Field Update: Nov. 15, 2010

Today the visibility was poor and therefore no helicopters could fly to camp. Joe and Lisa from UNAVCO resigned themselves to stay another day and enjoy our hospitality. The primary activity for today is to continue melting a hole through the ice shelf using the ANDRILL hot water drill system in preparation for conducting some tests and deploying the first mooring. All of this work takes place with equipment housed in a series of containers on the east side of camp that are aligned next to each other in a row. The ANDRILL hot water drill system includes generators that provide power, a melting tank that turns snow into water, boilers and a heat exchanger that heats the water to high temperature and pumps the water at pressure through two large hose rolled up on reels, which are all housed in a series of three containers. The hose reels are mounted on a skid that extends out the side of one of the containers and is covered by a white tent-like enclosure. The hoses feed out through the side of the tent and into the MECC, an orange container with blue canvas sides, across a trough that connects the two containers and supports the hose. The hoses entering the MECC are then passed through a pair of large capstans that are controlled by a computer that governs the speed of the hoses and displays other measurements from a load cell that allows the drillers to assess the rate of melting in the ice down hole.

The hoses have tools attached to them that focus the flow of the hot water to make a hole in the ice shelf. The pilot lance is used first to make a small, less than 10 centimeters in diameter hole in the ice through the entire ice shelf and into the seawater below. This is followed by running a series of larger diameter tools that are used to enlarge the hole to several 10’s of centimeters in diameter. These tools are lowered and raised through the hole, down and back, while jetting hot water out through their nozzles to ream out the hole and melt the ice on the walls. The largest of these tools, known as a ring reamer, can make about a 60 centimeter in diameter hole in the ice.

This sequential process gradually enlarges the hole in the ice shelf to quite a substantial diameter, one suitable for lowering instruments down through the ice and into the ice shelf cavity below. The whole process can take several days to set up, but then proceeds fairly rapidly once all the equipment is in place and the hot water drill system operators have gained sufficient experience to know how the ice will behave as it is being melted. The outcome is a large-diameter hole that extends more than 250 meters through the ice shelf. Making this hole is another operational milestone of our season, since the hot water drill has only been used to 85 meters in the past.

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