Amid 2012’s hot Nebraska summer, the UNL Engineering and Science Research Support Facility (ESRSF—or simply “the Engineering Shop”) and partners developed components for a different temperature extreme—the remote ice fields of Antarctica—with the Whillans Ice Stream Subglacial Access Research Drilling (WISSARD) project. The Engineering Shop’s work now travels far south to fulfill a groundbreaking research promise, with many challenges surmounted along the way and more ahead.
ESRSF Manager Jim McManis said the Engineering Shop began work in March 2011 for the project through the ANDRILL Science Management Office (SMO) at UNL. His team understood the importance that the SMO and its partners “came up to speed quickly with the tasks required to design, build, test and deploy a hot water drill system … for clean drilling into sub-glacial environments” planned in the austral spring of 2012.
“This hot water drill system will be traversed from McMurdo Station across the Ross Ice Shelf to the the site on the Whillans Ice Stream over subglacial Lake Whillans,” said ANDRILL SMO Executive Director Frank Rack, Ph.D. “The drill will be used to melt a 30 cm-diameter hole through 800 meters of ice to provide access for sampling and measurement devices that will be lowered into the subglacial lake on a wireline to collect water, sediment and microbiology samples.”
The ESRSF team, working closely with their partners from SMO and the Northeast Professional Engineering Consultants Group, designed, machined and fabricated components for the hot water drill system (HWDS) “to provide up to 72 gallons per minute (gpm) of hot water at up to 2,500 pounds per square inch (psi) pressure at a temperature of 95 degrees C, using a 1,000 meter-long, 1-1/4" internal diameter (ID) continuous length of thermoplastic hose,” according to SMO reports.
System Features Include:
• The main heating and pumping capacity, provided by six Alkota Model 12257K pressure washer, heater-pump units (HPU), each providing 12.0 gallons per minute of hot water, which are installed in two 40'-long ISO containers (four Alkota units in one ISO container and two Alkota units in the other). The system was designed to accommodate two additional Alkota units, if required, and the hose reel has been designed to accept up to a 1-1/2" ID hose, to provide additional capacity for making larger diameter holes through 800+ meters of ice sheet/ice shelf to meet the requirements of future planned and proposed projects at the grounding line of the Ross Ice Shelf. ESRSF technicians Mike Long and Mark Stroup custom-machined the hot water manifold system as well as other parts for the heater units, and ESRSF's John Hudgens and David Birdzell provided fabrication and welding support for the heater unit installations and hose reel structural frame.
• A Water Filtration and Decontamination Unit (WFU), containing 2 micron and 0.2 micron filters and UV filters at 185 nanometers and 254 nm, located between the main 3,700 gallon water supply tank (WST) and the two HPU containers.
• A 500-gallon insulated Melt Tank (MT) to provide start-up water for the system by melting snow using heated glycol pumped through a series of heat-radiating immersion plates that form a recirculation system. Waste heat is utilized from the two 225 kilovolt-amp (kVA) generators that provide power to the HWDS and the camp infrastructure. ESRSF‘s Hudgens and Birdzell provided technical support to fabricate and assemble the frame that supports the melt tank.
• Generators are linked to a power distribution module (PDM) to monitor and control the power output to the distributed modules: a Hose Reel Module (HRM), which incorporates the main hose reel and 1,000 meters of hose, two traction drives, and a return reel and hose attached to the return pump (the main and return hoses to pass through the roof of the HRM and be guided over crescents). Birdzell, ESRSF’s lead electrician, working with Chad Carpenter of the SMO, installed the high- and low-voltage electrical network. It was a unique application of Birdzell’s electrical knowledge and skills, amid a project stage with 12- to 15-hour work days to meet the project deadlines.
“The drill will be used to melt a 30 cm-diameter hole through 800 meters of ice to provide access for sampling and measurement devices that will be lowered into the subglacial lake on a wireline to collect water, sediment, and microbiology samples.”
A crescent extension system mounted on the roof of the HRM aligns the hose over the work deck and moonpool where the hot water drilling will take place. ESRSF welder Hudgens and machinists Stroup and Long took the lead in machining, fabricating and welding the rail assembly. Specifically, Hudgens’ skills ensured the quality of welds would meet or exceed the stringent requirements for operation in the harsh environments of Antarctica. Long and Stroup machined heavy duty steel parts for the trolley system to handle large forces that will be inflicted on the crescent trolley system during drill operations.
Half of the HWDS was delivered to Port Hueneme, Calif., in December 2011 and shipped to Antarctica on a cargo vessel that arrived in March 2012. The remaining half of the system was finished and pre-tested in August 2012 at UNL, including the reel container and the command and control system for the hot water drill.
Further testing of the system in Antarctica and deployment to Lake Whillans for the WISSARD Project are scheduled for late 2012 and early 2013, with a potential further season planned in 2013-2014, pending an extension of ARRA funding from NSF, among other factors.
The majority of the equipment is currently being staged on the ice near McMurdo Station and moved out to a test location on the McMurdo Ice Shelf for testing of the hot water drill with the additional work decks, and science and logistics modules that will be used in the field, Rack said. If everything goes well, there will be a decision to prepare the equipment for the traverse along the South Pole Traverse Route, and ultimately to melt a hole through the ice to provide access into Lake Whillans.
by Carole Wilbeck