Groundwater contamination is due to our everyday activities. It becomes vulnerable, especially where the population density is high, and the land use is intensive. In general, any activity which releases wastes or chemicals in the environment can potentially pollute the groundwater. Indeed, it is expensive and difficult to clean contaminated groundwater.
Before resolving water pollution, it is best to understand first how ground and surface waters are related. You can manage and fully understood everything if you acknowledge the fact that it is interconnected. If a water supply is near to the source of contamination, then there is a risk. If there is a stream or river nearby, then the groundwater can have a chance to become polluted.
Contaminating the Groundwater
When you release a contaminant in the environment, it may move within an aquifer in the same way groundwater moves. This depends on the chemical, physical, or biological properties. This is because some contaminants do not follow the groundwater flow because of their chemical or biological properties.
To some degree, transport within an aquifer of the substances is predictable. For example, both the contaminants and water can flow in the direction of the topography. This is from the recharge areas to the discharge areas. Permeable and porous soils transport water and other types of contaminants easily to an aquifer found below.
The contaminants move slowly, just like the groundwater. With this movement, the contaminants become concentrated as a plume. It flows on the same path as the groundwater. The speed and size of the plume will depend on the type and amount of contaminants. Its velocity, density, and solubility will also determine the speed of the plume.
The contaminants can flow rapidly through the rocks’ fractures. When there are fractured rocks, controlling and locating the contaminants are problematic. This is because the fractures are randomly spaced. It does not follow the land surface’s contours or the hydraulic gradient.
Meanwhile, the contaminants can also move in through macropores. Examples of this are animal burrows, abandoned wells, animal burrows, and others.
In the areas near the pumping wells, the risk of contamination increases. This is because water from the zone of contribution is drawn into the aquifer and well.
Some water wells draw water from rivers, streams, or lakes. The contaminants in these surface waters can contaminate the groundwater systems.
Some water wells rely on artificial recharge to add water to the aquifer. It often uses the water from irrigation, storm runoff, treated sewage, or industrial processes. This practice has increased concentrations of microbes, metals, nitrates, and other chemicals in the water.
In some cases, pumping can enable the groundwater from another aquifer to enter into the pumped water. This is known as interaquifer leakage. To maintain the groundwater quality, you must properly identify and protect the affected areas.
In general, the greater the distance between the groundwater and the source of contamination, the more likely to reduce the risk of contamination. In the soil layer, several processes may take place which can reduce the concentration of contaminants. Examples include biological degradation, oxidation, and adsorption. With this, it can reduce the concentration of contaminants even before it reaches the groundwater.
Even when the contaminants reach the groundwater directly, they can become less concentrated through dilution even if they did not pass through the unsaturated zone. It is the process of mixing with the groundwater. But since groundwater moves slowly, contaminants undergo less dilution. This is unlikely than in the surface water.
Sources of Groundwater Contamination
Groundwater becomes contaminated because of human activities or natural sources. Industrial, municipal, residential, commercial, and agricultural activities can lead to water contamination. The contaminants can mix with water because of the activities on the land surface. It can be through spills or releases from stored industrial wastes from sources below.
From above the land surface, water can be contaminated through leaking petroleum, septic tanks, and others.
Natural Sources of Groundwater Contamination
Substances found naturally in soils or rocks can be dissolved and get into the groundwater. Examples include chlorides, manganese, iron, fluoride, radionuclides, sulfates, and others. Other naturally occurring substances like organic matter can move in the ground.
Whether or not these substances can appear in the groundwater will depend on various conditions. Some substances can pose a health danger whenever ingested in huge quantities. Meanwhile, others can produce undesirable color, odor, or taste.
If the groundwater contains high concentrations of these substances, then it is not recommended for drinking. You cannot also use it for other domestic uses unless it is treated.
One of the main causes of water contamination is the effluent from cesspools, septic tanks, and privies. Around 25% of homes in America use septic systems to dispose of their human wastes.
Indeed, each system can release a small amount of waste only. But the widespread use of the system can be a serious source of contamination. If the septic systems are improperly designed and maintained, they can contaminate the groundwater. It can release viruses, bacteria, oils, detergents, and nitrates.
Apart from these, the septic systems can release cleaners that contain synthetic organic chemicals like methylene chloride and trichloroethene. It can contaminate the water supplies and interfere with the process of natural decomposition.
Local and state regulators require specific distances between the septic tanks and water wells. There are tools used to calculate suitable densities and distances for installing the drinking water wells.
Improper Garbage Disposal
Take note that hazardous wastes must be disposed of properly. It must be handled by a licensed waste handler via your locality. There are chemicals that you must not dispose of in the septic systems. The example includes oils, garden chemicals, paint, thinners, medicines, and disinfectants.
Moreover, industrial chemicals must not be disposed of in the drains at your workplace. It can only contaminate your water source. Companies must train their workers on how to dispose of the chemicals used on the site.
The different quantities and types of chemicals used at the industrial locations allow proper wastes disposal, an important factor for water protection.
Spills or Releases from Petroleum Products or Chemicals
Aboveground or underground storage tanks are commonly used to store chemicals. Homes have underground heating oil tanks. Some businesses store their fuel oil, diesel, gasoline, or chemicals in on-site tanks. Meanwhile, industries use storage tanks to keep chemicals for various industrial processes.
In America, there are around 4 million underground storage tanks. Through the years, many of the tanks have spilled in the ground.
Whenever there is a leak, the content can go into the soil and the groundwater. Indeed, tanks that meet the state standards are less likely to leak. However, they are not 100% foolproof. Moreover, the abandoned underground tanks are another problem that can pose a threat to groundwater.
Sloppy materials, improper chemical storage, and poor containers can be a threat to groundwater. Train cars and tanker trucks can pose a hazard to the environment too.
Every year, around 16,000 chemical spills occur from trains, storage tanks, and trains whenever the materials are transferred. In the area of the spill, the chemicals can be diluted with water. It can be washed away into the soil, which can increase the contamination.
In industrial landfills around America, solid waste is being disposed of. The chemicals which were supposed to be disposed of in the hazardous landfills end up in municipal landfills. Also, the disposal of household waste is not regulated.
As soon as the chemicals reach the landfill, they can leach into the groundwater through runoff and precipitation. New landfills are required by the authorities to have synthetic or clay liners. This protects the groundwater from possible contamination.
But for the old landfills do not have these safeguards. These are often located close to the surface waters or over the aquifers. It is in permeable soils with shallow water tables. This can increase the potential for the liquid from the landfill known as leachate to reach the groundwater.
Though landfills are closed, they can continue to threaten, especially if they are not capped with materials like clay.
The surface impoundments are shallow lagoons or ponds which the municipalities use to store, dispose of, and treat liquid wastes. Just like landfills, the new surface impoundment facilities require to have liners to prevent leakage.
Pipelines and Sewers
Sewer pipes that carry human wastes can sometimes leak fluids into the groundwater and soil. Sewage contains inorganic salts, organic matter, viruses, bacteria, and heavy metals. Other pipelines that carry industrial chemicals tend to leak. This is true whenever the materials being transported are corrosive.
Fertilizer and Pesticide Use
Crop production in the United States uses millions of tons of pesticides and fertilizers. Apart from farmers, businesses, homeowners, and municipalities also use such chemicals.
These fertilizers and pesticides have contaminated groundwater following registered use. Some of the pesticides can remain in the soil or water for many months and even years.
One source of contamination can be animal wastes that get into the ground from the farms.
Floor Drains and Injection Wells
The injection wells can collect stormwater runoff. It can contain the spilled liquids and dispose of industrial wastewater and commercial wastes. The injection wells are shallow, which include sumps. The dry wells are used to collect the stormwater.
Meanwhile, the floor drains are used by businesses to handle the spills. Nowadays, if a business can operate or handle the waste fluids into the septic system, it must submit information regarding its operation to the authorities.
Disposal wells that can pose threats to drinking water must be closed.
Improperly Constructed and Maintained Wells
If the water wells are improperly constructed, it can result in groundwater contamination. Problems like lack of concrete pads, inadequate covers, or faulty casings can allow the outside water to the well.
Meanwhile, if the wells are abandoned or improperly maintained, they can act as a conduit for the contaminants to reach the aquifer.
Moreover, some people use abandoned wells to dispose of their wastes like motor oil. These wastes may reach the aquifer, which supplies drinking water. Abandoned wells are usually uncovered, which is a potential habitat for viruses and bacteria.
Active and even abandoned mines can cause groundwater contamination. With precipitation, it can leach the soluble minerals from the mines up to the groundwater. The wastes contain minerals, sulfides, metals, and acids. Abandoned mines are used as waste pits.
Moreover, mines are pumped to keep them dry. Pumping can cause the contaminants to shift above groundwater.
Effects of Groundwater Contamination
If the groundwater is contaminated, it can result in poor water quality. It can lead to high cleanup costs, loss of water supply, and degraded surface water systems.
Take note that the consequences of contaminated groundwater are serious. For example, estuaries that have been impacted by high nitrogen have already lost their shellfish habitats.
When we talk about the water supply, groundwater contamination is severe. This is the reason why groundwater is not a recommended drinking water source. In some cases, groundwater can be cleaned and used once again, only if the contamination is not too severe. This is true if the municipality is willing to spend money on it. Through the years, follow-up monitoring is required.
Since groundwater moves slowly, contamination can remain undetected even for a long time. This makes cleaning very difficult and impossible. If the government result in the cleanup, it can cost millions of dollars to accomplish.
Cleaning the Groundwater
When the contaminant source has been detected, controlled, or removed, the groundwater can be treated. First, you can contain the contaminant to prevent it from migrating to other water sources. Second, you can pump the water, treat it, and return it to the aquifer.
Third, you can leave the groundwater in its place and treat either the contaminant or the water. Finally, you can allow the contaminant to reduce naturally, following the use of appropriate source control.
The selection of appropriate technology depends on various factors. You also have to take into account the cleanup goals and the potential risks. Different technology is used for different types of contaminants. Sometimes, several technologies are combined to achieve an effective treatment.
With the high cost and difficulty of cleaning, some choose to abandon the wells and find other water sources. Using this technique is more expensive but it is safer than obtain water from contaminated wells.
A temporary solution is for you to buy bottled water. But this is not realistic for long-term consumption. You can try installing water filters inside your home too. The community might decide to install new wells in a different area of the aquifer. In this case, it is best to monitor the new wells to ensure that the contaminants will not move into the new water supply.