Here are a few causes of oil spills inland:
Ilegal dumping Insufficient bunding Pipeline leaks
Train accident Road Tanker accident Aircraft accident
War Theft Bad working practices
Storage Oil change in the street Natural seeps
Third party damage Drilling accident Terrorism
As with most emergency situations, the initial hours after the incident are typified by a certain amount of confusion due to the lack of reliable information. How this situation influences the decisions of the clean up team leader which ultimately reflects on the performance of the team during the event.
The following items should help ensure those in charge of the operation initiate the most appropriate actions quickly and efficiently at the beginning. Removing any chance of the headless chicken management system, where people run around in circles never achieving anything constructive.
Action trees like these you will find below from CONCAWE (CONservation of Clean Air and Water in Europe) provide quickly the thought patten required for different responses. This speeds up the response process by reducing the thinking process.
Clean up Operations
One area that has a direct bearing on the performance of the team is the planned deployment of personnel and equipment to ensure there most effective use and the continued operation of a clean up team.
In any incident where oil is being recovered there are a number of physical tasks that must be carried out to assure success.
Whilst the whole process of cleaning up an oil spill may take a long time, there are a number of actions that need to be taken immediately which ensure that future actions can be carried out with the minimum risk to both the team and other life in the vicinity.
It is essential that the source of the oil is identified and, where possible, further leakage prevented. In some cases a tank may have lost all its contents, but in many cases the leak is identified before the total loss occurs. Then every attempt should be made to stop the release of oil, either by plugging the hole, closing the valves, or deflecting the oil into an alternative containment area.
Depending on where the spill is coming from, it may be possible to close valves in the pipe work to stop, or minimise, the amount of material being spilt.
Fire and Explosion
In any event where oil is spilled safety must be of prime consideration and all appropriate measures taken.
Few report have been written on the impact of oil on the ecology of rivers or lakes and how to treat successfully such occurrences. A notable exception to this is the cleaning of birds. Despite this fact, a number of useful points can be made.
In the event of a large spill, the team will have to coordinate remedial measures and clean up activities. Investigations have to be made into oil movement including how far it has gone and whether it has reached or is likely to reach, one or more water courses.
It is important that the decision makers know all the geographical and physical features of the area and the leader must know at all times what personnel and equipment is available to counter the spill. Because rapid and coordinated actions give the best results and lowest costs, effective communications are essential.
The leader of operations should have a comm’s centre at his base. All reports from the field are received and analysed there, this enables the leader to ensure that up to the minute directives are given to the operators in every location where remedial action is taking place.
Points to remember
Oil on the ground
Tank bunds should be built to retain 110% of the largest tank. Grandfather rules allow for tank farms older than 30 years to continue with earthern bund walls. New build's have to be made of concrete or other solid structure.
People that work in refineries or terminals where oil is stored in tanks should make a point of marking the lowest area within the bund so that pumps or skimmers can be positioned in the best place at the begining of the recovery operation. It is amazing that people walk these areas daily to check valves and verify quantities in tanks.
When the spill occurs nobody knows where the low spot is because now it is level with oil.
Drains are another basic problem if oil enters which way does it go?
With modifications and extensions to these places over the years this sort of important information tends to be forgotten. Dependent on the area and the oil type it could be many days or weeks before the oil is seen again.
Containment on impermeable surfaces
Surface containment: Purpose: to prevent the spread of oil on the surface and to prepare it for recovery.
Materials and equipment:
Method:Block drains, sewage systems, pipe and cable ducts to prevent risk of explosion or contamination of sewage plants or water courses.
Use absorbents to limit spreading Photos of Novi Sad Refinery 10 June 1999 Pay attention to fire hazards
Spills on permeable surfaces
In bunded areas:
In open areas:
Points to remember
If you have no other sorbent products available, dry sand or earth may soak up a spill of oil or chemicals. Sand bags can be used to channel substances to a collection point, to block off drains, contain spills or to dam ditches. Once contaminated, sand and sand bags should be properly disposed of and not washed into drainage systems.
Drain mats or surface drain seals seal a drain by covering the surface of a manhole cover or drainage gully. They stop liquid flowing into the drainage system and help contain it. There are different types, including clay mats and water-filled bags. Clay mats are single use but you may be able to have other types cleaned for re-use.
Keep drain mats close to where they might be used. Identify where liquid that is held back by a drain mat will collect as you may need to keep people away from it until it can be cleaned up.
Photo left shows oil spilled on an impermeable surface, running to a permeable surface where it will penetrate the soil under the influence of gravity and capillarity action.
Photo right shows a mat with a synthetic gel in the under part. The gel is heavy and flexible and seals with the ground as well as closing of the slots in the drain, closing it of to oil flow.
Photo right shows a yellow version of the mat.
I have not used this type but just showing that there are other manufactures making simular product.
Photo left shows the sad fact that some people do not have respect for our environment.
The blue and white sticker says (Don't Dump Save Your Creek). It is difficult to understand why someone would dump oily waste including a vehicles oil filter
If the spill has spread so far that it’s already entered the drainage system, try to stop it. If you can close the drainage system, you may be able to use its capacity as a temporary containment system to hold the pollutant safely until it can be dealt with properly. In some cases, it may be possible to hose any remaining spilt material into the sealed drainage system, allowing the incident to be dealt with more quickly and safely.
You must also be aware of what will happen to overflows from gullies and other entry or exit points to the drainage system. This will vary depending on where the drain flows to, slopes and weather conditions. Contaminated liquid may back up and discharge through storm overflows, collect in areas of the site or overflow and bypass the drainage system.
High rainfall will reduce the capacity of your drainage system and create higher volumes of contaminated water. It may cause flooding if the drains back up that could create a hazard itself. If your pollution incident response plan includes the option to contain spills in the drainage system, consider separating your roof and yard drainage from areas where a spill is likely and other site drainage.
Oil separators are designed to contain spills of hydrocarbons and other liquids that are lighter than, and don’t mix with, water. They won’t contain soluble substances such as soluble oils, biofuels, emission reduction solutions e.g. solvents that mix with water. An oil separator will not work properly if degreasing agents or detergents can drain to, or are put into, it.
Oil separators can be fitted with manual or automatic closing penstock valves at both inlet and outlet to contain larger spills. If you have a spill that has entered the drainage system, it may be possible to close the entrance to the separator to stop it becoming overwhelmed and protect it, or close the exit valve to allow the spill to collect in the separator. If your incident response planning includes using separators to contain large spills of hydrocarbons, you should not use bypass separators.
Check the separator after any spill has entered the drainage system and have it emptied and maintained if needed. Oil spills may have reduced your separator capacity and other spills may affect how well your separator works. Use a specialist contractor to maintain your separator.
If your drainage system does not have shut-off valves that you can close in an emergency, or they are not in suitable places, you may be able to seal your drainage system using pipe blockers. These can be fitted inside a pipe or gully. They’re usually purpose-made bags or tubes which are inflated with air, although a drain bung right can also be effective.
Old football bladders have been pushed into small culverts and inflated to close them off.
Make sure the pressure head of the contained liquid doesn’t cause the pipe blocker to fail.
Photo left shows one of the simplest ways to block a leaking container or pipe is to cover the hole with a temporary sealant. Leak sealing putty is available either ready mixed, or as a powder you mix with water. You should follow the manufacturer’s instructions to apply the putty. A more permanent method may be required before you can move the damaged container.
If you can, roll a small container, for example an oil drum, so that the damaged part is to the top and the material is no longer spilling from it. Secure the container so it can’t roll or turn back over. This will give you time to take action to stop already spilt material spreading further and to make other plans to secure the damaged container.
If possible, place a leaking primary container into a clean undamaged container to prevent more leakage . You will need to plan for this option to make sure the second container has no contamination, so any spilt material you put into it doesn’t react with its former contents, and is made from a material that won’t be damaged by the leaking material and cause a bigger problem.
Salvage/oversize drums photo right are large plastic drums with screw tops, designed to safely store leaking or damaged drums, or other containers. They’re made from chemically resistant plastic, but you should check with your supplier to make sure they’re suitable for the materials you have on site. Liners may be available to make re-use easier.
Oversize drums can also be used for temporary storage for a small quantity of a spilt liquid.
Here are two photos of the use of shore sealing boom at pipeline spills. They have been used successfully on various occasions to stop the oil spreading, as well as acting as dividers when cleaning the oil from the surface material.
The weight of the water in the bottom two tubes stops any oil getting past. This makes it easier to clean between the boom. when clean the booms are moved to stop any re-oiling of the cleaned area.
Left is a spill in the USA while right is the 1996 spill in the Komi region of the FSU.
The amount of oil retained in the soil at saturation is approx.per cubic meters dependent on it’s structure.
Concentrations exceeding 50 l/m3 are rare but can occur in dry soils beneath buildings and covered areas or where porous rocks are involved.
The rate of penetration is dependent on both the type of oil and the type of soil. Low viscosity oil and coarse gravel provide the combination with the fastest penetration rate. In practice very viscous oils, such as heavy fuel oils and some crude’s, do not penetrate soil to a significant depth.
Oil will penetrate quickly at the side of concrete constructions as the soil was disturbed when the hole was dug for the concrete to be poured. The back fill of soil is never compacted to the same state as undisturbed soil as can be seen from this photo left.
Pipeline tracks work the same, as the pipe is usually placed on a layer of sand, when back filled the trench becomes the passage of least resistence. Pipelines in hollows will end up with the trench filled where as pipelines up hill the trench will allow the oil to arrive by gravity to the lowest point. This then leave you with the problem of digging test holes up the hill to find the point of the leak.
In homogenous soil, maximum penetration occurs where pools of oil are formed on the surface. These provide a pressure head and encourage penetration.
Ground water movement is very slow; often between 0.5 m and 1.5 m per day. Thus, if oil reaches the groundwater table, there is usually plenty of time available to study the geology of the underlying strata and decide upon the best location for recovery of the oil.
Groundwater or aquifer
Aquifers are complicated systems, they are filled by rainfall, some rivers add to them other rivers take from them.
One of man's greatest treasures and a souce that will be needed long in the future, allowing oil to contaminate an aquifer will render it useless for drinking water for many years or for ever e.g. in the south of England during the 90's a towns water supply was contaminated by oil. This town had always been an agricultural area never industrial when the investigation came to its conclusion the pollution had come from a stockpile of fuel and oil for the "D Day" invasion of France during World War 2. It had taken 50 years for the oil to penetrate to the depth of the aquifer now lost forever.
One hundred and forty six groundwater sources have been closed since 1975 because of groundwater quality problems. At least 425,000 m3 per day have been lost in licensed output from the closures, about seven per cent of current abstraction levels.
The capital investment required to maintain drinking water quality is expected to be at least £15 to £36 million every year. Problems with groundwater quality cost the UK water industry £754 million between 1975 and 2004.
Water bearing formations
I copied the diagrams below from a CONCAWE report Nr 3/79 Protection of groundwater from oil polution.
Soil and rock are made up of small fragments or grains seperated by empty spaces or pours. More often than not the pours are connected by fine channels where groundwater may circulate.
The water content of the subsoil increases with depth; a distinction can be made between the unsaturated zone where the pours are only partly filled with water and the saturated zone where all pours are completely filled.
In the unsaturated zone, also referred to as the aeration zone or retention zone, the water is retained or suspended there by absorption over the surface of the grains and by capillary forces (miniscus effect) in the channels connecting the pours. The remainder of the porous space is filled with air, which is free to circulate. Within the water phase, the pressure is below atmospheric pressure.
In the saturated zone, the pressure within the water phase increases with depth. The limit where the pressure is equal to the atmosphere is called the free surface and represents the water table or piezometric surface. It corrisponds to the level of water in a well, i.e. static water level.
Above the water table and within the saturated zone is the capillary fringe where water is held by capillary suction. This zone may vary in thickness according to pour size in the sediment. The capillary rise will be maximum for the finest channels.
Capillary rise inches centimeters
Coarse sand 12 15
Medium sand 40 50
Fine sand 60 110
Silts or clays 175 250
Chalk 120 900
In real life the thickness of the capillary fringe may be expected to be constant in very homogenous mediums but may exibit large variations for non-homogenous soils.
Within the saturated zone groundwater freely circulates and may be tapped by wells. This zone may be seen as a reservoir, the capacity of which is the total volume of the pours filled with water. The associated geology is called an aquifer, water bearing formation or groundwater reservoir.
Types of aquifers:
In rock where water circulates through fissures, the rate of flow is much faster than in rock which have pours; consiquently any pollution can spread with greater ease. In addition, the direction of flow is more erratic and more difficult to predict the progress since the charicteristics of the terrain are more difficult to determine.
A aquifer acts as a storage reservoir and as a water carring body. The two main perameters associated with these functions are their porocity and permeability. The porocity of an aquifer refers to the volume of void spaces compared with the total volume. It may range between 5% and 45%.
The permeability is a measure of the ease with which water flows through the formation. It is a function of the average diameter of the pours and the shape and orientation of the grains.
Since the recovery of free oil means modifying the normal flow pattern, some understanding of the way groundwater moves is necessary.
In the majority of cases, groundwater moves under the influence of gravity, but the rate at which it moves may vary enormously, e.g. from meters per day to meters per year, dependent on the permeability of the aquifer and any gradient.
Below is a guide in meters per annum (mpa) or meters pre day (mpd):
In practice, the direction and shape of the natural flow pattern in an aquifer is modified by the presence of water extraction wells. When pumping from a well, an equilibrium is eventually reached between the outflow of water from the well and the inflow from the aquifer. The water table surface becomes conical in shape, the axis of which is the well.
This is known as the cone of depression, the distance up to the surface of the water table is influenced by the well which is being pumped is known as the radius of influence. All fluid in this zone will tend to migrate to the well.
Natural flow can therefore be considerably disturbed by man. When pumping takes place the water table may be lowered and it is possible to reverse the flow. This is a common phenomena where water extraction takes place.
The size of the cone of depresion will depend on the permeability of the surounding rock, as shown the lower permeabilty the wider the cone.
When pollution occurs in such areas careful hydrogeological monitoring is necessary to minimise its effects.
Measuring groundwater velocity
When oil has or is thought to have contaminated the groundwater it is very important to know in which direction and at what velocity the oil is being transported, particularly when drinking water wells are present in the area.
A reliable picture of the flow patterns can be obtained from a series of measurements:
This data may be used to add to mathematical models to predict the behaviour of the aquifer. Remember the better the data the better the result.
Looking at the surface relief gives us some idea of how the rocks are formed below the surface e.g. A hill will have it's roots below the surface and so the water will flow around the hill. How far out from the bottom of the hill can only be found out by drilling a series of boreholes. Having found the water we also have to know in what direction it is flowing.
Migration through the retention zone
The degree of penitration is a function of ground structure as well as the type of product involved. A product with low viscocity will penetrate more rapidly than one with a high viscocity. In homogeneous ground, without stratification or marked variations in pour size, the front of the penitrating product tends to be pear shaped, with the bulbous part at the bottom. The vertical penetration is due to gravity while the horizontal is due to capillary action. In permeable stratum the penetration is mainly vertical where as in less permeable stratum it is more horizontal. The heterogeneity of the subsoil has a considerable influence on the shape of the penetrating body.
In some places the water table is very close to the surface in this case trenches can be excavated in front and down hill of the incident when water enters the trench the oil will arrive on its surface allowing skimmers or absorbents to be used for its recovery. All of these incidents take a long time to complete, and can be very costly. The speed of the operation depends on the porosity of the substrate and the speed of the water flow.
Migration on the water table
When free oil reaches the capillary fringe and if the volume is large enough, it first forms a layer of increasing thickness under the influence of the further decending oil. This exerts pressure depressing the water surface. Gravity acts to restore the initial level and causes a pancake which moves laterally in the direction of the flow.
During the migration some oil clings to the grains of rock due to capillary action.
Three important considerations may lead to inaccurate estimations of oil present on the water table:
Piezometric (water table) monitoring
This involves a network of observation wells which allow the sector to be adequately momitored by observing fluctuations in the groundwater levels:
Recovery of oil from wells
The principal factor to be considered when recovering free oil is to use an existing gradient or induce one. The required total pumping rate to create the cone or cones of depresion will depend on the characteristics of the aquifer. These charateristics are found from seperate pumping tests. If the pumping rate is too high for one well the required rate can be obtained by installing more wells.
More rapid removal of oil is obtained in the early stages of recovery when several wells are used and additional soil contamination is kept to a minimum as the water table is lowered.
The correct spacing between the wells to ensure adequate overlapping between the cones of depression needs to be determined by to avoid oil bypassing the cones.
This is why this type of response is very
much a long term project and also very costly.
In some cases the cleanup has be completed only to find oil in a stream weeks later.
In some cases oil may travel great distances underground without affecting ground water before resurfacing this maybe because of impermeable layers or in agricultural land drainage systems.
In the case of land drains the system will need to be removed cleaned or replaced and so the cost rises again.
It cannot be stressed enough that when an incident happens, a response needs to be mounted immediately and major efforts are made to stop the penetration. If oil does penetrate into the soil there is a need to remove it as soon as possible to save time and money as well as the complicated work that will have to be undertaken.
The following remediation techniques section was taken from http://en.wikipedia.org/wiki/Groundwater_remediation
Ground water remediation techniques span biological, chemical, and physical treatment technologies. Most ground water treatment techniques utilize a combination of technologies. Some of the biological treatment techniques include bioaugmentation, bioventing, biosparging, bioslurping, and phytoremediation. Some chemical treatment techniques include ozone and oxygen gas injection, chemical precipitation, membrane separation, ion exchange, carbon absorption, aqueous chemical oxidation, and surfactant enhanced recovery. Physical treatment techniques include, but not limited to, pump and treat, air sparging, and dual phase extraction.
If a treatability study shows no degradation (or an extended lab period before significant degradation is achieved) in contamination contained in the groundwater, then inoculation with strains known to be capable of degrading the contaminants may be helpful. This process increases the reactive enzyme concentration within the bioremediation system and subsequently may increase contaminant degradation rates over the nonaugmented rates, at least initially after inoculation.
Stimulating existing indiginous microbes with nutrients to increase the population to assist with the decomposition of contaminates.
Bioventing is an in situ remediation technology that uses microorganisms to biodegrade organic constituents adsorbed in the groundwater. Bioventing enhances the activity of indigenous bacteria and simulates the natural in situ biodegradation of hydrocarbons by inducing air or oxygen flow into the unsaturated zone and, if necessary, by adding nutrients. During bioventing, oxygen may be supplied through direct air injection into residual contamination in soil. Bioventing primarily assists in the degradation of adsorbed fuel residuals, but also assists in the degradation of volatile organic compounds (VOCs) as vapors move slowly through biologically active soil.
Bio-sparging is an in situ remediation technology that uses indigenous microorganisms to biodegrade organic constituents in the saturated zone. In biosparging, air (or oxygen) and nutrients (if needed) are injected into the saturated zone to increase the biological activity of the indigenous microorganisms. Biosparging can be used to reduce concentrations of petroleum constituents that are dissolved in groundwater, adsorbed to soil below the water table, and within the capillary fringe.
Bioslurping combines elements of bioventing and vacuum-enhanced pumping of free-product that is lighter than water (light non-aqueous phase liquid or LNAPL) to recover free-product from the groundwater and soil, and to bioremediate soils. The bioslurper system uses a “slurp” tube that extends into the free-product layer. Much like a straw in a glass draws liquid, the pump draws liquid (including free-product) and soil gas up the tube in the same process stream. Pumping lifts LNAPLs, such as oil, off the top of the water table and from the capillary fringe (i.e., an area just above the saturated zone, where water is held in place by capillary forces). The LNAPL is brought to the surface, where it is separated from water and air. The biological processes in the term “bioslurping” refer to aerobic biological degradation of the hydrocarbons when air is introduced into the unsaturated zone.
In the phytoremediation process certain plants and trees are planted, whose roots absorb contaminants from ground water over time, and are harvested and destroyed. This process can be carried out in areas where the roots can tap the ground water. Few examples of plants that are used in this process are Chinese Ladder fern Pteris vittata, also known as the brake fern, is a highly efficient accumulator of arsenic. Genetically altered cottonwood trees are good absorbers of mercury and transgenic Indian mustard plants soak up selenium well.
Certain types of permeable reactive barriers utilize biological organisms in order to remediate groundwater.
Chemical precipitation is commonly used in wastewater treatment to remove hardness and heavy metals. In general, the process involves addition of agent to an aqueous waste stream in a stirred reaction vessel, either batchwise or with steady flow. Most metals can be converted to insoluble compounds by chemical reactions between the agent and the dissolved metal ions. The insoluble compounds (precipitates) are removed by settling and/or filtering.
Ion exchange for ground water remediation is virtually always carried out by passing the water downward under pressure through a fixed bed of granular medium (either cation exchange media and anion exchange media) or spherical beads. Cations are displaced by certain cations from the solutions and ions are displaced by certain anions from the solution. Ion exchange media most often used for remediation are zeolites (both natural and synthetic) and synthetic resins.
The most common activated carbon used for remediation is derived from bituminous coal. Activated carbon adsorbs or adheres to the volatile organic compounds from ground water by physically binding them to the carbon atoms.
Thank you John Brinkman for correcting this text.
In this process, called In Situ Chemical Oxidation or ISCO, chemical oxidants are delivered in the subsurface to destroy (converted to water and carbon dioxide or to nontoxic substances) the organics molecules. The oxidants are int
roduced as either liquids or gasses. Oxidants include air or oxygen, ozone, and certain liquid chemicals such as hydrogen peroxide, permanganate and persulfate. Ozone and oxygen gas can be generated on site from air and electricity and directly injected into soil and groundwater contamination. The process has the potential to oxidize and/or enhance naturally occurring aerobic degradation. Chemical oxidation hasnpeoven to be an effective techique for dense non-aqueous phase liquid or DNAPL when it is present.
Surfactant enhanced recovery
Surfactant enhanced recovery increases the mobility and solubility of the contaminants absorbed to the saturated soil matrix or present as dense non-aqueous phase liquid. Surfactant-enhanced recovery injects surfactants (surface-active agents that are primary ingredient in soap and detergent) into contaminated groundwater. A typical system uses an extraction pump to remove groundwater downstream from the injection point. The extracted groundwater is treated aboveground to separate the injected surfactants from the contaminants and groundwater. Once the surfactants have separated from the groundwater they are re-used. The surfactants used are non-toxic, food-grade, and biodegradable. Surfactant enhanced recovery is used most often when the groundwater is contaminated by dense non-aqueous phase liquids (DNAPLs). These dense compounds, such as trichloroethylene (TCE), sink in groundwater because they have a higher density than water. They then act as a continuous source for contaminant plumes that can stretch for miles within an aquifer. These compounds may biodegrade very slowly. They are commonly found in the vicinity of the original spill or leak where capillary forces have trapped them.
Permeable reactive barriers
Some permeable reactive barriers utilize chemical processes to achieve groundwater remediation. One particular type of permeable reactive barrier utilizes a swellable, organically-modified silica embedded in iron, which is injected in situ in order to create a permanent soft barrier in the ground. Water filters through the barrier, and the silica material absorbs toxins, such as TCE. The iron dechlorinates the solvents in the groundwater, often reducing toxicity levels below detectable limits with no toxic daughter products, no solid waste removal, and no air pollution. This type of permeable reactive barrier is also more dispersed than others.
Pump and treat
Pump and treat is one of the most widely used ground water remediation technologies. In this process ground water is pumped to the surface and is coupled with either biological or chemical treatments to remove the impurities.
Air sparging is the process of blowing air directly into the ground water. As the bubbles rise, the contaminants are removed from the groundwater by physical contact with the air (i.e., stripping) and are carried up into the unsaturated zone (i.e., soil). As the contaminants move into the soil, a soil vapor extraction system is usually used to remove vapors.
Dual phase vacuum extraction
Dual-phase vacuum extraction (DPVE), also known as multi-phase extraction, is a technology that uses a high-vacuum system to remove both contaminated groundwater and soil vapor. In DPVE systems a high-vacuum extraction well is installed with its screened section in the zone of contaminated soils and groundwater. Fluid/vapor extraction systems depress the water table and water flows faster to the extraction well. DPVE removes contaminants from above and below the water table. As the water table around the well is lowered from pumping, unsaturated soil is exposed. This area, called the capillary fringe, is often highly contaminated, as it holds undissolved chemicals, chemicals that are lighter than water, and vapors that have escaped from the dissolved groundwater below. Contaminants in the newly exposed zone can be removed by vapor extraction. Once above ground, the extracted vapors and liquid-phase organics and groundwater are separated and treated. Use of dual-phase vacuum extraction with these technologies can shorten the cleanup time at a site, because the capillary fringe is often the most contaminated area.
Monitoring-Well oil skimming
Monitoring-wells are often drilled for the purpose of collecting ground water samples for analysis. These wells, which are usually six inches or fewer in diameter, can also be used to remove hydrocarbons from the contaminant plume within a groundwater aquifer by using a belt style oil skimmer. Belt oil skimmers, which are simple in design, are commonly used to remove oil and other floating hydrocarbon contaminants from industrial water systems.
A monitoring-well oil skimmer remediates various oils, ranging from light fuel oils such as petrol, light diesel or kerosene to heavy products such as No. 6 oil, creosote and coal tar. It consists of a continuously moving belt that runs on a pulley system driven by an electric motor. The belt material has a strong affinity for hydrocarbon liquids and for shedding water. The belt, which can have a vertical drop of 100+ feet, is lowered into the monitoring well past the LNAPL/water interface. As the belt moves through this interface it picks up liquid hydrocarbon contaminant, which is removed and collected at ground level as the belt passes through a wiper mechanism. To the extent that DNAPL hydrocarbons settle at the bottom of a monitoring well, and the lower pulley of the belt skimmer reaches them, these contaminants can also be removed by a monitoring-well oil skimmer.
Ship's captain's know it only takes a teaspoon of oil to contaminate a ships drinking water supply.
So lets take that theory to a road accident 5ml of diesel can contaminate 75,000 lts of drinking water.
Here we have a road tanker on its side with a capability of loosing 30,000 lts of diesel which calculates to a possible contamination of 450,000,000 lts of drinking water.
Now let's visit Australia where we have 4 of these trailers in a road train.
Not letting this product get into a water course is of course extremely important.
The blocking of drains is one of the first priorities, this used to be made more difficult, when the fire brigade arrived they spread foam over the product thus obscuring any drains in the area. This has changed with legislation.
Oil in Urban areas
If oil is spilled on soft surfaces, or even into soil from buried tanks or pipelines, reference should be made to appropriate clean up methods.
Surface containment: purpose: to prevent the spread of the oil on the surface and to collect it for recovery.
Materials and equipment
Points to remember
The result of petrol getting into a sewer system was seen in Guadalajara, Mexico on April 22, 1992 when 5 explosions between 10:06 and 14:20 blew open the streets and carved an enormous 9 mile ditch down the middle of Avenida Gante 80 feet wide and 25 feet deep.
The blast threw a bus onto the second floor of a house.
Approximately 1,000 buildings collapsed or were heavily damaged. Initial reports by the Mexican Government and confirmed by team member Al Nixon of the Atlanta Red Cross said at least 2,000 people were injured, 200 people were killed and over 20,000 were left homeless.
Damages of building were estimated to be at $300 million.
An investigation into the disaster found that there were two precipitating causes:
In the aftermath, city officials and corporations pointed fingers at each other. Some people initially thought a cooking oil manufacturing company was leaking hexane, a flammable liquid similar to gasoline, into the sewers, but this was later found to be erroneous. Numerous arrests were made in an attempt to indict those responsible for the blasts. Mayor Enrique Dau Flores was indicted for ignoring the warnings; he subsequently resigned from office. Eight others in the government and PEMEX, the national oil company, were also charged in the case. Ultimately, however, these people were cleared of all charges.
Materials and equipment
Points to remember
Response in Lakes
The movement of the wind dominates the current force. The geometry of the lake and duration of the wind can result in columns of complex currents. Currents are usually stronger in the shallow parts than in deep areas. This is a main simplification of the movement of the wind in the flow of the lakes.
The effect of wind and waves during oil spills in rivers and lakes are important to know. In rivers wind is of secondary importance to the wind dependent on the width and amount of trees on the banks. In lakes, these effects normally determine the distribution of the oil.
The waves alter the movement and expansion of the oil. The slick absorbs the energy of the waves so that the amount of movement is decreased.
Collection points are usually visible with the areas debris build up, the removal of any debis need to done before the oil arrives as the oiled debris will cause another waste disposal problem.
This has various effects:
The current dynamic process as the wind it moves the water is complex.
The oil trajectory is the usually 3% of the velocity of the wind and in the same direction as the wind.
Current flow is unstable and it tends to break into patterns called Langmuir cells after the Nobel prize winning chemist Irving Langmuir.
These appear when the wind is stronger than 3-4 knots. They are formed from vortices in line with the wind.
The distance between these cells can be from centimeters to meters. They are seen as strips, smooth water where debris collects.
It is thought that these cells in theory cause the oil windrows.
This can only be used in very calm conditions with very weak currents. They create a current on the water surface which prevents floating liquids or debris from passing and therefore spreading. The current is generated by compressed air flowing through a thick walled pipe placed on the bed of the water body. The air rises through special nozzles incorporated in the pipe to the surface, forming a vertical bubble curtain in the water column. When it reaches the surface the vertical current is transformed into a horizontal current which acts as barrier.
Basic components of a bubble barrier
Main advantages of Pneumatic oil barriers
Points to be considered
If the spilt material mixes with water you can’t boom the watercourse as the pollution will just flow under the boom. If it‘s a small watercourse and has a low flow rate, you may be able to dam it and stop the water flow which will prevent the pollution spreading.
You will see below that different materials can be used to build a dam, e.g. sand bags, wooden planks, hay bales and soil. Keep these near any planned damming point and train people how to dam the watercourse.
You’ll need an alternative response plan in case high flow or rainfall makes damming impractical.
There are two types of basic dams – first, those ones that allow the water to flow normally and, second, those that form a large dam obstructing water flowing. The latter is easier to build because a barrier will increase the water level, and have outlets made in the barrier to allow the control of the water level in the barrier.
Hand-made dams, by excavators only, with sacks of sand, soil or with pre-fabricated materials, such as wooden boards, aluminium or steel plates, can be made with or without discharging the water.
If the water course is shallow and the width is small then in many cases dams can be built quickly and cheaply to reduce the spread of the oil. There is always a need to allow water to flow through the dam and in many cases this flow is regulated. If this is not done there is a danger that the weight of water will push the dam over. Care also has to be taken with flooding, as the water level rises at the dam it also starts to back up in the stream.
Here is a collection of different types of dams which appeared in a CONCAWE report no 10/83 A field guide to inland oil spill clean-up techniques.
They can quickly be put into place before the manufactured equipment arrives e.g. boom and skimmers.
Earth dam Plastic sheet dam Straw bale dam
Wooden plank dam Wooden weir and barrier
Prefabricated spade dam Impoved prefabricated spade dam Net barrier with sorbent
It needs to be said that the straw bale dam is very temporary as the straw absorbs large quantities of water and the bales left are tied with two thin polyproplene strings and are designed to be handled dry.
When wet they weigh considerably more than the string was made to withstand and they fall apart when removing them from the water thus causing even more contamination and work.
Right shows someone who has not learned the lesson yet. Here the bale when dry weigh approx.1 ton. Imagine when they get wet.
Just to cause another problem these bales are made like a swiss roll with the straw being held together with a plastic mess. So we have plastic as one type of waste the natural fibres as another and the oil as yet another all needing different destinations.
Big wide rivers, in many cases form boarder's between states or countries, the effect of the wind may determine which bank the oil will impact and therefore which language will be spoken and what law's will need to be adhered to.
Wider rivers with higher current speeds need to be studied to see where access and the best opportunity exists to recover oil.
Rivers normally flow in one direction but in some places rivers flow in opposite direction. This can be caused but the laying down of eroded material.
As shown in the diagram left above.
These areas give options that can be useful for recover operations.
River's are never satisfied with what they have and where they are. They are always trying to change their route by eroding the banks away as can be seen in this photograph right above. Over millenia this river has moved through the valley leaving Oxbow lakes behind throughout the area.
The two images above show different places where access is by river or parachute.
Left is the Arctic region of FSU the photo right is Amazonia, Brasil. In both cases there are thousands of square kilometers of rivers with access only from the river.
During the rainy season in tropical regions, you are just seeing the canopy of the trees under that is also water, up to 10 meters deep.
Left is a diagram showing many of the natural problems we find in rivers.
Meandering rivers always have faster currents on the outside of a bend, this is where the erosion is being done.
So when looking for boom collection points we need to be on the inside of the bend.
As in the diagram right deflection booms are positioned to deflect the oil to the inside where it will be recovered.
It is always advisable to position at least two collection booms as oil usually finds its way past the first one.
The distance between booms should be wide enough to let oil particles that got past the first barrier and have enough time to float to the surface before reaching the next and so on.
I have been doing it this way since I got involved in this business and have taught people all over the world to do it this way.
So why do we find the diagram right in a guide showing how to do it wrong.
Maybe it was done this way because that was where the trees were growing.
Note in some countries it is illegal to tie booms or any other equipment off to trees.
There are different schools of thought. Train both ways and decide which is right.
Left shows how to do it wrong as well.
Access is always the main problem, having enough time to position the booms before the oil arrives is obviously the aim.
The next access point downstream may be only 1 kilometer by river, we cannot always use the river e.g. too much equipment for the boat, no boat, too shallow ets.
By land it may be many kilometers of cart tracks and therefore to much time is spent to get there and position the equipment before the oil arrives.
When you find a good access point do the maximum possible to make sure the oil does not pass by. Recee the next access point and even position equipment there if you have the manpower and extra equipment.
If there is a large quantity of spilt oil, the installation of many containment barriers will be needed. One single barrier will not block or deflect all the oil in moving water.
Water courses with currents of more than 1 meter per second (Mps) bring more difficulties.The type of barriers to be used will be decided by local conditions and material availability.
Some operations start in quite rivers only to be interupted later by flood waters.
There is always a need to know what the weather is doing as well as the topography of the region.
It may be sunny where you are, but miles away in the hills where your river comes from, it is raining.
Sometimes it may take hours or days for the flood water to reach your site but you need to be prepared.
This is a real problem in tropical regions where hours of rain produces tons of water and the level may rise a couple of meters for a short time.
Booms should always be secured with ropes with less breaking strain than the boom. As in the case above, the rope breaks but the boom remains with you.
In this case when the river calmed down the oil was over 30 kms from this point.
(There is a section on weather forecasting in the Marine section of this site below the Beaufort scale.)
Booms should be anchored either in the river or on the banks to maintain the angle as good as possible. In currents of more than 1mps, shorter lengths of boom should be used to provide more anchor points at the connections.
The fewer anchor point the greater the likelyhood of sections of the boom bellying and oil getting away.
Stakes of either wood or steel are usually used in these cases and many long lengths of rope. Make sure you have enough of both.
The photo right is a recent spill in the Rio Guarapiche, Venezuela. The mind boggles as to why you have boom but have to use half naked men instead of anchors.
In order to reduce the stress and strain on boom anchor points a series of booms are positioned one behind the other to work like a cascade allowing the oil to be directed into calm water recovery points photo left.
This reduces the strain dramatically as the booms are seperate and not in a continous length.
Each boom is angled across the river to allow the oil to flow off the end onto the next and so on until it arrives in the collection boom at the bank.
There needs to be a good seal against the bank to allow the oil to become thick enough for recovery to take place.
This can be difficult in many places as environmental agencies will not allow the bank to be dug away to allow a smooth seal with the boom.
If the boom is not sealing properly, a vortex will form in the point of the boom near the shore which will entrain the oil under the boom. This problem is lessened when heavy fuel oil or cold conditions increase the viscosity of the oil.
The photo right shows how with no seal any oil that is directed to the shore will just escape through the gap.
I have argued that a little damage to a river bank which can be repaired after the operation, is better than many kilometers of oiled river banks.
The photo left shows the use of a trench to contain oil and be recovered by vacuum trucks.
The boom could do with being at a better angle but with the volume of oil it would be difficult to achieve.
Note: oil escaping under the apex of the boom is caught by the back up.
As over 60% of inland oil spills occur in rivers with currents in excess of 0.5 (mps), various techniques and equipment have been developed over the years some are common and others are very rare to find. Here is a small selection of some of these innovations.
Here is a type of boom right that seems to be difficult to find these days. It was designed to work in fast currents.
Skirts were made shorter and holes were made to allow the water to flow through the skirt reducing the water pressure and therefore reducing the likelyhood of the boom being submerged.
The photo right is a pallet of this type of boom in a base in Baku, Azerbaijan.
If you don't have this boom available. The boom skirt can be rolled up and tied around the floatation to reduce drag and facilitate deployment. Deploy the boom so that the current faces the smooth backside of the rolled up skirt.
After deployment, cut enough of the ties loose starting at the apex to permit the boom to bow out due to increased drag on the skirt. Leave the remainder of the skirt tied. The floatation and compressed skirt are enough to deflect oil at shallow angles.
The Flow-Diverter system was tested in the 1970s and was found to be effective at diverting and converging oil at speeds up to 5mps.
In more moderate currents it can be used in place of an anchor, towboat or outrigger arm to deploy and position the outboard end of a deflection boom.
Photograph left is of the prototype.
The diverter is a unique stable catamaran design that consists of two hulls. Each hull comprises of symmetrical foils with integral buoyancy.
The foils are pinned to a rigid connecting structure so that they can pivot but remain parallel to each other. Two or more catamaras can be connected together with cables to increase the total sweep width. Two control lines are anchored to the shore or to a boat and are used to deploy the system by adjusting the foil angle to the oncoming water.
With the control lines secured, the system is launched into the current and drives out into the a stable position balanced by by the hydrodynamic lift force of the passing water and the tension in the lines.
The foils create a strong transverse surface current downstream to achieve the desired diversion and consolidation affect on the floating oil. Unlike most skimmers and deflection booms, the diverters are not adversely affected as current increases. The oil is diverted by the same amount irrespective of current speed.
The photograph left is current at 1.5 mps and the right is at 2mps.
The USCG Research and
These photographs above are from tests done at OHMSETT, New Jersey, USA.
The Boom Vane© is simply a series of vertical vanes which drive into the current. The boom is attached to a towing bridle which is towed behind. The main tethering rope is anchored on the river bank upstream of the recovery point, when the Boom Vane is launched it drives into the current on an arch as in the diagram. The faster the current the tighter the angle of the boom.
There is a serious safety issue with this equipment, dependent on whether it is fitted with a spring on the rudder or not.
If the spring is fitted then a sharp tug on the thing red line will stop it in mid stream and start to return to the original bank.
It can be stopped and started again which is useful if a boat needs to pass during operations.
If the spring is not fitted it cannot be stopped until it reaches its stopping point. If someone gets the rope around his foot he is going with it until it stops and there will be no slack in the rope to escape until that point.
This version is .55m high and was designed for operations in shallow waters (less than 1 m / 3'). It may also deployed off a towing vessel to reach near the shoreline with booms and absorbents, where it is too shallow for the vessel to go.
To make things difficult for people using this equipment for the first time, the colour code is wrong, this has been reported to the manufacturer but nothing has changed. It can be put together to work from both banks of a river or from both sides of a vessel.
The colours are red and green which are maritime colours for port and starboard unfortunatly they are the wrong way around. It would be easy to deploy it from the port side using the red indicators but for it to work they need to be green. Its not difficult to get the paint out and change it, but some people do and others don't which just leads to even more confusion.
Having said this it is a very good piece of equipment, they come in various sizes 0.5m and 1m for rivers the bigger the size the faster the current needs to be for it to work correctly. There is also an open sea version where the vessel provides the current speed. This should dramatically reduce the damage to offshore booms as only one vessel is needed.
I have used the boom vane in shelted bays and close to the shore with good results. (there is an offshore version which is mentioned in the booms section).Video of boom vane click here.
These boom deflectors act like the boom vane but are smaller and fit in between the boom sections, each one drives into the current removing the need for anchors. This is particularly useful in shallow rivers.
These types of inventions reduce the manpower requirements and response times but mainly the need for anchor points and the amount of rope required for the deployment.
This device, known as Capt Blombergs Hydro dynamic Circus© is now a River Circus©.
It uses a small opening which then opens into a wide collection area with a skimmer is fitted in the middle.
The oil flows through the gap at speed when it gets into the wide area it slows down giving the skimmer time to work.
A simple system to deploy but requires a depth of approx. 0.5m next to the bank.
This is the Mini Fastflo© which works on the same principle as the Circus oil enters through a restriction which then widens allowing the flow to reduce in speed and enter the skimmer section at the back.
As can be seen it will work in very shallow rivers or streams and is simple to deploy.
The Boom Vane is a device for boom deployment in rivers and other waterways. This powerful yet light response tool allows for rapid deployment of small boom in fast waters, without the use of boats, anchors or fixed installations.In-situ burning
Burning is being considered with growing interest as a response tool for wetlands as a viable strategy in various countries.
Photo left is the result of a burst pipeline in a peat bog in Minnesota, USA.
Burning of wetland grasses has have been conducting prescribed burns of wetlands to rejuvenate wetlands that have accumulated high litter loads; generate green vegetation or open spaces to attract wildlife for many years, to restore habitats in areas that are historically dependent on frequent wildfires to sustain these ecosystems.
Burning of oiled wetlands is relatively new and will not be allowed in many countries.
The presence of oil in a wetland may have two important effects: the high BTU of the oil may increase the temperature and heat penetration of the burn, and oil residue may remain after the burn.
Deciding how to respond to an oiled wetland is a complex issue for which there can be no single answer.
It must be determined if any cleanup is necessary or desirable a consultation with a biologist, botanist, or ecologist would be extremely helpful in accessing options.
Cleanup in a wetland appears to be justified when oil can be removed with minimum impact, when other natural resources (such as migrating birds) are at high risk of being oiled, or when unassisted recovery is likely to be very slow.
Photo right was taken during the Komi, FSU spill in 1996. This was done to minimise spreading of the oil into the Kolda River which flows into the Arctic Ocean. There were also no waste disposal routes in this remote location.
Natural recovery may be the best option to follow when:
In-situ burning as a spill response method may provide a means to remove the oil from the impacted area without resorting to mechanical cleanup methods, which may be destructive or impossible to carry out.
Text taken from RRT6 ISB Guidelines 1996