From this type of analysis, by consultation and from prior experience, it will then be possible to establish the Visual Character Objective (VCO) and the Visual Performance Standard (VPS) for each Unit. The VCOs are a strategic statement of intent for each unit, based on viewing opportunities, regional significance and perceived community concerns. This then acts as a standard against which future planning and management actions can be evaluated. The VPSs are the minimum performance standards required to meet the VCOs. An example only is produced for the sake of explaining the strategic process.
The refinement of compliance criteria and performance criteria (type and colour of building materials, scale of development, landscaping treatments etc.) will be defined during the development of the Local Area Plan and in line with community expectations revealed through the consultative process. This is fundamental in establishing the desired character style for such units as the village centre. This may of course alter some of the VCOs and VPS’s developed here and those documented below should be read as indicative only to illustrate the process.
5.3 Visual Character Units
The following visual units have been discerned for the study area:
Rural Rural cluster Rural isolated Rural ribbon Road corridor Forest slope Forest ridge Tourist/recreational Damaged Power Corridor
Given the current visual character of the study area, these VCU’s have been defined for Ridgeway as follows:
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Rural (R) This unit is composed of cleared paddocks within the central plateau area of Ridgeway (P2-3), with single housing development in mixed lot sizes. The rural unit with generally large lot sizes is typical of semi-urban farmland, with a mixture of hobby farms, horses, and nurseries. The preservation of the surrounding bush cover has led to a generally harmonic and non-intrusive situation, creating the impression of an island pasture in a sea of forest. There are some interesting and innovative house styles (P10).
This area is largely invisible to any vantage point, only a slight break in canopy or the odd roof being noticeable from the Springs (P14) or Summerleas Road in Fern Tree.
Rural cluster (RCL) This unit is exemplified by the housing around the central plateau habitat and to the east of the rural unit (P6), although certainly lacking a true central node. A variety of house styles (P7) and block sizes are set in a gardenesque rural cluster, dominated by a mixture of exotic and native vegetation. Set on an island of plateau, crest, and ridge habitats, the cluster is defined by the enclosing native vegetation. As noted above some of the housing can only be seen from Summerleas Road in Fern Tree.
Rural isolated (RI) This category describes the isolated homesteads and associated gardens/fire breaks situated within the encompassing forested habitats. There are only a few of this category, on a variety of blocks and with different housing styles (P8-9-10).
Road corridor (RC) This is simply the road corridor zones, particularly along the upper part of the Southern Outlet (P12). The Outlet is an open highway with a wide view into part of Ridgeway when heading south from under the Mount Nelson overpass. Within the Ridgeway area the roads are characterised in the plateau area by a grid layout in cleared farmland (P4), but more winding alignments with natural edged features (no curb and gutter) away from it, the forest canopy often providing a strong sense of natural enclosure with typical tunnel- like view fields. There are also a few significant external view fields over parts of the region (P5) where there has been a break in the downslope canopy cover, usually associated with housing.
The narrow, winding rural style of these roads, often with remnant large trees close to the edge, as in Ridgeway Road, are an important component in the local context and add a significant element in establishing the character of such settlements. With the quality scenery overlooking the Reservoir along that Road, these features are worthy of preservation in maintaining that sense of place.
Forest slope (FS) The steep slopes of the many catchments in the study area are covered in the most part by a continuous swathe of forest and thick undergrowth (P13). This provides the strong sense of visual unity for this unit, which is often described as the backdrop landscape. The forest enforces the notion of a wilderness setting when seen in combination with the rugged steep slopes and gullies over which it is mantled.
In the regional context the upper slopes are in themselves part of significant viewing fields from the South Kingston area (P13), parts of Summerleas Road in Fern Tree, the Springs and the Southern
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Outlet, and their protection is important. Development has to be undertaken with great care.
Forest ridge (FR) This zone is very similar to the one above only that it is distinguished by its topological setting along a prominent ridge line (P3-8). These features while locally prominent usually provide the skyline for areas further away and lower down. In this context they are visually important and development has to be undertaken with extreme caution if regional view fields are to be enhanced and protected.
Tourist/Recreational (T) There are five spaces of recreational or potentially tourist value, including the park close to the entrance to Ridgeway (P1), the views of the Reservoir (P11) along Ridgeway Road (or its possible future use), a little used recreation reserve up the usually locked Chimney Pot Hill access road, the small area at the upper end of Hall Street, and potentially, the Chimney Pot Hill lookout area with its sweeping views. Many of these features fall below the generally accepted 1ha size for this type of landscape system mapping, but the sites have potential despite their current use and, in two cases, their restricted access.
Damaged (D) This unit occurs at the site of the old Quarry near the Ridgeway Reservoir. This large abandoned quarry along Ridgeway Road detracts from the fine views along this Road and is a possible a target for some Landcare work.
Power Corridor (PC) This is a linear utility space which, although small in width, has a significant impact on the local landscape. This is because the power lines are placed straight up the hillsides through a corridor that is regularly cleared of vegetation, creating a strong line with colour and texture contrast against the surrounding forest.
Visual Visual Character Visual Performance Standard Character Objective (example only) Unit Rural To minimise the visual Development to be of a scale intrusion of suburban style and colour in harmony with the housing in a predominately scale and natural colours of rural landscape and to the site. preserve the regional skyline. Rural To minimise the visual Development to be of a scale Residential intrusion of ridgeline and colour in harmony with the Ridge development and preserve the scale and natural colours of regional skyline. the site. Rural To maintain cluster Developments must conform to a Cluster development with high visual unified character style, with amenity by developing a complimentary treatment of character style. design, colour and scale. (The character style for the cluster to be decided by community consultation) Rural To ensure isolated Development to be kept below Isolated developments do not the tree line and in a style predominate the rural and colour that harmonizes landscape. with the scale and natural colours of the site. Tree clearance to be a minimum to
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meet fire requirements. Road To enhance and maintain the Maintain existing alignments, Corridor scale and rural character of natural road edges and the roadways. drainage features (e.g. grassed swales) To protect the viewshed from the Southern Outlet. Development to be kept to a minimum and to be of a scale and colour in harmony with the scale and natural colours of the site Forest Slope To maintain the forest cover Development not to be of the slopes. encouraged on steep forested slopes or to meet specific performance criteria. (e.g. minimal clearance of vegetation and development to be kept below the tree line and in a style and colour that harmonizes with the natural colours of the area) Forest Ridge To protect the remaining Development to be generally ridgelines in forest avoided on the remaining cover and ensure any ridges or to meet specific development is visually performance criteria. unobtrusive (e.g. minimal clearance of vegetation and development to be kept below the tree line and in a style and colour that harmonizes with the natural colours of the area) Tourist/ To enhance, preserve and New structures, furniture Recreational promote high quality or signs to conform to a features and utilise a unified character style. distinct Fern Tree character theme.
6.0 RECOMMENDATIONS
The identification of habitats in Ridgeway has been presented as a guide for the outline development plan for the area. As such this hazard analysis has focused on three major areas critical for the further development of suburban development, namely slope stability, hydrology and vegetation/fire hazard. These issues have been addressed through the identification of discreet habitat units which form the basic building blocks in a planning process which has been termed ecography. It is part of an integrative process and other layers of information have been incorporated into the overall model, including areas of flora and fauna conservation, and visual analysis. Transportation and communication networks, community centres and nodes and other economic and population issues can be added at another stage in the evaluation.
The ultimate goal of this first level of analysis must be aimed at the overall objectives of sustainable development, particularly with regard to water quality and soil stability, but also conservation and visual issues. The gradual degradation on environmental values is sometimes so slow as not to be noticed by the passage of one generation. The cumulative impacts of suburbia with its roading and hard surfacing, and the land-uses/animals it supports, golf courses, industrial sites, dogs, lawn fertilising etc. greatly alter the local floristic and aquatic ecosystems. The identification of
RIDGEWAY Page 19 Catchment Mapping Habitats and Hazards
Habitat units and their ability to sustain development is one step in the direction of redressing the balance of previous cycles of poor environmental planning. The introduction of planning controls and codes of practice for certain land uses, and the integration of environmental design in future suburban layouts will further improve the situation.
The integration of Habitat capability zoning into local area structure plans is only one aspect of good land use planning. As a generic tool it is of vital interest to town planners. What it cannot do is replace the need for site specific information on which to judge any development application. It draws certain lines and warns that certain problems may exist at a site. In order that preliminary screening of applications addresses the issues raised here it is appropriate to develop guidelines for more detailed information.
In regard to Ridgeway:
1. For all rock types if the slope of the land parcel is above 12o then the applicant should be asked for a full geo- technical report. Evidence of dispersibility would also generate such a request. This threshold angle may be lowered if site evidence, test pits or other anecdotal evidence indicates a potential for site instability.
2. If the site has more than 1m of "soil" above bedrock on dolerite clay slopes exceeding 9o then the applicant should be asked for geo-technical or engineering advice in relation to any cut slopes and footings for houses and retaining walls.
3. If the land parcel contains a drainage line or recharge basin the applicant should be asked for an environmental management plan that addresses stormwater generation and disposal, riparian buffers and landscape design and maintenance (fertilisers).
4. If the site is in a fire hazard zone a fire plan should be developed in liaison with the local Fire Officers that addresses the Tasmania Fire Service Guidelines for subdivisions in bushfire prone Areas.
RIDGEWAY Page 20 Catchment Mapping Habitats and Hazards
7.0 GLOSSARY
Ecography Ecography is the mapping and modelling of landscape ecosystems, their site networks, characteristic Habitats and resource economies. It provides an integrated model for land use and environmental planning, incorporating land use, vegetation and wildlife mapping within an ecological model of any landscape.
Landform A geomorphologically discreet unit often composed of a suite of landscape ecosystems. They are geologically distinct and usually demarked from one another by aspect and a range of similar topographic units.
Landscape Ecosystem A landscape ecosystem is a site network, Habitat and terrain based spatial system. They are characteristic assemblages of Habitats and sites, defining their identity and image, while providing a framework for recording and monitoring their environmental resources. This is achieved by defining ecosystems comprising heterogeneous suites of characteristic Habitats in the landscape, integrated by their patterns of topography, vegetation communities, resource economies, settlement nodes and network systems.
Habitats Habitats are defined by their homogenous regolith topography and (subject to fire history) biogeography, and identified by their characteristic patterns of soil, flora and fauna.
RIDGEWAY Page 21 Catchment Mapping Habitats and Hazards
8.0 REFERENCES
Catling, P C, and Newsome, A E. “Mammal Communities of Heath” in Heaths in NSW, National Parks and Wildlife Service, Sydney, 1981. Davies, J B. Land Systems of Tasmania Region: 6; South, East and Midlands - A Resource Classification Survey". Department of Agriculture, Hobart, 1988. Douglas, James & Associates. "Jubilee Road Environmental Capacity Review", Hobart, 1995. Elton, D. “The Loddon-Campaspe Region: Some Theoretical and Practical Considerations for Habitat Inventory Surveys”. Discussion Paper, Arthur Rylah Institute for Environmental Research, Melbourne, 1981. Hofto, P J; Sloane, D J; Weldon, B D. "Engineering geology of the Greater Hobart Area", Report for the Urban geological Mapping project, Department of Resources and Energy, Hobart, 1991. Gulson, L. and North, A., "Briefing Notes: Conserving the Environmental Values of Mount Nelson", Hobart, 1995. Johnson, D. "Mapping Vegetation of Hobart", Masters Thesis, University of Tasmania, 1994. North, A. "Botanical Surveys of Hobart Bushland Stage 1", Hobart City Council, 1996. North, A. "Botanical Surveys of Hobart Bushland Stage 2", Hobart City Council, 1997. Petris, S. and Potter, P, "A National Bushfire Preparedness Strategy", Australian Fire Authorities Council and Emergency Management Australia, Canberra, 1995. Taylor, R. “Fauna of South Hobart and Lenah Valley: Values and Issues Related to Urban Planning in the Context of Sustainable Development”, Report to Tasque Consultants and Hobart City Council, 1997. Tane, H. "Ecography: Mapping and Modelling Landscape Ecosystems", Murray Darling Basin Commission, Canberra, 1994. TFS (Tasmania Fire Service), "Planning Conditions and Guidelines for Subdivisions in Bushfire Prone Areas", Hobart, 1995.
RIDGEWAY Page 22
BOTANICAL SURVEY OF HOBART BUSHLAND
STAGE 2
RIDGEWAY - PRECINCT 44 RIDGEWAY RESERVE KNOCKLOFTY RESERVE MCROBIES GULLY
ANDREW NORTH
September 1997
FOR HOBART CITY COUNCIL
A Botanical Survey of Hobart BushlandsStage 2: Ridgeway and HCC Reserves
SUMMARY
This report details the second stage of a botanical survey of bushland in Hobart. Stage 1 surveyed Lenah Valley and South Hobart. Stage 2 includes private bushland in Ridgeway and several Council Reserves including Ridgeway Reserve, Knocklofty Reserve and McRobies Gully, along with several smaller reserves.
The project involved mapping native vegetation using recognised plant community classifications, mapping locations of rare and threatened plant species and mapping major weed infestations. Summary reports have been developed for each of the Council reserves with species lists, descriptions of plant communities, and summaries of management issues. These are maintained on the Bushlands Reserves Database maintained by The Council.
An approach for prioritising conservation significance of plant communities has been developed and is explained in detail. This includes incorporating the most recent information on the reservation status of plant communities. Plant communities mapped in stage 1 are also referred to in this report.
The findings from the survey undertaken for stage 2 detail populations of :
2 vulnerable plant species (both listed in schedule 4 of the Threatened Species Protection Act 1995) 12 rare plant species (7 are listed in schedule 5 of the Threatened Species Protection Act 1995). 2 plant species currently unreserved anywhere in Tasmania
Plant communities mapped for both stage 1 and 2 include:
6 communities considered in critical need for further conservation 4 communities considered in urgent need for further conservation 2 communities considered important and requiring some conservation 3 communities of non-priority for conservation
Generally bushlands around Hobart are of high conservation value and include a very high proportion of significant plant communities.
Recommendations are made to conserve the best examples of high priority plant communities and species through acquisition for reserves and through appropriate planning controls.
1 Andrew North Consultant Botanist A Botanical Survey of Hobart BushlandsStage 2: Ridgeway and HCC Reserves CONTENTS SUMMARY ...... 1
GLOSSARY...... 3
1. INTRODUCTION...... 5 1.1 BACKGROUND...... 5 1.2 STUDY AREA...... 7 2. METHOD ...... 7 2.1 APPROACH ...... 7 2.2 SURVEY METHODOLOGY ...... 7 2.3 MAPPING...... 8 2.4 ASSESSMENT OF CONSERVATION SIGNIFICANCE ...... 8 2.4.1 Plant Species ...... 8 2.4.2 Plant Communities...... 10 3. RESULTS ...... 12 3.1 PLANT SPECIES OF CONSERVATION SIGNIFICANCE...... 12 3.2 PLANT COMMUNITIES ...... 14 3.2.1 Priorities for conservation...... 16 4. RECOMMENDATIONS...... 20 4.1 PLANNING ...... 20 4.2 RESERVE MANAGEMENT...... 20 5. REFERENCES...... 22
FIGURES AND TABLES FIGURE 1 - Study Area...... 6 TABLE 1 - Plant species of conservation significance ...... 12 TABLE 2 - Reservation status of mapped forest communities ...... 18 TABLE 3 - Priority for conservation of forest communities in Hobart...... 19
2 Andrew North Consultant Botanist A Botanical Survey of Hobart BushlandsStage 2: Ridgeway and HCC Reserves
GLOSSARY
• CAR - Comprehensive, Adequate and Representative forest reserve system. Under the NFPS (refer below) a commitment was made to develop a national reserve system which: captures the full range of forest communities; maintains the ecological viability and integrity of populations of species and communities; and reflect the biotic diversity of communities.
• Conservation significance - The priority for conservation of a plant species or plant community based upon its reservation and its rarity (this is described in detail in part 2.4).
• CRA - Comprehensive Regional Assessment of forests. Under the NFPS Governments set guidelines to have this undertaken to establish a CAR in the development of a RFA.
• Environmental weeds - Species of plants which have a demonstrated capability to invade native plant communities in which they do not naturally occur.
• Floristic classification - Description based on the actual species which compose the vegetation.
• GIS - Geographical Information System - A device for managing mapping information within a computer based system which allows separation of the information to facilitate analysis.
• Ground truthing - Checking of vegetation on site to confirm its classification.
• JANIS - Joint Australian and New Zealand Environment and Conservation Council NFPS Implementation Sub-committee. A Technical Working Group established in 1993 to draft national reserve criteria for the NFPS.
• Mapping units - Components of classification which make up the map. In this case each plant community or vegetation type.
• NFPS - National Forest Policy Statement (Commonwealth of Australia, 1992). Agreed by all States, Territories and The Commonwealth Government, this outlines forest management objectives for public and private forests throughout Australia.
• Physiognomy - This term describes the character of the vegetation such as 'shrubby', 'grassy', 'heathy', and 'sedgey'
• Plant community - A unit of classification of the vegetation based upon structure, physiognomy and floristics. An introduction to the classification of Tasmanian
3 Andrew North Consultant Botanist A Botanical Survey of Hobart BushlandsStage 2: Ridgeway and HCC Reserves plant communities is given in the publication “The reservation status of Tasmanian vascular plant communities” (Kirkpatrick et al, 1995).
• RFA - Regional Forest Agreement. To be signed in October, 1997 between the Commonwealth Government and the Tasmanian State Government. This has the intent of providing resource security whilst meeting defined targets for forest conservation.
• Structure - A term applied to vegetation indicating its division and classification on the basis of height and cover.
4 Andrew North Consultant Botanist A Botanical Survey of Hobart BushlandsStage 2: Ridgeway and HCC Reserves
1. INTRODUCTION
1.1 BACKGROUND
The city of Hobart includes extensive areas of natural bushland which abut much of the suburban settlement. The city suburbs are characterised by this bushland which currently occupies approximately 4100 hectares (53%) of the municipality. Land use planning often has the potential to impact upon the bushland areas. Therefore information regarding the nature of the bushland areas is important to ascribe values which can then be taken into account when making land use planning decisions.
Hobart City Council has been actively seeking to further knowledge of bushland within the municipality over recent years. GIS based mapping of all the vegetation within Hobart, using aerial photographic interpretation has been previously undertaken (Johnson, 1994). Using mapping units based on structure and physiognomy following Specht (1981), the Hobart Vegetation Map has proved to be useful for land use planning recommendations. It has been used for botanical reviews applied to the Mt Nelson Structure Plan (Gutteridge Haskins & Davey, 1995) and for municipal wide studies such as The Open Space Study (Acer Wargon & Chapman, 1997).
This report describes the findings from the second stage of a study which develops the information provided by the Hobart Vegetation Map to describe the plant communities which make up the various mapping units and identify locations of plant species of conservation significance. The first stage covered bushland in two Hobart suburbs, South Hobart and Lenah Valley (North and Freeman, 1996).
Since that report there have been developments in the understanding of Statewide conservation values of forest and woodland vegetation. A comprehensive regional assessment (CRA) of Tasmanian forests has been undertaken to contribute to outcomes to be derived from the Regional Forest Agreement (to be signed between The Commonwealth and The Tasmanian State Governments in October 1997).
The Hobart Vegetation Map is based mainly upon aerial photographic interpretation which enables accurate mapping of the boundaries of various vegetation units. This study has involved detailed field investigation to determine the plant community classifications of each mapping unit shown. Interpretations made for the Hobart Vegetation Map have been checked. The bushland within the study areas has been mapped to show the conservation significance of each mapping unit. The information provided from this study allows for mapping to be based upon recognised state-wide plant community classifications. Each community can be related to recognised conservation and reservation status classifications. In addition locations of populations of plant species of conservation significance and major weed infestations can be mapped to further contribute to the process of prioritisation of the conservation significance of vegetation throughout the municipality.
5 Andrew North Consultant Botanist A Botanical Survey of Hobart BushlandsStage 2: Ridgeway and HCC Reserves
Figure 1 : Study Area
6 Andrew North Consultant Botanist A Botanical Survey of Hobart BushlandsStage 2: Ridgeway and HCC Reserves
1.2 STUDY AREA
The study areas include:
Private bushland within Ridgeway (Precincts 43A, 43C, 43E, 44A & 44B), Private bushland within South Hobart (Precinct 35B)
Public Reserves managed by Hobart City Council:
Ridgeway Reserve Knocklofty Reserve McRobies Gully Landfill Buffer Rangeview Crescent (New Town Rivulet Linear Park, Lenah Valley) Ancanthe Park, Lenah Valley Haldane Reserve, Lenah Valley Ripley Road, Lenah Valley
In addition the reporting of several reserves investigated in Stage 1 (North & Freeman, 1996) have been included in this stage of the project:
Kalang Avenue (North and South) Strickland Avenue-Featherstone Creek Marlyn Road (Lower) Strickland Bends
2. METHOD
2.1 APPROACH
A botanical survey was undertaken and the following information was obtained:
• Species data (floristics) to provide locations of rare and threatened species and to enable plant community classification to be made. • Boundary locations of each perceivable plant community. • Locations of major environmental weed infestations.
Comprehensive species lists were compiled for HCC Reserves, and summary reports were produced. This information is maintained on The Bushland Reserves Database (on Microsoft Access ) within Council.
2.2 SURVEY METHODOLOGY
Each mapping unit selected for survey was 'ground truthed', during which a representative plot was made. Using a standard form (Appendix 3), all species encountered within this nominal area were recorded. Relative abundance of each species was indicated as being either dominant, present or occasional, along with basic information gauging cover of each structural layer as listed on the record sheet. Tree and shrub height was also estimated. This information is required for plant
7 Andrew North Consultant Botanist A Botanical Survey of Hobart BushlandsStage 2: Ridgeway and HCC Reserves community classification. Additional species encountered within each community, but falling outside the plot locality, were also recorded. Some species were collected to enable accurate identification. A number of the most significant collections have been lodged with the Tasmanian Herbarium. Where there was a perceivable change in the vegetation, whether previously mapped or not, a new plot was taken.
Access limitations, precluded survey of some of the more remote sites. The locations of plots provides an indication of the area of cover. Given the large size of the study area, priority was given to maximising the area of survey and not to the making of plots.
For this study a total of 108 plots were taken during the period December 1996 to March 1997.
2.3 MAPPING
Mapping unit boundaries were ground truthed where possible. Time constraints on the project did not allow for all community boundaries to be investigated, unless there were major discrepancies between what was observed and what was shown on the Hobart Vegetation Map.
Plant community boundaries, where indistinct, have been indicated with a dashed line on the maps. This may be because two communities merge into one another so that there is a broad boundary (Section 2, North, in Acer Wargon & Chapman, 1996), or because the alignment of the boundary could not be accurately mapped from the ground.
Locations of populations of plant species recognised as possessing conservation significance (Flora Advisory Committee, 1994 & Threatened Species Protection Act, 1995) were also mapped.
Major infestations of environmental weeds, in particular Radiata Pine wildlings, Blackberries, Gorse, Broom and Spanish Heath were also recorded and mapped.
2.4 ASSESSMENT OF CONSERVATION SIGNIFICANCE
2.4.1 Plant Species
The rationale for ascribing conservation significance to vascular plant species is given in Box 1.
8 Andrew North Consultant Botanist A Botanical Survey of Hobart BushlandsStage 2: Ridgeway and HCC Reserves
Box 1
CONSERVATION VALUES OF VASCULAR PLANT SPECIES
Conservation Status
The conservation significance of a given plant species at the State level is determined by the Flora Advisory Committee of Tasmania (1994), which provides lists of species according to various categories of threat and rarity. Elements of these lists have been adopted throughout Tasmania within the Threatened Species Protection Act (1995). A select number of species are also included nationally within the Endangered Species Protection Act (1992).
Threatened species are sub-divided into three categories (FAC 1994): • x - presumed to be extinct and is defined as a taxon which has not been located anywhere in Tasmania recently despite thorough searching, or has not been collected for more than half a century. • e - endangered with extinction within 20 years if present land use trends or other causal factors of decline continue. • v - vulnerable with extinction within 50 years.
In the Threatened Species Protection Act 1995, these species are listed in Schedule 3, for 'x' and 'e' and Schedule 4 for 'v'
Rare species are defined by strict criteria relating to their known distribution. There are several sub- categories of rare species (FAC 1994): • r1 - recorded from an area of less than 100 x 100 km. • r2 - recorded from less than twenty 10 x 10 km grid squares throughout Tasmania. • r3 - considered to be rare, but does not fit either category r1 or r2.
A selection of rare species, listed by the Flora Advisory Committee, which are considered to be 'at risk' are listed in Schedule 5 of the Threatened Species Protection Act 1995.
Other categories used by the Flora Advisory Committee includes: • k - unknown risk status, but very likely to fall into one of the above categories.
Reservation Status The following criterion has been adopted by the Flora Advisory Committee.
For a plant species to be considered reserved, it must be known to exist in at least one ‘secure Reserve’. Secure reserves include reserves and parks requiring the approval of both Houses of Parliament for their revocation. They include: National Parks, Aboriginal Sites, Historic Sites, Nature Reserves, State Reserves, Game Reserves, Forest Reserves, Wellington Park, and insecure reserves in the World Heritage Area which is protected by international agreement under the World Heritage Convention.
A plant species which does not satisfy this criterion is considered to be unreserved (u) - Kirkpatrick et al (1991), Flora Advisory Committee (1994).
9 Andrew North Consultant Botanist A Botanical Survey of Hobart BushlandsStage 2: Ridgeway and HCC Reserves
2.4.2 Plant Communities
The rationale for ascribing priorities for conservation to the various plant communities within Hobart was developed for the Hobart Open Space and Natural Values Review (Acer Wargon & Chapman, 1997). Communities were categorised into four groups depending upon their priority for conservation. In descending order of priority these were ‘critical’, ‘urgent’, ‘important’ and ‘low-priority’. This was determined by reviewing the current effectiveness of the existing reserve system to adequately represent a proportion of each community type (Kirkpatrick et al, 1995). A similar approach has been adopted for the Comprehensive Regional Assessments (CRA) of forests which has been undertaken to develop a Regional Forest Agreement to which The Commonwealth and all State Governments are committed under the National Forest Policy Statement (Commonwealth of Australia (1995), signed by Tasmania in April, 1995 (refer Box 2).
Regional conservation significance has also been considered. Tasmania has been sub- divided into 10 Bioregions (Thackway & Cresswell, 1995) which have been included in assessments of reservation undertaken for the CRA (PLUC, 1997). The area within the Hobart municipality is included in the Midlands Bioregion, and above 300m within the D’Entrecasteaux Bioregion.
Floristic classifications for plant communities are based on a statistical technique known as ordination using a programme known as Twinspan described by Hill (1979). Wet forest vegetation has been analysed by such a method. Dry sclerophyll vegetation has not been classified to this level of resolution and so classifications are based upon a structural classification developed by Specht et al (1974).
Priority classifications for forest communities were developed by Kirkpatrick and Brown (Kirkpatrick et al, 1995) from 1:500 000 vegetation mapping of Tasmania (Kirkpatrick and Brown, 1991) taking into account the current reservation and conservation status of each community. These were used for the assessment made for vegetation in South Hobart and Lenah Valley (North and Freeman, 1996). More accurate mapping at 1:100 000 (PLUC, 1997) has allowed for re-assessment of the reservation status of communities, and comparison with the JANIS criteria (refer Box 2). Using the priority classes developed by Kirkpatrick and Brown (ie critical, urgent, important and non-priority), the communities according their adequacy of reservation have been allocated to these groups.
Definitions for each category in descending order of priority are determined as follows:
• Critical Communities. Those where current reservation is less than 20 % of the target levels within Tasmania. • Urgent Communities. Those where current reservation is between 20 and 80 % of the target levels within Tasmania. • Important Communities. Those where current reservation > 80 % but is below the target level, both state-wide and regionally, or the community is localised in Hobart.
10 Andrew North Consultant Botanist A Botanical Survey of Hobart BushlandsStage 2: Ridgeway and HCC Reserves
• Non-priority Communities. Those which are adequately reserved and are not of regional or local significance.
Box 2
PLANT COMMUNITY RESERVATION STATUS
Representativeness (Kirkpatrick et al, 1995)
• Well Reserved - A viable area of a community is found within two or more reserves within Tasmania, or two or more viable areas are well separated within one reserve, or if all its known occurrences are within viable, secure reserves. • Poorly Reserved - A community is found in one or more reserves within Tasmania, but it does not satisfy one of the conditions required to be well reserved. • Unreserved - A community which is not known from any reserve
For this assessment, reserves include those areas considered to have the highest security of tenure. These include reserves and parks requiring the approval of both Houses of Parliament for their revocation. They include: National Parks, Aboriginal Sites, Historic Sites, Nature Reserves, State Reserves, Game Reserves, Forest Reserves, Wellington Park, and insecure reserves in the World Heritage Area which is protected by international agreement under the World Heritage Convention.
Quantitative Representation (PLUC, 1996)
Reference has also been made to more recent quantitative assessments of reservation for forest communities. These have been determined as part of the Tasmanian component of the Comprehensive Regional Assessment (CRA) for the Tasmanian and Commonwealth Regional Forest Agreement (RFA). Reference is made to target levels of reservation proposed to achieve a Comprehensive, Adequate and Representative Reserve System (CAR) for forests in Australia (JANIS) (Forest Taskforce, 1995).
JANIS criteria are based on proportionate representation of the forest estate in reserves to the levels that were present prior to European settlement (given as pre-1750 for conformity with the IUCN guidelines). 15% of pre-1750 area of each forest type is used to represent an adequate level of reservation..
PLANT COMMUNITY CONSERVATION STATUS
The conservation status of communities was assessed based on the following criteria:
Rare communities
• R1 - total area generally less than 10 000 ha • R2 - total area generally less than 1 000 ha • R3 - patch sizes generally less than 100 ha
Vulnerable communities • V1 - approaching greater than 70 % depletion • V2 - where threatening processes have caused either loss or significant decline in species that play a major role within the ecosystem or have caused a significant alteration to the ecosystem process
Endangered communities • E1 - distribution has contracted to less than 10 % of pre-1750 range • E2 - less than 10 % of pre-1750 area remains • E3 - 90 % of area is in small patches and is subject to threatening processes
JANIS recommends that 60 % of the existing area of rare and vulnerable and 100 % of the existing area of endangered communities is reserved. (PLUC, 1996).
11 Andrew North Consultant Botanist A Botanical Survey of Hobart BushlandsStage 2: Ridgeway and HCC Reserves
3. RESULTS
3.1 PLANT SPECIES OF CONSERVATION SIGNIFICANCE
TABLE 1 - Plant species of conservation significance
Species Conservation Location Notes Status Scleranthus fasciculatus v Ancanthe Park Several hundred plants in Knawel Schedule 4 grassland above museum Ridgeway Reserve 4 plants at two locations near Lower Reservoir, Waterworks Velleia paradoxa v Knocklofty Reserve Confined to DRY-G4v in north Spur Velleia Schedule 4 where responding to grass fire Acacia gunnii r3 Ridgeway Reserve 5 plants near Gentle Annie Falls Ploughshare Wattle Knocklofty Reserve 1 plant above AUSAT station Austrofestuca hookeriana r2 Ridgeway Reserve Wet soaks near picnic site at Hooker’s Fescue Schedule 5 Ridgeway Danthonia procera r2 u Ridgeway Widespread on dry sites on Tall Wallaby-grass Schedule 5 Ridgeway Reserve mudstone and dolerite Knocklofty Reserve McRobies Gully Dichelachne inaequiglumis r2 Ridgeway Reserve Local on ridgeline south of Asymmetric Plume- Schedule 5 Tolmans Hill grass Eucalyptus cordata r2 Ridgeway Reserve Two populations on the western Silver Gum slopes of Chimney Pot Hill Festuca plebeia r2 Ridgeway Reserve Local on south west slopes of Common Fescue Chimney Pot Hill Gahnia rodwayi r2 Ridgeway Reserve Occasional but locally Rodway’s Saw-sedge Schedule 5 Ridgeway abundant. Scattered populations throughout DRY- G3 Knocklofty Reserve Localised on western slopes. Lepidium pseudotasmanicum r2 Ancanthe Park Localised to dry sites beneath Tasmanian Peppercress Schedule 5 Ripley Road dense canopies Knocklofty Reserve Precinct 35B Olearia ericoides r2 Ridgeway Widespread on dolerite usually Heathy Daisy-bush Ridgeway Reserve in DRY-G3 Knocklofty Reserve McRobies Gully Picris angustifolia r2 Barossa Hill Occasional Hawkweed Oxtongue Ridgeway Reserve Ridgeway Knocklofty Reserve Common on east facing slopes after bushfire Vittadinia muelleri r2 Barossa Hill Localised to disturbed sites Cut-leaved New Holland Schedule 5 Ridgeway Reserve Daisy Knocklofty Reserve Allocasuarina duncanii r1 u Ridgeway Rare with two single plants at Duncans She-oak Schedule 5 distinct locations, both on east facing slopes Deyeuxia sp. Ridgeway Reserve Two localised populations. Bent Grass sp. McRobies Gully Specimens are being examined by the Tasmanian Herbarium to determine their taxonomic status
12 Andrew North Consultant Botanist A Botanical Survey of Hobart BushlandsStage 2: Ridgeway and HCC Reserves
13 Andrew North Consultant Botanist A Botanical Survey of Hobart BushlandsStage 2: Ridgeway and HCC Reserves
3.2 PLANT COMMUNITIES
This section provides short descriptions of all the plant communities that were mapped.
• DRY-inVERT - Inland Allocasuarina verticillata closed forest This occurs on rocky dolerite slopes and crests, and is best expressed on private land in Ridgeway, although there is a small patch on Council land above Ridgeway Road in Ridgeway Reserve.
• DRY-gAM - Eucalyptus amygdalina grassy woodland Typically occupying thin soils on mudstone, usually with a northerly aspect. This subsumes two ‘described’ grassy woodland communities - Eucalyptus viminalis - Poa sieberiana - Evp and Eucalyptus viminalis / Eucalyptus amygdalina - Dianella revoluta - Evd (Kirkpatrick et al, 1988). It occurs locally on slopes above the Lower Reservoir in Waterworks Reserve. A localised example also occurs on the western slopes of a small knoll in Knocklofty Reserve where it occurs on sandstone, which more typically supports a heathy understorey (DRY-H2). This location may be influenced by run-off from dolerite occurring on the crest of the knoll.
• DRY-gPULC - Eucalyptus pulchella grassy woodland This is the most widespread community in the study area typically occupying the upper slopes and crests on dolerite. Within its range it shows considerable variability. On the driest sites it has a dense grassy sward beneath an open canopy often with Eucalyptus viminalis codominant. On other sites Eucalyptus globulus is prominent. These sites have affinities with Eucalyptus pulchella-Bossiaea prostrata grassy woodland - Epb (Kirkpatrick et la, 1988). Where drainage is slightly impeded a dense diverse scleromorphic low shrub layer gives the community a ‘heathy’ appearance. Sword sedges (Lepidosperma spp.) are often present and Eucalyptus ovata is locally prominent. This community is common at Ridgeway and Ridgeway Reserve but also dominates the Knocklofty Reserve. There are localised patches of this community on mudstone, usually on crests or insolated upper slopes, where soil is deeper than usual. There are two sites on ridges each side of McRobies Gully.
• DRY-gVIM - Eucalyptus viminalis grassy woodland. Very localised to the northern boundary of Knocklofty Park above Mt Stuart. This has closest affinities to Evam - Eucalyptus viminalis / Allocasuarina verticillata grassy woodland (Kirkpatrick et al, 1988). It also occurs on rocky slopes in the south east corner of Ridgeway where it extends into Kingborough. A moderately dense tall shrub layer includes Allocasuarina littoralis, Acacia dealbata and Bursaria spinosa. This has affinities with Evaa - Eucalyptus viminalis / Eucalyptus amygdalina - Acaena echinata / Dichondra repens grassy woodland and with Eva - Eucalyptus viminalis - Acaena ovina grassy woodland.
• DRY-gGLOB - Grassy Eucalyptus globulus dry sclerophyll forest
14 Andrew North Consultant Botanist A Botanical Survey of Hobart BushlandsStage 2: Ridgeway and HCC Reserves
This characteristically includes a prominent tall shrub layer over a grassy understorey. It is widespread on the mid-lower east facing slopes of Knocklofty Park and on the eastern slopes of a hill north of McRobies Gully. This community would in the absence of fire support a wet forest community Eucalyptus globulus - Poa labillardierei - Hypochoeris radicata wet sclerophyll forest (WET-GLOB1).
• DRY-hAM-sand - Heathy Eucalyptus amygdalina dry sclerophyll forest on sandstone Examples occur on the lower north facing slopes above Waterworks Reserve, and the south eastern part of Knocklofty Park, where much of the community is considerably degraded due to a history of quarrying, logging, grazing and subsequent weed infestation.
• DRY-hTEN - Heathy Eucalyptus tenuiramis dry sclerophyll forest This usually occupies very dry north and west facing slopes. hTENsand - on sandstone. Good examples of this community occur on insolated slopes above Waterworks Reserve. It supports a particularly diverse low shrub layer. hTENmud - on mudstone. Typically occupying rocky mudstone crests, where bare ground is prominent. It occurs along Huon Road in Ridgeway Reserve.
• DRY-shOB - Shrubby Eucalyptus obliqua dry sclerophyll forest This community is not confined to any one particular aspect, but does occupy sites which have some moisture availability. It typically occurs on south facing slopes which would support wet forest but have had a frequent fire history or on north and east facing mid to lower slopes. shOB-dol. Widespread in Ridgeway and Ridgeway Reserve around shallow gullies and mid-slopes. shOB-arg. Widespread on mudstone on slopes above Sandy Bay Rivulet at Fern Tree, below Chimney Pot Hill Road (both north facing), on south facing slopes above Waterworks Reserve, and McRobies Gully on north and east facing slopes. shOB-silic. Localised to damper environments on sandstone such as on south facing slopes above the Upper Reservoir at Waterworks Reserve, and along Salvator Rosa Glen at Knocklofty.
• DRY-shTEN-dol - Shrubby Eucalyptus tenuiramis forest on dolerite. This is confined to a single location on the west facing slopes of a spur below Badger Hill. A diverse low shrub layer is dominated by Pultenaea juniperina over a scattered layer of Poa gunnii.
• DRY-shPULC - Shrubby Eucalyptus pulchella forest This community favours rocky dolerite crests and is particularly prominent on Chimney Pot Hill.
• WET-GLOB1 - Eucalyptus globulus - Poa labillardierei - Hypochoeris radicata wet sclerophyll forest Characterised by the combination of tussock grass (Poa sp.) and a shrub layer which is dominated by broad leaved species, most notably Bedfordia salicina. It occurs on south facing aspects of drainage lines on Knocklofty Reserve and in Ridgeway.
15 Andrew North Consultant Botanist A Botanical Survey of Hobart BushlandsStage 2: Ridgeway and HCC Reserves
• WET-GLOB0100 - Eucalyptus globulus - Bedfordia salicina - Beyeria viscosa wet sclerophyll forest Occupying wetter sites than the previous community it includes a greater diversity of broad leaved species along with a suite of ferns. In the Ridgeway area this community is localised, although it intergrades with Eucalyptus obliqua - Olearia lirata - Pultenaea juniperina wet sclerophyll forest (WET-OB0110), and so its influence is more widespread than is indicated by the maps.
• WET-OB010 - Eucalyptus obliqua - Olearia lirata - Pultenaea juniperina wet sclerophyll forest Confined to moist aspects on dolerite which have not had an over-intensive fire history. This community is essentially a facet of shrubby E.obliqua forest that includes some broad leaved species. Most notably Bedfordia salicina but also occasionally Pomaderris apetala and Olearia argophylla. Eucalyptus globulus is often codominant in the canopy, and usually includes the tallest trees on site, however E.obliqua is typically dominating a regrowth layer. It was recorded in Ridgeway Reserve on south and east facing slopes above the reservoir, and also on slopes above Dunns Creek in Ridgeway.
• WET-OBO110 - Eucalyptus obliqua-Acacia dealbata-Olearia argophylla wet sclerophyll forest This occupies south facing slopes and creek lines where moisture availability is greatest. These two environments support two facies of this community. The latter, includes sites which have been protected from fire and so support a rich fern component and a diversity of broad leaved shrubs. Good examples occur along Sandy Bay Rivulet between Huon Road and Waterworks, in some sections of Dunns Creek and Vincents Creek in Ridgeway, and along McRobies Gully above the tip face. The other facies usually occurs on sedimentary rock. Although a fire history is noted, fire- sensitive mesophytic species persist. This is best represented on south facing slopes above Sandy Bay Rivulet, between Huon Road and Pillinger Drive (both in Ridgeway Reserve) and on the slopes above McRobies Gully.
3.2.1 Priorities for conservation
Plant communities mapped for the study areas have been related to the classifications used for the RFA vegetation maps for which there is information on the extent present and proportion currently reserved statewide (Table 2). This includes communities mapped in Stage 1 (North and Freeman, 1996).
Applying criteria developed in section 2.4.2 it is possible to place the communities that have been mapped for Hobart into one of four categories which provide, in descending order, a method of prioritising the conservation values of each community (Table 3).
It is important when applying these priorities to any particular patch of bushland, that other factors which contribute to the viability of the community are considered. These include:
16 Andrew North Consultant Botanist A Botanical Survey of Hobart BushlandsStage 2: Ridgeway and HCC Reserves
• Location - Isolated remnants are likely to be less viable than areas connected to larger areas of native vegetation. Areas down slope of disturbances and sources of nutrients or weeds are more susceptible than those up slope. • Size - Larger patches are less susceptible to ‘edge effects’. • Shape - Once again edge effects are less significant if the patch has a higher surface to perimeter ratio, ie an area approximating to a circle is likely to be more viable than a narrow or convolute shaped patch. • Natural integrity - Level of weed infestation is important.
The presence of rare or threatened species enhances the conservation values of an area of bushland. The habitat potential for significant fauna is also a contributing factor to these values.
17 Andrew North Consultant Botanist A Botanical Survey of Hobart BushlandsStage 2: Ridgeway and HCC Reserves TABLE 2 - Reservation status of mapped forest communities
Community Code Plant Community 2 Equivalent CRA Conservation JANIS Criteria 3 Current Extent of Current Extent of Current Extent of 1 Mapped Forest Status 3 (target level of Reservation Reservation in Reservation in Community 3 reservation) Statewide 3 Region < 300m Region >300m Midlands 3 D’Entrecasteaux 3 DRY-inVERT Inland A. verticillata Allocasuarina verticillata - 15% of pre-1750 15% 12% - closed forest DRY-gAM Grassy E.amygdalina E.amygdalina inland V1 60% of existing 8% 6% - dry sclerophyll forest DRY-gPULC Grassy E.pulchella E.pulchella - E.globulus - - 15% of pre-1750 7% 7% woodland E.viminalis DRY-gGLOB Grassy E.globulus dry grassy/shrubby forest sclerophyll forest DRY-shPULC Shrubby E.pulchella dry sclerophyll forest DRY-gVIM Grassy E.viminalis E.viminalis grassy - 15% of pre-1750 1% 1% 27% woodland DRY-hAM-sand Heathy E.amygdalina E.amygdalina on V1 60% of existing 6% 9% 17% dry sclerophyll forest sandstone DRY-hTEN-mud Heathy E.tenuiramis Inland E.tenuiramis V2 60% of existing 6% 7% 7% DRY hTEM-sand dry sclerophyll forest mudstone / sandstone DRY-sdOv Sedgey E.ovata Shrubby E.ovata E2 100 % of existing 4 % 2 % 3 %
DRY-shOB-dol Shrubby E.obliqua E.obliqua dry - 15% of pre-1750 14% 17% 24% DRY-shOB-mud dry sclerophyll forest DRY-shOB-sand doleritic /argillaceous / siliceous DRY-shTEN-dol Shrubby E.tenuiramis E.tenuiramis on dolerite - 15% of pre-1750 40% - 60% dry sclerophyll forest WET-GLOB0100 E.globulus wet E.globulus grassy V2 60% of existing 29% 30% 14% WET-GLOB1 sclerophyll forest WET-OB010 E.obliqua wet E.obliqua wet - 15% of pre-1750 13% 17% 19% WET-OB0110 sclerophyll forest WET-REG1001 E.regnans wet E.regnans - 15% of pre-1750 14 % 23% 15% sclerophyll forest 1 - North et al in press 2 - Kirkpatrick et al, 1995 3 - PLUC, 1997
JANIS criteria are set at 15 % unless the community is considered rare or threatened (refer Box 2) when the target level is raised to 60 % for rare or vulnerable communities and to 100 % for endangered communities.
18 Andrew North Consultant Botanist A Botanical Survey of Hobart BushlandsStage 2: Ridgeway and HCC Reserves TABLE 3 - Priority for conservation of forest communities in Hobart
This includes all communities mapped in both stages 1 and 2.
Priority Plant community Mapping unit % of target Notes level 1 CRITICAL Grassy White Gum DRY-gVIM 7 % Woodland < 20 % of Sedgey Black Gum DRY-sOV 4 % target level Forest Grassy Black DRY-gAM 13 % Peppermint Forest Heathy Black DRY-hAMsand 10 % Peppermint Forest on sandstone Heathy Silver DRY-hTENmud 10 % Peppermint Forest DRY-hTENsand URGENT Grassy White DRY-gPULC 47 % Peppermint Forest 20 - 80 % of Grassy Blue Gum DRY-gGLOB 47 % target level Forest Shrubby White DRY-shPULC 47 % Peppermint Forest Blue Gum Wet Forest WET-GLOB 47 %
IMPORTANT Shrubby Silver DRY-shTENdol 267 % Very localised in Peppermint Forest Hobart < target level Inland She-oak Closed DRY-inVERT 100 % Localised in both state-wide Forest Hobart and regionally NON- Swamp Gum Forest WET-REG 93 % > 100 % in region PRIORITY Stringybark Wet Forest WET-OB 87 % > 100 % in region
Shrubby Stringybark DRY-shOB 93 % > 100 % in region Dry Forest
1 - Calculated from: current extent of reservation ÷ JANIS criteria × 100
For example Grassy White Gum Woodland is not rare, vulnerable or endangered and so has a target reservation level of 15 %. Currently only 1 % is reserved and so only 1/15 (7 %) of the target level is so reached. Grassy Blue Gum Forest is considered vulnerable, and has a reservation target level of 60 %. Currently 29 % is reserved, which equates to 29/60 (47 %) of the target level.
Although the level of reservation of the three non-priority communities does not meet the JANIS criteria, they are more than adequately reserved in the Bioregions within which Hobart is located so that the balance would best be ‘picked up’ from regions elsewhere in the State.
19 Andrew North Consultant Botanist A Botanical Survey of Hobart BushlandsStage 2: Ridgeway and HCC Reserves
4. RECOMMENDATIONS
The findings from this study are relevant for both planning decisions by Council and for determining management priorities for some of the reserves.
4.1 PLANNING
Schedule 1, Part 1 of the Land Use Planning and Approvals Act (1993) states that one of the objectives of the Resource Management And Planning System Of Tasmania is:
“To promote the sustainable development of natural and physical resources and the maintenance of ecological processes and genetic diversity.”
Schedule 1 Part 2 states that one of the objectives of the Planning Process Established By Land Use Planning and Approvals Act (1993) is:
“To require land use and development planning and policy to be easily integrated with environmental, social, economic, conservation and resource management policies at State, regional and municipal levels.”
Such policies include the Threatened Species Protection Act (1995) and the imminent Regional Forest Agreement between the State and Commonwealth Governments.
It is therefore the responsibility of Council to incorporate within Planning Schemes, Structure Plans and Local Area Plans clear intentions to maintain the existing biodiversity that occurs within Council and to recognise conservation priorities as they have been identified in this report.
Areas identified with the high conservation values which are of good quality (taking into account the points given in section 3.2.1) require careful consideration to ensure development planning does not threaten their viability. This may be achieved by zoning for non-residential, proposed as ‘Bushland Conservation Zone’ in the Open Space Study (Acer Wargon Chapman, 1997); or for low-density with controls proposed as ‘Bushland Residential Zone’ (ibid). Alternatively it may be achieved by establishing areas which would best be set aside as public reserves. These could be integrated into the existing reserve system allowing for public access and use of open space. This information could help prioritise an acquisition programme as defined in the Open Space Study (ibid).
4.2 RESERVE MANAGEMENT
Locations of rare and threatened species and significant plant communities, along with major weed infestations are indicated on the maps. Summary reports for each reserve (Appendix 1) give priorities for management for each reserve. It is recommended management plans are developed for all reserves, perhaps applying a generic management plan framework for the smaller reserves with individual issues specific to each reserve addressed separately. The role of fire management is a particularly important management issue. Fire management plans should be developed for each reserve, but they must be related to the general management
20 Andrew North Consultant Botanist A Botanical Survey of Hobart BushlandsStage 2: Ridgeway and HCC Reserves actions and objectives for each of the reserves, most specifically weed control, which would need to be undertaken in conjunction with burning programmes.
21 Andrew North Consultant Botanist A Botanical Survey of Hobart BushlandsStage 2: Ridgeway and HCC Reserves
5. REFERENCES
Acer, Wargon & Chapman (1997). City of Hobart Open Space Study - Final Report. Volume 1. In conjunction with Lesley Gulson and Andrew North. Unpublished report for Hobart City Council.
Commonwealth of Australia, (1992). National Forest Policy Statement - A New Focus For Australia’s Forests. AGPS, Canberra
Commonwealth of Australia (1995). National Forest Conservation Reserves - Commonwealth Proposed Criteria. AGPS, Canberra
Commonwealth of Australia(1992). Endangered Species Protection Act.
Flora Advisory Committee (1994). Native Higher Plant Taxa Which Are Rare Or Threatened In Tasmania. Parks & Wildlife Service, Tasmania.
Forest Taskforce (1995). Interim Forest Areas - Tasmania. A Report for the IFA Assessment Process. Dept. Prime Minister and Cabinet, Canberra.
Gilfedder, L (1995). Flora and Plant Communities of Jubilee Road, South Hobart In Jubilee Road Environmental Capacity Review. James Douglas & Associates. Unpublished report for Hobart City Council.
Gutteridge Haskins and Davey (1995). Mt Nelson Structure Plan. Unpublished report for The City of Hobart
Hill, M.O (1979). A Fortran Program For Arranging Multivariate Data In A Two- Way Table By Classification Of Individuals And Attributes. Cornell University, Ithaca.
Johnson, D.J. (1994). Mapping The Vegetation Of Hobart: The Application Of Synusiae Based Mapping For The Purpose Of Conservation Management. Unpublished Master of Environmental Studies thesis for the Department of Geography and Environmental Studies, University of Tasmania.
Kirkpatrick, J.B., Gilfedder, L. and Fensham, R. (1988). City Parks And Cemeteries, Tasmanias Remnant Grasslands And Grassy Woodlands. Tasmanian Conservation Trust, Hobart.
Kirkpatrick, J.B., Peacock, R.J., Cullen, P.J., Neyland, M.G. (1988). The Wet Eucalypt Forests of Tasmania. Tasmanian Conservation Trust, Hobart.
Kirkpatrick, J.B., Barker, P., Brown, M.J., Harris, S., and Mackie, R. (1995). The Reservation Status of Tasmanian Vascular Plant Communities. Wildlife Scientific Report 95/4. Parks and Wildlife Service, Tasmania.
22 Andrew North Consultant Botanist A Botanical Survey of Hobart BushlandsStage 2: Ridgeway and HCC Reserves North, A.J. & Freeman, S. (1996). Botanical Survey Of Hobart Bushland, Stage 1, Lenah Valley And South Hobart. Unpublished Report for Hobart City Council.
North, A.J, Johnson, K., Ziegler, K., Duncan, F., Hopkins,K., Ziegeler, D. and Watts, S. (in press). Flora Values Of Raps And Forest Reserves In Tasmania. Forestry Tasmania, Hobart.
Specht, R.L. (1981). Conservation of Vegetation Types. In Groves, R. H. (Ed) Australian Vegetation. 393-410.
Specht, R.L., Roe, E.M. & Boughton, V. H. (1974). Conservation Of Major Plant Communities In Australia And Papua-New-Guinea. Australian Journal of Botany Supplement No. 7: 1-667.
Tasmanian State Government (1995). Threatened Species Protection Act, No.83 of 1995. Government Printer, Hobart, Tasmania
23 Andrew North Consultant Botanist A Botanical Survey of Hobart BushlandsStage 2: Ridgeway and HCC Reserves
APPENDIX 1
RESERVE SUMMARY REPORTS
24 Andrew North Consultant Botanist RIDGEWAY LOCAL AREA PLANNING PROVISIONS
FAUNA AND HABITAT OVERVIEW
Prepared for Hobart City Council by: Raymond Brereton Consultant Wildlife Ecologist 25 Darling Parade Mount Stuart Tas. 7000.
October 2000 CONTENTS
SUMMARY ...... I
INTRODUCTION...... 1 Background ...... 1 Study area...... 1 METHODS ...... 1 Literature review ...... 1 Assessment of conservation significance ...... 2 Conservation significance categories ...... 3 HABITATS ...... 4
FAUNA...... 1 Fauna of conservation significance ...... 3 Habitats of conservation significance...... 5 MANAGEMENT ISSUES...... 5 Habitat loss and fragmentation...... 5 Fire ...... 6 Domestic pets ...... 7 Introduced and nuisance species ...... 7 Disturbance...... 7 Site degradation and pollution...... 7 MAINTENANCE OF FAUNAL VALUES...... 8
ACKNOWLEDGMENTS...... 9
REFERENCES...... 9
APPENDIX 1 ...... 11
APPENDIX 2 ...... 14
SUMMARY
This report contains an assessment of the conservation significance of the vertebrate and invertebrate fauna and their habitats in the area covered by the Ridgeway Local Area Plan.
Nineteen faunal species of conservation significance occur in the Ridgeway area including five threatened species listed on the Tasmanian Threatened Species Protection Act 1995 and/or the Commonwealth Environment Protection and Biodiversity Conservation Act 1999. Seven of the significant species are associated with wet forests. The closed understoreys, deep litter layer and decaying logs which characterise these habitats support wet forest specialists, including one mammal species, five bird species, one species of snail and a log dwelling beetle.
A number of species are dependant on structural components found only in old growth forest particularly habitat trees (trees with hollows). The threatened swift parrot and the significant blue-winged parrot nest in tree hollows within the study area along with six other bird species. Twelve mammals species are dependant on tree hollows for shelter and breeding.
Significant habitats for fauna in the Ridgeway local area include grassy Eucalyptus globulus forest, which is important foraging habitat for swift parrots and shrubby E. tenuiramis forest.
The maintenance of faunal values within the study area will require the protection and management of significant fauna sites and habitats.
i INTRODUCTION
This report contains an assessment of the vertebrate and invertebrate fauna and their habitats in the area covered by the Ridgeway Local Area Planning Provisions. Threatened and significant fauna and their habitats are identified and recommendations have been made regarding future development decisions or management actions which may impact on them.
Background
The Hobart City Council has initiated a project to prepare Local Area Planning Provisions for Ridgeway. Key outcomes of the project include:
• An environmental inventory and capability assessment of the study area, based on an integrated bio- physical assessment of its catchments and resources.
• An integrated resource assessment and land use planning framework for the study area. This framework should define the desired nature and character of the area and the related performance criteria for its environmentally sustainable development and management.
This study forms part of Stage 1 of the project which involves the collection and analysis of a wide range of information about the study area including information about its fauna and habitat values.
Study area
The Local Area Planning Provisions study incorporates the area within the City of Hobart south of Ridgeway Park and east of Summerleas Road with the north eastern boundary being the southern outlet.
The predominant habitat in the study area is dry forest with shrubby or grassy understoreys, either Eucalyptus pulchella grassy woodland on ridges and north facing slopes or shrubby Eucalyptus obliqua dry forest on south facing slopes. Grassy Eucalyptus globulus forest is present in the drier drainage lines and wet forest occurs in the deeper wetter gullies.
METHODS
Literature review
The following sources were consulted for this assessment:
Draft Wellington Park Management Plan: Values use and management inventory for public comment (1996)
- Includes a review of all published reports on flora and fauna on Mt Wellington
Fauna of Mount Wellington (Taylor and McQuillan 1994)
- A review of the information on the fauna of Mt. Wellington
Fire Management Strategy For Wellington Park: (1999)
- Identifies the faunal values of Mt. Wellington
Report on the faunal values of Waterworks Reserve (Brereton 1997b).
Fern Tree Local Area Plan: Fauna and Habitat Overview (Brereton 1998)
GTSpot Database, Parks & Wildlife Service
1 - a database of Geo Temporal Species point observations in Tasmania
A number of other papers which reported on particular species or groups of species on Mount Wellington were also referred to including:
- Green (1989), Ratkowsky & Ratkowsky (1976), Thomas (1986) and Thomas (1979) for birds,
- Rounsevell et al. (1991) for mammals.
Assessment of conservation significance
The conservation significance of a given species at the State level is determined by the its listing on the schedules of the Threatened Species Protection Act 1995. In the Act, there are three categories of threat status.
1. Endangered (Schedule 3). These are taxa, which are either:
• in danger of extinction because long term survival is unlikely while the factors causing the species to be endangered continue operating, or
• presumed extinct on the grounds that no occurrence of the taxon in the wild can be confirmed during the past 50 years.
2. Vulnerable (schedule 4):
• a species which is likely to become endangered while the factors causing it to be vulnerable continue operating.
3. Rare (schedule 5):
• a species which has a small population in Tasmanian that is not endangered or vulnerable but is at risk.
The Scientific Advisory Committee established under the Act advises on the listing and de-listing of species, threatening processes and the criteria to be followed in determining critical habitats. The Threatened Species Protection Act 1995 provides mechanisms for protecting species listed in the schedules, by such methods as Interim Protection Orders, Land Management Agreements and Conservation Covenants. It is also an offence under the Act to take listed species without a permit. “Take” includes kill, damage, destroy and collect.
Some species and ecological communities are also listed on the Commonwealth Environment Protection and Biodiversity Conservation Act 1999. An action will require approval from the Environment Minister if the action has, will have, or is likely to have a significant impact on a species listed in any of the following categories:
1. A native species is extinct in the wild if:
• it is known only to survive in cultivation, in captivity or as a naturalised population well outside its past range; or
• it has not been recorded in its known and/or expected habitat, at appropriate seasons, anywhere in its past range, despite exhaustive surveys over a time frame appropriate to its life cycle and form.
2. A native species is critically endangered if:
• it is facing an extremely high risk of extinction in the wild in the immediate future.
2 3. A species is endangered if:
• it is not critically endangered; and
• it is facing a very high risk of extinction in the wild in the near future.
4. A species is vulnerable if:
• it is not critically endangered or endangered; and
• it is facing a high risk of extinction in the wild in the medium-term future.
An action does not require approval form the Environment Minister under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 if:
• the action is approved under, and taken in accordance with, a State management plan that is accredited by the Commonwealth for the purposes of a bilateral agreement or;
• the action is approved under, and taken in accordance with, a Commonwealth management plan that is accredited by the Environment Minister for the purposes of a Ministerial declaration or;
• the action is a forestry operation taken in a Regional Forest Agreement region or;
• the action has been authorised by a Government decision on which the Minister’s advice has been sought.
Further information about the operation of the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 and guidelines on what a significant impact might be on a listed species can be found at: http://www.environment.gov.au/epbc/proponents/significance_guidelines/significance_guidelines.html
Conservation significance categories
In this study two categories of conservation significance have been used:
1. Threatened species:
• Includes species that are listed on Schedules 3, 4 and 5 of the Tasmanian Threatened Species Protection Act 1995; or Schedule 1 of the Commonwealth Endangered Species Act 1992.
2. Significant species:
• Includes species listed as rare, requiring monitoring or insufficiently known in Tasmania (Vertebrate Advisory Committee 1994, Invertebrate Advisory Committee 1994), species which are unreserved or poorly reserved in Tasmania, species identified as rare or uncommon in the region or species which have a declining range or populations in the region.
The categories requiring monitoring and/or insufficiently known as defined by the VAC 1994 are:
Monitoring: Species which has declined nationally but remains relatively secure in Tasmania or species which suffer disturbance e.g. culling, persecution.
Insufficiently Species suspected of being rare or threatened but there is insufficient information known: to determine its status accurately.
3 HABITATS
The five main natural habitats identified for the Ridgeway area are consistent with the vegetation communities identified by North (1997). The natural habitats and the equivalent vegetation communities are listed in Table 1. The location and extent of the natural habitats can be seen on the Ridgeway vegetation map (North 1997). One wetland and two man made habitats are also described.
1. Shrubby Eucalyptus tenuiramis forest (Et)
This habitat is the DRY-shTEN-dol shrubby E. tenuiramis forest community on dolerite identified by North (1997). It is confined to a single small area on the west facing slopes of a spur below Badger Hill. The understorey is dominated by Pultenea juniperina over scattered tussocks of Poa gunnii.
2. Eucalyptus pulchella grassy woodland (Ep)
This habitat is the DRY-gPULC E. pulchella grassy woodland community identified by North (1997). It is the most widespread habitat in the study area where it occurs on dolerite on upper slopes and ridgetops. E. viminalis and E. globulus can also be present and the understorey is dominated by native grasses (Poa sp.) however, sedges (Lepidosperma sp.) and low dry shrubs can also be common.
3. Grassy Eucalyptus globulus forest (Eg)
This habitat is the WET-GLOB1 E. globulus-Poa labillardierei-Hypochoeris radicata wet sclerophyll forest community identified by North (1997). It occurs along drainage lines and is characterised by the presence of tussock grasses (Poa sp.) and a shrub layer dominated by broad leaved species commonly Bedfordia salicina.
4. Shrubby Eucalyptus obliqua dry forest (Eo)
This habitat is the DRY-shOB shrubby E. obliqua dry sclerophyll forest community identified by North (1997). This habitat is widespread in the study area where it predominantly occurs on south facing slopes where there is some moisture. The shrub layer is characterised by the presence of Goodenia ovata, Monotoca glauca and Oxylobium ellipticum. The sword sedges Lepidosperma sp. and Gahnia grandis are also commonly present.
5. Wet forest (wf)
Wet forest habitat in the study area is wet Eucalyptus obliqua forest and is comprised of the two types identified by North (1997), WET-OB010 E. obliqua-Olearia lirata-Pultenea juniperina wet sclerophyll forest and WET-OB0110 Eucalyptus obliqua-Acacia dealbata-Olearia argophylla wet sclerophyll forest. Wet forest occurs along Dunns Creek and the south facing slopes above. Eucalyptus globulus is often present and it is typically characterised by a secondary layer of small trees dominated by Acacia dealbata over a shrub layer of Olearia lirata, O. argophylla, Pomaderris apetala, Bedfordia salicina and Pultenea juniperina.
5. Waterways and wetlands (w)
Aquatic habitats in the Ridgeway area are restricted to Dunns Creek, the only permanent stream and a number of man made dams.
6. Urban (u)
Includes the urban areas of Ridgeway and refers to the modified habitats found in gardens.
7. Pasture land (p)
There are areas of land cleared of native vegetation and replaced by pasture grass within the study area. 4 Table 1. The natural habitats at Ridgeway and equivalent vegetation communities after North (1997).
No. Habitat Code Vegetation Community Code RFA Community Code RFA status
1 Shrubby Eucalyptus tenuiramis Et Shrubby Eucalyptus tenuiramis DRY-shTEN-dol E. tenuiramis forest on dolerite TD forest forest on dolerite
2 Eucalyptus pulchella grassy Ep Eucalyptus pulchella grassy DRY-gPULC E. pulchella-E. globulus-E. P woodland woodland viminalis grassy/shrubby dry forest
3 Grassy Eucalyptus globulus Eg Eucalyptus globulus-Poa WET-GLOB1 Eucalyptus globulus grassy GG Vulnerable forest labillardierei-Hypochoeris forest radicata wet sclerophyll forest
4 Shrubby Eucalyptus obliqua dry Eo Shrubby Eucalyptus obliqua dry DRY-shOB E. obliqua dry forest O forest sclerophyll forest
5 Wet forest wf Eucalyptus obliqua-Olearia WET-OB010 E. obliqua wet forest OT lirata-Pultenea juniperina wet sclerophyll forest
Eucalyptus obliqua-Acacia WET-OB0110 E. obliqua wet forest OT dealbata-Olearia argophylla wet sclerophyll forest
1 FAUNA
There have been few studies of the fauna of the Ridgeway area and consequently there is limited information, particularly of reptiles, amphibians and invertebrates. A list of the fauna of the study area and their habitats is provided in Appendices 1 and 2.
Mammals
The mammal fauna is quite diverse with 25 species likely to occur in the study area, although a number of common and widespread species in Tasmania are rare including; the Tasmanian devil (Sarcophilus harrisii) and eastern quoll (Dasyurus viverrinus) or apparently absent, the wombat (Vombatus ursinus). All of Tasmania's eight bat species have been recorded from the adjacent Ridgeway Park and are likely to occur within the study area.
One threatened mammal species, the eastern barred bandicoot and five significant species, the platypus, southern brown bandicoot, long-nosed potoroo, Tasmanian bettong and the little pygmy-possum occur in the study area (Table 1 & 2). Twelve species of mammals are dependant on tree hollows for shelter and breeding.
Birds
Forty-seven bird species have been recorded from the study area, nine of which are endemic and seven are summer visitors. These birds migrate from the Australian mainland in early spring to breed in Tasmania and leave again in the autumn. Four introduced species have been recorded, starling, blackbird, laughing kookaburra and European goldfinch.
Two threatened species occur in the study area. The swift parrot breeds only in Tasmania and is dependant on the nectar from flowering blue gums Eucalyptus globulus during the breeding season. It is listed as endangered because of its small population size and the loss of foraging habitat within its breeding range (Brereton 1997a). There is a known nesting site in shrubby E. obliqua dry forest on the south western boundary of the study area below Summerleas Road (Brereton 1997a). There could be other nesting sites within the study area in old growth E. obliqua forest where suitable hollows are present. The swift parrot has also been recorded foraging on flowering E. obliqua within the study area after breeding. This eucalypt species flowers in late summer and early autumn.
The grey goshawk is listed as rare because of its small population size and its dependence on old growth wet forest. Adult birds and young have been observed in the Fern Tree area and it is suspected that it nests in one of the wet gullies including Dunns Creek. Nests are usually located in blackwood Acacia melanoxylon or eucalypts close to streams (Brereton and Mooney 1994).
Seven significant bird species occur in the study area (Table 2). Four are restricted to wet forest habitats, scrubtit, pink robin, olive whistler and Bassian thrush. The remaining three species are uncommon in southern Tasmania. The blue-winged parrot is known to breed in the Fern Tree area. It nests in hollows in old growth eucalypts. The Australian owlet-nightjar is rarely observed in Tasmania. Bob Patterson (pers. comm.) mist netted this species twice in the course of a five year banding study of birds he carried out in the Fern Tree area between 1988 and 1992. The beautiful firetail is patchily distributed in dense grassy habitats. Six species of birds recorded from the study area nest in tree hollows.
Reptiles
The study area supports a diverse reptile fauna including ten lizard species and all three Tasmanian snake species (tiger snake, copperhead and white-lipped snake). Three of the lizard species are endemic to Tasmania, Niveoscincus ocellatus, Niveoscincus pretiosus and Cyclodomorphus casuarinae. Reptiles depend on obtaining heat from their environment to raise their body temperature to a level where activity is possible. They do this by basking in the sun or absorbing heat from their surroundings. Thus, the open habitats in dry 1 forests and rocky areas support a more diverse reptile fauna. Two skink species commonly occur in wet forests, the metallic skink Niveoscincus metallicus and the more arboreal Tasmanian tree skink Niveoscincus pretiosus.
There are no threatened reptile species in the study area and only one significant species, the mountain dragon Tympanocryptis diemensis. This species is uncommon in the Hobart area where it is restricted to dry forests and open woodlands. The mountain dragon appears to be sensitive to disturbance particularly urban development.
Amphibians
Only four frog species are known from the study area, one of which is endemic to Tasmania, the Tasmanian froglet Crinia tasmaniensis. Three of the frogs occur in damp situations in wet forest Litoria ewingi, Crinia tasmaniensis and Crinia signifera. Limnodynastes dumerili is more often associated with permanent water bodies, it occurs in some of the small dams within the study area along with Litoria ewingi and Crinia signifera.
Fish
There is very little suitable habitat for fish in the study area and there are no native fish records. However, the jollytail (Galaxias maculatus), spotted galaxias (Galaxias truttaceus) and the eel (Anguilla australis) have been recorded in streams running off Mount Wellington and could occur in Dunns Creek, the only permanent stream in the Ridgeway study area.
Invertebrates
The invertebrates are a poorly studied group within the Ridgeway area. However, some groups have been sampled. Kevin Bonham (pers. comm.) has recorded nine species of snails and Peter McQuillan has collected 15 species of moths (GT SPOT database).
Two threatened invertebrates occur in the study area. The broad-striped ghost moth (Fraus latistria) has been recorded in Eucalyptus viminalis dominated E. pulchella grassy woodland. This species only occurs in Tasmania where it is only known from five locations. Ghost moths are nocturnal and have a brief flight period in March-April when they are active after dusk. Adults do not feed and the larvae live in soil coming to the surface at night to feed on grasses and sedges.
The Mt. Mangana stag beetle (Lissotes menalcas) has been recorded from the Silver Falls Track (GT Spot database) at Fern Tree. This beetle species inhabits wet forests where it lives in logs feeding on wood rotting fungi (Meggs 1996) and is likely to occur in suitable wet forest habitat along Dunns Creek at Ridgeway.
One other species of terrestrial invertebrate is considered to be of conservation significance. The newly discovered snail (Allocharopa sp) which is endemic to south-east Tasmania. It occurs in the Wellington Range and Huon/Channel area (Kevin Bonham pers. comm.).
2 Fauna of conservation significance
Tables 1 and 2 list those threatened or significant species which have been recorded from the study area.
Table 1. Threatened fauna
Species Common name Status Habitat Tas/Nat Perameles gunnii Eastern Barred -/V Occurs in grassy forests and grasslands Bandicoot (both native and introduced). It also utilises gardens in urban areas and is vulnerable to predation by cats and dogs. Accipiter Grey Goshawk R/- A pair is known to breed in the Fern novaehollandiae Tree-Ridgeway area. Nests are usually located in Acacia melanoxylon in riparian habitats (Brereton & Mooney 1993). Lathamus discolor Swift Parrot E/E Known to breed in Ridgeway area. Nests in hollows in old growth eucalypts (Brown 1989, Brereton 1997a). Recorded foraging in flowering Eucalyptus globulus and E. obliqua in the study area. Lissotes menalcas Mt. Mangana stag beetle V/- Lives in decaying logs in wet forest. Fraus latistria Broad-striped Ghost R/- Recorded from E. pulchella grassy Moth woodland at Ridgeway (Nielsen & Kristensen 1989). Key
E Endangered
V - Vulnerable
R - Rare
M - Requires monitoring
K - Unknown risk status
3 Table 2. Significant species
Species Common name Status Habitat Ornithorhynchus anatinus Platypus Although widespread in permanent waterways across Tasmania, there is concern that it is disappearing from waterways in catchments that have been altered by land management practices Isoodon obesulus Southern brown Occurs in grassy and shrubby dry bandicoot forests. It is uncommon in the study area and is vulnerable to predation by cats and dogs. Potorous tridactylus Long-nosed Potoroo It is associated with dense vegetation and is generally uncommon in the Hobart area and is restricted to the wetter habitats in the study area. Bettongia gaimardi Tasmanian bettong M Extinct on the mainland and has a patchy distribution in Tasmania. It is restricted to dry forests in the study area. Cercartetus lepidus Little Pygmy-possum M This species has a restricted distribution on the Australian mainland and is uncommon in Tasmania. Accipiter cirrhocephalus Collard Sparrowhawk Forest dependant species which is rare in the Hobart area. Neophema chrysostoma Blue-winged Parrot This species is uncommon in southern Tasmania and is known to breed in Ridgeway area. Nests in hollows in old growth eucalypts. Aegotheles cristatus Australian Owlet K Inhabits dry forests where it as an Nightjar apparently rare species. Sericornis magnus Scrubtit Endemic species which is rare in the Hobart area. It is a wet forest specialist, usually associated with dense ferny gullies. Restricted to Dunns Creek. Petroica rodinogaster Pink robin Wet forest specialist which is rare in the Hobart area. It is restricted to wet forests and rainforests. Pachycephala olivacea Olive Whistler Wet forest specialist which is rare in the Hobart area. It is associated with dense shrubby understoreys. Zoothera dauma Bassian Thrush Wet forest specialist which is rare in the Hobart area. It is restricted to closed wet forests and rainforests. Tympanocryptis diemensis Mountain Dragon K Occurs in dry forests. Allocharopa sp. snail Newly discovered species endemic to south-east Tasmania. Occurs in the Wellington Range and Huon/Channel area (Kevin Bonham pers. comm.).
4 Habitats of conservation significance
The grassy Eucalyptus globulus forest present in the study area particularly in some of the drier gullies is important foraging habitat for the swift parrot (see habitat map). This forest type is also listed as vulnerable in Tasmania because is has been extensively cleared for agriculture and settlement and it is undergoing is a continued decline (PLUC 1997). The E. pulchella grassy woodland in the study area is potential habitat for the broad-striped ghost moth. It is a common and widespread forest type within the study area.
The small patch of shrubby Eucalyptus tenuiramis forest which is restricted to the west facing slopes of a spur below Badger Hill is important habitat for species which prefer heathy understoreys, such as the bettong.
The Ridgeway area contains a small area of wet forest along Dunns Creek which is habitat supports a number of faunal species which are rare and restricted in the Hobart area including two threatened species and four significant species (see habitat map). These wet forest specialists are dependant on the habitats that these forests provide, particularly the closed understoreys, the well developed litter layer and decaying logs.
There are structural components which occur across all habitat types which are essential to the maintenance of faunal populations. Old growth forest which have abundant trees with hollows (habitat trees) provide shelter for possums, bats and invertebrates and nest sites for some bird species including the threatened swift parrot and the blue-winged parrot (see habitat map). Fallen timber provides shelter for invertebrates and reptiles and amphibians and is also a food resource for some invertebrates, which either feed on them directly or on the wood rotting fungi they host including the threatened stag beetle Lissotes menalcas. The presence of a deep litter layer will provide shelter for a range of invertebrates particularly snails.
MANAGEMENT ISSUES
Habitat loss and fragmentation
Further residential development in the Ridgeway area is likely to reduce the available habitat for fauna through clearing and degradation of bushland, particularly development which extends further into forest areas. The loss of habitat will reduce the carrying capacity and will result in the loss of populations and species from the area. Development may lead to the loss or degradation of one or more of the identified habitats. The following is a summary of which fauna are likely to be lost if habitats are destroyed or degraded.
Litter layer
The surface soil layers, leaf litter and fallen timber host a diversity of invertebrates. These substrates also support amphibians, reptiles, birds and mammals which feed on invertebrates. Bettongs and potoroos also feed on the subterranean fungi which occur in the soil. Leaf litter, fallen timber and rocks provide shelter for invertebrates and reptiles and amphibians.
Ground layer
The low shrubs, grasses and sedges are home to a variety of invertebrates. The ground layer also provides shelter for mammals and nest sites for ground birds.
5 Shrub layer
The medium and tall shrubs and small trees support a number of invertebrate groups (Eg. spiders, nectar feeding insects, leaf eating invertebrates). The shrub layer also provides a foraging substrate for birds which feed on invertebrates or on nectar from flowering shrubs. The eastern spinebill, honeyeaters, thornbills, and the grey fantail are the most likely birds to be encountered in the shrub layer. These birds also nest in the shrub layer. The sugar glider, pygmy-possums and possums forage in the shrub layer for invertebrates and nectar.
Canopy
The canopy is comprised of eucalypt species. A variety of invertebrates can be found on eucalypts; the leaves are fed on by a number of species and others shelter beneath the bark. Birds such as the pardalotes forage for lerps on leaves and the grey shrike-thrush, strong-billed honeyeater and black-headed honeyeater probe under bark for invertebrates. Honeyeaters forage in eucalypt flowers for nectar. Eucalypt leaves, buds and flowers are a source of food for possums. The hollows in old trees are used by possums and bats for shelter and as nest sites by bird species (Eg. parrots, owls, striated pardalote).
The loss of any particular structural layer will result in the loss of the associated species, for example clearing of the litter, ground and shrub layer will lead to the disappearance of a range of invertebrate, amphibian, reptile, bird and mammal species. Even if the canopy is retained it will only provide habitat for a limited number of species.
Fire
Fire plays an important role in maintaining biodiversity in Australia. Changes in the fire regime (season, frequency and intensity of fire) can cause progressive changes in plant and animal communities. Both long- term exclusion of fire and frequent burning have been shown to lead to changes in forest structure, and loss of flora and fauna species.
The forests in the study area show the effects of frequent burning. Much of the forest is regrowth forest, old growth forest is restricted to a few sheltered slopes and gullies. Also, much of the fallen timber has been removed by frequent fires. This has resulted in the loss of habitat for reptiles and invertebrates, and may be responsible for the apparent rarity of some species of wet forest specialists around Mt. Wellington including velvet worms, snails and the Mt. Mangana stag beetle Lissotes menalcas (Taylor and McQuillan 1994). Stream invertebrates can be adversely affected by fire damage to gully and riparian vegetation and through increased siltation.
Further residential development is likely to lead to an increase in wildfire's and the more frequent and widespread use of prescribed burning to reduce fuel loads in the remaining bushland. Both of which will have a detrimental impact on the fauna of the study area. The increased occurrence of fire will further reduce the extent of the wet forest and will result in loss of old growth forest. This loss of habitat will lead to changes in the fauna, the wet forest specialists (e.g. pink robin, scrubtit, Bassian thrush) will become rarer and some may disappear from the area. Invertebrate species which inhabit damp litter and rotting logs (e.g. amphipods, snails and Lissotes menalcas) will be lost as the wet habitats become more open and drier. The loss of habitat trees which provide nesting and roosting sites for birds and mammals will also have an impact on species abundance and diversity.
Although dry forests are adapted to frequent fires and some may be even fire promoting, frequent firing can lead to a loss of structural diversity which will have an impact on the fauna. The understorey will become more open and logs and litter, which provide shelter and food for invertebrates and reptiles, will be reduced.
6 Domestic pets
Dogs and cats pose a threat to the fauna of the Ridgeway area. Cats are known predators of amphibians, reptiles, birds and small mammals and they have been implicated in the local extinction of species (Environment Australia 1999). Predation by feral cats is listed as a key threatening process on the schedules of the Commonwealth Environment Protection and Biodiversity Conservation Act 1999.
Domestic dogs will attack echidnas, possums, potoroos, bettongs and reptiles resulting in the loss of these species from the area. The barking of dogs disturbs birds and mammals. Many species will avoid an area because of the presence of dogs even if they are not directly threatened. Cats and dogs, if unrestrained, will wander widely and the impact of their presence will extend beyond the immediate vicinity of any houses.
Introduced and nuisance species
Human habitation attracts introduced species such as mice, rats and introduced birds. The black rat is a good climber and thus has access to a wide range of food sources and there is evidence that the black rat preys on the eggs and nestlings of birds (Watts and Braithwaite 1983).
Although few introduced bird species occur in the Ridgeway area, any further residential development will inevitably be accompanied by the invasion of introduced species. Many introduced species aggressively defend territories and successfully compete for space, food and nest sites with native birds. The blackbird which is already widespread in the study area may compete with ground dwelling species. The blackbird is also considered to be the principal dispersal agent of some weed species, especially soft fleshy fruited species (Eg. New Zealand mirror bush (Coprosma repens), boneseed (Chrysanthemoides monilifera ssp. m) and blackberry (Rubus spp.), (Loyn and French 1991). The starling nests in tree hollows and competes with native species for nest sites. Starlings have been known to evict native birds from nest hollows (Brown 1989).
The introduced freshwater snail Potamopyrgus antipodarum inhabits waterways in or adjacent to disturbed habitats that have been altered by urban development or by agricultural or forestry activities (Taylor and McQuillan 1994). It is thought that this species has had a dramatic impact on the hydrobiid snails (a large family of small freshwater snails) with some species now reduced to remnant populations on the upper edges of their range above the disturbed areas inhabited by Potamopyrgus (Taylor and McQuillan 1994).
Disturbance
The construction of houses within natural habitats will lead to an increase in disturbance to fauna both during the construction phase and also after the completion with the continual presence and movements of residents and vehicles. This disturbance will not be confined to residential areas but will also have an impact on the adjacent bushland areas. This will result in those species most sensitive to disturbance moving away from the area and a decreased use by other less sensitive species.
Site degradation and pollution
The presence of houses often leads to the dumping of rubbish, including garden waste, into adjacent bushland. Fertilisers and pollutants from urban run-off also enter the ecosystem. These processes lead to weed establishment and invasion into the adjacent bushland, the pollution of waterways resulting in a degradation of habitats and the consequent reduction in the abundance and diversity of fauna.
7 MAINTENANCE OF FAUNAL VALUES
To maintain faunal values within the Ridgeway local area a number of measures need to be considered for inclusion in the planning of any future development.
• The protection of significant habitats and sites from development and disturbance including; swift parrot nesting sites, broad-striped ghost moth habitat, old growth forest, wet forest, grassy Eucalyptus globulus forest and shrubby E. tenuiramis forest.
• Controls on the clearing of bushland including ground vegetation (shrubs, grasses and sedges), litter and fallen timber, shrubs and trees, particularly habitat trees. These controls will need to consider fire protection requirements.
• Restrictions on the ownership of cats and dogs and on the movements of both.
• Containment of run-off and garden waste from houses.
• Fire management planning which considers the requirements of the fauna and maintains their habitats.
8 ACKNOWLEDGMENTS
I would like to thank Jess Abrahams, Will Fletcher and Kevin Bonham,.for providing information on the fauna of the Ridgeway area.
REFERENCES
Brereton, R. & Mooney, N. 1994. Conservation of the nesting habitat of the grey goshawk (Acccipiter novaehollandiae) in Tasmanian State Forests. Tasforests 6:79-89.
Brereton, R. 1997a. Management prescriptions for the swift parrot in production forests. Report to Tasmanian RFA Environment and Heritage Technical Committee.
Brereton, R. 1997b. Report on the faunal values of Waterworks Reserve. Prepared for HCC Waterworks Master Plan.
Brereton, R. 1998. Fern Tree Local Area Plan: Fauna and Habitat Overview. Unpublished Report to Hobart City Council
Brown, P.B. 1989. The Swift Parrot Lathamus discolor: a report on its ecology, distribution and status, including management considerations. Department of Lands, Parks and Wildlife.
Environment Australia. 1999. Threat Abatement Plan for Predation by Feral Cats. Biodiversity Group, Environment Australia, Canberra.
Environment Protection and Biodiversity Conservation Act 1999. Commonwealth Government.
Fire Management Strategy For Wellington Park (1999). Prepared by AVK Environmental Management and IFERM Pty Ltd for the Wellington Park Management Trust
Green, R.H. 1989. Birds of Tasmania: An annotated checklist with illustrations. The author Launceston.
Invertebrate Advisory Committee. (1994). Interim List of Native Invertebrates which are Rare or Threatened in Tasmania. Edition 1. Species at Risk, Tasmania - Invertebrates. Parks and Wildlife Service, Tasmania.
Loyn, R.H. & French, K. 1991. Birds and environmental weeds in south-eastern Australia. Plant Protection Quarterly 6(3): 137-149.
Meggs, J.M. (1996). Distribution and conservation status of two threatened species of lucanid in Tasmania. National Estate Grants Program Report, Forestry Tasmania, Hobart.
Nielsen, E. S. & Kristensen N. P. 1989. Primitive Ghost Moths: Morphology and taxonomy of the Australian genus Fraus Walker (Lepidoptera: Hepialidae s. lat.). Monographs of Australian Lepidoptera. Vol. 1. CSIRO Australia.
North, A. 1997. Botanical Survey of Hobart Bushland Stage 2: Ridgeway-Precinct 44, Ridgeway Reserve, Knocklofty Reserve, McRobies Gully. Report for Hobart City Council.
PLUC. 1997. Corrections to Environment and Heritage Report Volume V. PLUC RFA Information Sheet No 11. Tasmanian Public Land Use Commission, Hobart.
Ratkowsky, A.V. & Ratkowsky, D.A. 1976. The birds of the Mt. Wellington Range, Tasmania. Emu 77: 19- 22.
9 Rounsevell, D.E., Taylor, R.J. and Hocking, G.J. 1991. Distribution records of native terrestrial mammals in Tasmania. Wildl. Res. 18:699-717.
Taylor, R.J. & McQuillan, P.B. 1994. Fauna of Mount Wellington. The Tasmanian Naturalist 116: 2-19.
Thomas, D. 1979. Tasmanian Bird Atlas. Fauna of Tasmania Handbook No. 2. University of Tasmania, Hobart.
Thomas, D.G. 1986. The birds of Mt. Wellington - Comparison of two 10ha plots of dry and wet sclerophyll. Tasmanian Bird Report. 15: 11-16.
Threatened Species Protection Act 1995. Tasmanian State Government, No. 83 of 1995. Government Printer, Hobart, Tasmania
Vertebrate Advisory Committee. 1994. Native vertebrates which are Rare or Threatened in Tasmania. Edition 1. Species at Risk, Tasmania - Vertebrates. Parks and Wildlife Service, Tasmania.
10 APPENDIX 1
RIDGEWAY VERTEBRATES. Species are listed are in taxonomic order.
Mammals
Species Common name Status Habitat Tas/Nat Ornithorhynchus anatinus Platypus S w Tachyglossus aculeatus Echidna Ep, Et, Eo, Eg, wf, Dasyurus viverrinus Eastern Quoll S Ep, Eo, Eg, Et, p Sarcophilus harrisii Tasmanian Devil Ep, Eo, Eg, Et, p Antechinus swainsonii Dusky Antechinus wf, Isoodon obesulus Southern Brown Bandicoot S Ep, Eo, Eg, Et Perameles gunnii Eastern Barred Bandicoot -/V Ep, wf, u, p Pseudocheirus peregrinus Common Ringtail Possum wf, Eo, Eg, u Trichosurus vulpecula Common Brushtail Possum Ep, Eo, Eg, Et, wf, u, p Cercartetus nanus Eastern Pygmy-possum Ep, Et, Eo, Eg, wf, Cercartetus lepidus Little Pygmy-possum S Ep, Et, Eo, Eg, wf, Potorous tridactylus Long-nosed Potoroo S Eo, wf, Bettongia gaimardi Tasmanian Bettong S Ep, Eo, Et Thylogale billardierii Tasmanian Pademelon Eo, wf, Macropus rufogriseus Red-necked Wallaby Ep, Eo, Eg, Et, p Nyctophilus timoriensis sherrini Tasmanian long-eared Bat e Ep, Eo, Eg, Et, wf Nyctophilus geoffroyi Lesser Long-eared Bat Ep, Eo, Eg, Et, wf Chalinolobus gouldi Goulds Wattled Bat Ep, Eo, Eg, Et, wf Chalinolobus morio Chocolate Wattled Bat Ep, Eo, Eg, Et, wf Falsistrellus tasmaniensis Eastern Falsistrelle Ep, Eo, Eg, Et, wf Vespadelus regulus Southern Forest Bat Ep, Eo, Eg, Et, wf Vespadelus vulturnis Little Forest Bat Ep, Eo, Eg, Et, wf Vespadelus darlingtoni Large Forest Bat Ep, Eo, Eg, Et, wf Rattus lutreolus Swamp Rat Eo. wf, Rattus rattus Black Rat i Ep, Eo, Eg, Et, wf, u Mus musculus House Mouse i Ep, Eo, Eg, Et, wf, u Oryctolagus cuniculus Rabbit i Ep, Eg, Et, p
Key to status codes
State National E - Endangered E - Endangered S - Significant species V - Vulnerable V - Vulnerable e - endemic species R - Rare i - introduced species su - summer visitor See text for habitat codes
11 Birds
Species Common name Status Habitat Tas/Nat Accipiter fasciatus Brown Goshawk Ep, Eo, Eg, Et, wf,
Accipiter novaehollandiae Grey Goshawk R/- Eo, wf, Accipiter cirrhocephalus Collared Sparrowhawk S Eo, wf, Falco berigora Brown Falcon Ep, Et, u, p Vanellus miles Masked Lapwing u, p Phaps elegans Brush Bronzewing Eo, wf, Calyptorhynchus funereus Yellow-tailed Black-Cockatoo Ep, Eo, Eg, wf, u, p Platycercus caledonicus Green Rosella e Ep, Eo, Eg, Et, wf, u, p Lathamus discolor Swift Parrot E/E (su) Eg, Eo, wf Neophema chrysostoma Blue-winged Parrot S(su) Eo, wf Dacelo novaeguineae Laughing Kookaburra i u, p Cuculus pallidus Pallid Cuckoo su Ep, Et, u, p Cuculus pyrrophanus Fan-tailed Cuckoo su Ep, Eo, Eg, Et, wf, u, p Chrysococcyx lucidus Shining Bronze-Cuckoo su Eo, wf, Ninox novaeseelandiae Southern Boobook Ep, Eo, Eg, Et, wf, Podargus strigoides Tawny Frogmouth Ep, Eo, Eg, Et, wf, Aegotherles cristatus Australian Owlet-nightjar S Ep, Eo, Eg, Et, wf, Malurus cyaneus Superb Fairy Wren Ep, Eo, Eg, Et, wf, u, p Pardalotus punctatus Spotted Pardalote Ep, Eo, Eg, Et, wf, Pardalotus striatus Striated Pardalote Ep, Eo, Eg, Et, wf, Sericornis humilis White-browed Scrubwren e Eg, Eo, wf, Sericornis magnus Scrubtit S (e) wf, Acanthiza pusilla Brown Thornbill Ep, Eo, Eg, Et, wf, Acanthiza ewingii Tasmanian Thornbill e wf, Anthochaera paradoxa Yellow Wattlebird e Ep, Eo, Eg, Et, wf, Lichenostomus flavicollis Yellow-throated Honeyeater e Ep, Eo, Eg, Et, wf, Melithreptus validrostris Strong-billed Honeyeater e Eo, wf Melithreptus affinis Black-headed Honeyeater e Ep, Eo, Eg, Et, wf, Phylidonyris pyrrhoptera Crescent Honeyeater Eo, wf, Phylidonyris novaehollandiae New Holland Honeyeater Ep, Eo, Eg, Et, wf, Acanthorhynchus tenuirostris Eastern Spinebill Ep, Eo, Eg, Et, wf, Petroica multicolor Scarlet Robin Ep, Eg, Et, Petroica phoenica Flame Robin Ep, Eo, Eg, Et, wf, Petroica rodinogaster Pink Robin S wf, Melanodrynas vittata Dusky Robin e Ep, Eo, Et Pachycephala pectoralis Golden Whistler Eo, Eg, wf, Pachycephala olivacea Olive Whistler S Eo, wf, Collurincla harmonica Grey Shrike-thrush Ep, Eo, Eg, Et, wf, Rhipidura fuliginosa Grey Fantail su Ep, Eo, Eg, Et, wf, Coracina novaehollandiae Black-faced Cuckoo-shrike su Ep, Eo, Eg, Et, wf, Strepera fuliginosa Black Currawong e Ep, Eo, Eg, Et, wf, Birds cont. 12 Strepera versicolor Grey Currawong Ep, Et Corvus tasmanica Forest Raven Ep, Eo, Eg, Et, wf, p, u Cecropis nigricans Tree Martin Ep, Eo, Eg, Et, wf Zosterops lateralis Silvereye Ep, Eo, Eg, Et, wf, Carduelis carduelis European Goldfinch i u, p Emblema bella Beautiful Firetail S Eo, wf, Zoothera dauma Bassian Thrush S Eo, wf, Sturnus vulgaris Common Starling i Ep,Eo, u, p Turdus merula Blackbird i Ep, Eo, Eg, Et, wf, u
Reptiles
Species Common name Status Habitat Tas/Nat Tympanocryptis diemensis Mountain Dragon S Ep, Eo, Et, Bassiana duperryi Three-lined Skink Ep, Eo, Et, Lampropholis delicata Delicate Skink Eg, Eo, wf Niveoscincus metallicus Metallic Skink Ep, Eo, Et, Eg, wf, u, p Niveoscincus ocellatus Ocellated Skink e Ep, Eo, Et, Eg, Niveoscincus pretiosus Tasmanian Tree Skink e Eo, Eg, wf, Pseudemoia entrecasteauxii Southern Grass Skink Ep, Egernia whitei White's Skink Ep, Eo, Et Tiliqua nigrolutea Blotched Blue-tongue Ep, Eo, Et, u, p Cyclodomorphus casuarinae She-oak Skink e Ep, Eo, Eg, wf Austrelaps superbus Lowlands Copperhead Ep, Eo, Et Drysdalia coronoides White-lipped Snake Ep, Eo, Et, Eg, wf Notechis ater Tiger snake Ep, Eo, Et, Eg, wf
Amphibians
Species Common name Status Habitat Tas/Nat Crinia signiferra Common froglet w, Eo, Eg, wf Crinia tasmaniensis Tasmanian Froglet e w, Eo, wf Limnodynastes dumerelli Banjo Frog w, p Litoria ewingii Brown Tree Frog w, Eo, Eg, wf,
13 APPENDIX 2
RIDGEWAY INVERTEBRATES. Species are listed are in taxonomic order.
PHYLUM Species Status Habitat CLASS Tas/Nat Order GASTROPODA Sigmurethra (snails) Allocharopa sp. S (e) wf Allocharpa legrandi e wf Caryodes dufresnii e wf, Eo Elsothera ricei e wf, Eo Helicarion cuvieri e wf Paralaoma caputspinulae wf, Eo Pernagera kingstonensis Ep, Eg, Eo Prolesophanta nelsonensis e wf Stenacapha hamiltoni Ep, Eg, Eo Tasmaphena ruga Ep, Eg, Eo Thryasona diemenensis e wf UNIRAMIA INSECTA Coleoptera (beetles) Lissotes menalcas V (e) wf Lepidoptera (moths, Fraus latistria R (e) Ep butterflies) Agrotis porphyricollis Artigisa lignicolaria Diarsia intermixta Cosmodes elegans Epicyrtica lichenophora Leucania exarans Leucania obusta Mamestra dictyota Neumichtis expulsa Neumichtis spumigera Praxis edwardsii Proteuxoa DPILH17 Proteuxoa flexirena Schrankia capnophanes
14
RIDGEWAY AREA
LAND CAPABILITY ASSESSMENT
Potential
for
Agriculture/Horticulture
Information for Local Area Planning Provisions
Completed by: Complete Agricultural Consulting Services June 2000 1
Contents
Executive Summary 2
Introduction 3
1. Purpose of Ridgeway Local Area Assessment 4
2. The Study Area 4
3. Locality Details 4 3.1. Planning Scheme Classification 4 3.2 Local climate 4 3.3 Topography and Aspect 5 3.4 Vegetation 5 3.5 Geology and Soil Types 5 3.6 Drainage issues 5 3.7 Erosion 6 3.8 Water Supply 6
4. Land Use & Capability 6 4.1 State policy on the Protection of Agricultural Land 6 4.2 Land Classification 7 4.3 Verification of Assessment 7
5. Suitability of the land for Agriculture 8
6. Potential Enterprises & Market Outlook 9 6.1 Possible enterprises 9 6.2 Summary of possible agricultural activity 10
7. Agricultural Social and Economic Issues 11
8. Summary 11
9. Recommendations for future development 11
1 2
Executive Summary
The Land Capability Assessment revealed the Study Area comprises Class 4 to Class 7 Land (as described in Appendix 2) with the majority of the land being a composite of Class 6 and 7.
The topography and the south-south west aspect of much of the land, the shallow stony soils, a lengthy cold winter period with frosts experienced into late spring are the most significant matters that limit the primary industry enterprises that can be undertaken on a sustainable basis.
As the Study Area is primarily rated as Class 5 to 7 Land there is no reason under the State Protection Of Agricultural Lands Policy to withhold approval to provide for further development in line with that provided for under the existing planning zones of Rural B and C.
The following recommendations are made:
1. Maintain the planning classification of Rural B and C zones with clear provision for rural management operations.
From the viewpoint of agricultural land capability, maintain the present planning zones Notation within the planning scheme to provide land owners with an ongoing capacity to undertake rural operations.
2. Provide for agricultural assessments/land management plans before approving the clearing of vegetation on all areas with slopes greater than 10%.
Containing land clearing on the steeper slopes through administering a land management process in order to limit erosion.
3. Ensure a Fire Management Strategy is developed for the Area and an Action Plan is adhered to by both Council and land owners.
A Fire Management Strategy with an Action Plan, developed in association with land owners, is required to contain the impact of fires that lead to erosion.
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Introduction
An assessment of the Land Capability, of the Ridgeway locality, for agricultural - horticultural use, was undertaken in June 2000 by Mr F W Walker, Manager, Complete Agricultural Consulting Services.
The purpose of the assessment was to ascertain the presence of Prime/Significant Agricultural Land within the Ridgeway Local Area and to identify potential agricultural/horticultural enterprises that maybe undertaken on a sustainable basis.
In undertaking the assessment the agricultural environment of all the land forms that make up the Study Area were reviewed and conclusions made based on the principles that apply to Land Classification, as outlined in the Land Capability Hand Book - Guidelines to the Classification of Agricultural Land in Tasmania, published by the Tasmanian Department of Primary Industry Water & Environment.
Land within the Study area has been mapped at a scale of 1:5000; Land Class boundaries have been estimated from infield inspections of the more accessible areas.
Factors limiting the use of land for agriculture are noted and recommendations made for future planning and development.
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Land capability Assessment Ridgeway Local Area Planning Provisions
1. Purpose of Ridgeway Local Area Assessment
Council is required, under the provisions of the State Policy on the Protection of Agricultural Lands, to establish land capability as function of Planning Schemes. This Study has been undertaken in order to identify the significance of land to agriculture within the Ridgeway Local Planning Area.
2. The Study Area
The Study Area incorporates land within the City of Hobart south of Ridgeway Park and east of Summerleas Road with the north eastern boundary being the Southern Outlet. A map of the Study Area forms Appendix 1.
3. Locality Details:
3.1 Planning Scheme Classification
The area under review comprises approximately 310 hectares and is presently zoned as ‘Rural B or C’ within the planning scheme managed by the Hobart City Council.
3.2 Local Climate
The long term rainfall is reputed to be 750 to 1000 mm (approx. 30 to 50 inches) per annum with a predominant winter distribution. The higher rainfall occurs in the west- south-west sector.
Frosts are common throughout the winter and early spring period. It is important to note that late frosts, into November, can also be experienced in some years. Summer temperatures are, on average, slightly lower than those recorded in Hobart, except for the sheltered eastern perimeter adjacent to Proctors Road.
The prevailing wind is from the west and north-west which impacts on the north-north easterly slopes. The south facing slopes are affected by the cooler southerly airflows.
Agriculturally most of the area is regarded as “late season”.
3.3 Topography & Aspect
The Study Area is dominated by a number of prominent ridges and deep gullies containing tributaries that flow into Browns River. Approximately two thirds of the Area is steeply sloping land much of which has a southerly or westerly aspect.
Some of the slopes adjacent to the settlement of Ridgeway have been cleared of native vegetation in order to undertake agricultural pursuits. A significant amount of the sloping land east of Badger Hill has a favourable east-north-easterly aspect.
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Photos Nos 1 and 2 depict the predominant land forms and vegetation of the land adjacent to the settlement of Ridgeway. Photo No. 3 shows Class 5 land that comprises the lower slopes adjacent to Proctors Road.
3.4 Vegetation
The steeper slopes and gullies in the main support native vegetation comprising a variety of eucalypt forest with associated shrub under growth. Rainforest species have been reported in gullies and on sheltered southern slopes (Ref 1, p9). The slopes are covered by Eucalypt forest and woodland with a more open canopy near settlements and on hard, stony ground. The principal dolerite soil type carries associations of White Peppermint, Bluegum and Stringybark forest/woodlands.
The majority of the Area is under native vegetation.
3.5 Geology and Soil type
As reported in Ref 1(p6) most of Ridgeway area is composed of Jurassic dolerite which forms various ridge landforms and underlies the plateau section of the Study Area. There is a small section of Permian mudstone at the north eastern extremity of the Study Area.
Podzolic Soils on Dolerite (PSD) comprise the predominant soil type. With a shallow clay loam-loam top soil over a yellow brown/gravelly clay these soils carry considerable stone which limits cultivation/intensive use. Photos Nos. 4 & 5 depict typical profiles. The PSD’s are interspersed with small areas of brown loam-sandy loam particularly in the eastern sector.
Most of the developed areas adjacent to the Ridgeway settlement comprise stony Podzolic Soils on Dolerite (PSD). A small area of brown Ferrosol type soil with a moderately deep profile, as shown in Photo No. 6, extends along the eastern edge of the developed country adjacent to the local settlement.
Steep exposed slopes commonly contain a stony, shallow (<0.50m) duplex soil comprising a clay loam/sandy clay loam over a yellowish brown light clay. Protected gullies have a clay loam surface over a yellowish brown light clay.
A small section of infertile Podzolic Soils on Mud Stone in the north east sector has no significance for primary industry operations.
The extent of the stone problem is pictured as follows: Photo No. 7 indicates the amount of stone on land adjacent to Badger Hill, with nearby Class 6 land in Photo No.8. Photo No. 9 depicts Class 5 Land together with an area Class 6/7 as stony ridge/outcrop.
3.6 Drainage Issues
Drainage is satisfactory over the majority of the Study Area; the significant slopes aid natural drainage in this moderately high rainfall area. Winter flooding is not a problem.
The variable water tables provide a very limited source of water for small waterholes.
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3.7 Erosion
Most of the land area falls within the Department of Primary Industry and Fisheries (DPIF) Chimney Pot Hill System No.34962. It is stated in the DPIF Land Systems of Tasmania Region 6 Report (p197) “The land system not particularly prone to erosion, although sheet, rill, and gully erosion problems sometimes occur on the crests and slopes following disturbance.”
Evidence of rill/small gully erosion is noticeable adjacent to tracks and fire trails. Where drains have been established on significant slopes beside roads significant erosion occurs. Tunnel erosion was noted on Class 5 Land, adjacent to Proctors Road, as shown in Photo No. 10.
It would be prudent, in this medium-high rainfall area, for land with a slope greater than 10% not to be deployed in primary industry enterprises with operations requiring annual cultivation. All the steeper gullies should remain under existing vegetation; any disturbance will result in major erosion problems.
As fire management is an important factor in controlling erosion it is imperative a soundly devised fire management strategy is implemented.
3.8 Water Supply
There are general limitations on the availability of water for irrigation; from Council advice it appears only limited amounts can be sourced from the HCC supply system over and above normal residential requirements. In addition, Council advise the availability of supply can vary across the Study Area.
Subject to the provisions of the Water Resources Act administered by DPIWE some land owners maybe able to build small supplementary storages in select locations. However, the topography limits the construction of cost effective dams.
The Tasmanian Department of Infrastructure, Energy & Resources advise there are no known bores in the Study Area and it is not considered likely that drillers would tap into useful flows.
A restricted supply to much of the Study Area is a significant constraint to establishing high value, intensive agricultural/horticultural operations.
4. Land Use & Capability
4.1 State Policy on the Protection of Agricultural Land
The Policy seeks to ensure that the State makes the best use of good quality agricultural land, providing a consistent approach to planning decisions involving development. The provisions of the Policy complement the role local government in the preparation of planning schemes.
While presently in draft form the Policy is being implemented and is considered functional by the State Government.
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4.2 Land Classification
In undertaking the capability assessment the agricultural environment of all land forms that make up the Area are reviewed and the conclusions made are based on principles that apply to Land Classification as outlined in the DPIWE Land Capability Hand Book - Guidelines to the Classification of Agricultural Land in Tasmania.
An outline of the Land Classes applying in the Land Capability Assessment process is presented in Appendix 2.
At first glance some sections of the Study Area may appear to be a good environment in which to undertake intensive primary industry operations. Some observers could expect the open cultivated areas to be good agricultural land and provide a base for a range of intensive, high value enterprises. However, on close inspection these areas fail to rate as either prime land or significant agricultural land with the best described as average Class 4 Land.
In summary the land forming the Study Area is rated as follows:
Land Form Land Capability Class Area (ha) (approx.) Gullies & steeply sloping stony land Class 7/6
Undulating shallow soils, Class 5/6 with some stone outcrops
Moderate slopes, better soils Class 4/5 with little stone
Gentle slopes with deep Class 4 well drained soils
In applying the land capability assessment process it is confirmed there is no significant agricultural land within the Study Area, with the best land being described as average Class 4.
The various land classes are outlined in the map forming Appendix 1. Because of the variation in the land form across the Study Area the boundaries between the classes are not actual but approximate.
4.3 Verification of Assessment
As the Department of Primary Industry Water & Environment was found to be finalising, on a scale of 1:25,000, the classification of lands in the region, the findings of Complete Agricultural Services (CACS) were reviewed with the Departmental Officer undertaking the infield work. It was noted that the CACS assessment is consistent with the work undertaken by the Department.
5. Suitability of the Land for Agriculture
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Whereas the Study Area is devoid of significant agricultural land it is noted that it would be possible to practise some forms of agriculture within the prevailing environments. In identifying particular enterprises, attention must be given to the following factors limiting land use:
5.1. Climate
The length of the cold late autumn- winter-early spring period experienced in the Study Area limits the forms of agriculture/horticulture that can be undertaken successfully. Late spring frosts in particular render the area unattractive for many primary industry operations.
The predominantly high winter rainfall is also a restricting factor, coupled with a distinct dry late summer period.
Agriculturally most of the area is regarded as “late season” and suited to non frost sensitive forms of intensive agriculture/horticulture. The installation of appropriate frost monitoring and protection equipment would still be necessary for many horticultural enterprises.
5.2. Topography & Aspect
The steep slopes across much of the Study Area again limits the potential for agricultural operations. Much of the Class 5 land is on a significant slope requiring great care in using machinery.
5.3. Soils
The predominant podzolic soils are inherently low in fertility and are not well suited to many intensive forms of production, especially those requiring regular cultivation. The shallow and stony nature of much of the topsoil is a major detracting factor.
It is estimated that approximately 30% of the Study Area is suited to agricultural operations with most of it as bush/run country grazing.
5.4 Vermin Control
Being adjacent to extensive bushland the Study Area will always be invaded by native animals. Wallabies and possums cause major damage to establishing horticultural enterprises, necessitating significant capital outlays in vermin proof fencing.
5.5 Water supply
A supplementary water source is necessary for many intensive agricultural enterprises to be conducted throughout the Study Area. However, it would be possible to undertake floriculture activities focusing on spring - early summer production without additional supplies.
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In summary, the topography and the south-south west aspect of much of the land, the shallow stony soils, a lengthy cold winter period with frosts experienced into late spring are matters that collectively limit the primary industry enterprises that can be undertaken.
6. Potential Agricultural/Horticultural Enterprises & Market Outlook:
6.1 Possible Enterprises & Market Outlook
Possible primary industry enterprises for the area and their market outlook are reviewed. They are put forward as general suggestions only; individual landowners need to confirm the suitability of the following enterprises and others to their particular properties. Intensive enterprises will require the removal of significant amounts of stone.
Berry fruits Strawberries, Raspberries, Blueberries, Longanberries. Blackcurrants (with frost protection) The area is suited to berry-fruit production for the fresh market and pick your own enterprises. However, the local market outlook for fresh produce is best described as very competitive and returns very much depend upon the marketing skills of the grower. There is a limited market for blackcurrants; it is not advisable to enter into commercial production without a juice contact.
Floriculture Cut flower trade: late spring bulbs, freesias, roses Erica species (as a perennial crop) Liliums Boronia Foliage (for florist use in bulking arrangements).
The market outlook is favourable for reliable suppliers of quality items, but it is essential for producers to make formal arrangements within local markets and not rely on selling material as it is produced.
The late season environment provides for a ‘follow on’ of supply of produce from other early and mid season areas.
Orcharding
Stone fruit Early spring frosts and a poor water supply essentially rule out the establishment of high returns from capital intensive stone fruit orchards. It is possible that in using temperature data loggers suitable areas could be identified.
Pome fruit Apples have been produced in favourable environments immediately adjacent to the settlement of Ridgeway. However, in some years mid-late October frosts would limit/prevent fruit set thereby impacting negatively on the enterprise.
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Whereas the market outlook is favourable for stone fruit exports, it is not so for the large amount of fresh fruit that will be coming onto the local market in future seasons. The local pome fruit market is well supplied; returns are unlikely to recover production costs.
Market Gardening
General lines of mid to late season crops could be grown with supplementary irrigation over mid to late summer. Winter crops of turnips/swedes and other root vegetables could be grown in the friable Class 5 soils once cleared of stone.
The market outlook is not favourable for small lines of produce. Forward contracts are necessary to supply quality items in line with the terms of quality assurance programs.
Protected (Glasshouse) Crops
The cool climate experienced across much of the area makes the locality unattractive for major protected cropping operations.
Livestock
The small holdings in the Study Area are generally not suited to any significant form of livestock production. The larger units (10ha plus) may provide a pasture base for exotic lines of stud livestock (such as Alpacas), but these would be very limited and thus of little consequence to advancing Tasmanian primary industry.
It is noted goats provide for effective utilisation of bush and scrub country. Photo No. 11 indicates the effect of containing vegetation/providing fire breaks through managing undergrowth with goats. . Photo No.11 indicates the impact of the January 1999 fires on open woodland and the level of grass fuel build up that occurs when livestock are excluded.
Vineyards
Without access to local heat summation data it would not be prudent to invest capital in establishing a significant vineyard. Significant frost protection systems would be necessary to mitigate the impact of spring frosts.
Forestry
Some land areas would be suitable for private forests, but as the Area is subject to frequent major fires, such an enterprise is not considered a prudent proposition.
6.1 Summary of possible Agricultural Activity
With the major constraints identified above it is unlikely significant small scale agricultural activity will occur as more favourable rural environments for intensive enterprises are to be found near Hobart.
It would be advisable for property owners to develop Farm Plans prior to clearing any land.
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Agricultural social and economic issues
Land use is, to a large extent, determined by the values and goals of the individual land owners. It is noted that the majority of land owners as at June 2000 are content to use the land primarily as a residential base, in the main drawing income from off the property. Several commented that they wished the area to remain as is.
With improvements to the water supply it is possible over time more intensive agricultural operations will occur in the most favourable environments the Study Area as new land owners recognise the potential of their land.
Managing intensive agricultural/horticultural enterprises invariably requires the application of pesticides and fungicides and use of noisy machinery. Provision should be made in the Planning Scheme for agricultural activity in order to provide for normal rural management operations. Such action will provide for more efficient handling of complaints by Council.
Land use will need to be controlled in the section of the Study Area that comprises part of the Ridgeway Water Catchment.
As noted in the DPIF Land Systems of Tasmania Region 6 Report (p197) report, the land system is mainly used for water catchment, grazing, nature conservation and recreation - in the form of orienteering, bushwalking and trail riding. As the Study Area becomes more densely settled rural managers/land owners may not be in a position to accommodate the current level of recreational use.
8. Summary
As the Study Area is primarily rated as Class 4 to 7 land there is no reason under the State Protection Of Agricultural Lands Policy to withhold approval to provide for further development in line with that provided for under the existing planning classification of Residential A and B.
Whislt agricultural/horticultural enterprises can be undertaken within the environments of the Study Area, the land is not of agricultural significance. In summary Council can give approval to subdivision/provide for residential purposes without impacting on the States agricultural potential.
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9. Recommendations for future development
1. Maintain the planning classification of Rural B and C with clear provision for rural management operations.
From an agricultural land capability perspective, maintain the planning zones B and C. Notation within the planning scheme to provide land owners with an ongoing capacity to undertake rural operations.
2. Provide for agricultural assessments/land management plans before approving the clearing of vegetation on all areas with slopes greater than 10%.
Containing land clearing on the steeper slopes through administering a land management process in order to limit erosion.
3. Ensure a Fire Management Strategy is developed for the Area and an Action Plan is adhered to by both Council and land owners.
A Fire Management Strategy with an Action Plan developed in association with land owners is required to contain the impact of fires that lead to erosion.
F W Walker Manager Complete Agricultural Consulting Services. June 2000
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References
1. HCC and D. Elton, (1998) Ridgeway Catchment Mapping - Habitats and Hazards
2. Davies, J. B. Land Systems of Tasmania Region 6: South South-east and Midlands - A Resource Classification Survey. Dept Agriculture< Hobart,1988.
3. Grose, C. J. 1999. Land Capability Handbook: Guidelines for the Classification of Agricultural Land in Tasmania. Dept Primary Industries Water & Environment.
4. Dimmock, G. M., 1956, Reconnaissance soil map of Tasmania. Hobart. CSIRO Divisional Report 13/55.
5. Resource Planning and Development Commission 1999. Draft State policy on the Protection of Agricultural Land.
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Appendix 1
The Study Area
Ridgeway Local Area Plan Land Classification Summary
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Appendix 2
Land Capability Classification An Explanation
Land capability classification is an internationally recognised means of land classification, used to evaluate the capability of land to support a range of land use on a sustainable long term basis.
Land capability assessment takes into account the physical nature of the land (eg. geology, soils, slope) plus other factors (eg. climate, erosion hazard, land management practices) which determine how that land can be used without damaging or destroying its long term potential for sustainable agricultural production. It also takes into account limitations that might affect agricultural use, eg stoniness, drainage, salinity and flooding.
Land capability assessment is therefore based on permanent biophysical features of the land (including climate) and does not take into account the economics of agricultural production, market issues, social or political factors.
Do not confuse land capability assessment with suitability assessment, which in addition to the biophysical factors does note the suitability to growing a particular crop, market issues etc. in evaluating the best use of an area of land.
The Tasmanian system of capability classifies land into seven of classes as described below:
Class 1
Multiple use land suited to intensive cropping and grazing. It is capable of being cropped eight years out of ten in rotation with pasture or equivalent without risk of damage to the soil resource or loss of production. An example of such land is the best of the NW Coast cropping soils.
Class 2
Land suitable to intensive cropping and grazing with minor limitations that can be readily overcome by management and minor conservation practices. The limitations present increase the risk of damage to the soil resource through over cultivation or the risk of yield loss is such that the length of the cropping phase is reduced to five to eight years out of ten.
Class 3
Land suitable for intensive cropping and grazing, but with more pronounced limitations than for Class 2. The limitations are such that either cultivation or cropping should be limited to two to five successive crops in a rotation with pasture or equivalent to prevent damage to the soil resource or, the risk of crop failure or yield reduction with average climatic conditions is such that significant losses can be expected five to seven years out of ten.
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Soil conservation practises and sound management are needed to overcome the moderate limitations to cropping use. The range of crops able to be grown is generally more restricted than on Class 1 or 2 land.
Class 4
Land marginally suitable for cropping because of severe limitations which restrict the crops that can be grown, and/or make major conservation treatment and careful management necessary.
Cropping rotations should be restricted to one or two years out of ten in a rotation with pasture or equivalent in order to avoid damage to the soil resource or are limited by climatic conditions such that there is a very high risk of crop failure or by yield decline in most years. The land is well suited to intensive grazing.
Class 5
Land with slight to moderate limitations to pastoral use. The land is unsuitable for conventional cropping, although some ares on easier slopes maybe cultivated for pasture establishment-renewal/forage crops. The effects of limitations on the grazing potential maybe reduced by applying appropriate soil conservation measures and land management practises.
Class 6
Land marginally suited for grazing because of severe limitations. This land has low levels of production, high risk of erosion, low natural fertility or other limitations that severely restrict agricultural use.
Class 7
Land with very severe to extreme limitations which make it unsuitable for agricultural use.
Limitations
In the above descriptions limitations refer to physical factors or constraints which affect the versatility of the land and determine its capability for long term sustainable agricultural use.
Interpretation
As indicated above Land Capability Classification should not be confused with suitability assessment which is frequently undertaken by land owners and agri-business personnel.
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Photo No.1
View across the across Class 5/4 land adjacent to Ridgeway Settlement.
Photo No. 2
Class 5 land at the North East of the end of Hall Street showing open woodland and controlled undergrowth.
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Photo No.3
Section of Class 5 land adjacent to Proctors Road
Photo No. 4
Soil profile of Class 5 Land showing typical shallow clay loam topsoil over clay. This profile can overlay sheet rock formation of dolerite.
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Photo No.5
Embankment indicating shallow topsoil over clay subsoil and gravel. Class 5/6 Land on upper slope above Proctors Road.
Photo No. 6
A Brown Ferrosol type soil forming Class 4 land.
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Photo No.7
Stony land adjacent to Badgers Hill.
Photo No. 8
Class 6 Land adjacent to Badgers Hill.
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Photo No.9
View across the across Class 5Land adjacent to Class 6/7 east of Hall St.
Photo No. 10
Class 5 land at the adjacent to Proctors Road with significant tunnel erosion.
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Photo No.11
Controlled grazing with goats, resulting in reduction of fire hazard as shown to the right of fence line.
Photo No. 12
Recovery 18 months after the January 1999 bush fires; significant grass growth in semi open woodland.
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Septic Tank Survey
Method | Discussion | Conclusions
March 31 1998 | Ben Ridder
On the 5 February 1998, 439 survey forms were sent out, mostly to houses in the Hobart suburbs of Fern Tree, Ridgeway and South Hobart. Also included in the envelope was a brochure on septic tanks, a reply paid envelope, and a covering letter explaining the reason for the mail-out.
METHOD The survey forms were of two main types. The first was sent to those residing at properties identified in the rates database as not paying a sewerage levy. For houses where it appeared that the owners may not be living at the property (postal address different from property address), it was assumed they were renting it to tenants. In such cases a second style of survey form was sent to the property owner in addition to the survey sent to the property address. This was seen as necessary given that the questions on the first survey would have made little sense to a landlord. The forms were formatted in such a way that the suburb of origin of returned surveys could be determined while ensuring that they could not be traced to individual properties. The South Hobart survey, for example, had double spacing between the words “SEPTIC TANK SURVEY”. None of the envelope contents contained an address. This was instead printed onto a sticky label and put on the envelope itself. All the contents were folded by the folding machine at the HEC printing office, including the reply paid envelopes. Delivery was carried out be Australia Post as per a normal letter. Table 1 - SURVEYS SENT / RETURNED area ID number wrong TOTAL surveys sent addresses SENT returned Fern Tree FT 223 7 216 121 [56%] Lenah Valley LV 27 1 26 9 [35%] Mount Nelson MN 18 18 8 [44%] Ridgeway RW 41 2 39 23 [59%] South Hobart SH 37 37 21 [57%] Other other 18 1 17 1 [6%] Property Owners OWN 75 1 74 20 [27%] TOTALS 439 12 427 203 [48%]
“Wrong addresses” includes survey forms which were returned because the address or resident name was in some way incorrect. Data from the returned surveys was entered into an Excel spreadsheet for analysis.
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Comments on the method 1) Once survey forms began returning, it became apparent that the HEC, in printing the surveys, had neglected to double-side those for Ridgeway. Hence there are very few results from the second page for this area. 2) Most of the returned “property owner” surveys seem to have been sent by residents who both own and reside at the property in question, rather than landlords. This situation would arise when, for example, the postal address was listed as a post box. Although this variable response renders these particular surveys not very statistically useful, they still contain valuable feedback.
ANALYSIS The statistical analysis of the returned surveys only includes those from Fern Tree, Lenah Valley, Mount Nelson, South Hobart and Ridgeway. The “other” survey is not used as only 1 was returned, while the “property owner” surveys are excluded for reasons discussed in 2) above. Comments from these excluded surveys may still be referred to however. The responses relating to composting toilets are presented after the survey questions have been addressed. In the tables found below, a figure in brackets indicates the number of responses that were taken into account. Discarded responses are then discussed in the accompanying text. 1) Years of residence Fern Tree Lenah Mount Ridgeway South [121] Valley [9] Nelson [23] Hobart [21] [8] average years 13.6 10.1 11.9 12.5 15.5 of residence longest 44 33 36 40 48 residence
2) Number of people in residence Fern Tree Lenah Mount Ridgeway South [121] Valley [9] Nelson [8] [23] Hobart [21] average 3.0 2.6 3.3 2.7 2.6 number of people number of 5 0 0 1 0 6+ dwellings
In calculating the “average number of people”, 6+ dwellings were taken to equal 6. 3) Ownership status ownership Fern Tree Lenah Mount Ridgeway South status [121] Valley [9] Nelson [8] [23] Hobart [21] own 117 9 7 23 21 renting 4 0 1 0 0
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4) Type of disposal system type Fern Tree Lenah Mount Ridgeway South [120] Valley [9] Nelson [8] [23] Hobart [19] septic tank 118 7 8 23 16 composting 1 0 0 0 2 toilet sewerage 1 2 0 0 1
Not included in these figures are 1 response from Fern Tree where the person did not know what system was used, and 2 responses from South Hobart where the houses were using the pan system (Old Farm Road). Those in Lenah Valley who indicated they were on the sewerage system had lived at the residence for 6 and 7 years, while the person in South Hobart had been there for 20 years. It may be possible that the rates database was incorrect in these cases. 5) Age of septic tank Fern Tree Lenah Mount Ridgeway South [117] Valley [7] Nelson [8] [23] Hobart [16] average date 1973 1981 1985 1981 1975 of installation number older 53 2 1 5 6 than 1970 don’t know 12 0 1 0 1
6) Maintenance for septic tank The following table has been compiled from residents who have lived on the present property for 5 years or longer. frequency of Fern Tree Lenah Valley Mount Ridgeway South pump-out [86] [5] Nelson [7] Hobart [9] never 21 [24%] 2 3 N/A 2 4 years or 28 [33%] 0 3 N/A 3 less between 4 21 [24%] 3 0 N/A and 8 years greater than 16 [19%] 0 1 N/A 2 8 years
The following table is compiled from residents who have lived on the present property for less than 5 years. frequency of Fern Tree Lenah Valley Mount Ridgeway South pump-outs [31] [2] Nelson [1] Hobart [6] never 19 2 1 N/A 4 2 years or 5 0 0 N/A 1 less between 2 7 0 0 N/A 1 and 4 years
-3- “never” has been used to indicate that the septic has not yet been pumped by the present owners. Included in this classification were “?” and those who had only removed scum rather than a full pump out. The frequency for responses such as “3 to 5 years” was taken to be the average, for this case 4 years. Those who indicated they were on the sewerage system, or “pumped when necessary” were not included in this component of the analysis. Responses which indicated that the number of years between pump-outs was longer than the time they had lived at the address were interpreted as “never”. 7) Nature of maintenance / modifications For this section only the 117 septic tank responses from Fern Tree will be analysed. nature of maintenance/ number of modifications responses new septic tank 5 [4.3%] new trenches 5 [4.3%] trenches extended 2 [1.7%] remove roots / blockages 5 [4.3%] other 3 [2.6%] Actizyme 6 [5.1%]
None of the responses included more than one of these problems. 8) Problems problem Fern Tree Lenah Mount Ridgeway South [119] Valley [7] Nelson [8] [23] Hobart [18] none 72 6 4 N/A 11 smelly 9 0 0 N/A 1 boggy 12 0 3 N/A 2 smelly and 5 0 0 N/A 0 boggy occasionally 8 0 1 N/A 2 smelly / boggy no trenches 4 1 0 N/A 0 doubt about 7 0 0 N/A 1 trenches
Responses relating to both septic tanks and composting toilets have been included in this table. “doubt about trenches” was used to describe people who did not know where the trenches were, or believed that they had no trenches despite being on a septic system. Circumstances listed as causing bogginess included extra people staying in the house, winter or frosty weather, heavy rain, and use of the washing machine. Circumstances listed for smells included extra people, and use of the washing machine. Totaling these figures shows that 34 residences in Fern Tree [29%] and 5 in South Hobart [28%] have reported problems with their systems.
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9) Comments comments Fern Tree Lenah Mount Ridgeway South [118] Valley [7] Nelson [8] [23] Hobart [21] no comments 45 4 2 N/A 9 septic is satisfactory 22 2 1 N/A 5 septic is unsatisfactory 13 0 0 N/A 0 would like more information 8 0 0 N/A 1 like the idea of composting 8 0 0 N/A 2 toilets and recycling greywater other comments 22 1 5 N/A 4
If it is assumed that those with no comments were generally satisfied with the existing situation, the results from this table can be compiled to show that 60% [90/149] of residents are quite happy for things to remain the same while 9% would prefer to be connected to the sewerage system. 6% would appreciate further information, with another 6% in favour of more environmentally friendly options of on-site disposal. Composting toilets
Five surveys were returned from houses using composting toilets [FT89, SH2, SH13, OWN4, OWN18]. Survey system date of comments installation FT89 unspecified 1994 not happy with the system SH2 Clivus 1993 not happy - system not working - Multrum believes inappropriate for conditions SH13 Dowmus 1995 quite happy with system [dry] OWN4 Clivus 1995 Settlers Green - quite happy with Multrum system OWN18 unspecified 1994 quite happy with system
Those happy with the system emphasised the importance of regular maintenance - adding newspaper/water/sawdust. The FT89 survey noted that they only maintained the system twice per year. SH2 had moved into a residence in which the system was already installed, and so perhaps was not familiar with the regular maintenance required. They note that undecomposed waste is removed once per year and buried in the back yard, while not mentioning whether regular maintenance is carried out. An additional 7 surveys indicated that they would like to switch to a composting system, mainly because they liked the idea of recycling waste on-site. A couple of these suggested that Council offer a subsidy for installation which would be paid back through increased rates for a few years. One resident [SH21] was under the impression that septic tank approval was required in order to get composting toilet approval - this is in fact not the case.
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TRENDS The following trends are apparent in the survey data: • Fern Tree and South Hobart exhibit older septic systems and residents who have been established for longer. • residents who have lived at the property for less that 5 years are more likely to have never pumped out the septic tank. • it seems that houses with larger families [4 or more people], in which the septic tank is not pumped out frequently, are more likely to experience problems such as boggy trenches and smells. • similarly, houses with 1 or 2 occupants are less likely to experience problems, despite often displaying a low pump-out frequency. • use of the product Actizyme seems to be quite effective at alleviating smells and reducing the need for pump-outs. • composting toilets need to be maintained relatively frequently in order to work effectively.
COMMENTS The following comments have been chosen as a representative sample of most of the ideas expressed in the returned surveys. They are referenced by the code given to each survey during the data entry process. FT4 - “I think the existing system was done on the cheap with the intention of only one person using it - therefore really quite inadequate (however if I maintained it, it may be adequate). PS - I really hope you can’t trace this, or I’ll probably be in deep shit !”. FT21 - “We are content with our septic system - it has been trouble free. We would like to see the continued use of efficient septic tanks in our area”. FT28 - “HCC’s records regarding location of tanks/trenches are not accurate and should be updated”. FT34 - “The system at the Tavern appears to be seeping water along the faults in the mudstone and trickling out into the gutter along Summerleas Road”. FT38 - “Runoff on Huon Road in Fern Tree can be boggy and smelly” FT47 - “Your... pamphlet prompted me to check-out tank... the solids have built up... just below the inlet... So I had better have it pumped out. Not bad for 14 years !”. FT55 - “...our front garden has frequently been inundated with run-off from our neighbour’s greywater trench system. Our system is failing but we have been advised that a new septic system could not be used at the site. Council endorsement of other systems would be welcome”. FT63 - “More information RE septic systems on change of ownership of residence”. FT79 - “Automatic dishwasher power often destabilises the septic. I would be interested in a waste water system for the kitchen and laundry”. FT80 - “I do not know where my septic tank is. I am just assuming I have one somewhere”. FT85 - “Shallow soil overlying jointed bedrock on slopes allows absorption trench liquid to move downslope and create odour / health problems... Sewerage system is needed ASAP”. FT97 - “... Would have liked to know about all the options for wastewater as I would have chosen to modify system if I’d known about them”. FT103 - “I believe proper maintenance is essential. The use of Actizyme or other ‘sweeteners’ to stimulate micro-organism growth seems to be very effective. Unfortunately these are fairly expensive - a cheaper ‘bulk’ source would be very welcome”. FT108 - “Under current request to [replace system] from Council” “We feel that upgrading of septic tanks should be uniformly applied and not just arbitrarily where complaint has been made”. FT113 - “[boggy trenches are] not noticeable as the whole area... is all very wet during winter, spring and early summer”.
-6- RW5 - “The septic system works fine - if sewerage means higher rates I’m quite happy to keep my existing system”. SH2 - “The composting toilet is a Clivus Multrum which does not work in the Tasmanian climate. I have to remove a considerable amount of waste once a year and bury it because it has not composted down completely. Also the model is too small to work properly”. SH21 - “I would like to get a composting toilet since I think they are environmentally superior. I do not like the idea that septic tanks above me could pollute the stream that borders my property. I understand that to get composting toilet approval, I need septic approval but I am too close to the stream for that. So I am in a “catch-22” situation, relying on the Council to take away my waste once a week”. OWN2 - “I think they [septic tanks] are good in my situation. I’d like to be able to use bathwater on the garden”. OWN6 - “If the Council bought hundreds of composting toilets and sold them to the residents maybe the Council could get us all a discount... I’m interested to know more - but let me know before I retire”. OWN11 - “There is a spring running alongside the lower side of the [septic] tank and this is often wet and boggy” “We have used ours successfully but LOOK FORWARD TO THE PROMISED (15 years ago) SEWERAGE CONNECTION for our area (Fern Tree)”. OWN17 - “A better system than... treatment plant and sea dumpage” MN1 - “... self congratulating pamphlet in which you state ‘.. treatment system recognised as one of the most advanced in Tasmania’. What a non-statement !!! Our Council has wasted millions on capital works and will waste millions on annual expenses pumping sewage up and down Sandy Bay Road”. MN2 - “Although the HCC is happy to demand rates at the same rate in the dollar as houses which are provided with all services we receive none and certainly do not expect to ever be connected to the sewerage system. This survey is therefore a waste of time”.
DISCUSSION Response rate The quantity of surveys returned is encouraging; overall there was a 47% response rate which is unusual considering that only a one third response can be generally expected for a mail-out survey. Bias The possibility exists that the desire of residents to avoid connection to the sewerage system and subsequent rate increases would have biased the results. Such residents may have neglected to mention septic tank problems on the survey form to give the impression that there was no need to change the existing situation. This is a valid concern given that several responses did actually mention a desire not to be connected to sewerage because of the effect on rates. This bias can be partially alleviated by analysing the pump-out results [see below]. Frequency of pump-out Looking at the pump-out results for residents living in Fern Tree for 5 years or longer indicates that 37 households pump their tanks less frequently than every 8 years [including “never”]. Further analysis shows that 22 of these households have 2 or less occupants and would hence be placing little burden on the septic system. This leaves 15 properties [17%] where the septic tank would be overloaded and probably failing. Of these 15, 5 did report problems, suggesting that there are 10 properties [12%] where problems have not been reported. System performance By adding the figures relating to “problems” [~29%] and “frequency of pump-out” [~12%], it could be expected that ~41% of septic systems in Fern Tree are experiencing problems. Given that there may be some respondents who misrepresented their frequency of pump-out, this figure could be a bit higher. By applying this proportion to all systems in Fern Tree [223] it could be anticipated that ~90 were experiencing problems. Note that most of these problems would be minor and posing no risk to health or water quality.
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Water quality Some surveys reported that effluent from neighbouring properties was overflowing into their yards, or into gutters along Huon and Summerleas Roads. It could therefore be inferred that cases exist where fecal material is ending up in local creeks. Actizyme 6 surveys from Fern Tree reported satisfaction with the product Actizyme. This consists of small wheat pellets containing “enzymes” which boost bacterial action in the septic tank, thereby reducing odour and sludge bulk. Several people complained about the price, being about $3.70 per 100g, and suggested that Council offer it to residents at a subsidised rate. Sewerage connection From the comments on the returned survey forms, 60% of residents seemed happy with the existing situation, while only 9% actually specified that they were not happy with their system. It could be inferred that this 9% would prefer connection to the sewerage system. Composting toilets The responses from those using composting toilets seemed to suggest that frequent maintenance was required if they were to function effectively. There were 10 others who were interested in using composting toilets and/or recycling greywater. Given the high level of maintenance required it is felt that these systems should only be encouraged in cases where the resident is quite motivated to undertake the maintenance required. Education Anecdotal evidence suggests that the survey and pamphlet prompted an increase in business for those who pump-out or otherwise maintain septic systems. Such are the benefits of distributing educational material about a subject which has received little previous attention.
CONCLUSION The two primary conclusions from this survey are that: 1) Most people using septic systems in Hobart municipality are generally satisfied with the situation and would not wish to be connected to the sewerage system. 2) At least 40% of properties in Fern Tree are experiencing some sort of problem, with this figure possibly being between 45 and 50% if it is felt that the results may have been biased by fear of rate increases. Note that this figure includes very minor problems, such as occasional smell or bogginess. The actual proportion of problems which would be posing a health risk, causing neighbour disputes and contaminating waterways would be very small. Given that most of these problems could be solved through better management by the residents, it seem that connecting the area to sewerage mains would be unnecessary, not to mention unpopular with the community. Some recommendations arising from the report are as follows: 1) Hobart City Council should distribute follow-up information to all those properties which received the survey form and pamphlet. This second mail-out would address comments made by residents on the survey forms, and communicate the results presented in this report. This would serve to increase community awareness of septic tank management issues, and strengthen the image of the Council as concerned about community problems and available for advice. 2) Several responses from Fern Tree mentioned the presence of effluent leaking into gutters along Huon Road. Given the public importance of this road it is recommended that Council officers place priority on addressing the problem septic tanks in this area. 3) It would be worthwhile to undertake some monitoring of fecal coliforms downstream from Fern Tree. One suitable site would be the junction of Fork Creek and Browns River. Such measurements would compliment the qualitative results of the above survey process.
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SEWAGE DISPOSAL OPTIONS FOR FERN TREE This section has been included to consider the relevance of the above results to wider questions surrounding the future of sewage disposal in Fern Tree. The salient points are as follows: • Up to 50% of septic systems in Fern Tree may be experiencing problems. • Most of these problems would not constitute a public health risk, and could be adequately addressed by improved management practices. • Residents of Fern Tree would most likely be opposed to changes in the existing situation. Some of the alternatives for managing sewage disposal in Fern Tree are as follows: 1) Do nothing - Given that no public outcry has emerged over the existing situation, the “do nothing” [carry on as usual] option has some merit. It is worth noting however, that environmental regulations are liable to become more stringent in future years, and it would be a relatively easy task to at least undertake some community education programs. It would also be in Council’s best interests to carry out water quality monitoring to compliment the results of the survey process. 2) Connection to the sewerage system - There were 13 responses from Fern Tree which implied that this was their preferred option. When investigating this option in the past, Hobart City Council has resolved that the costs would be prohibitively expensive. Such studies however, have probably not taken into account all of the costs of each option. These are outlined below: costs of sewerage connection • additional loading on the sewage treatment plant • sewerage system maintenance • infrastructure capacity would be underutilised costs associated with use of septic tanks • septic tank maintenance • Environmental Health Officer time investigating septic problems
Given the cost involved, the existence of a significant problem with the existing situation would first have to be conclusively demonstrated, particularly given apparent community sentiment. 1) Communal systems - There are numerous combinations of Aerobic Wastewater Treatment Systems / septic systems and communal use arrangements managed by the Council which would work effectively in parts of Fern Tree. All would require a similar analysis to that suggested for sewerage connection above. 2) Prohibition of particular systems - Some systems perform better than others under particular circumstances. Composting toilets, for example, are effective almost anywhere, but only if they receive regular and appropriate attention. Septic systems however, require very little attention yet must be well designed for particular site conditions or they will experience problems. All systems have their advantages and disadvantages, advocates and opponents. One option for the Council would be to weigh all the evidence and prohibit systems in areas where they were deemed not suitable. A less contentious option is to ensure that each system inspected will function effectively given the site conditions. This requires that Environmental Health Officers have a good working knowledge of all the available alternatives, and apply this knowledge in a consistent fashion. 3) Compulsory maintenance - Council could require households to pump out septic tanks on a regular basis so as to avoid overflow problems and trench blockage. Given the varying needs of individual houses, this would require some sort of inspection. It could be assumed that such inspections would generate a considerable amount of additional work for Environmental Health Officers as some systems would be deemed unsuitable and require upgrading. It may however, be beneficial for Council to carry out a once-off inspection of all systems, recommending maintenance where required, and dispensing educational material. Such a project would occupy one person for at least 6 months, and could only be carried out if a firm policy on the future of sewage disposal in the area had been decided upon. 4) Maintenance subsidy - Rather than enforce maintenance, it may be more effective, and palatable to residents, for Council to offer discounted maintenance. This could include cheaper pump-outs and supply of products such as Actizyme. Given that these residents do not pay the -9- sewerage component of their rates, this would effectively constitute a direct subsidy from those rate-payers who do pay the sewerage levy. This could be overcome by charging properties in unsewered areas a small levy which would be returned to them in the form of a discount on maintenance fees [food stamps for septic tanks]. 5) Further education - As discussed previously, the simplest and most effective way to improve community management of septic systems is to maintain a close relationship between Council officers and the community, with a high priority placed on ensuring that residents are sufficiently educated in the ways of maintaining their system.
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