The Rasp

[Rob]

After the mammoth pumping session at the Rasp in Peak Cavern this weekend, me and eviljeff went there last night to remove yet more pumps and pipes from the end. When we got to there sump 0 was completely empty! After some desperate squeezing and then a little digging we got through the constriction where the sump normally is and crawled off for 10m before reaching a "large" (3m wide, 2ft high!) room off to the west. Straight on was far too small and, heading through this chamber, only a few small ways on remained. Only one was big enough to get into, still heading downstream, and only for about 4m. At the furthest point i managed to just reach a haul cord that had been forced around a rock column by the winter floods!
For those of you who dont konow, sump 0 is the downstream end of the Rasp, heading south towards Minor Sump. It has always been about 50cm deep, even in very dry conditions. At first i thought silt must have been washed through by all the pumping we had done, but the rope proved that it was insignificant compared to flow rates in flood. Therefore, the only reason i can think of for it to be empty is that the pool had dried out due to the draught, which has been blowing through since friday night once sump 2 had been dropped. It doesn't seem a realistic idea but it is the only thing that has changed.
Does anyone know of this mechanism happening elsewhere or am i just talking crap?

 

[Pitlamp]

Rob - which are you calling "Sump 0"?  I presume you mean the one immediately on the left when you emerge into the Rasp from the low sharp crawl - that right?  If so the correct name is the Rasp Downstream Sump.

You may think I'm being a bit nit picky but if sumps get different names it doesn't half cause problems for future sump index compilers!

But well done anyway - I was really interested to read this info.

How did you get on upstream?!

 

[Rob]

Yes, that's the one. I was unaware it had a name, cheers for pointing it out.
As for upstream, have a look at the SUSS section of this forum.

 

[Pitlamp]

Got it - thanks for drawing my attention to it.

Out of interest can you tell us the total estimated distance from the start of upstream Sump 1 to the point you reached at the weekend?  Even a general direction?

This looks like proper caving; a right good effort!

 

[Rob]

Out of interest can you tell us the total estimated distance from the start of upstream Sump 1 to the point you reached at the weekend?  Even a general direction?

Hard to say cos it keeps changing size and you keep getting disorientated going through ducks on your back. I'd estimate about 35m in total from sump 1 to sump 4. We will know the distance a lot better once we have removed all the pipes and measured their length, cos they all fit end to end. As for direction, it seems to follow the same northwards trend along the pipe vein, maybe veering NE at the very end, but again, very hard to say given the circumstances.

 

[SamT]

so it wasn't surveyed then - tut tut.

 

[Cave_Troll]

back you go lads

 

[Pitlamp]

Thanks Rob - if you could post revised figures as well (when you've had chance to measure the pipes) it'd be most helpful.  We have a new Peak District Sump Index in the pipeline (which will no doubt list lots of other juicy sumps for you lads to get shut of before we have to face trying to dive them).  I still think you did great, even if you haven't got any numbers (yet)!

 

[SamT]

I wasnt really serious - but if you'd have had the time and inclination and enegy - it would have been a nice touch.

Seriously - good effort. Sounded like a mamoth but  well orchestrated task. Good on you all -  :bow:

 

[Johnny]

Does anyone know of this mechanism happening elsewhere or am i just talking crap?

Rob

I think that the desiccation of a sump by a draught is possible and that it happens to both Pool Chamber and Namread sumps in Bagshawe, when they fall sufficiently to allow the draught from the Hollywood Bowl series through they drop very quickly. Hope this helps.
Well done lads sounds like you gave that dig a propper hammering, its the only thing they understand!