Environmental Effects of Natural Catastrophes

Hurricanes

Hurricanes are one of nature’s most powerful storms. Generally known as a tropical cyclone, it gains energy from warm ocean waters bringing high winds, flooding, inundation and other issues to coastal and inland areas.

The greatest risk posed to human health as a result of a hurricane is flooding and inundation.

Severe flooding can significantly affect inland areas, often causing devastating injury and property damage.

Intense flooding can migrate soil and agricultural nutrients from fields into water ways which then seep into larger bodies of water such as dams, lakes, bays, and estuaries.

When introduced into bays and estuaries, the foreign agricultural nutrients may have deleterious effects on fish, shellfish, and other aquatic organisms. In many areas, the excess nutrients during floods creates nutrient-rich water allowing algae to flourish.

This spike in algae growth depletes oxygen in the water and creates ‘dead zones’ where fish and shellfish cannot survive, negatively impacting local watermen and tourist industries who greatly depend on aquatic life for income.

Hurricane flooding might also release pollutants such as mining fines, oil and grease-soaked sediments, metallic objects, nutrient-laden silt and polychlorinated biphenyls (PCBs) that were originally trapped in rivers and streams. Coupled with this, flooding often causes sewage lines and petroleum pipelines to fail which may release the piping contents into the flood waters. These pollutants often cause long-term environmental damage to receiving waters.¹

Prior pollution disposal methods for industrial areas along the coast such as burial of “tank bottoms” may also pollute surrounding areas as wind-driven waves unearth the contaminants and deposit them into new sites. This can be substantially harmful to the surrounding fish and vegetation.

Hurricane flood waters also have the potential to cause damage to underground storage tanks (USTs). During rapid floods, UST systems can become submerged or displaced, leading to damaged tanks or even the releases of regulated substances into the environment. The displaced petroleum may migrate into the flood waters, eventually polluting the surrounding area.²

 

1972, Hurricane Agnes: Within a ten-day timeframe, Hurricane Agnes washed more pollutants into Chesapeake Bay than it had received within 25 years.³ The extensive amount of water introduced pollutants and lowered salinity levels, leading to a 100% mortality of oysters and 90% mortality of soft shell claims in some areas of the bay. Hurricane Agnes also reduced the amount of aquatic grasses in the bay which provided critical habitats to key species for spawning and improved water clarity.⁴

 

2005, Hurricane Katrina: During Hurricane Katrina, the Murphy Oil refinery was inundated with flood waters, damaging equipment and several onsite above ground storage tanks (ASTs), releasing over one million barrels of oil from the refinery and affecting as many as 10,000 homes in the surrounding neighborhoods.⁵

The released content, mostly diesel range oil, required extensive remediation to remove the spill from houses, roads, city canals and other urban community areas. In total, over 1,800 homes were coated with oil and the affected area was over one square mile.

 

2019, Hurricane Dorian: After the recent Hurricane Dorian, Equinor ASA responded to damage done to its Bahamas South Riding Point oil storage terminal. As a result of the hurricane’s high winds and wind-driven waves, five of the largest ASTs located at the terminal were severely damaged causing the release of massive amounts of oil. Unfortunately, Equinor did not have a sufficient onsite emergency plan in place and had to import response assets from Louisiana and Florida in order to effectively remediate the spill.^{6, 7}

Equinor recently stated that they are quickly working to locate and remediate the escaped oil to avoid future releases in an event of another emerging storm.⁸

Windstorms & Tornadoes

During natural occurrences involving high winds, building foundations and equipment including storage tanks can be severally damaged. Common failures of tanks due to high-wind exposure includes⁹:

•  Overturning or tipping tanks over
•  Sliding or pushing tanks off foundations
•  Buckling of tank walls

The higher the wind speed, the greater the pressure on a tank. ASTs should be equipped with both a primary and emergency vent. If the vents are not properly secured during a windstorm, suction may be generated and cause the roof of the tank to release liquids. Buckling of the tank walls can also prevent proper operations of the tank and potentially allow fugitive emissions to escape around the roof gaskets.

A common rule of thumb: a doubling of wind speed increases the wind pressure on the tank by its square.

The buoyancy of a tank is another risk factor to take into consideration during high winds. There must be sufficient ballast, usually a liquid product or water in the tank to keep it anchored onto the foundation and prevent floatation in the event of flooding. In certain areas of the United States, if the tank does not contain a sufficient amount of substance to prevent floating, the tank can be filled with water to avoid buoyancy.¹⁰

The amount of fluid in a tank can also prevent buckling by providing outward pressure which counteracts the force of the high winds. An important consideration for pre-storm planning is to contact a professional engineer to determine the standard amount of tank fluid necessary to prevent wind damage or tank failure. This information should then be noted in the site’s emergency response plan.

An unwritten rule to remember: At least three feet of liquid is required to avoid tank floatation.⁹

Also note that high winds can remove insulation from tanks that store heated fluids, requiring reinstallation in order to keep the tanks at proper temperature for processing.

Flooding

Floods are often unpredictable, and the aftereffects can be damaging and costly to mitigate. This type of disaster is caused by many different phenomena including natural processes such as heavy rains, snow melt, earthquakes, tsunamis or hurricanes.¹¹

Flooding inundates large areas of the ground surface and can cause serious damage to the interior of buildings such as dry wall, carpets, flooring, furniture and electronics. If drying of building interiors is not completed quickly and thoroughly, mold can form which will require remediation. Due to the silt and mud in flood waters, it is common that inundation of carpets, furniture and equipment are often ruined and require complete disposal. However, after floods, disposal space is often at a premium, generating higher prices.

Any buried wastes in a stream bed or floodplain can be maneuvered by the flash flood waters and deposited downstream. A common problem that occurs includes contaminated sediments depositing in coastal wetlands, causing long-term environmental problems.¹²

Earthquakes

Earthquakes generate ground shaking, seismic waves, induced soil liquefaction, landslides, and transverse movement of the ground. Subsequently, this has the potential to damage physical structures such as ASTs, process equipment and various types of pipelines including oil, gas, water, and sewage. Damage to these may release hazardous materials into the environment.^{13, 14}

The 1994 Northridge earthquake in Southern California for example, resulted in the failure of a buried pipeline and released 190,000 gallons of oil into the Santa Clara River. This mass release resulted in a fine of $7.1 million dollars, requiring the replacement of nearly 150 acres of river bottom. 

Typically pipelines withstand ground shaking with few releases. However, when the earth experiences intense lateral and vertical movements, pipelines are more prone to failure and the substance within may be released. It is crucial to strategically route pipelines to avoid areas where extensive ground movement is likely to occur during unexpected earthquakes.

In addition to careful route selection, a thorough review by geologists and civil engineers is warranted. The estimated ground movement should be noted, and the pipeline’s material and other design features should be evaluated to ensure reasonable ‘earthquake resistances’ are set in place.

Wildfires

A wildfire is an unplanned fire that burns in a natural area such as a forest, grassland or prairie. Human-made or natural, wildfires are subject to local and regional weather patterns and can generate its own wind, increasing the speed and unpredictability with which these fires spread. These factors and more can intensify the dangers posed by wildfires.

The primary effect of wildfires is the burning of buildings, infrastructure (power lines, roads, etc.), coupled with significant degradation of air quality and injury to humans.

Secondary effects include runoff, flooding, erosion and debris flows. After a wildfire, rainfall can greatly increase runoff from an area and transport large amounts of soil and silt into receiving bodies of water. This increased silt negatively affects aquatic organisms and fish habitats.

Wildfires can destruct native vegetation and often result in non-native weed species overtaking an area. This can present negative effects if the native vegetation of an area was important economically or supported other animals and vegetation.¹⁵

Removal of native vegetation also can reduce the slope stability of an area.

With the vegetation removed, soils are exposed to rainfall and no bonding effect of the vegetation roots are present.

Strong rains can infiltrate soil layers with water, which can create sliding or slipping layers which decreases the slope stability of a burned area.¹⁵

Due to the interruption of infrastructures, wildfires can affect the provision of necessary services such as:

An emergency watch should be instituted in times of known or suspected wildfires, so that when a warning occurs the facility can be shut down and evacuated quickly.¹⁶

Emergency Planning for Natural Catastrophes

The potential for natural catastrophes should be incorporated in a facility’s emergency planning. If a facility does not currently have a plan in place, Local Emergency Planning Committees (LEPCs) are required to develop threat maps in response to significant hazards within the area as well as provide information about chemicals in the community to citizens. These established LEPCs threat maps are easily accessible and can be used as a reference during preparation.

While creating an emergency plan for natural catastrophes, the history of the area should be investigated using records from United States Geological Survey (USGS) and National Oceanic and Atmospheric Administration (NOAA) to detect prior earthquakes, floods and fires. It is important to determine likely hazards for the area in order to include adequate planning for response and property recovery.

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