Field Update: Nov. 18, 2010

One of the tasks for the ANDRILL Science Management Office (SMO) in the pre-season was to provide a capability for shot hole drilling for the Coulman High seismic experiment. We contacted the Ice Coring and Drilling Services (ICDS) office at the University of Wisconsin and arranged to borrow a mobile shot hole drill in “as is” condition and brought it to Lincoln, NE to get it ready for field use. Steve Fischbein, Daren Blythe and Dar Gibson worked with the UNL Engineering and Science Research Support Facility (ESRSF) to refurbish and rebuild this existing system and then ship it to Antarctica to use out at Coulman High for the surveys. The shot hole drill is a pressure-washer system, with two heaters, high pressure pumps that are connected to a water supply and many valves and hoses that circulate water through the system and down-hole, after passing through a drill tower. The system makes a series of 3” diameter holes that extend down 25 to 40 meters deep into the ice, which are then used to emplace explosives.

The shot hole drill system was traversed on an Aalenner sled with all of the other containers and sledges that were brought out to Coulman High earlier in the season. The sled was open to the elements, so snow has gotten into all of the nooks and crannies in the system and the first step is to clear all of this out and get the system warmed up again before trying to test it out.

The mobile shot hole drill is mounted on a Komatik sled inside the Aallenner sled with components tucked all around it for ease of transport. A Herman-Nelson heater attached to air blower hoses is used to warm up the drill and melt some of the ice surrounding the valves and other fittings. Dar and Graham sweep out all of the loose snow and then they let the Herman-Nelson do its work warming the hoses, fittings and valves.

The drill tower is mounted on another type of sled, with the hose reel, but it has been folded down for transport and must be reassembled. The motor controller for spooling out the hose also needs to be tested and evaluated to see if there is enough control on the speed to control the hose as it goes off the drum and down, or back up, the hole. Today we are just making sure that everything goes together again and that we haven’t lost any pieces in the transport between Nebraska and Antarctica and from McMurdo out to Coulman High. Then we’ll start the system up and see if it makes a good hole in the ice of the appropriate depth for the shot holes. The important thing is to make all of the shot holes the same depth, nominally about 35 meters deep in the ice. This is necessary to establish a known geometry for the seismic experiment, with all of the shots (explosive charges) at known depths in the ice, spaced 50 meters apart from each other over 2.5 kilometers of lateral distance to the west of the origin, and all of the receivers spaced 25 meters apart along the surface of the ice in the opposite direction from the origin, which is the proposed location of the Coulman High drill hole.

In order to check out the hose, Dar and Graham roll it all off the spool and lay it out – all 50 meters of hose - over the surface of the ice.

Meanwhile, Daren is getting the portable water tank ready and has enlisted Tristan’s help in providing enough snow to melt to create the water supply.

Daren gets the box with the water tank filled with snow and lifts it onto a small sled that can be pulled by a snowmobile to prepare for the system test.

The last step in the process is to get the nozzle for the hose ready, which means screwing together some pieces of metal that have been machined to focus the flow of water coming through the hose so that it can cut into the ice using the hot water provided by the heaters and high pressure pumps. The shape and composition of the metal pieces are intended both to make the right sized hole and to provide enough weight to make the drill melt straight down without deviating to the side. We want to melt a 3” diameter hole that is vertical and open all the way down to 35 to 40 meters into the ice.

Everything is checked and all of the components seem ready, but something is wrong with the electrical system. Whenever they try to test the drill a fuse blows and it all shuts down again, so it’s back to troubleshooting mode to find out what is going wrong. They won’t be able to conduct a full test of the system today, but they’ve made progress in preparing the system to melt a hole through the ice and will come back another day to finish this task. We’ve learned once again that you need to test and re-test and that every job holds the potential for delays and surprises. It’s a harsh continent.

Previous Update | Next Update | All News