Courtesy of Photo courtesy of the Darwin Foundation

Response

When oil is spilled, the response team must be fast and decisive. In this section you'll find out how decisions are made, and how oil is cleaned up and recovered.

"Polluter Pays" Principle

In Canada, the party that causes pollution damage is responsible for paying the costs of clean-up and any resulting economic losses for environmental damages.

Some people have recommended registering each cargo load, so that its chemical "fingerprint" is recorded. This way, if a spill occurs and a unique blend of hydrocarbons is found in the water, the polluter can be identified and taken to court. If found guilty, the polluter would have to pay for the damage.

What Happens When A Spill Does Occur?

Once a spill is discovered, the senior employee at the site is informed, and he or she reports the spill to the government authority (or authorities) named in the contingency plan. Then the government authority sends a representative to monitor the clean-up and ensures it is done adequately. Depending on the seriousness and location of the spill, the polluter may be assisted by one or more levels of government. International assistance may be requested when it is needed, or when the spill affects another country.

The potential impacts of the spill are evaluated and workers begin trying to control it as quickly as possible. Once the leakage has been stopped, the team concentrates on containing the oil. If necessary, the team leader will set priorities for "booming". As much of the oil is recovered as possible. The next step is to clean up the affected area and dispose of oil and debris.

Weather Affects Response Activities

The response team depends on weather reports to provide information that is essential for tracking, containing and cleaning up a spill. The location of the accident, the season, the time of day, and the type of response actions planned will influence what information is useful. Decisions on which clean-up and containment methods to use depend on present and forecast weather conditions at the spill site. Meteorologists provide:

• forecasts of wind shifts and strengths;
• warnings of severe weather, such as thunderstorms, lightning and hurricanes;
• information on wave heights, air and sea temperature, and air mass stability;
• forecasts of the icing potential, wind chill, fog, and visibility; and
• information on the presence and movement of ice flows.

How Do We Know Where The Oil Is Going?

When oil is spilled, it is essential to track it and forecast where it is going. The main technique for spotting oil is observation by trained personnel from a low-flying plane or helicopter. Unfortunately, this is not always easy. Cloud shadows, wind patterns on the water and seaweed can be mistaken for oil slicks. Fog and cloudy weather make oil slicks hard to see. Visual observation is not possible during storms or at night.

There are other methods. Tools include cameras that are sensitive to ultraviolet and infrared light (light wavelengths that are beyond our range of vision). Computerized tracking and dispersion simulation models are often used to locate and follow spills. A number of other high technology techniques like radar, microwave and laser-induced fluorescence are also being tested for spill surveillance. Tracking buoys are sometimes used - the buoys drift with the oil and transmit their location by radio or by satellite.

What Are The Limitations?

Traditionally, oil booms could not be used in currents over 1.0 knot because oil would escape under the boom. However, new boom technologies allow oil booms to be used in relatively calm waters without any oil escaping.

How Do We Control The Oil's Movement?

By containing or diverting it. This prevents spreading, so that a smaller area is affected and clean-up is easier. It also keeps oil from highly sensitive areas that are quickly damaged.

Floating Booms

Floating booms are mechanical barriers that extend above and below the surface of the water to stop or divert the flow of oil. They are used in three ways: to surround oil slicks to reduce spreading and concentrate the oil for clean-up; to protect areas like harbour entrances or biologically sensitive sites; and to divert oil to an area where it can be recovered.

The effectiveness of a boom depends on wave size, currents and wind conditions.

Sorbent Booms and Barriers

Sorbent booms and barriers absorb a moving oil slick using a porous material. They are used only when an oil slick is thin, because once their surface is saturated with oil they don't work well. They must be removed carefully so that oil is not squeezed back into the water.

How Do We Recover Oil From Water?

Once the oil is contained, it must be recovered from the water's surface. Equipment and people are quickly put to work. Here's how.

Skimmers

Skimmers mechanically remove oil from the water surface without causing major changes in its physical or chemical properties. The effectiveness of any skimmer depends on the type of oil spilled, the thickness of the slick, the presence of debris, the location of the spill, ambient weather conditions and calmness of the water.

Sweep System

A sweep system is a combination skimmer and boom that is attached to a ship or small boat. As the vessel moves forward, the system contains and collects the spilled oil. It is then pumped into storage tanks.

Sorbents

Sorbents are materials that recover oil either through absorption or adsorption. They are used for final clean-up of trace amounts of oil or to remove oil from areas that skimmers can't get at. There are two basic types: natural organic materials like peat moss and sawdust; and synthetic organic sorbents like polypropylene, polyester foam, polystyrene and polyurethane. Sorbents are normally applied by hand, and recovered with nets, rakes, forks and pike poles.

Manual Recovery

Shoreline Clean-up and Restoration

When oil is spilled on water, some of it often reaches the shoreline. Shoreline clean-up can be very difficult and time-consuming. It is often impossible to protect all shoreline areas from oil contamination so priority is assigned to the most sensitive areas.

Large waves crashing onto rocks and cliffs can remove and disperse oil naturally. These areas are generally left alone. Also, particularly sensitive areas like marshes are often better left alone once contaminated, since clean-up operations can cause more damage than if the oil were left to degrade naturally. Walking on marshes drives the oil deeper; when they have to enter a marsh, clean-up crews often put boards down to spread their weight, or use flat-bottom boats.

Shoreline clean-up often involves many people using simple hand tools such as rakes, shovels, wheelbarrows and garbage bags, high- and low-pressure hoses and sorbent materials to soak up the oil. Although these methods are very simple, they are often the most effective. Clean-up must be done carefully. Some experts believe that much of the biological damage observed on Alaskan beaches after the Exxon Valdez spill was caused by clean-up activities.

The method of clean-up that is most appropriate will depend on the type of shoreline and its biological resources.

Chemical and Hydraulic Dispersion

Chemical clean-up agents may be used if permission is granted by the appropriate authority. Such agents are not permitted in fresh water or near biologically sensitive areas.

High-pressure water hoses

are used to wash oil from coarse sediments, rock surfaces and artificial structures. Low-pressure water flushing has been used to remove oil from fine sediments, shores with vegetation and marshes without causing excessive damage to plants and animals.

Steam Cleaning

Steam can be used to clean artificial structures or rock faces.

Removal

On sand beaches, graders and scrapers may be used to remove large amounts of oil. Mechanical removal from pebble or cobble beaches is more difficult. On most types of beach, some material is removed manually. Care must be taken to ensure that beach erosion does not take place where sediment has been removed.

What Happens Once The Oil Has Been Recovered?

Two things - the water is separated from the oil, and the oil is disposed of along with any remaining sorbent materials and other debris.

Separation

All oil recovery methods produce some mixture of oil and water. Separation devices like settling tanks are often attached to skimmers. Many synthetic sorbents can be pressed or squeezed to remove the absorbed oil. Sometimes the oil and water are collected in recovery vessels that have taps at the bottom; once the water has settled, it is removed from the bottom.

Disposal

Regulations respecting the disposal of oil and debris are established by local, provincial and federal governments. Disposal is one of the most difficult problems associated with clean-ups. Relatively fresh oil may be re-refined. Sometimes recovered oil is burned.

What Happens if the Oil Can't be Recovered?

Sometimes, particularly in stormy weather, oil cannot be recovered. This can be a problem, but under some circumstances it is actually a solution. High waves, as in the 1993 Braer spill, can break up the oil, mixing it into the water and dispersing it into the water column. Natural processes such as oxidation and bio-degradation eventually reduce the oil to its basic components.

Chemical Dispersants

Chemical dispersants are detergent-like materials that are sprayed onto the spilled oil. In Canada, their use is strictly regulated by the federal government. They must pass toxicity and effectiveness tests before they can be used. Their use is approved on a case-by-case basis. Use of dispersants can prevent damage to some bird populations. However, dispersion of oil into the water column can pose significant risks for other marine life.

In-situ Burning

In-situ burning can be used to burn the oil while it is on the water's surface, but the oil must first be contained to make it thick enough. Studies have shown that the smoke plume produced is an acceptable trade-off under some circumstances.

When Is It Best Not To Respond?

In three situations:

1. When oil is spilled in a sensitive environment, it is sometimes best to leave the clean-up to nature, as the activity itself may cause more damage.
2. Sometimes natural removal processes are faster or more effective than human efforts. For example, some storms can make shoreline conditions unsafe, but may also remove the oil quite effectively.
3. Areas such as the Shetland Islands where the Braer spill occurred are also best left, because the action of high-energy waves will break up the oil.

What About The Wildlife That Has Been Affected By Spills?

Canada has skilled emergency groups that work quickly to rescue the wildlife affected by an oil spill. However, cleaning wildlife is a lot of work, is expensive, and is usually ineffective. Even if an oil spill is small, it can have a dramatic impact on bird and animal populations.

What Should We Expect From Clean-up Operations?

The success of clean-up operations has a lot to do with where a spill happens. If oil is spilled in an enclosed area like a harbour, the area can usually be well cleaned. If oil is spilled in an exposed area or in the open ocean, crews have a difficult time controlling the oil during times of adverse weather conditions. This usually means that clean-up efforts are less successful.

Facts and Figures

• In March 1989, the Exxon Valdez supertanker ran aground in Alaska. According to Science News, about 50 percent of the oil spilled from the Exxon Valdez was degraded naturally on beaches, in the water and within tidal sediments. Clean-up costs for the spill exceeded $2 billion.
• According to the United States Coast Guard, tanker accidents contribute only 5 percent of the estimated 2.3 million tons of petroleum hydrocarbons entering the seas each year.
• According to Scientific American, United States oil imports are expected to grow by 50 percent by the year 2000.
• Cleaning an oiled bird takes a lot of time. First a veterinarian must spend about an hour examining the bird. It then takes two people two days each to clean the bird. Once it is cleaned, the bird is placed in captivity for 20 to 40 days. There are about two hours of work each day while it is in captivity.

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