14 July, 1999
Things are hopping now! The hot water drill, which is used to drill through the ice to the bed of the glacier, was set up by University of Wyoming post-doc Joel Harper, and PSU grad student Don Lindsay. The drill is operational and easily drilled a trial run of 15 meters. Steve Malone (University of Washington seismologist) and I set up two seismometers in the ice to record any movements of the ice related to the deflection of the ice dam and to record any shuddering of the ice due to sudden changes in sub-glacial hydraulic pressure. Joe Walder (USGS, Vancouver) and Michelle Cunico (PSU grad student) made their way to Hidden Creek Lake basin, inflated their water craft, and did a trial launch onto the water. St. Olaf undergrad Andrew Malm ran a couple of ice radar lines (using ground penetrating radar equipment) to estimate the depth to the bed of the glacier. Dennis Trabant (USGS, Fairbanks) and I placed survey reflectors onto the dam. Everyone encountered problems in their equipment and set up. It was a day to work out glitches.
It was an exciting moment when the drill began making progress through the ice. Setting up and operating the hot water drill is as follows. The equipment consists of a sump pump, a heating plant, a power plant, hose which can handle high temperature water, and a large boom supported by two legs which feeds the hose into the hole. The sump pump is used to get water from a nearby source of clean water to the heating plant. The heating plant has a series of coils through which the water passes to be heated by diesel-fired flames. The power plant consists of a generator which provides electricity to the sump pump, a smaller pump which feeds the water into the heating plant, and a motor which lowers the hot water hose into the hole. The hose, of which there is 600 meters in length, is made of a durable plastic which is insulated with fiberglass. The tripod has two legs which support (prop up) a drilling boom. The drilling monument has an attached motor which drives the hose through a series of wheels (also attached to the boom) and into the hole. So, the process, in the end, is quite simple. Water is accessed from a nearby pool, and is pumped into the heating plant. After being heated to 240 degrees farenheit, the hot water makes its way through the hose to the drill tip (appropriately called a stinger in this case). The hot water extruded from the stinger is expected to melt its way through the glacier. If a rock is encountered, the hose will be backed out, and a new hole will be started.
It is possible that the drill will pass through an englacial conduit. An englacial conduit is a channel which drains water from the surface, into, and through the glacier. It is expected that numerous englacial conduits exist in glaciers which are undergoing active melting, such as the Kennicott Glacier. The presence of an englacial conduit bisecting the hole will affect the pressure transducer measurements in the hole. So, after a hole is drilled, a borehole video camera will be lowered into the hole to look for these features. Hopefully drilling tomorrow will take us to the bed of the glacier.
The Kennicott Glacier (as with most glaciers in Alaska) is a temperate valley glacier. Being a valley glacier, snow accumulates and adds to the mass of the glacier in the high mountain peaks. From the flanks of these peaks the glaciers flow down and into adjacent valleys. As temperate glaciers, they flow down to elevations where temperatures exceed the melting temperature of the ice during the summer. This is where active melting (called ablation) occurs. The portion of temperate glaciers which extend into the lower elevation valleys are sopping wet during the summer. Water flows across the surface, pools into meltwater ponds and lakes, and sometimes flows into the interior of the glacier via moulons, and other englacial conduits. In addition, by the time the glacier has flowed into the valleys they have passed by adjacent rocky outcroppings. Rocks fall from these outcrops and onto the glacier and are transported down the valley. So, the lower tongue of a temperate valley glacier is wet and commonly mantled with rocks. That is the case with the Kennicott Glacier. By the time the glacier reaches its terminus at McCarthy, it looks more like a rock pile.
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