T-Junction Dig 23
June 22 - 23, 2002

Still Learning

19.28 feet to Carroll Cave or 99.22 feet below surface 

Diggers: John Bowles, Greg Buckley, Bill Gee, Tom Grant, Marty Griffin, Earl Hancock, Lannis Hancock, Tim Hancock, Mike Hartley, Peddgie Heinz, Rick Hines, Andy Isbell, Tom Lounsbury, Dave McCool, Bill Pfantz, Kerry Rowland, Zulena Rowland, Rose Shaw, Jeremy Eaton, Paul Worsey. 

After digging about 100 feet we are still learning.  We have found a communication system that works.  We have improved the pull with more explosives combined with the use of a jackhammer.  We turned up the compressor regulator to increase pressure and improve the drill performance.  We have simplified the blast cycle procedure to eliminate the drill template and the heavy steel pipe or rail in the hole.  

Communication between the mezzanine man and the downhole man has become increasingly difficult with increasing depth.  The waterproof radio headsets used on the prior digs have proved awkward at best.  This week we tried a "speaking tube".  A 100' 1" polyethylene flexible tube was fitted with vacuum cleaner tubes on both ends.  The vacuum cleaner tubes have a 2-inch cup connector on one end that served as an ear/mothpiece.  The only problem is "training" the downhole man to use it instead of yelling which seams to be more natural.  When the downhole man speaks normally into the mouthpiece he can be heard clearly by the "phone man" on the surface.

We continued to experiment with the cycle procedure change started on the prior dig.  Instead of trying to use 6 or 8-drilled holes to try to lower the bottom of the 30-inch hole in a single step we are now doing it in two steps.  First a 3-hole blast removes approximate half the material and then a second set of holes are drill, loaded and shot to hopefully round out the 30-inch shaft.  The advantage of doing two "half-blasts" is that the volume of material going down the 9-inch hole is less per blast so we are less likely to plug the 9-inch hole and have therefore eliminated the heavy steel that we have been lowering into the 9- inch hole that allowed us to meter the debris down the 9-inch hole.  One man can typically drill and load so the number to hauls of a man up the shaft is the same.  The heavy steel drilling template has been replaced with a short section of PVC pipe used as a simple gauge to locate the radial distance for the drilled holes.!  

We still need to look at the procedure and try to minimize the number of objects hanging down the hole at one time.  Even without the drilling template and I-beam we have the following down hole after the explosives are set.
1)  Man on safety line
2)  Phone plastic tube
3)  Elevator on 4 to 1 block and tackle
4)  Det cord
5)  Drill on haul rope with air hose
6)  Canvas bucket to haul explosives and push rod
7)  Second canvas bucket to haul detonators
8)  12V electric light
The potential for tangles has increased with depth.

The compressor was set to generate 100 PSI which worked fine at shallower depth but now the drill is about 170 away and there is apparently sufficient pressure drop in the line when the drill is operating to cause it to "drop out" at times.  I found the regulator on the compressor and reluctantly turned it up to 115 PSI.  I was somewhat afraid to turn it up since the compressor appears to be near death and I did not want to work it harder than necessary.  It used a full case of oil this weekend. Hopefully it will hold together for another 18 feet. 

We have been using a small pneumatic chisel to shape the hole after a blast and it does a fair job but is very slow at removing large amounts of fractured rock.  We borrowed a larger version of a pneumatic chisel and a jackhammer from Hertz Equipment in Springfield.  We got the equipment late Saturday and have not fully tested it yet but it looks very promising for helping improve the pull per blast cycle.  The pistol grip chisel works on the sidewalls and the jackhammer takes the bottom down.  It looks like we may be able to use three heavily loaded holes to fracture the rock and then remove any that is left in place with the chisel and jackhammer.  Thank you Hertz!

We did load the holes heavier this weekend and that did help the pull.  The first shot used 3 sticks of dynamite per drilled hole.  Later blasts used 4 sticks per hole.  We used three different delays on the holes so that only 4 sticks detonate at a time.  With the old 8-hole procedure we used 3 delays but 4 holes were on a single delay (6 second delay that should spread out the 4 blasts over several 100 milliseconds) and two holes were on zero delay. The two zero delay holes with 3 power-splits each will generate a larger shockwave than the 4 sticks of dynamite shot at one time this weekend.  We will still need to reduce the charge, as we get closer to the cave.     

I observed a change in the rock strata at about 90 feet below the surface.  I believe the upper layer consist of dolomite with 20 - 30% flint nodules.  The lower layer consists of a lighter gray dolomite with bands of almost white 3 or 4-inch thick layer.  The light gray layers are about twice as thick as the white layers.  There are no flint nodules in the lower layer.  Perhaps we have crossed from the Roubidoux to the Gasconade formation.  I expected to cross that boundary earlier.  At about 94 feet we intersected a 10" high mud filled "cave", another sign that we may be in to the Gasconade.  I would appreciate professional help on the geology.

On the last of seven blasts this weekend we had our first "no fire".  We fired the electric det and det cord as normal but only heard one bang, not three as expected.  Looking down from the top we could see that none of the main charge went off.  At the time we though we had pulled the non electric shock tubes in two after the det cord got hung up on the elevator as we were raising the driller.  Dave McCool had left just before the last shot and took the excess det cord back to Rolla.   We had no dets or det cord to finish the job.  I got on a phone and after leaving several messages around the state I finally reached Matt Sutcliffe, owner of Premier Pyrotechnics, on his cell phone.  Even though Matt was several hundred miles away on a job he offered to help.  Bill Gee and I drove about 25 miles to Premier Pyrotechnics office.  Earl and Lannis followed along in their van just in case we needed to haul things in two separate v! ehicles (turned out not to be necessary).  We picked up 6 electric caps and headed back to the dig.  Thank you Premier Pyrotechnics!

When we arrived back at the dig we connected four electric dets in series as instructed by Dr Worsey (I reached him by phone from Premier).  Tom Lounsbury went down the hole with the electrics to try to salvage the shot.  He was to put one electric in the dynamite in each of two holes that had no stemming (that's another story) and a third det as deep as possible in to the third hole after removing as much stemming as possible.  The forth det was to be attached to the severed shock tube.  Tom found about 70 feet of det cord at the bottom and the non-el tubes were intact.  At this point I thought we were home free (but that was not to be).  Tom attached the four dets to the det cord.  I tried to communicate that the tail of the det cord needed to be away from the working end of the det cord and the non-els but we were not using the phone tube and he left the pile of det cord on top of the non-el tubes.  Again only one bang, not three as! expected.  We soon realized that the pile of det cord was the problem.  I connected our last two dets in series and Tom took them down.  We were hoping the two unexploded charges would be the ones with out stemming but we weren't that lucky.  Tom set one det in the exposed end of the dynamite in one hole and taped the last det to the short section of shock tube attached to the non el in that charge.  We were concerned that the severed shock tube could have enough moisture in it that it might not go off.   With Tom at the surface we crossed are fingers and fired the det.  Again, only one bang.  Hopefully the charge with the severed shock tube was a zero delay and went off at the same time as the charge with the direct electric det.  When the smoke cleared Tom went down again.  We were delighted to hear that all was well.  At last we could pack up and go home.

As I drove home I tried to think of an explanation for the severed det cord.  Could the elevator have broken it?  Not likely.  The det cord used consisted of two sixty feet sections knotted together (another story).  Tom said he had seen the knot in the unexploded det cord at the bottom.  Could the knot have caused the det cord to break just above it?  Not likely.  Then it hit me.  As Bill Gee and I attached the original electric det to the det cord we had 20 or 30 feet of excess det cord to deal with.  With Dave gone we had no chose except to waste it, but how?  Bill carefully hung it down the far side of the shaft, which looked good to me at the time.  I assume the det cord tail, that has a tendency to coil, may have crossed the 30" shaft and touched the working end of the det cord leading to the non-els and the dynamite.  The tail could have cut the working end before the explosion reached that far.  This ma! y not be "the explanation" since the distance to the cut point would have been longer through the tail than directly down the working end.  Also I believe Bill would have been able to see the free end of the det cord.  (Bill, call me to discuss).  The final possibility may simply be defective det cord.  (Paul, how likely is that)? 

Congratulations to Dr Paul Worsey for making his first trip to the bottom.

Thanks to first timer Tim Hancock for being a great help.  Please come again.

Thanks to Zulena Rowland and her helpers, Kerry and Peddgie, for the excellent Mexican feast we shared Saturday night.  

Thanks to Dave McCool for his entertaining fireworks and waterspout demo.  The frogs may wish to thank him for improving their habitat by making a 4-foot deep crater at the edge of their shallow pond.  The two tons of mud that was in the pond covered everything within a few hundred feet.  My van was parked the closest, with the side doors open.  It not only got coated on the outside but also on the inside.  Particularly annoying was the large blob that landed in my milk crate CCC file box!  Oh well, cavers love mud! 

Event Schedule

Saturday, June 29:  Seismograph maintenance and jackhammer and chipping at dig.  Sorry, no explosives available. Call Eddie Simmons to sign up.  417-736 3195

July 6-7:  Dig with explosives

Sunday, July 14:  CCC meeting at the Truman Lake shelter house.  We'll have lunch at noon (please bring a dish) and the meeting will follow.

July 20-21:  Dig - Breakthrough weekend.   

Rick   913 897 4258    rickhines@aol.com