people have come this way since
1st May 2001
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An extract from an article by Jonathan Wright - "Carbon Dioxide: A danger underground"
Since the extremely high water levels experienced during February and March 1990, concentration of carbon dioxide has occurred at the water levels within the mine. The first occasion, when the matter was brought to our attention at the Caves was at the beginning of April 1990, after a caver had been down to the pit bottom area and was unable to light his 'roll up'; after cursing his lighter he then began to wonder whether there was a more serious implication.
We took a Draeger hand pump and the appropriate tubes down to pit bottom (where the oil is) we used candles to help check the oxygen levels; half-way down the incline, towards the shaft the candle would not remain alight. In order to check the air down by the shaft I walked into the bad air holding my breath and took a reading which showed a CO2 concentration of 5.25%!
The CO2 levels are variable and appear to increase as the water level rises.
The cause of the problem is not clear, some cavers have said there has always been this level of CO2 and no-one has bothered to measure it before (like Radon?)!
The problem came to light after the extremely high water table during the winter of 1990, although I believe that the air has always been suspect. The water may have pushed 'old' air from out of pockets particularly from within the shaft. Sewerage and rotting materials over the years may have taken their toll, using up oxygen and increasing CO2 levels during their breakdown.
Carbon dioxide is abundant in limestone rock, sometimes the rock can reach a purity of up to 98% calcium carbonate, giving a carbon dioxide content of 44%! Carbon dioxide is extremely soluble in water, forming carbonic acid (CO2 + H2O = H2CO3). Calcium carbonate when either heated or treated with an acid gives off carbon dioxide; CaCO3 = CaO + CO2
Some of the old miners we have talked to remember 'bad air' in the mine particularly in the Sling Mine area. Since the shafts have been filled, the problem would not have improved. Recently John Pit on the Sling gale was infilled making matters considerably worse as this shaft was draughting towards New Dun and providing some ventilation to the pit bottom area.
Jonathan Wright
June 91.
Caves & Caving - Update by Forest of Dean Regional Correspondant Paul Taylor
The situation appears to be at an almost stalemate situtation. Although the local council have issued an enforcement order (120 days to comply) the site owners have now changed the name of the company and installed a new set of directors, this being a possible way around picking up the bill for the removal of the infill/pollution.
A company has been employed, we are informed, to carry out tests and prepare a report on what is going to be required to empty the shaft.
With Greenpeace now involved and their own report indicating the inclusion of PCBs and other similar chemical cocktails, the cost is likely to be very high and not one that the site owners are going to want to pay.
The inference is that even with the shaft emptied, access to the lower reaches of the system is likely to be restricted by the installation of grilles, something that the Forest of Dean seems to be getting over its fair share of.
Caves & Caving - Update by Forest of Dean Regional Correspondant Paul Taylor
For a long time now the general caving fraternity have been unable to gain access to the Old Ham - New Dunn - Old Bow complex of mine passages without being accompanied by a mine deputy.
Even with this person present on the trip, the lower levels of the mines have still been well out of bounds.
This situation was brought to about by the spread of contaminated air within these levels caused by the vast levels of pollutants that over the years have been tipped down the mine shaft from the engineering works around the shaft top.
There has over the last few years been much lobbying and complaining done by various bodies, concerned people and companies. A variety of writs have been issued and numerous plans put forward on how to deal with the problem and clear up the site. Until recently these have involved vast sums of money and a total stalemate position had been reached.
It is pleasing to report that an acceptable, workable and realistically priced plan has been put together and work is now underway on removal of the pollution.
Full details have not as yet been released as to the extent of the work or to what depth they intend to go, however I think it is fair to say that any move is a move in the right direction and I'm pretty sure that those who have been responsible for the pollution in the first place are very unlikely to carry out any similar acts.
Hopes are high within the local caving community that the work will lead to a clearing of the bad air and a subsequent return by cavers to the lower mine levels.
Snippet of Info from the GSS
A borehole has been drilled down into the mine to monitor the atmosphere by the Environment Agency but there is no open access as there are still high levels of CO2 in the lower levels.
It is possible to arrange higher-level trips with leaders from Clearwell Caves and RFDCC
THE ROYAL FOREST OF DEAN CAVING CLUB
NEWSLETTER No 132
Trip Down New Dunn Mine, Bethan Stallwood Ph.D
Since being made aware of the waste that has been dumped down a shaft to the New Dunn Mine, I decided it would be a great idea to get the students at the University of Gloucestershire involved. As a result, an entire 3rd year course was based around the contamination; both in trying to determine the nature of the contamination, and in terms of trying to find a solution.
It was my intention that I would provide the students with a sample collected from the bottom of the shaft. However, the students became so interested in the case study, it was thought that a trip down New Dunn Mine was required.
Therefore a trip was arranged to take the seven students (most of whom are studying Environmental Management or Environmental Science) and me down the mine. They were to be accompanied by local cavers, John Hine aka 'Mole', Ladi Broadman and Jonathan Wright and we would go to 400ft, to see the problem first hand, and to collect some more samples. But things weren't quite as simple as that.
The Mines' Inspectorate had worries over the low O2 levels that are known to occur at this depth (due to the contamination). Initially it was requested that we all carry emergency O2 packs, but after discussion (and presenting data which showed the oxygen concentrations had been consistent over the past few months), it was agreed that we could journey down the mine, so long as the oxygen levels remained above 19%.
The night before our expedition, Jonathan and Craig Cameron (another local caver) went down to the base of New Dunn Shaft to verify the state of the atmosphere before taking us down. So, on the morning of Friday 31st March 2006, we set off (with all the necessary safety equipment, including a flame safety lamp and multi gas meter). Many of the students had not been caving before, and the confined spaces and squeezes were met with some trepidation (and near tears). But they all soldiered on, and about 2 hours later we had the shaft full of waste nearly in our sights.
A Lesser Horseshoe bat was spotted just in front of us, but the flame safety lamp was beginning to flicker, and the oxygen meter read 19%. Jonathan had no choice than to call us to a halt. Everyone was bitterly disappointed. But we were close to the shaft, and the students got a real sense of the cave system and the devastation the waste was causing. They could also appreciate the logistical problems for the remediation of the mineshaft. Reluctantly, we began our ascent, somewhat disappointed, but with renewed vigour to help find ways to solve this long-standing pollution problem.
Back in the laboratory, we wanted to find out whether bioremediation could be employed to clean up the organic component of the waste. Bioremediation involves the harnessing of microbes to break down contaminants into carbon dioxide and water. The method is used routinely in the remediation of contaminated land, as well as on disasters such as the Exxon Valdez and the Sea Empress.
For our experiments, microcosms were set up with samples that had been collected previously. These were simple microcosms; 25 grams of the tarry sludge in a flask. To these, one or a combination, of: plant food (N:P:K), mushroom compost, a liquid medium especially formulated to encourage bacterial growth, a bacterial culture and water, were added. The microcosms were then incubated, and then were sampled after 4 weeks and then again after 12 weeks. ALcontrol, a commercial analytical chemistry lab in Cheshire, kindly agreed to do all the analysis free of charge, as they too were interested to see whether the sludge could be bioremediated.
The analysis of an initial sample of the nasty, tarry stuff oozing from the heap of waste and making its way down various tunnels (including the one leading to a major water body) showed it to be weathered petroleum and oil. It was found to consist of 30% aromatic compounds, many of which were polyaromatic hydrocarbons. There was also a high percentage of resins and asphaltenes.
In the best-performing microcosms, by the end of the experiment (after 12 weeks) the petroleum hydrocarbons had decreased by 57%, and the resins and asphaltenes by 37 % and 10% respectively. These results are really encouraging, as these are amongst the nastiest components of the oil. All of the results, for that matter, are encouraging, as so much of the sludge has been biodegraded in just 12 weeks.
This research is on-going, as I am writing this, there are students frantically analysing the results, and preparing to give a seminar on the contamination of the New Dunn Mine, and how it can be cleaned-up.
The students have thoroughly enjoyed being part of such an interesting and tragic contamination issue. I would really like to thank all those who have helped us with this work, especially Jonathan Wright.
Bethan Stallwood Ph.D.
Lecturer in Biological Sciences, University Of Gloucestershire
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