Ian Houshold and Phil Bradley

ACKMA Journal No. 17. December 1994. Pages 14-18

Editor’s Foreword.

In July 1994, the Tasmanian Parks and Wildlife Service released its Newdegate Cave Rehabilitation Plan.  It was put together by lan Houshold, the P&WS Karst Officer, and Phil Bradley, the Ranger-in-Charge of Hastings Caves.  The plan is extremely comprehensive, and covers all conceivable aspects of the management of the cave and its karst environment.  In the first part of the document, the karst area and the cave are described and its myriad of problems identified.  Part 2 deals with specific rehabilitation issues and management responses in each area, covering walkways, walkway definition, drainage and refuse, reticulated water, path lighting, lampenflora control, lint cleaning, bulk debris and rubbish removal, walkway and formation cleaning, and cave lighting and electrical systems.  Part 3 sets out a timeline for implementation. while Part 4 details a recurrent maintenance timetable. 

This plan must rate as one of the most comprehensive yet developed for a single Australasian cave, and it can clearly be recommended as model for others to emulate.  An edited summary of the plan follows.  Copies of the full document can readily be obtained from Ian Houshold, Earth Science Section, Parks and Wildlife Service, Hobart.  Of course, ACKMA members attending the 11th Conference in Tasmania next May will be able to view Newdegate Cave and assist with further input into its sorely-needed rehabilitation.

SUMMARY OF THE REHABILITATION PLAN

SIGNIIFICANCE OF THE CAVE AND EFFECTS OF VISITATION

Newdegate Cave was developed for intensive tourism through a series of upgrades between the late 1930s and the early 1970's, and as a result there was little formal planning for the long term future of the cave. Natural features of the system have suffered as a result of staff having to work around a style of development which does not integrate environmental management with the development of walkways and electric lighting. 

Many features are continuing to be degraded - dust and lint carried in by visitors accumulate on formations, and unsightly and destructive plant growth on both formations and sediments is continuing as a result of inappropriate lighting.  Many parts of the cave were used as dumps for unsafe stairways, old cable, conduit and other refuse.  This is affecting the habitat of cave fauna. Accumulations of mud and sawdust on formations are degrading the resource either through the coating being incorporated by subsequent calcite deposition or etching of the formation by humic acids leached from the sawdust.

Although selected areas have been cleaned it will be impossible to carry out a thorough cleaning program until adequate pathway drainage has been built and holding tanks for contaminated water installed.  Cleaning without these will only spread the pollution further through the system - rather than dispersing, it is likely that any mud or organic deposits will build up in ponded or sumped areas in the lower parts of the system, creating a malodorous mess.

In the past few years much research has been applied to the development of measures for the sustainable use of tourist caves, with a lot of original work carried out in Australian caves. Integration of cave cleaning systems with walkways, the development of low voltage lighting systems, and use of appropriate materials for track formation and surfacing are being tested in caves around the country, however the individual character of each particular cave means that certain practices will only be suitable for specific sites.  Much room exists for further developments as knowledge of karst management practices increases and more appropriate lighting and cleaning technology becomes available.

These measures, as well as others particularly suited to Newdegate Cave are necessary if the environment of the cave is to be restored and maintained in an acceptable manner.  Considerable effort has been expended in the development of a 'clean' walkway from the carpark to the cave, and on an upgraded visitor information shelter at the cave entrance.  Now that clean access to the cave has been guaranteed the time is right to begin a redevelopment which will allow ongoing use occur without the environmental degradation which is inevitable given existing conditions. 

Newdegate cave forms the focus for the great majority of tourists to southern Tasmanian cave areas, and has done for many decades.  Catering for approximately 40 000 visitors per year it is one of the most popular tourist attractions in the south of the state.  It is centered on one of the most diverse regions of karst in the country, and borders the extensive Western Tasmanian Wilderness World Heritage area.  The cave is the most highly-visited attraction in the state reserve system south of Hobart.  Information related to the World Heritage area and surrounding state reserves is disseminated by information officers stationed at the cave.

The cave is electrically lit and concrete or earth pathways have been constructed with many steps giving easy access through the first 300 m of the system.  Unfortunately the existing developments within the cave are having an adverse effect on the cave environment.  In common with many cave developments of the 1930's - 1960's the infrastructure was very little concerned with the ongoing maintenance of natural environmental conditions. 

Development of caves for tourism is now seen as an extremely complicated process.  Caves possess no inherent carrying capacity for humans.  Processes of geomorphic and biological evolution within cave systems occur generally over a far greater time span than surface environments, environmental ranges are far more constrained and hence environmental tolerance of both land forms and species is far tighter than for almost any surface environment (Kiernan 1988).  This is a relatively recent viewpoint however, stemming from an upsurge in  scientific investigation into karst processes in the 1970s.

Throughout Australia cave managers have realized that in most cases existing lighting and walkways, and provisions to keep the caves clean are unsuitable, with many developments remaining relatively unchanged from the early part of the century.  Newdegate Cave is certainly in this category at the moment, as the last major developments in the cave occurred in the late 1960s when wooden walkways were replaced with concrete structures, significant areas were rewired, and new switching stations were installed.  Most of the developments did not however consider the sustainability of cave formations, sediments or biota, and the impacts which have occurred since the cave was first opened for intensive tourism in 1939 have continued to increase the visitor numbers.

These impacts fall into the following categories:
1) Introduction of foreign materials - materials introduced during development.
2) Materials brought in by visitors - dust and organics, seeds and spores.
3) Problems caused through inappropriate lighting.

Likely deterioration if no action is taken

In general terms, the sooner that these issues are addressed the easier the job of rectifying the damage will be, and the scale of impacts will be proportionally lessened.  The following examples illustrate the necessity for swift action. 

As deposition of calcite is an ongoing process the more time that is allowed to elapse between the introduction of sediments and/organics etc onto active flowstone surfaces and its cleaning, the harder the surface will be to clean and in many cases it will be impossible to clean.  In some cave areas weak acid has been used to dissolve the surface film from formations in order to remove incorporated sediments.  This practice is not acceptable in caves in Tasmania's National Parks as the risk it poses to the cave ecosystem does not justify the gains which may be achieved. 

Similarly, where sawdust has been introduced and is adhering to speleothems humic acid will continue to leach from the deposits and will continue to etch the surf.-ice until removed.  Where lampenflora exists speleothem surfaces will continue to be etched and in some cases algae will be further incorporated into the crystal structure, staining the speleothem green or blue. 
Bulk debris such as disused wooden stairways etc will continue to decompose, providing an unnatural source of nutrients for the system, whilst oxidation of different metals present in disused electrical systems, light fittings and handrails will continue to stain the surfaces on which they rest. In the absence of effective track definition natural cave sediments and speleothems will continue to be eroded by visitors.

In order to clean the cave without the risk of further damage it is imperative that cleaning takes place as soon after introduction of foreign materials as possible.  As outlined below, the sooner a program of track definition, drainage modifications, cleaning and re-lighting is commenced the easier it will be to maintain original features in as natural a state as possible.

It would be unacceptable to begin cleaning much of the cave before drainage, water supply and storage, and sludge pumping facilities are constructed.  The waste water would merely be flushed deeper into the system, affecting previously unaffected areas, and concentrating harmful materials in sumps and pools below the presently developed tourist section. Removal of bulk materials has already begun, and should be continued.  Identification of lampenflora is in progress, as are trials of methods used to kill existing infestations. Limited cleaning of sawdust, lint and silt deposits has been carried out in the recent past. However, only a small proportion of the total problem may be addressed prior to the establishment of appropriate infrastructure to cope with relatively large amounts of water necessary to effectively clean the majority of the cave, the runoff and dead plant material from treated lampenflora and the development of a more appropriate lighting system.

REHABILITATION AND ONGOING MAINTENANCE OF NEWDEGATE CAVE

This rehabilitation plan has been devised in order to return Newdegate Cave, its contents and associated ecosystems to as natural a condition as possible, and to maintain the cave and its contents in this condition given the use of the system by approximately 40 000 visitors per year. It is difficult to predict to what extent the natural systems of the cave may be restored, as very little baseline information exists, and visitor impacts have been addressed in only a piecemeal fashion for the five decades that the cave has been open to tourists.

As noted in Part 1, the natural carrying capacity of most cave systems is effectively zero humans. In comparison with most surface ecosystems the cave environment has almost no capacity to restore itself after an impact has occurred.  Cave managers must be aware of the rate of natural change within a cave system, the effects of accelerated change due to visitation, and the most up to date methods of addressing impacts on the system without unknowingly exacerbating the  problem locally or spreading problems any further from the impact site.

The collection of adequate baseline data for the Newdegate Cave system will only be possible after many years monitoring of natural systems in order to account for the high natural variability of the local ecosystem.  The present lack of baseline data does not however preclude taking steps to rehabilitate the system in the short term.  The scale of visitor impacts to date deviate sufficiently from baseline conditions that a reasonable estimate may be made of measures necessary to return the system to an approximation of its natural state.  The system may then be more finely tuned as useable amounts of baseline data become available.

Setting up such a monitoring system is beyond the scope of this report, and should be addressed as part of an ongoing management plan for the cave and reserve. This plan draws on personal experience gained from cave rehabilitation projects throughout Australia and on documentation of projects worldwide.  It reflects, as far as is known, the state of the art in all areas of walkway and illumination design, cleaning techniques and maintenance procedures.  Some of these areas have attracted far more interest and research than others. Electrical systems and lighting design for example are presently progressing rapidly with the introduction of low voltage lighting systems, the use of optical fibres and miniature and automated switching systems. On the other hand much research still needs to be undertaken in the areas of lampenflora control and ongoing cleaning procedures.  Trials of different materials and procedures are proposed for these areas. 

The plan is divided into ten sections, each concentrating on a specific, interrelated set of issues.  Each section briefly describes these issues (and should therefore be interpreted in the light of Part 1 where a more holistic approach is taken) then describes the proposed management response.  Individual objectives, related actions, costs and time scales are tabulated, then specific technical details are provided for each aspect of the program.  In the final section a timeline for completion of the project is presented, along with a proposed maintenance schedule, to be followed after the original redevelopment is completed.

Implementation of the proposed plan will rectify past and ongoing degradation caused by inadequate infrastructure and practices thereby restoring the unique show cave near to its  natural condition.  Measures are provided to control visitor impacts on the sensitive cave  environment.

On completion the project will dramatically improve the tourism product and provides scope for increased visitation during selected periods without compromising the cave environmental management principles.

The project focuses on the following key areas:
Walkaway surface upgrade and restoration to prevent tracking of sediments.
Installation of shoe washing facilities and matting to minimize introduction of foreign materials.
Defining walkways and assembly areas to protect cave formations.
Installation of curbing, pathway drainage and refuse system to contain and remove introduced sediments.
Reticulated water installation to facilitate cleaning programs.
Installation of pathway and emergency lighting systems to eliminate lampenflora growth and improve cave aesthetics and visitor safety.
Removal of all introduced foreign debris detrimental to the cave ecosystem.
Intensive cleaning and washing of walkways and delicate cave formations.
Major upgrade of lighting system and electrical services to improve cave presentation and aesthetics.

It must be stressed that this is not a management plan for the cave or the reserve as a whole. Numerous issues such as the limits of acceptable change within the system, visitor numbers both per tour, per day and per year, interpretation of the karst, monitoring of both baseline and visitor induced variations to natural processes, and the protection and development of the reserve surrounding the cave are beyond the scope of this plan and must be addressed in an overall management document.  This rehabilitation plan merely forms a part of an all encompassing management plan which is sorely needed for such a significant and popular reserve.

PLAN OF NEWDEGATE CAVE

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