NEW CAVES FOR OLD: CLEANING, RESTORATION AND REDEVELOPMENT OF SHOW CAVES
ABSTRACT
The high number of visitors in most show caves creates special pollution and maintenance problems of a type not usually found in "wild" caves. The contaminants, techniques for their removal and preventative measures are dealt with. By today's standards early development methods leave much to be desired. At Jenolan Caves various means have been devised for correcting the damage caused in an era when the concept of cave management hardly existed.
INTRODUCTION
This paper endeavours to cover the following aspects in the management of show caves:
- The nature and sources of contamination.
- The equipment and techniques for cleaning speleothems.
- The type of redevelopment needed to minimise future contamination.
- The restoration of areas damaged by the 'mistakes' of earlier times.
Most of the material presented relates to Jenolan Caves; not just because of the authors' proximity, but more deservedly so because the staff at Jenolan have clearly done pioneering work in this field. Experience in other countries is referred to when appropriate.
It must be admitted that back in 1961 when the speleological fraternity first heard that the show caves at Jenolan were to be steam cleaned, there were expressions of shock and dismay. The very idea of taking such a noisome piece of industrial machinery into the pristine cave environment, just showed how uncouth the guiding staff could be.
Of course, as events unfolded, it was soon revealed that the show caves were a long way from being pristine. They were in fact, in many areas, unbelievably filthy. The steam cleaning move was to be the first step in a long saga of cleaning, redevelopment and restoration that has continued to the present day.
BRIEF HISTORY AND BACKGROUND OF THE JENOLAN EXPERIENCE
The caves were discovered by Europeans in 1839 (Havard 1934, Dunlop 1967). By 1848 some public inspections were taking place. With the appointment of Jeremiah Wilson as Caretaker in 1867 they became more organised.
On July 22, 1880, electric light was used in the Margherita Cave (Havard 1934). The claim that this was the first use of electric lighting in any cave in the world has yet to be challenged. Visitor numbers by early 1890 had increased to 1500 per year (Dunlop l967).
Lighting of the Imperial Cave was finished in 1887 and it appears that by the turn of the century no candles were being used for regular inspections. Subsequent discoveries were all developed with electric lighting before being shown.
Some cave inspection figures for this century are:
1911 - 21325 (Dunlop 1967)
1926 - 83985 (Dunlop 1967)
1966 - 160000+ (Dunlop 1967)
1984 - 212000 (E Holland, pers. comm.)
The total length of the show caves is over 7km making Jenolan the third longest system in Australia (R Ellis, pers. comm).
In the late 1920s eleven caves were being shown. However, closure of the more difficult and less attractive caves, had, by 1951 reduced this number to eight (Newbould 1974). This fact, coupled with greatly increased visitor numbers, naturally put a heavy load on the remaining caves.
The "different" show caves at Jenolan are, in fact, all part of the one system, intersected by a large arch. For example, to see the 'Jubilee Cave' it is necessary to walk the length of the 'Imperial Cave'.
The awareness of widespread pollution and the first tentative steps to deal with it began soon after the appointment of Mr F Harman as Senior Guide in 1955 (Newbould 1974). Mr Harman had been guiding some ten years prior to his appointment. He was in a good position to observe the correlation between the increased visitor numbers and the rapid discolouration of speleothems in all caves.
Experiments with detergents and scrubbing brushes proved that much of the contaminating material could be removed, but a more efficient process was required.
Harman conceived the idea of steam cleaning the caves. Enquires around the world for any better ideas provided fruitless, so eventually, in spite of considerable unease, the first experiment with a steam cleaner took place in the Orient Cave in May 1961 (Newbould 1974, 1976).
The process appeared to work but some equipment problems had to be sorted out. It was not until March 15, 1968, that full time work on the Orient Cave got under way. Redevelopment work began at the same time in this and other caves. The Orient work was completed on September 30, 1972, and the cave reopened October 1, 1972 (Newbould 1974).
Although some early problems with the steam equipment were overcome there still remained enough to cause a reluctance to move on to the other caves.
The Senior Guide of the time, Mr J Culley, was intimately aware of these problems and the time scale involved. If the time to do the Orient Cave was multiplied by all the other caves it didn't bear thinking about.
In 1976 he saw an industrial high pressure water cleaner at work and immediately saw its possibilities in cave cleaning. Work began in the Imperial Cave in February, 1976, using such a cleaner. Its success in time saving at least can be measured by the fact that all the caves then being shown, including the Orient, were cleaned within eight years.
Restoration and redevelopment proceeded apace of which more will be said later.
THE CONTAMINANTS
NATURAL PHENOMENA
i Atmospheric dust and bushfire smoke
In well ventilated caves these make up some of the natural contaminants and it is of course questionable to what extent these should be removed, if at all.
ii Cave Fauna
Bats in particular and some bird colonies can make quite a mess - dropping excrement by the tonne, staining decorations and attracting a whole host of other inhabitants. However unsightly this might be, it would be universally accepted that this is part of the natural environment and that cleaning operations would not be permitted anywhere that might disturb such colonies.
CONSEQUENCES OF DEVELOPMENT WORK
iii Cave Soil
In some cases it was simply a matter of cave soil getting into areas where it shouldn't be. During wet periods visitors transport mud on their shoes to formerly clean parts of the system - or splash it directly on to nearby decorations (Newbould 1976). Track cutting has in some cases unwittingly interfered with natural drainage patters causing muddy water to flow across crystal floors. In drier periods the soil can rise as a dust cloud to be deposited over a much wider area.
Moving on to the man made contaminants the list is almost endless.
iv Smoke from early lighting
Tallow and sperm candles caused smoke discoloured patches on the walls and ceilings of the older caves (Havard 1934).
Even after electric lighting was installed larger features continued to be lit for some time by magnesium ribbon (Dunlop 1967).
The magnesium fallout, being mainly a white powder. probably has not caused much visual pollution; but it could certainly confuse any close analysis of cave deposits.
Acetylene lighting was never installed at Jenolan, but where it has been used in other caves the soot problem has been severe (Hamilton-Smith, pers. comm).
v Soot from coal burning fires
In 1954 an access tunnel was driven into the Orient Cave (Driscoll 1977). It has been suggested that the close proximity of a boiler house and the coal fires in the Caves House added to the pollution of the Orient Cave. It was not until some seven years later that a second airtight door was suggested (Newbould 1974).
vi Boiler Ash
The above mentioned tunnel was initially paved with clay and boiler ash (Newbould 1974). This mixture was carried on visitors' shoes directly into one of the best show caves at Jenolan.
vii Broken Glass
From numerous broken light bulbs. Chips of glass were found, rather painfully, when bare hands were used to gather debris from the bottom of pools (R Guy, pers. comm.).
viii Pitch
Used to seal electrical work. Fortunately not that much of it, but where it has dribbled onto flowstone it is very obvious and difficult to remove.
ix Cotton and Rubber
Some sixty years ago visitors were not only being electrified by spectacular cave scenes. The cotton and rubber insulation on the electric wiring was rotting away to the point where in 1920 it had to be replaced with lead sheathed cables (Dunlop 1967).
x Verdigris
It was common practice for early electricians to secure cables with short lengths of copper wire cemented to a suitable surface - usually best quality flowstone. When sufficient moisture is present a green stain will surround these points.
"Wishing Wells" collecting coins for charity were in use at least until the 1950s. The practice has since been discouraged but some coins are still thrown. Green stains can still be seen around one of these "wells" (CD Bramston, pers. comm.)
xi Iron
Fortunately most of this remains concentrated in the form of junk - old handrails, platforms, tools et cetera - tucked in odd corners of the system. Kept out of sight it does little harm. The more obvious problem is in ironwork where electrical spikes, stanchions et cetera have removed. Often again from best flowstone.
xii Wood Sap
In Yallingup Caves, Western Australia, metal screws and spikes were driven into wooden wall plugs. The wood produced sap stains which are particularly difficult to remove (E. Hamilton-Smith, pers. comm.).
xiii "Archaeological" Material
A recent restoration work party stumbled across what might be called an early track workers' site. Billies, home made thermos flasks and similar items were found. A more curious find emerged as layers of rubble were removed - pieces of newspaper spaced some distance from each other and the main site.
These were taken out and carefully spread on the guides' lunch table so that their historical value might be better determined. The full significance of what they were all studying so closely did not dawn on them until someone pointed out that each and every piece of paper bore a characteristic brown stain (E Holland, pers. comm.).
xiv Lampenflora
A green biological growth associated with the introduction of electric lighting. It is normally limited to areas within a metre or so of light sources and is rather easy to deal with (Lefevre and Laporte 1969, Nelson 1975, Johnson 1980, ASF 1983, Stelcl 1984).
xv Litter
The usual items - paper, food scraps, tissues, children's toys et cetera are mostly close by the track and easily removed. Babies manage to hurl their dummies a surprising distance. There was at least one instance at Jenolan where a beautiful crystal grotto was stuffed with a soiled baby's napkin (D Bamston, pers. comm.).
xvi Graffiti
As all the show caves at Jenolan are gated and tourist parties fairly closely controlled, this has remained a minor problem. Typical graffiti is applied with pencil, crayon, lipstick or scratching.
DETRITUS FROM VISITORS
xvii
Some of the sludge collected during cleaning operations has been analysed and shown to be particles of human skin (E Holland, pers. comm.). The small amount shed by each visitor must start to become significant in caves loaded with tens of thousands of visitors per year. This could account for the strong smell of decaying biological matter reported where sludge has collected in pools and sumps.
Human hair is another item that can be clearly seen in the gutters along heavily used trails.
Rubber, leather and plastic from footwear is another inevitable input. At Chillagoe Caves it is evident that the use of expanded metal on raised paths has accelerated this problem (E Hamilton-Smith, pers. comm.).
But the most surprising and most abundant contaminant of all was revealed in a Department of Mines report to be lint (Newbould 1974). The textile fibres shed by visitors' clothing remains to the present day the major form of pollution at Jenolan (Newbould 1976).
Where it has fallen on active flowstone it has been encapsulated in fresh calcite and turned sparkling white surfaces to a dull grey black colour.
Where air currents have carried it aloft it has collected on roof decorations in the form of beards and streamers more reminiscent of a textile mill.
Close to busy trails it can be scooped up by the handful.
The problem of human detritus is not new. In the so called "clean rooms" of science and industry it has long been recognised and dealt with by continuous filtering of the air supply and clothing visitors and workers alike from head to toe in especially "clean" garments - a solution hardly acceptable in caves.
The point to be made here, is that unlike many of the other contaminants, human detritus is a continuous daily input to the caves while ever they are being shown. If they are not to become stinking lint lined tunnels this material must be removed at regular intervals.
This list is not meant to be exhaustive. It obviously does not cover the problems faced by cave systems close to settled or industrial areas. Jenolan is especially fortunate in being surrounded for the most part by reserve and forest lands. It seems fairly safe even from agricultural chemicals. There seems to be a sewage problem of some sort but even this appears to be from mostly downstream of the caves.
Before moving on to cleaning methods, the staff at Jenolan have pointed out that in many caves there are large areas that either cannot or should not be cleaned by any of the existing techniques.
Mudbanks obviously cannot be touched with any pressure medium. What appear to be bare limestone walls are often coated with a soft surface breakdown material and/or a fine crystal structure. Removal of this would destroy a large part of the caves natural character.
CLEANING MACHINES
Steam Generators
The Chief Guide at the time, Mr F Harman, requested an electrically powered generator right at the start, but, as such a machine could not be located, the first machine used at Jenolan was kerosene powered. The results of the cleaning process were described as excellent, but the machine itself was rejected because it produced soot (Newbould 1974).
A second machine from another company was tried. Water was flashed directly into steam within a small combustion chamber close to the output nozzle, but tests showed it was not satisfactory.
Propane fuelled machines are not available that would have a much cleaner exhaust. However, any oxygen consuming machine could be a danger to the operators in small badly ventilated caves.
An electric machine was eventually found but it needed changes to make it more portable. The main components were modified so they could be moved separately and then reconnected at each working site. This machine of course solved the soot and fume problem but it required too much electrical power (30kw) for it to be connected to the cave lighting system. An especially heavy supply cable had to be fed into the cave to run it. The machine was still heavy and the steam hose clumsy to use. Even today there is no electrically powered machine that would overcome these problems. In spite of these difficulties it was used to clean the Orient cave completely, taking some 480 days (Newbould 1974, Belfield 1977).
The Orient consists of several high roofed chambers with hardly a metre not decorated in one way or another. The only equipment provided for gaining access to the walls and ceiling was a scaling pole, wire rope ladders and some ropes; items designed formation, not everyday working. It is a tribute to the climbing of Ron Newbould and dedication of all concerned that the job was done at all.
High Pressure Water Cleaners
Two early model machines were still in use at Jenolan. These machines deliver cold water at a pressure of approximately 750 psi (Anon 1976) at the rate of approximately 2.5 GPM. ¾" garden hose is used for the input supply.
From a practical operating point of view this type of machine is a long way in front of any steam generator.
It is light and compact enough to be easily moved by one man. Current models of the above mentioned capacity weigh only 50 kg.
It has a low power requirement. The Jenolan machines use only 1.5hp (2kw) and can be connected to the cave lighting system.
The pressure hose and the gun are both very light.
In most cases a cave need not be closed while it is being cleaned.
"Difficult to get at" walls and ceilings may be cleaned from a distance using the long "effective reach" of the water jet. This reduces the risk of floor damage by equipment or boots. The need for climbing equipment is also minimised.
These machines are now available with a wide range of features: various power sources, hot or cold water, detergent mixing and pressures up to 69000 kPa (l0000psi). There is a "baby" machine about the size of a shoe box that delivers 2 gallons/minute at 400psi and weighs only 5kg (information from Anderson Cleaning Equipment Pty Ltd). For cave cleaning the value of hot water or detergent is questionable. From the Jenolan experience there would seem to be little or no advantage in pressures higher than 750psi. In fact any higher pressures could result in serious damage to calcite surfaces.
Vacuum Cleaning
At Jenolan some experiments have been carried out on dry powdery speleothems using a domestic vacuum cleaner. The experiment was limited by the equipment available but it appeared to have possibilities (E Holland, pers. comm.).
Probably the output, that is the pressure end of a domestic cleaner would be a safe way of blowing dust off. The problem would be to collect it before it settled elsewhere. A high volume filter unit that could pull in airborne dust at a range of 1 or 2 metres would be needed. This technique could be applied to speleothems that would be damaged by even the gentlest flow of water. On the other hand industrial cleaners that pick up steel swarf would easily pick up dense pockets of lint close to trails before it is washed into areas more difficult to clean. At this stage such ideas are speculative.
EFFECTIVENESS OF MACHINE CLEANING
Steam versus Water
It should be pointed out here that neither process removes the contaminant. It is simply loosened and blasted off elsewhere - usually over previously cleaned areas and the operator. Both processes do this quite well and any difference would be marginal. The overall result is highly dependent upon preparatory work, operator skill and post cleaning operations of which more will be said later.
Steam or hot water can be used to kill off lampenflora. Although no experiments took place at Jenolan, overseas reports show a high success rate. If surface temperatures of 70°C or more can be held for a minute almost all plant material can be killed (Aley 1972). On hard surfaces steam does an excellent job (Williams 1975). There are reservations however. Where algae is growing in crevices the heating medium will not reach and it may regenerate. If excessive heat and pressure is used on soft or crusted surfaces serious damage can occur (Lemon 1975).
Fragile Speleothems
It is obvious that the full working pressure of either steam or water machines cannot be applied to straws, helectites, shawls et cetera. Long straws cannot even be approached. An instance was reported at Jenolan, where a long straw began to vibrate when a water cleaner was in use on other decorations some 6m away.
Shorter straws, say 0.2m, can be approached with care. Side loads are clearly dangerous. The columnar strength of straws is much greater, and this fact was used to advantage during steam cleaning by directing the steam flow from a point vertically beneath them (R. Newbould, pers. comm.).
In general, fragile items are handled either by reducing nozzle pressure, or by keeping it well away. In the case of steam, it was allowed to drift onto surfaces where dripping condensate would do the cleaning, rather than any direct force from the machine. At other times only warm water was used. Sometimes with detergent in the water and the heat cut back further, a mass of soapy bubbles was allowed to exude over helictites (R Newbould, pers. comm.).
In the case of the high pressure water machines in use at Jenolan the working pressure is fixed, but they have two sizes of round jet nozzles and one fan jet. The latter is used to create a fine mist, directed from several metres away at the items to be cleaned. Even without detergent this has proved to be quite effective. The mist, coalescing on dirty straws and helictites returns to the floor as "black rain" (E Holland, pers. comm.).
Detergent is no longer used in any of the cleaning operations at Jenolan.
Removal of Graffiti
Pencil can be removed fairly easily. Crayon and lipstick are more difficult (J Culley, pers. comm.).
Where it occurs on surfaces that are not to be washed, the cleaned patch can be almost as objectional as the graffiti. A "feathering" technique is used at Jenolan to ease the transition between the cleaned and uncleaned areas.
Calcification of Contaminants
Sometimes hours or even days may be spent changing a dirty grey lump of stone into a sparkling white display. It can be very disappointing for an operator to find, after all this work, that one black patch resists all efforts to remove it. The contaminants have, of course, been trapped under fresh calcite. Assuming some process was available, should this material be removed? This question was put to the staff at Jenolan, but there was a natural reluctance to commit themselves either way.
Perhaps the wisest answer came from John Culley (previously Senior Guide and now Senior Ranger). In his 25 years at Jenolan, he has seen much regeneration. If entrapment has occurred, the area is still active or is likely to become active again. His answer is patience; in time the calcite will build up a sufficient thickness to heal any discolouration.
Extending this idea further, in cases where a drip appears to have dried up permanently there may be a case for temporarily installing an artificial drip of a suitable solution with controls for optimum build up rate.
Bruised Calcite
The water jet is quite effective for removing the unsightly impact marks made by picks or rocks. The chalky material and broken crystals are flushed out leaving only the small change in surface level which is much less obvious.
DAMAGE BY MACHINE CLEANING
Surface Damage
On hard surfaces steam is unlikely to cause any crystal damage providing nozzle temperature is kept below 100°C (Aley 1972, Lemon 1975).
Water pressure at 750psi is safe enough on suitable surfaces. Higher pressures should be avoided.
Breakages
This is one area where steam could be said to have an advantage. A short distance from the nozzle the energy level begins to dissipate very rapidly. Distant items are therefore protected from inadvertent movements.
A solid water jet on the other hand retains a high level of kinetic energy even at a range of 10 to 20 metres. Promiscuous spraying by a careless operator could destroy a whole cavern full of decorations within seconds. The answer of course is that careless operators should not be allowed anywhere near a cave system. Breakages have occurred from the use of both steam and water: but of course all operations in a cave put speleothems at risk - whether it is using a broom or changing a light globe. The low percentage of breakages is a small price to pay in view of the overall improvement to the cave environment.
EFFECT ON CAVE FAUNA
Unfortunately, at Jenolan, no formal examination of the cave population was undertaken before or after any of the cleaning operations. However, the guides have been interested in this question and their casual observations are as follows:
In the Orient Cave, faced with steam and detergent, the population moved out. Later, when the cave was being hosed down with clean water the cave life returned (Newbould 1974).
The impression gained during high pressure water cleaning is that certain creatures - springtails and wetas - seem to be attracted to the areas being cleaned. Areas near bat chambers have been cleaned with no obvious effect on bat activity or population
MANUAL SPOT CLEANING
A hand powered knapsack spray has been found useful for small areas in the interval between major cleaning runs.
Lampenflora
While the purist might favour steam over chemicals there seems to be ample evidence that the right chemicals in small doses to negligible harm to the cave or its inhabitants. Household bleach (sodium hypochlorite) has been used at Jenolan with good effect. Calcium hypochlorite has been suggested in some quarters as being preferable because any residue would be more compatible with the cave environment (Rohde & Kerbo 1977, Johnson 1980, Rohde 1982). A butyl-alcohol concentrate has been used in the Congo Caves with success (Oosthuizen 1981).
It is interesting to note that a patch of green algae on "Lots Wife", in the Imperial Cave, could not be shifted with the high pressure water cleaner. After bleaching solution was applied for a few minutes, there was nothing left but the smell of chlorine (K Oliver pers. comm.).
Graffiti
Hydrochloric acid has been used with some success (Knutson 1974). One technique for rock walls is to apply a paste consisting of dilute HCl and cave mud. The mud keeps the acid in contact with the affected area and helps to preserve a natural colour. On calcite surfaces a stronger solution (without mud) is applied and then rinsed off once it has done its job (J Poleson, pers. comm.).
General advice seems to be - practice on broken pieces first and use cautiously (Plantz 1977).
Graffiti on mud coated walls can be smoothed over using the fan jet at an angle (K Oliver, pers. comm.).
It should be mentioned that the graffiti of early explorers is usually considered to be historic material and is left in place.
Rimstone Pools
The cleaning of these and other floor areas containing loose or friable material can be the most time consuming job of all. Because most of the loose material may be natural and may include oolites, most high velocity cleaning is out of the question.
Sometimes these rimstone pools fill with a thick stinking sludge washed down from areas being cleaned above them this must be scooped out, usually by hand, into buckets and taken outside. When the sludge is more liquid it can sometimes be siphoned out. Repeated flooding with water will allow some of the lighter material to be picked off rims.
The floor area has to be worked over inch by inch for foreign items - stone chips, slivers of glass, litter items et cetera. Bare feet, knee and elbow pads are essential. The whole process can take days for one pool.
GENERAL ASPECTS OF WATER CLEANING PROCESSES
Operator Safety
No one should work alone - especially when climbing or using machinery.
Eye protection is a problem when using the high pressure cleaners. Water and grit ricochet back to the operator from all directions. Conventional safety goggles quickly become splattered and grit laden water often still finds its way down into the operator's eyes. When working near fragile items, operators often remove their goggles so they can see better where the jet is and what it is doing (R Guy, pers comm.).
When one considers that it is not just grit, but all sorts of biological material - fungi et cetera - that the operator's eyes are exposed to, it is clearly a dangerous situation. A fully waterproof headpiece, such as used in the chemical industry, would have to be an improvement. Some screening of the viewing lens might help reduce the splatter problem
Wet weather gear is usually worn, but only to keep the dirt off. The operators end up soaked by high humidity and water down the neck.
Lighting
The cave lighting system often has to be switched off to protect bulbs from thermal shock, so a good independent lighting system is important. At Jenolan, several 1000W quartz iodine lamps are used - waterproof of course. These are supplemented with miners' cap lamps where necessary.
Water Supply
Lengths of ¾" garden hose have been used for distances up to 200m. The more flexible, the better it will coil up. Rubber should be avoided as it will leave black marks. Industrial hose joiners are preferred because "click on" domestic joiners often click off at embarrassing moments.
In some areas at Jenolan the hose problem has been reduced by piping water through handrails. Modern cave development plans normally include a permanent water supply incorporated in the trails.
PLANNING A WATER CLEANING OPERATION
It is not sufficient to just set up the gear and start spraying. The whole area must be studied carefully from several aspects before doing anything.
Which surfaces can be cleaned and which should be left alone? Are there any fauna colonies? Can some of the dirt be swept up before it is washed elsewhere? Is overspray likely to damage fragile areas? Should spot cleaning be carried out first? Is any restoration work planned? Should it be done before or after the cleaning? Perhaps the most important and most difficult question to deal with is where is the run-off going to end up?
From considering this question it will become obvious that cleaning should start at the high points and move progressively to the low areas. But, the run-off must be watched all the way. Otherwise a previously uncontaminated crystal grotto could drown under a pool of black sludge.
If the lowest point of the drainage is a difficult area such as a series of rimstone pools as mentioned earlier, then it will obviously be worthwhile to trap as much of the sludge as possible before it reaches this point. An important step is to wash down all the cleaned surfaces with low pressure water after the high pressure cleaner has finished.
The whole operation will be a lot easier if development work has been carried out with these considerations in mind.
This brings us to the next section of this paper. It should be made clear that although redevelopment, restoration and cleaning are under separate headings, they are all related, and it would often be futile to perform one without the other.
REDEVELOPMENT AND RESTORATION
Concrete Trails
The first moves towards the current redevelopment ideas began in the late 1950s. At that time, virtually all the trails at Jenolan consisted of cave soil and rubble. Concrete was only used for steps and bridging. The Senior Guide, Mr F Harman, wanted to put down concrete trails. For a while the "purists" said no - natural materials only must be used (F Harman, pers. comm.).
The redevelopment of the Jubilee Cave was probably the turning point. It is for the most, part a low roofed cave with trails cut down through extensive areas of soil - and it is very wet. The impracticality of using soil for trails soon became evident to all (J Poleson, pers. comm.).
There were still objections to the appearance of concrete so, Harman said, "colour it"
Bags of cement were carried in with great difficulty. Water was collected in drums positioned under drips. The work began using a mixture of three parts cave gravel and one of cement. A hand mixer was available, but it was too hard to operate in the confines of the cave so mixing was done in situ (J Poleson, pers. comm.). The result was exactly what was needed - a stable washable surface with a texture and colour that fitted in with the surroundings.
Concrete, coloured with cave soil has been used extensively throughout the Jenolan system. There is still concern expressed about some of the large areas that have been covered. However, some of the staging areas are necessary if a large party is to communicate with and be supervised by their guide (K Oliver, pers. comm.).
Drainage
A very important part of trail building is the control of unnatural drainage from cleaning operations. It is equally important that it not interfere with natural drainage.
A conflict can arise where a trail crosses a sloping active calcite floor. The downhill side could be starved of its normal water supply.
A solution used at Jenolan, is to install a sump, usually under the trail, with an access manhole. These sumps are big enough to act as settling ponds. The overflow water is therefore relatively free of silt and rubbish as it continues on its way over the downhill side of the slope.
Wherever possible gutters and the surface of the trail are sloped towards these sumps. In some cases baffles have been fitted on the grease trap principle, so that floating matter will be caught. In other cases, when no overflow is desirable they are simply holding tanks and must be emptied periodically (J Culley, pers. comm.).
Retaining Walls
In many areas of Jenolan, trenches have been cut through soil and gravel to provide visitor headroom. Stabilising the paths alone has proved insufficient. Children dig loose material on to the paths. In wet periods, the trail drainage may not be able to handle the silt laden run-off.
The trench sides, which still collect a lot of lint, do not present a cleanable surface.
In older areas drystone walls have been used, with good practical results. However, the very construction skill that would be admired outside the cave, detracts somewhat from the natural look on the inside.
An extension of the "natural" concrete idea has been developed for retaining walls. This was first used in the Selina Cave in the Imperial Cave.
Once the footing area has been prepared, a layer of concrete 70-80mm thick and a shovel mouth wide, is laid down. Before it has set, local gravel and soil are thrown into the outside edge. This process is repeated, layer by layer, until the wall is the required height. Discarded ironware is sometimes built in for reinforcing where required. On thinner walls wire netting or mesh, if it is available, is hung off spikes driven into the soil (J Culley, pers. comm.). The layer technique removes the need for formwork. It also introduces "natural" irregularities which would not be present with formwork.
Once again, this "stucco" technique produces a stable washable surface. In many areas it has been carried out so skilfully that casual observation could not pick it from the natural cave gravels.
Removal of Excavation Material
In the past, soil and rubble from the above mentioned trenches was often just dumped each side of the trail. Restoration work has revealed a surprising number of instances where this material covered a crystalline floor. Tonnes of it have been removed and the effect is quite dramatic. Sections that once looked like sewerage excavations are now attractive areas.
Lighting
Work in this area has involved the following:
- Removal of unsightly fixtures and cables
- Concealment of new wiring
- Improved lighting of features
- Reduction of light intensity where possible to minimise lampenflora
The problem remaining in this area is that when outside contractors are doing this work they often ignore advice from the guides and use their own interpretation of the rule book to justify chopping through calcite floors.
Another problem arose from a strange selectivity in funds for redevelopment. The guides' requisitions for proper tracklight shades were refused (J Culley pers. comm.).
In desperation. the guides began using discarded tins - dog food cans were popular and may be seen to this day in various stages of decay. They have since developed a less obviously homemade shade using scrap sheetmetal fashioned by hand in their spare time.
Trail Netting
In earlier times at Jenolan there was a tendency (not without justification) to fence everything. In some cases however. it has clearly been made continuous for no other reason than it must have been easier than stop-start construction. Current policy is to remove or lower it where possible. Sometimes the trail can be shifted to put temptation out of reach. In other cases it is just a matter of relying on close supervision of small parties.
A question hangs over the role that netting plays in the generation of lint. A Department of Mines report suggested that it aggravated the shedding of lint from visitors' clothing and that it be replaced with a less abrasive mesh (Newbould 1974).
The removal of netting in Mammoth Cave, Margaret River appears to have reduced the lint problem (E Hamilton-Smith, pers. comm.). On the other hand, guides can point to heavy lint deposits in sections well away from any netting. There was even a suggestion that where netting is always wet, it actually collects lint before it goes further.
It is probably a question of degree and will not be resolved until deposition rates can be thoroughly investigated.
MEASUREMENT OF DUST FALLOUT
Some preliminary work has been done at Jenolan and is best explained by the following extract from the Journal of The Sydney Speleological Society:
For a substrate on which to collect a dust film it was decided to use glass Petri dishes. These are cleaned, their optical transmission is measured, and they are placed in the position to be sampled. From time to time the optical transmission of each dish can be measured and the accumulation of dust can be recorded. With a number of sampling sites in areas of different characteristics it would be practical. by statistical analysis of the measurements to separate the effects of each factor that can change the rate of dust deposition.
One or more of these factors may prove to be useful to control the rate of dust deposition.
An instrument has been constructed which is sensitive enough to measure a finger-print on the glass plates. It is portable so that it can be taken to the sampling site to measure the glass plates in situ. In addition, measurements of temperature, humidity and air movement at each site will be made. As availability of equipment allows, automatic recording of the cave climate will be done by a self contained instrument system left in the caves.
From these measurements it is hoped that we can separate the effects, if any, of the following factors:
(a) number of visitors
Geometric effects
(b) distance from path
(c) level with reference to the path
(d) distance from the entrance
Cave microclimate
(e) humidity
(f) temperature
(g) air velocity
(h) morphology of the cave
Other effects
(i) seasonal variations
(j) presence of wire mesh" (Michie 1978).
The intitial run proved the obvious - fallout is greatest close to visitor trails. More work over a larger period of time is needed before the above factors can be separated out (N Michie, pers. comm.).
CONCLUSIONS
One of the lessons to be learnt from Jenolan is the damage that can be done by outside contractors who are indifferent to the area. It is imperative that any work in the caves be either performed, or at least closely supervised, by people who have both sympathy for and understanding of the issues involved.
It is easy, as many of us have, to stand back and criticise the work of the guiding staff. They readily admit that mistakes have been made. Only on closer inspection will it be seen that they faced many difficult problems and have solved a high proportion of them in imaginative ways. It must be remembered that they are chosen for their guiding skills - NOT as cleaners, concreters, plumbers, landscapers or metalworkers. We can be thankful that so many of them have taken an interest beyond the call of duty so to speak.
It is also very clear that successive administrations have not supported the staff as well as they might have, especially in the field of technical advice and long term planning. Much of the work done by the guides could have been done quicker and better, had a wider range of materials and ideas been available to them. The older Speleological Societies is one source where a wealth of technical and scientific expertise could be available at minimal cost.
With visitor numbers still climbing, the next few years could be a testing time for Jenolan, a test for the work already done, and a challenge for all concerned to see that short term ideas do not destroy what has been built up.
Recently, the Senior Guide kindly showed the authors through the Imperial Cave. They remembered it as a long dusty tunnel that one hurried through to see more interesting things at the other end. Not any more - crystal floors, not seen this century, have suddenly appeared - the whole place sparkles and Lot's Wife positively glows.
It is a new cave.
Acknowledgements
Elery Hamilton-Smith drew attention to the need for the Jenolan work to be recorded. We are grateful for his advice, information and encouragement
The work could not have been attempted without the close co-operation of the guiding staff - some active still, some retired.
Frank Harman, John Culley, Ernst Holland, Ron Newbould, John Poleson, Richard Guy, Keith Oliver and Denis Bramston.
Many thanks are due for the interviews, inspections that were arranged and the dusting off of old records, photos and memories - some going back thirty years. Much of the information recorded here was compiled from two ninety minute tapes recorded at Jenolan on Sunday, August 11, 1985, during interviews with Ernst Holland, Keith Oliver and Richard Guy.
ADDENDA
High pressure water guns are now available with an infinitely variable pressure control that can be easily fitted to existing equipment. It is a simple flow dividing device that would allow low pressure rinsing at the turn of a knob.
Turret mounted nozzles are also available that would allow a quick change from a straight to a fan jet (information from A J Chown Engineering, Sydney).
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