U.S. Army Engineer Research and Development Center’s Cold Regions Research and Engineering Laboratory researchers have been working in coordination with others for the past 12 years to develop novel systems in which to clean oil from ice laden waters.
CRREL’s Nate Lamie, electronics engineer, and Leonard Zabilansky, research civil engineer, recently hosted a sequence of experiments onsite using the laboratory’s Geophysical Research Facility to develop and evaluate techniques to quantify volume of oil burned in ice. The U.S. Department of the Interior’s Bureau of Safety and Environmental Enforcement contracted scientists Paul Panetta, an acoustics expert and principal investigator, and Richard Byrne from Applied Research Associates Inc. to conduct the tests.
In-situ burning is a technique often used for mitigating oil spills, especially in ice-covered water. However, the actual burn efficiency or quantification of oil burned is unknown.
“The objective of the recent testing,” said Lamie, “was to develop and test methods to directly measure the volume of oil burned and the burn rate in real time during in-situ burns using both underwater acoustics measurements and above water cameras. And the overall objective is to be able to use this technique in the field.”
The GRF, an outdoor 60-foot-long by 22-foot-wide by 7-foot-deep concrete basin with a refrigerated retractable roof, was prepared for testing by growing an ice sheet (approximately 12 inches at center) above the water’s surface and then cutting an ice cavity (a 1-meter by 1-meter hole) in the saline ice, in which crude oil would be “spilled” to a 1-centimeter layer.
Six visible spectrum and four infrared cameras were stationed around the burn to capture the images from multiple vantage points, in addition to the mid-wave IR and high-resolution, long-wave IR cameras. Staged under the ice-covered water at the bottom of the tank was a stationary platform with an array of temperature and acoustic sensors, and a remotely operated underwater vehicle, which was also fitted with acoustic sensors. Additionally, a web camera streamed the testing live to scientists participating from afar.
“We mounted acoustic sensors on the submerged ROV to measure the thickness of oil during the burn, and the results compared well with the stationary systems,” said Byrne. “The stationary systems were used for tests earlier in the spring. This current series of testing is a continuation of the program. A new aspect of this testing, was installing the acoustic sensor on the ROV, as the next step towards field deployment.”
“Thermal imaging measures the heat of the burn, the hotter the burn the higher the combustion, leaving less soot resulting in a cleaner burn,” said Zabilansky. “And the acoustics measures thickness of oil as it burns. We are trying to minimize the residue of heavy tar sitting on the surface.”
Once the basin was prepared and cameras were turned on, the oil was spilled onto the water cavity’s surface and a propane torch was used to light the oil on fire. To determine the efficiency of the burning, after the fire burned out, special absorbent pads were weighed and then placed on the ice cavity to soak up any unburned oil. The pads were then weighed for the weight of the residual oil, bagged and ready for further offsite analysis.
By measuring oil thickness during the burn, and visible and infrared measurements of the flame, researchers were able to calculate the volume of oil burned, as well as the instantaneous combustion rate.
There were a total of five successful burns in three days.
“This was a good study,” said Zabilansky. “We were able to evaluate the instruments and to measure the efficiency of the burns.”
These tests will help researchers develop a more efficient burn by creating an easily deployable evaluation method to quantify oil volume and, in conjunction, measure improvements to burn techniques.
“We are building the knowledge [how to attack the spill] while building the toolkit,” said Byrne.
Striving to improve rapid mitigation techniques of oil spills in sensitive Arctic environments supports the Corps’ mission of environmental stewardship and ERDC’s mission for creating innovative solutions for a safer, better world.