Mendip Caves and their Risings

[truescrumpy]

Since the coalmining in Sioth Walles and the Mendip ceased, has anyone done research into the groundwater levels?
The reason is that the shafts were deeper than the water table, which massive pumps were used to extract the water out of the mines, therefore would have changed the groundwater flow paths (course), Now mining finished hence the pumps turned off and the mines flooded, Surely the groundwater flow paths now won't be the same as the original flow path ? And also is the 'fresh' water is now contaminated due to toxic suphates and heavy water ??  :-\

Confusing !

 

[francis]

And also is the 'fresh' water is now contaminated due to toxic suphates and heavy water ??

Is'nt heavy water D20 (di-deuterium-oxide) and used for making nuclear bombs? Beats me what that's doing down a mine...

Francis

 

[ChrisB]

toxic suphates and heavy water

Should that be "heavy metals"?

 

[whitelackington]

Since the coalmining in Sioth Walles and the Mendip ceased, has anyone done research into the groundwater levels?
The reason is that the shafts were deeper than the water table, which massive pumps were used to extract the water out of the mines, therefore would have changed the groundwater flow paths (course), Now mining finished hence the pumps turned off and the mines flooded, Surely the groundwater flow paths now won't be the same as the original flow path ? And also is the 'fresh' water is now contaminated due to toxic suphates and heavy water ??  :-\

Confusing !

How deep did The Somerset Coal Mines go.
Did any get below sea level :doubt:

 

[truescrumpy]

And also is the 'fresh' water is now contaminated due to toxic suphates and heavy water ??

Is'nt heavy water D20 (di-deuterium-oxide) and used for making nuclear bombs? Beats me what that's doing down a mine...

Francis

Thats a point!!
That may explain why the nuclear power stations are situlated  nearby  

 

[truescrumpy]

How deep did The Somerset Coal Mines go.
Did any get below sea level

GRAHAMMM WHERE ARE THOU.... You wanted here

 

[graham]

What makes you think that the Somerset coal mines had an effect on water levels in teh limestone, surely the deep Eastern Mendip limestone quarries will have had a greater influence.

 

[cap n chris]

Just over 1,800ft deep at Nettlebridge, apparently:

http://en.wikipedia.org/wiki/Somerset_coalfield

 

[Les W]

The somerset coalfield will have had no bearing on the water levels of the Carboniferous Limestone as the two are distinct and separated by a fault running along the Nettlebridge Valley. The valley has a surface river and as this represents the "water table" at this point it will also act as a barrier to flow across from the Mendips to the coal field. The mines were drained into this and other local rivers so the water table will have been maintained by this flow anyway. To the south the caves all drain from the northern flank into this river as well (Stoke Lane Slocker, Fairy, etc.) and are active stream caves so they also represent the height of the "water table". All of this actually means very little because the concept of a water table does not exist in the Carboniferous Limestone. Any "water tables" are all very local (perched sumps) as the rock is actually impermeable and cannot support a water table, the water can only travel along fissures within the rock beds.

What I am trying to say is that the depth of pumping in the coal measures will hav little or no effect on water levels on the Mendips.

 

[cap n chris]

What I am trying to say is that the depth of pumping in the coal measures will hav little or no effect on water levels on the Mendips.

Yeah, but it's hard to say. I think you've done well saying it, BTW.

 

[whitelackington]

I admit to knowing nothing about The Somerset Coalfields.
However i find it difficult to agree with Les.
If they were on Mendip and are very deep, they will fill up with water.
Some were only recently abandoned, eventually, one imagines this water will seep out.
Surely it must have some effect on Mendip hydrology.
Scientifically, I thought everything affected everything else, even if only a small amount.

 

[Les W]

The Somerset coalfield is to the North East of the Mendip Hills. It is not "on Mendip".

The effect of pumping on water tables is generally quite local with a depressed cone around any point that is pumped, or wells, etc.
Streams are only the surface embodiment of the local water table and represent a lowering of the local table either side of the stream. all these cause a gradient towards the low point and water will flow this way. Water to the south of the stream will flow North and water to the North will flow south. This means that the water from the Northern flank of the Mendips will flow north to the stream in the Nettlebridge valley and there it will flow downstream towards Frome. Water from the coalfield will flow south to the stream where it too will flow to Frome. The only chance for Mendip water to make it to the coalfield would be for the water table in the coalfield to be depressed by so much that it started to rob water from the surface stream. As the drainage water in the mines was pumped to this very stream (among many) it is very unlikely that the stream water was flowing into the mines as it would be pointless (and very expensive) to discharge drainage water at a point where it would just run straight back into the mine.

All this is moot as Carboniferous Limestone does not support a general water table. Any water tables are very local and drainage lines are known to cross without mixing on the Mendips and in Yorkshire (and probably elsewhere). All the water from the North flank of the Mendips in close proximity to the Somerset coalfield drains to St Dunstans Well. This resurgence occurs at the lowest point in the impervious rocks along the valley where they "overflow" the "dam" of impervious rocks. This point has been caused by downcutting of the surface stream and has no connection to the coalfield, it is also above the valley floor and the main stream in the valley. Therefore there is NO hydrological connection between drainage on the North flank of Mendip Hills and the Somerset Coalfield.  :read:

 

[truescrumpy]

The Somerset coalfield is to the North East of the Mendip Hills. It is not "on Mendip".

The effect of pumping on watertables is generally quite local with a depressed cone around any point that is pumped, or wells, etc.
Streams are only the surface embodiment of the local water table and represent a lowering of the local table either side of the stream. all these cause a gradient towards the low point and water will flow this way. Water to the south of the stream will flow North and water to the North will flow south. This means that the water from the Northern flank of the Mendips will flow north to the stream in the Nettlebridge valley and there it will flow downstream towards Frome. Water from the coalfield will flow south to the stream where it too will flow to Frome. The only chance for Mendip water to make it to the coalfield would be for the water table in the coalfield to be depressed by so much that it started to rob water from the surface stream. As the drainage water in the mines was pumped to this very stream (among many) it is very unlikely that the stream water was flowing into the mines as it would be pointless (and very expensive) to discharge drainage water at a point where it would just run straight back into the mine.

All this is moot as Carboniferous Limestone does not support a general water table. Any water tables are very local and drainage lines are known to cross without mixing on the Mendips and in Yorkshire (and probably elsewhere). All the water from the North flank of the Mendips in close proximity to the Somerset coalfield drains to St Dunstans Well. This resurgence occurs at the lowest point in the impervious rocks along the valley where they "overflow" the "dam" of impervious rocks. This point has been caused by downcutting of the surface stream and has no connection to the coalfield, it is also above the valley floor and the main stream in the valley. Therefore there is NO hydrological connection between drainage on the North flank of Mendip Hills and the Somerset Coalfield.  :read:

Good write up Les  

Can this be the same as when the Cornish Miners who came to the Mendip in 19th C, surely it must have polluted the water as well as changing the groundwater flow paths ?

 

[Les W]

Due to the fact that the Cornish miners worked within the Carboniferous Limestone (and the Dolomitic Conglomerate) the effect of their shafts would have only had a very local effect.

 

[Les W]

I admit to knowing nothing about The Somerset Coalfields.
However i find it difficult to agree with Les.

I think, knowledgelackington, that it would be a good idea to ascertain some information before attempting to argue a point in an informed debate.

If you don't agree with me, that is fine, but if you admit to knowing nothing about a subject then it is pointless trying to debate it. You need to support arguments with facts.

 

[truescrumpy]

So we now know that water courses have not changed, does this point to the possible fact that there is a risings on the moors covered over by this awful clay which sealed it  and waterworks strategically positioned use their pumping stations to draw the water. (does that means there is a cave passage/risings at that point?

 

[Hughie]

So we now know that water courses have not changed, does this point to the possible fact that there is a risings on the moors covered over by this awful clay which sealed it  and waterworks strategically positioned use their pumping stations to draw the water. (does that means there is a cave passage/risings at that point?

Definitely one rising with a pumping station positioned on it. I don't think it's in use any more, but not sure.

 

[whitelackington]

Rumur has it that Tyning's Barrow's Swallet rises in gough's, I bet it hasn't been stream tested.
If people say it has, i wouldn't mind betting they meant Tyning's Stream which drains into the origonal entrance to G.B. Cavern

 

[ChrisB]

If they were on Mendip and are very deep, they will fill up with water.
Some were only recently abandoned, eventually, one imagines this water will seep out.

They will only fill up with water if the water table is higher. Water will only drain out if the water table is lower.

Having drained in, what would make the water drain out again?

 

[graham]

Rumur has it that Tyning's Barrow's Swallet rises in gough's, I bet it hasn't been stream tested.
If people say it has, i wouldn't mind betting they meant Tyning's Stream which drains into the origonal entrance to G.B. Cavern

WTF is 'e on about now?  : : :