Pollution's Impact On Aquifers And Groundwater: A Hidden Danger

Groundwater is a vital source of drinking water and food crop irrigation for over a third of the global population. However, it is susceptible to pollution from human activities and natural sources. Contaminants can include toxic metals, hydrocarbons, pesticides, and fertilizers, which can have severe ecological and health impacts. As groundwater moves through unseen aquifers, pollution can be challenging and costly to detect and remediate. Therefore, it is essential to implement preventive measures and improve monitoring and management strategies to protect this precious resource.

Poorly constructed wells near agricultural land

Poorly constructed wells located near agricultural land pose a significant risk of groundwater pollution. Wells are prone to contamination when they are not properly sealed or maintained, allowing pollutants to seep into the groundwater.

Agricultural activities contribute to water pollution through the use of agrochemicals, organic matter, drug residues, sediments, and saline drainage. Pesticides and fertilizers, commonly used in farming, can find their way into groundwater supplies over time. When wells are poorly constructed or maintained, these chemicals can easily infiltrate the well and contaminate the groundwater.

In addition, improperly constructed wells can introduce a vicious cycle of polluted groundwater. Structural issues or improper construction methods leave wells vulnerable to coming into contact with contaminated surfaces or water, resulting in contaminated groundwater.

To prevent groundwater pollution from poorly constructed wells near agricultural land, it is essential to ensure proper well construction and maintenance. Well owners should prioritize education and follow recommended practices to protect the quality of their water sources. By addressing these issues, we can minimize the risk of groundwater pollution and protect this valuable resource for future generations.

Improperly constructed wells

Wells that are not constructed correctly introduce a vicious cycle of polluted groundwater. Problems with the well can leave it vulnerable to coming into contact with contaminated surfaces or water, resulting in contaminated groundwater.

Wells are constructed by drilling machines or by driving pipe into the ground. Driven wells are shallow and, despite being cased, can be contaminated easily because they draw water from aquifers near the surface. Dug wells are also shallow and are not cased continuously. In contrast, drilled wells can be thousands of feet deep and are continuously cased, reducing the risk of contamination.

Wells should be located so that rainwater flows away from them. If rainwater pools near a well, it can seep into it and potentially cause health problems. The local geology often dictates what type of casing can be used. Well caps are placed on top of the well casing to prevent debris, insects, or small animals from getting into the well. Well screens are attached to the bottom of the casing to prevent too much sediment from entering the well.

It is important that geotechnical and hydrogeological matters are considered before any construction work begins. An environmental engineer, environmental scientist, or hydrogeologist should be engaged to report on constraints and risks to the project and inform strategies to minimise adverse outcomes.

Improperly abandoned wells

The risks associated with improperly abandoned wells include groundwater contamination, methane emissions, and surface-level pollution. In terms of groundwater contamination, old wells with degraded well casing or cement can allow oil, gas, or salty water to leak into freshwater aquifers. This can have serious consequences for human health, as contaminated groundwater can contain toxins that lead to diseases such as hepatitis and dysentery, as well as long-term effects such as certain types of cancer.

To address the issue of improperly abandoned wells, regulators require well operators to remove all equipment and plug the wells to prevent leaks. Typically, cement is pumped into the well to fill the top and bottom portions and any areas where leaks may occur. State or federal regulators define specific plugging procedures depending on local conditions and risks. In some cases, voluntary industry programs and government agencies have stepped in to plug orphaned wells and prevent further contamination.

To protect groundwater from the risks associated with improperly abandoned wells, the Department of Water Resources (DWR) has published standards for well construction and destruction in Bulletin 74. Local environmental health agencies are responsible for implementing these standards, and in most jurisdictions, permits are required to construct or destroy a well. By following these regulations and standards, we can help to prevent groundwater contamination and protect this vital resource for future generations.

Septic systems, sewers, and pipelines

Septic systems are commonly used for wastewater treatment by homeowners who also rely on private wells for drinking water. If a septic system is faulty or located too close to a drinking water well, contaminants can enter the drinking water. Septic systems that are poorly designed, installed, or maintained can contaminate groundwater with pathogens, chemicals, or nutrients. This can lead to illnesses caused by bacteria like E. coli, excessive algal growth due to nitrogen, and reduced oxygen levels from phosphorus pollution.

Improper septic systems can also contaminate surface waters, impacting recreational swimming areas and causing illnesses, beach closures, and hazards to humans and pets. Additionally, excessive nitrogen discharges can affect sensitive coastal waters, while phosphorus pollution can harm inland surface waters.

Pipelines, particularly those transporting fossil fuels like oil and gas, pose significant risks to groundwater. Pipeline construction and spills can contaminate drinking water sources, streams, and rivers. For example, the Mariner East 2 pipeline resulted in drinking water contamination for dozens of families and caused hundreds of spills, with thousands of gallons of drilling fluid released into the environment.

The potential for harm from pipelines is well-known, yet government agencies continue to approve their construction. This has led to environmental destruction, violations of indigenous rights, habitat destruction, and negative impacts on farms and landscapes.

Sewers are also a potential source of groundwater pollution. Sewer systems can leak untreated wastewater, which can contaminate groundwater with bacteria, viruses, and chemicals. This can occur when sewers are improperly designed, constructed, or maintained, or when they exceed the treatment capacity of the surrounding soil.

Landfills

Leachate from landfills contains many toxic and harmful substances such as heavy metals, persistent organic pollutants, and bacteria. Groundwater contaminated by leachate can cause various health issues, including an increased risk of cancer and infant death, as well as motor and cognitive dysfunction in children.

The age of the landfill is a significant factor in determining the degree of groundwater pollution. Older landfills tend to have higher concentrations of pollutants, which can take many years to decrease to safe levels. Closing landfills also helps improve water quality, though this takes time and may not always be feasible.

To prevent groundwater pollution from landfills, isolation distances between landfills and drinking water sources are crucial. These distances vary depending on the type of aquifer and local hydrogeological conditions. In some cases, the required isolation distance can be reduced by modifying the characteristics of the vadose zone, such as increasing its thickness or reducing its permeability.

Frequently asked questions