T-Junction
Dig 15
December 15 & 16, 2001
Halfway There
Only 57.18' to go (118.5' from ground surface to cave ceiling)
Diggers: Bernhard Arnold, Bill Gee, Chad Hines, Rick Hines, Ron Lather,
Seokbin Lim, Tom Lounsbury, Dave McCool, Jeff Page, Bill Pfantz, Kerry Rowland
After cleaning and squaring up the hole from the last blast on the prior week
the distance to go was 65.18 feet, or a gain of 15.4 feet for the week long dig
(12/1/01 thru 12/8/01).
Three blasts were completed this weekend. Eight holes were drilled for
each blast and all holes were drilled approximately 4' deep. Three
different time delays were used for the eight holes. We attempted to load
3.5 power split sausages in each hole. Sandy debris washing into the holes
on the last blast prevented loading all the holes to the bottom and only 17
sausages were loaded.
We were concerned about plugging the 9-inch pilot hole since it plugged twice
during the week long dig and since we knew that there was a ½" pipe
standing in the pilot hole. We hung a 3" by 8' long I-Beam into the
9" hole with about 4' sticking out. After the blast we were able to
wiggle the chain attached to the I-Beam and slowly meter the debris down the
hole. It worked, no plug.
The I-Beam was used again for the second blast Saturday afternoon. We did
not attempt to clear the debris until Sunday morning. By then there was 4
feet of standing water in the 30" hole. Again, wiggling the chain
flushed the material down the 9" hole. The material took several
minutes of gurgling to work itself down to the cave. For the third blast
we tested 3 sections of heavy (5/16") chain hanging in the hole.
Again, no plug. The chain test is not totally convincing since the amount
of material blasted on the third blast was only about half that involved on the
prior two.
Each of the holes in the first set was lined with a 5' by 1.3" OD PVC pipe
with 1/16" walls. The pipes kept the sandy material out of the
drilled holes and made loading easy. We attempted to remove the tubes and
leave the explosive in the holes but the tubes were locked in the holes by grit.
We got a pull of 3.8' on the first blast.
For the second blast we were back to using wooden plugs in the drilled holes
since we blew up the PVC pipe. They were difficult to load. The two
center holes were loaded first and we tried to load the bottom heavy by doubling
over the half sausage in the 3.5 sausage string. It was difficult to get
the double section to the bottom. On the 6 perimeter holes the sausage was
not doubled at the bottom. On 5 of the 6 holes 2.5 sausages slid in
without a problem. The sixth hole was about half filled with sand and was
cleaned out before final loading. The last sausage was doubled up at the
top and pressed into the hole. About 2" of stemming topped off each
hole. The pull on the second blast was 3.2'.
Several partially plugged holes on the third blast resulted in a large step
being left on one side of the hole. The step covered 40 percent of the
hole. The pull on the high side of the step was 1 foot and was 3.8' on the
low side.
Based on a 1 foot pull for the third blast the total for the weekend was 8.0'.
Next week we will blast out the step.
On the third blast we used an 18" section of the pipe to plug two of the 8
drilled holes. The holes protected with the pipe did not fill with sand
and explosive is believed to have been loaded to the bottom.
Next week we will try short sections of PVC pipe in each hole. We will
also measure the depth of each hole and use the air blaster to clean the holes
if necessary before loading explosives.
Another problem seemed to be insufficient air pressure at the drill to keep it
operating at full power. It would periodically stop rotating and drop down
on the drill. We have about 130' of ¾" hose between the drill and
the compressor and assumed that we are getting too much pressure drop in the
hose. If we can come up with about 80' of 1.25" or 1.5" pipe we
will hard plumb from the compressor to the dig and connect the ¾" hose at
the dig. Is there anyone out there with pipe to donate?
Thanks this week go to Bill Gee who participated in his first dig. He did
an excellent job of keeping record for the weekend. Thanks to Gerry
Gattenby for providing the I-beam, a new drill template and other steel.
Thanks to Chad Hines for bravely testing the new 2:1 pulley system to make the
last drop of the weekend to collect measurements on the third blast.
We need help for next weekend. Please call or email if you can help
on one or both days.
Sunday crew photo attached.
Rick
913 - 897 - 4258