< On March 15, 1979, the British tanker "Kurdistan" broke in two, spilling about 7,500 tons of Bunker ' C ' oil into the Cabot Strait between Newfoundland and Nova Scotia. Clean up operations continued through the summer at a total cost of $5.5 million. The Canadian Coast Guard incurred 90% of expenses with the remainder shared by other Federal departments and the governments of Newfoundland and Nova Scotia.
Impact on the shoreline was minimized because of the lessons learned after the "Arrow" spill. This time the stern section was brought to Port Hawkesbury for lightering operations while the bow presented other problems, and was sunk south of Sable Island off the Scotian Shelf.
The Federal government responded quickly as the Canadian Coast Guard relayed accident reports to other organizations involved. They played the role of on-site Commander and became the lead agency in the response effort. That day, the Environmental Protection Service of Environment Canada activated the Regional Environmental Emergencies Team (R.E.E.T.) to advise the on-scene Commander. Three subgroups of R.E.E.T. dealt separately with the bow, stern, and clean up of oil. The affected shore areas of Newfoundland and Nova Scotia were observed into the summer by a network of Federal and Provincial departments, and daily flights by the Canadian Coast Guard and Departments of National Defense monitored the oil's progress.
The Canadian Coast Guard and Environmental Protection Service cooperated in a joint clean up effort. As a result, approximately 880 km of shoreline was manually cleaned during the spring and summer and recleaned as oil came ashore.
In a few cases, a short temporary access road was constructed to remove oiled material. In areas where access was difficult or where the shoreline was highly sensitive, removal of oiled material was by helicopter. Removal of oiled debris and oil was carried out manually by rakes and shovels because after the "Arrow", some shorelines were negatively altered by heavy equipment. Clean up efforts were also directed at fishing gear, slipways, booms, and boats. The "laundromat" used during the "Arrow" clean up was back in operation from June 3rd-20th and more than a hundred nets, traps, oil retainer booms and rainwear were cleaned.
Priorities for the clean up were based on the degree, type of oiling, accessibility and shore type as well as the shore's significance to the fishing industry, recreation, and conservation. Aesthetic concerns often dictated that additional clean up work be carried out even when there was no longer an environmental threat, particularly on beaches and populated areas. Pebble-cobble beaches presented more of a problem. Because of the difficulty of removing oil between larger cobbles and boulders, greater reliance was placed upon sediment transport and the cleaning action of waves. Kelp banks, which absorbed initial oil, were cleaned with relative ease as were small amounts of oiled pebbles. Oil which formed a hard "pavement" at high tide, was broken up to allow erosion processes to operate more effectively.
Because of the difficulty in gaining access to rocky shores, they were cleaned by natural processes. Oil was also confined, with few exceptions, to the edge of the shores and small channels through marshes. In one case, clean up efforts of Big Glace Bay Lake was suspended because more harm was being done by trampling vegetation than by removing the small amount of oil remaining. During the Kurdistan spill, the lessons of nine years before were still fresh in the mind of those involved in the clean up and they were determined not to repeat those mistakes.
In more recent years, Environment Canada has used past oil spills to further improve oil spill response, recovery, and clean up methods. In the 1990's, technology is accessible to quickly address spill concerns. The development of a user-friendly computer program has made it possible to combine a large number of variables in order to make decisions such as whether to use dispersants, response priorities and ecological, financial, and aesthetic concerns. For example many constraints were in place during the Exxon Valdez response to avoid the disturbance of bald eagles, pinniped pupping, and moulting, and salmon and herring spawning. The SCAT (Shoreline Cleanup and Assessment Team) reports on shoreline conditions and its database were also critical during the Exxon Valdez crisis to meet communication leads, set clean up priorities, select treatment techniques, obtain land owner approvals, direct clean up crews, and to document and track progress.
Data is now obtained for aerial and ground surveys and is summarized often in map form for use in response. Aerial video, documentation forms, sketch maps and response recommendations are particularly useful in identifying treatment techniques and response requirements. Video alone can determine the nature of the shoreline, vessel, and helicopter accessibility, exposure, and general oil conditions.
If oiling is extensive, heavy equipment is now more efficient than manual labour. Manual clean up is effective with light shoreline oiling and when access to a shoreline is difficult. Some kinds of motorized earth-moving equipment are still practical for sand shorelines, and in some cases, for sandy gravel shoreline types. A wide range of equipment is available including graders, front-end loaders, bulldozers, drag lines and clamshells. Another machine is the sieve used in Bermuda for many years as a means of removing tar balls and debris from beaches. On flat sand beaches, motor graders can efficiently remove surface oil by scrapping only the oiled surface layer. Motorized vacuum systems may be of some value in mud, sand or sandy gravel environments and the outer edge of marshes. Others like pressure spraying are effective for cleaning rock and boulder beaches, boulder barricades, rocky cliffs, and man made structures. Small oil skimmers, low pressure flushing and sorbents are preferred for salt marshes.
Today the objective of response is to accelerate the recovery of areas affected by spilled oil. The preferred response option may be to leave the oil and monitor recovery if trying to remove or treat the oil causes more damage. After the Exxon Valdez in 1989, the short-term ecological effects of clean up activities were compensated by the long-term benefits to ecological recovery.
The use of flushing techniques is also a present practice for oil spills. Water pressure and temperature can be adjusted to meet the operation's objectives. After the Exxon Valdez spill, techniques changed from flooding and low-pressure, ambient water flushing, to flooding and moderate pressure and warm water flushing.
It has been recently discovered that naturally occurring bacteria and fungi oxidize hydrocarbons to produce carbon dioxide and water. The application of an additive to accelerate the process of biodegradation provides nitrogen and phosphorus to microbes. This approach, called bioremediation, has been effective but will not remove large volumes of oil quickly if the oil is thick and heavily weathered.
Oddly, chemical dispersants are still effective on fresh or light oils by breaking the oils into small droplets. Hydrocarbon-based dispersants may be used to treat viscous or weathered oil. They dissolve or soften coatings to permit removal by flushing, high pressure blasting, steaming, or by natural wave action. Water-based dispersants can be used to directly assist in the removal of oil or to prevent the reformation of slicks where the removal is primarily mechanical.
For disposal, oil and water mixtures can be separated in treatment tanks and the recovered oil then sent to a refinery. Present waste management activities retrieve and separate mixtures of not only oil and water, but oil and sediment and oil and debris. The oil content of recovered materials is variable but generally less than 1% by weight.
Waste minimization has advantages over wholesale waste removal, especially in treating sediments (Marty, et al, 1993). The purpose of this "in-situ" treatment is to accelerate the natural recovery of the shore zone and this type of treatment is preferred for waste minimization. This technique offers a number of options including bioremediation, chemical treatment, debris burning, relocation to the surf zone, sediment tilling, or natural recovery.
"In-situ" burning of spilled oil on coastal waters must be conducted before hydrocarbons become spread out, volatiles are lost, and emulsions form (Allen, 1988). "In-situ" burning has effectively destroyed floating oil in a number of incidents like the Exxon Valdez where trial burns resulted in a 98% removal rate of oil from the sea surface (Allen, 1991). This type of burning leaves a very small amount of residue and considerably reduces the volume of material to be disposed. This burning technique also decreases the potential for erosion, increases clean up efficiency, requires less manpower, decreases secondary environmental impacts, and helps decrease transportation and disposal costs.
In most cases, the disposal method is defined after the clean up. The preferred waste management strategy is to separate wastes as soon as they are generated into categories with different properties. To accomplish this, a temporary oily waste disposal site close to the clean up site should be established before transporting oil and contaminated material. If the spill is small or occurs at a distance from any facility, effective oil-water separators can be constructed. One method can be used to remove oil from a sump pit using a drum or any portable tank to provide oil/water separation.
Once disposal is finished, it is necessary to consider what changes might result from the clean up activities and how they might be rectified, on completion of the operation. For instance, it may be desirable to replace beach sediments if removal has reduced the volume of material on the beach. As a rule of thumb, the replacement material should always be the same size or coarser than that removed. Where animals or plants have been removed or damaged by the oil or clean up, it may be possible to re-colonize or replant key species. Dune restoration may also involve the placement of fences to trap sand before planting is carried out.
As a result of the mistakes and innovations from past spills, it is easier and more practical to clean up oil effectively without permanently changing the ecosystem or sedimentary structure of the spill area. Yes, some clean up methods that were initially discredited have been modified for use in a variety of situations. However, it should be noted that every procedure and decision is based mainly on the ecological ramifications of every technique, and that is the guiding principle directing oil spills in the '90's.
