The following has been received the following from John
Gunn and is passed on for your information.
Alan Wood, Hon. Secretary, National Caving Association
A survey undertaken by John Gunn and Dave Nixon on 29 & 30
July 1999 found dangerously low concentrations of oxygen (down to
18.8%) and high concentrations of carbon dioxide (up to 2%) in
Knotlow. Concentrations of hydrogen sulphide and methane in air
were zero throughout. Water samples were taken and a fuller
report will follow. However, the purpose of this note is to warn
cavers not to attempt to enter Knotlow until further notice.
The Environment Agency has posted warning notices on all
entrances, including the entrances to Hillocks and to Whalf Mine
as a precaution although no direct measurements have been made in
these parts of the system.
Farms in the area are being visited in an attempt to locate the
source of the pollution and, as always, any observations from
cavers would be welcome.
John Gunn, Limestone Research Group (LRG), University of
Huddersfield
An Update
In a previous report it was noted that, as of 24 February, there
were no problems with 'bad air' anywhere in Knotlow and no visual
evidence of water pollution apart from some pink growths in the
level between the base of Fourways Shaft and what will henceforth
be called the Knotlow Farm Engine Shaft to avoid confusion with
other 'Engine Shafts'. The LRG are retained by English Nature to
provide a 'rapid response' capability whereby we visit the site
as soon as possible after a report of pollution and repeat the
air, sediment and water sampling. However, the contract allows
for a maximum of five visits which means that we have to have a
definite reason to undertake sampling. During April and May there
were conflicting accounts from visitors to the system, some
reporting no problems, others 'bad air'. Following these, on 20
May, Paul Hardwick tested the oxygen, hydrogen sulphide and
methane concentrations in air by lowering a meter down the three
shafts:
Climbing Shaft
Chapel Dale Engine Shaft (also known as the 210' of simply as
'the' Engine Shaft)
Fourways Shaft (also known as Crimbo Hollow Engine Shaft)
No evidence of 'bad air' was obtained, and oxygen levels were
>19%. This was confirmed by a party who visited on 31 May and
reported 'no smells' although visitors on 4th & 6th June
reported 'bad smells'. This presented us with some difficulty as
the air monitoring equipment, without which we cannot undertake
any visit to the mine because of Health & Safety
considerations, costs £120 to hire in, and it was decided not to
undertake a full sampling visit until there was a certainty that
there was a pollution problem. This visit was made on 29 July by
John Gunn and Dave Nixon when we also hired in a carbon dioxide
meter which proved to be extremely useful. As on 20 May, the
oxygen, hydrogen sulphide and methane, plus carbon dioxide
concentrations in air were measured by lowering the meters down
the three shafts with the following results:
Climbing Shaft: oxygen > 20%; carbon dioxide <0.5%
Chapel Dale Engine Shaft: carbon dioxide >0.5% @ -20m &
>1.0% @ -35m.
oxygen >19% to base.
Fourways Shaft: carbon dioxide >0.5% @ -20m & >1.0% @
-25m.
oxygen >19% to base.
The lids of the two deep shafts were left open to aid ventilation
and we descended the climbing shaft making continuous
measurements as we proceeded.
The carbon dioxide meter has two alarm levels, the first at 0.5%
and the second at 1.0%. The first alarm level was triggered while
descending the 2nd pitch into Pearl Chamber (S2) and the second
between Pearl Chamber and 'The Chain' (S3). oxygen levels were
declining and the alarm level of 19.0% was triggered at S4, the
junction between the level which continues through two low, wet
squeezes to the Bung Series and a series of climbs down to the
Waterfall Pitch. At this point there was also an intermittent bad
smell but after due consideration we decided, somewhat
reluctantly that a relatively swift trip down to Waterfall
Chamber was justified both to measure the gas concentrations and
to obtain water samples for the Environment Agency.
However, the risks involved in a trip down the north crosscut to
the base of Fourways Shaft were not considered to be justifiable
and a rapid exit was made. The following day [30th July] a return
was made with breathing apparatus and David Nixon descended
Fourways Shaft. The level leading to Knotlow Farm 'Engine Shaft'
was found to be grossly polluted but the Chapel Dale Level was
essentially pollution free so that at the foot of 'Fourways
Shaft' the oxygen concentrations were slightly higher and the
carbon dioxide concentrations slightly lower than in the upstream
part of the mine (Table 1). Hydrogen sulphide and methane
concentrations were zero throughout the mine.
Our current thoughts are that polluted water, with a high content
of organic material, is entering the mine from the Knotlow Farm
'Engine Shaft' and from a bedding plane near the top of the
Waterfall Pitch. One litre water samples were collected from a
number of sites and are being analysed by the Environment Agency.
Officers from the Environment Agency are visiting farms in the
area in an effort to determine where the pollution is coming from
and it is hoped that the results of the water analyses will
provide an indication as to whether sewage or silage is the major
constituent. However, it is important to understand that the
derogation of the air quality is an indirect result of the water
pollution since it appears to be due to oxidation of the organic
matter which is deposited in the cave. Hence, although the
pollutant inputs may be sporadic the foul air will be more
persistent, a factor likely to be exacerbated by the poor natural
ventilation in the mine. Consideration is being given to how the
organic material may be flushed out of the system more rapidly
and to how ventilation might be improved as well as to the
question of the ultimate source of the material.
Given the low oxygen and high carbon dioxide cavers are strongly
advised not to attempt to enter Knotlow until further notice. The
Environment Agency has posted warning notices on all entrances,
including the entrances to Hillocks and to Whalf Mine as a
precaution although no direct measurements have been made in
these parts of the system.
John Gunn, Limestone Research Group (LRG), University of
Huddersfield