Предотвращение аварийных разливов нефти и нефтепродуктов при порывах трубопроводов на переходах через водные преграды

Outside force damage can include the effects of: earth movement, lightning, heavy rains and flood, temperature, high winds, excavation by the operator, excavation by a third party, fire or explosion external to the pipeline, being struck by vehicles not related to excavation, rupture of previously damaged pipe, and vandalism. The range of excavation damage runs from damage to the external coating of the pipe, which can lead to accelerated corrosion and the potential for future failure, to cutting directly into the line and causing leaks or, in some cases, catastrophic failure.

An oil spill is a release of a liquid petroleum hydrocarbon into the environment due to human activity, and is a form of pollution. The term often refers to marine oil spills, where oil is released into the ocean or coastal waters. Oil spills include releases of crude oil from tankers, offshore platforms, drilling rigs and wells, as well as spills of refined petroleum products (such as gasoline, diesel) and their by-products, and heavier fuels used by large ships such as bunker fuel, or the spill of any oily white substance refuse or waste oil. Spills may take months or even years to clean up.

Oil also enters the marine environment from natural oil seeps. Public attention and regulation has tended to focus most sharply on oil pipelines.

Figure 1. Oil Spill Consequences

The oil penetrates into the structure of animals, reducing its insulating ability, thus making the birds more vulnerable to temperature fluctuations and much less buoyant in the water. It also impairs or disables animals and birds abilities to escape from dangerous.

Most animals affected by an oil spill die unless there is human intervention. Marine mammals exposed to oil spills are affected in similar ways as seabirds. Oil coats the fur of Sea otters and seals, reducing its insulation abilities and leading to body temperature fluctuations and hypothermia. Ingestion of the oil causes dehydration and impaired digestions. Because oil floats on top of water, less sunlight penetrates into the water, limiting the photosynthesis of marine plants and phytoplankton. This, as well as decreasing the fauna populations, affects the food chain in the ecosystem. There are three kinds of oil-consuming bacteria. Sulfate-reducing bacteria (SRB) and acid-producing bacteria are anaerobic, while general aerobic bacteria (GAB) are aerobic. These bacteria occur naturally and will act to remove oil from an ecosystem, and their biomass will tend to replace other populations in the food chain.

Cleanup and recovery from an oil spill is difficult and depends upon many factors, including the type of oil spilled, the temperature of the water (affecting evaporation and biodegradation), and the types of shorelines and beaches involved.

Figure 2. Clean-up efforts after an oil spill.

Methods for cleaning up include:

Bioremediation: use of microorganisms or biological agents to break down or remove oil.

Bioremediation Accelerator: Oleophilic, hydrophobic chemical, containing no bacteria, which chemically and physically bonds to both soluble and insoluble hydrocarbons. The bioremedation accelerator acts as a herding agent in water and on the surface, floating molecules to the surface of the water, including solubles such as phenols, forming gel-like agglomerations. Undetectable levels of hydrocarbons can be obtained in produced water and manageable water columns. By overspraying sheen with bioremediation accelerator, sheen is eliminated within minutes. Whether applied on land or on water, the nutrient-rich emulsion creates a bloom of local, indigenous, pre-existing, hydrocarbon-consuming bacteria. Those specific bacteria break down the hydrocarbons into water and carbon dioxide, with tests showing 98% of alkanes biodegraded in 28 days; and aromatics being biodegraded 200 times faster than in nature they also sometimes use the hydrofireboom to clean the oil up by taking it away from most of the oil and burning it.

Controlled burning can effectively reduce the amount of oil in water, if done properly. But it can only be done in low wind and can cause air pollution.

Dispersants act as detergents, clustering around oil globules and allowing them to be carried away in the water. This improves the surface aesthetically, and mobilizes the oil. Smaller oil droplets, scattered by currents, may cause less harm and may degrade more easily. But the dispersed oil droplets infiltrate into deeper water and can lethally contaminate coral. Recent research indicates that some dispersants are toxic to corals.

In some cases, natural attenuation of oil may be most appropriate, due to the invasive nature of facilitated methods of remediation, particularly in ecologically sensitive areas such as wetlands.

Dredging: for oils dispersed with detergents and other oils denser than water.

Skimming: Requires calm waters

An oil skimmer is a machine that separates a liquid from particles floating on it or from another liquid. A common application is removing oil floating on water. These technologies are commonly used for oil spill remediation but are also commonly found in industry. They were used to great effect to assist in the remediation of the Exxon Valdez spill in 1989.

Oil skimmers are commonly found in three types: weir, oleophilic, and drum:

Weir skimmers function by allowing the oil floating on the surface of the water to flow over a weir. The height of the weir may be adjustable. These devices will collect water when oil is no longer present. Weir skimmers are also available in floating, self-adjusting variations. These models allow them to be effectively used even in changing water levels.

Drum skimmers function by using a rotating element such as a drum, to which the oil adheres. The oil is wiped from the surface of the drum and collected. They are very efficient and do not pick up any appreciable amounts of water even when oil is not present.

Oleophilic skimmers are distinguished not by their operation but by the component used to collect the oil. Ropes, discs, or drums are treated with a substance or otherwise manufactured to adhere to oil.

Solidifying: Solidifiers are composed of dry hydrophobic polymers that both adsorb and absorb. They clean up oil spills by changing the physical state of spilled oil from liquid to a semi-solid or a rubber-like material that floats on water. Solidifiers are insoluble in water, therefore the removal of the solidified oil is easy and the oil will not leach out. Solidifiers have been proven to be relatively non-toxic to aquatic and wild life and have been proven to suppress harmful vapors commonly associated with hydrocarbons such as Benzene, Xylene, Methyl Ethyl, Acetone and Naphtha. The reaction time for solidification of oil is controlled by the surf area or size of the polymer as well as the viscosity of the oil. Some solidifier product manufactures claim the solidified oil can be disposed of in landfills, recycled as an additive in asphalt or rubber products, or burned as a low ash fuel. A solidifier called C.I. Agent (manufactured by C.I. Agent Solutions of Louisville, Kentucky) is being used by BP in granular form as well as in Marine and Sheen Booms on Dauphin Island, AL and Fort Morgan, MS to aid in the Deepwater Horizon oil spill cleanup.

Vacuum and centrifuge: oil can be sucked up along with the water, and then a centrifuge can be used to separate the oil from the water - allowing a tanker to be filled with near pure oil. Usually, the water is returned to the sea, making the process more efficient, but allowing small amounts of oil to go back as well. This issue has hampered the use of centrifuges due to a United States regulation limiting the amount of oil in water returned to the sea.

A containment boom is a "temporary floating barrier used to contain an oil spill. Booms are used to reduce the possibility of polluting shorelines and other resources, and to help make recovery easier. Booms help to concentrate oil in thicker surface layers so that skimmers, vacuums, or other collection methods can be used more effectively. They come in many shapes and sizes, with various levels of effectiveness in different types of water conditions."

This technique requires the area to be completely boomed off, forming a protective barrier. Conventional oil boom, tidal-seal boom, or a combination of each can be used to exclude spilled oil from a sensitive area.

Figure 3. Oil spill containment boom shown holding back oil

Often the first containment method to be used and the last equipment to be removed from the site of an oil spill, they are "the most commonly used and most environmentally acceptable response technique to cleanup oil spills in the world."

Booms used in oil spills can be seen as they rest on the surface of the water, but can have between 18 to 48 inches of material that hangs beneath the surface. They're effective in calm water, but as wave height increases oil or other contaminants can easily wash over the top of the boom and render them less useful.

In any oil spill, the use of a single conventional boom is not effective in protecting environmental resources even with the correct draft and aspect ratio. For speeds of over 1 knot (of the water and hence the oil), the boom will fail to stop the oil because of drainage under the boom. The approaching oil needs to be decelerated before it meets the boom. Drainage failure may be avoided by using a series of well-designed booms.

Booming Tactics

Containment Booming - Placing a boom in a body of contaminated water for the purpose of holding or slowing the movement of contamination.

Diversion Booming - Placing a boom in a body of contaminated water for the purpose of diverting the contamination to a collection point.

Deflection Booming - placing a boom in a body of water for the sole purpose of changing the course of the contamination. (Note: This method is used for contamination that is not intended to be recovered, and therefore not typically associated with oil spills).

The Deflection Boom tactic is for waterborn spills where there is some current, usually from 0.5 to 3.0 knots. The boom is placed at an optimum angle to the oil trajectory, using the movement of the current to carry oil along the boom and then releasing it into the current again with a new trajectory. The angle is chosen to prevent oil from entraining beneath the boom skirt. Boom may be held in place by anchors, vessels, or a boom control device.

Deflection Boom may be used to temporarily avoid impacts to a sensitive area, but there is no recovery associated with the tactic, thus no oil is removed from the environment. For this reason, Diversion Boom or Free-oil Recovery is preferable to Deflection Boom whenever feasible. However, Deflection Boom may be more effective than Exclusion Boom at protecting a sensitive location, where currents over 0.75 knots exist.

The two alternatives for this tactic are Fixed Deflection and Live Deflection. In Fixed Deflection, boom is anchored to the shoreline or bottom. In Live Deflection, the boom is attached to vessels and held in position by the power of the vessels or one end of the boom is anchored and the other end held in position with a vessel. Live deflection is a very difficult tactic to execute. It should only be utilized where fixed deflection cannot be achieved, usually because deep water precludes anchoring.

The general strategy is to:

1. Identify the location and trajectory of the spill or potential spill.

2. Identify, prioritize, and select sensitive areas to be protected from impact.

3. Select a deployment configuration that best supports the operating environment and available resources.

4. Mobilize to the location and deploy the tactic.

5. Place boom using secured anchor systems, mooring points, vessels, boom control devices, etc.

6. Monitor and adjust the boom on an appropriate basis.

Exclusion Booming - placing a boom in a body of water for the purpose of blocking off a sensitive area from contamination.

Exclusion Boom is not recommended for fast water operating environments; consider Diversion Boom or Deflection Boom tactics instead is the advice from. However, when Diversion Boom and Deflection Boom tactics are not suitable and resource protection is still needed, say, fast high tide in a sensitive estuary for instance, then an arrangement of booms with a decelerator is needed.

Tide-seal boom - typically, tidal-seal boom is deployed at the shoreline/water interface on both shores and is secured/anchored into position. Conventional oil boom is then connected to the tidal-seal boom and is secured with additional anchor systems to form a barrier and to maintain shape.

This technique is most efficient in low current areas. Freshwater outflow from a river or stream may assist in maintaining boom configuration and pushing oil away from the area inside the boom.

The general strategy is to:

1. Identify the location and trajectory of the spill or potential spill.

2. Identify, prioritize, and select sensitive areas to be protected from impact.

3. Select a deployment configuration that best supports the operating environment and available resources.

4. Mobilize to the location and deploy the equipment.

5. Secure boom with anchor systems and/or mooring points.

6. Monitor the boom on an appropriate basis.

7. If oil contacts the outside of the boom, utilize an appropriate recovery system to remove it.

Anchor Systems

Boom is secured in place using standard anchoring systems. Anchor sizes vary depending on the boom type and the operating environment.

A special type of boom, tidal-seal boom, is used on some boom arrays where the array contacts the shoreline to prevent oil from escaping.

Tidal-seal boom typically contains three chambers as shown in Figure EX-2. Two of the chambers are filled with water, and contact the shoreline in shallow water and shoreline areas. The third chamber is usually filled with air, and provides flotation as the water level rises. Tidal-seal boom should be used in areas with a smooth bottom of gradual slope and avoided where there are large rocks and sharp breaks in the bottom.

Equipment used includes:

Booms: large floating barriers that round up oil and lift the oil off the water

Skimmers: skim the oil

Sorbents: large absorbents that absorb oil

Chemical and biological agents: helps to break down the oil

Vacuums: remove oil from beaches and water surface

Shovels and other road equipments: typically used to clean up oil on beaches

Prevention

Seafood Sensory Training - in an effort to detect oil in seafood, inspectors and regulators are being trained to sniff out seafood tainted by oil and make sure the product reaching consumers is safe to eat.

Secondary containment - methods to prevent releases of oil or hydrocarbons into environment.

Double-hulling - build double hulls into vessels, which reduces the risk and severity of a spill in case of a collision or grounding. Existing single-hull vessels can also be rebuilt to have a double hull.

Skimmers - are things that skim the slick (oil) off the top of the water. Boomers- are inflatable, rubber blockades that trap the oil, so it is easier to skim.

Environmental Sensitivity Index maps are used to identify sensitive shoreline resources prior to an oil spill event in order to set priorities for protection and plan cleanup strategies. By planning spill response ahead of time, the impact on the environment can be minimized or prevented. Environmental sensitivity index maps are basically made up of information within the following three categories: shoreline type, and biological and human-use resources.

Shoreline type

Shoreline type is classified by rank depending on how easy the garet would be to clean up, how long the oil would persist, and how sensitive the shoreline is. The floating oil slicks put the shoreline at particular risk when they eventually come ashore, covering the substrate with oil. The differing substrates between shoreline types vary in their response to oiling, and influence the type of cleanup that will be required to effectively decontaminate the shoreline.

Biological resources

Habitats of plants and animals that may be at risk from oil spills are referred to as “elements” and are divided by functional group. Further classification divides each element into species groups with similar life histories and behaviors relative to their vulnerability to oil spills. There are eight element groups: Birds, Reptiles Amphibians, Fish, Invertebrates, Habitats and Plants, Wetlands, and Marine Mammals and Terrestrial Mammals. Element groups are further divided into sub-groups, for example, the `marine mammals' element group is divided into dolphins, manatees, pinnipeds (seals, sea lions & walruses), polar bears, sea otters and whales. Issues taken into consideration when ranking biological resources include the observance of a large number of individuals in a small area, whether special life stages occur ashore (nesting or molting), and whether there are species present that are threatened, endangered or rare.

Figure 4. Bird after an oil spill

Spill Volume Estimation

By observing the thickness of the film of oil and its appearance on the surface of the water, it is possible to estimate the quantity of oil spilled. If the surface area of the spill is also known, the total volume of the oil can be calculated.

Oil spill model systems are used by industry and government to assist in planning and emergency decision making. Of critical importance for the skill of the oil spill model prediction is the adequate description of the wind and current fields. There is a worldwide oil spill modeling (WOSM) program. Tracking the scope of an oil spill may also involve verifying that hydrocarbons collected during an ongoing spill are derived from the active spill or some other source. This can involve sophisticated analytical chemistry focused on finger printing an oil source based on the complex mixture of substances present. Largely, these will be various hydrocarbons, among the most useful being polyaromatic hydrocarbons. In addition, both oxygen and nitrogen heterocyclic hydrocarbons, such as parent and alkyl homologues of carbazole, quinoline, and pyridine, are present in many crude oils. As a result, these compounds have great potential to supplement the existing suite of hydrocarbons targets to fine tune source tracking of petroleum spills. Such analysis can also be used to follow weathering and degradation of crude spills.

Another source of hazardous waste is the sludge that results from pipeline pigging operations. Scraper and cleaning pigs deposit waste mate-rials at pig receipt sites that must be tested; the material will likely contain hazardous levels of benzene and listed metals.

It must be noted that state air and water quality rules also affect pipeline operations. In some states, regulations are more restrictive than federal requirements. To help meet all these standards, industry organiza-tions have also published guidelines and recommended procedures.



DEPLOYMENT CONSIDERATIONS AND LIMITATIONS

SAFETY

* Daily weather evaluation is recommended, and should include distance to safe harbor, transit times and exposure of vessels.

* Vessel masters should have experience in the appropriate operating environment and tactic. Local knowledge is preferred.

* Vessels, including skiffs, must have a minimum of two crew aboard.

* Vessels setting anchors and tending the boom should be able to safely transit seas which exceed the boom's operating limitation.

* If possible, vessels in transit to/from an operation or staging area should transit in pairs.

* A communications schedule should be established and followed, between vessels in transit and the Operations Section or Radio Dispatcher.

* Extreme care should be used when taking strains on anchoring systems using the aft cleats of small vessels and skiffs.

* Extreme care should be given when selecting deadmans for the anchoring systems onshore.

* Buoy lights should be considered for night operations.

* Response personnel should wear PPE as required by the incident-specific Site Safety Plan.

* For fast water deployments, consider adding a spotter/rescue person downstream for potential recovery of a casualty, i.e. overturned boat or man overboard.

* Anchor trip lines should be made of material strong enough to handle a moderate strain during boom reconfigurations.

Responders normally used the trip line to reposition and reset the anchors.

DEPLOYMENT

* Calm/Protected/Fast water environments are most commonly used for this tactic.

* If the spill is in still water under calm conditions, consider Containment Booming.

* Boom control devices, such as the Boom Vane™, allow diversion booms to be set and retrieved from shore without a vessel.

They also allow for continuous adjustment of boom angles.

* Do not assume 100% efficiency with one boom system.

* When deployed by vessels/crews of opportunity, remember that this tactic requires more training and skill than towing a Uboom.

* Readjust angles and widths between boom sections as necessary to meet changing conditions.

* Continuous monitoring of system efficiency is required.

* Planning for a marine environment should be based on average high tidal conditions.

* A Title 41 Fish Habitat permit is required to work inside any anadromous stream. Due to the possibility of contaminating spawning habitat, avoid diverting and/or collecting oil inside a stream mouth if possible.

* See Shoreside Recovery for methods to keep oil from contaminating beaches at recovery points.

* Anchor systems must be selected based on the maximum stress that might be expected to occur on the boom array, considering stronger currents and winds than when the anchor is set.

* The scope of the anchor line should be at least 3 times the depth of the water. If the anchor fails to hold, try increasing the line scope to five times the depth of the water and/or double the length of the anchor chain. Finally, if additional anchor holding is required, anchors can be ganged or set in series.

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