Fresh water makes up around 3% of the entire earth’s water supply, most of which is found below the ground’s surface. Groundwater is responsible for about 40% of the world’s drinking water which is drawn up from boreholes and dug wells. In some instances, this water can become polluted as a result of various industrial and farming practices and when this occurs, the water must be remediated as soon as possible to prevent further damage.

What is groundwater exactly?

Put simply, groundwater is water that is located below the ground’s surface. This is usually found in underground layers of water-bearing permeable rock, rock fractures or unconsolidated materials called aquifers. This water can be brought to the surface by being drawn up from a well, may intersect with nearby bodies of water or seep out of a rock formation or hillside.

Aside from being used for drinking water, groundwater is also essential for farmers to water and irrigate their crops and companies use it to manufacture certain products.

What is groundwater remediation?

Groundwater remediation is the process of treating polluted groundwater. This is carried out to make the water safe for humans and to reduce any negative impacts the contamination or pollutants may have on the environment. Soil or sediment can also be remediated if it is contaminated as a result of coming in contact with contaminated groundwater.

Groundwater remediation is carried out with the intention of either removing the contamination or pollutants entirely or converting them into safe products. Whichever method is chosen, the goal is the same: to have clean, safe water, free from contamination.

What causes groundwater to become polluted?

Groundwater can become polluted in a number of ways. For one, it can be due to certain farming practices such as the application of fertilizer or pesticides on crops. Additionally, it can be contaminated by spills from industrial operations and leaks from landfills can also cause groundwater contamination. When pollution occurs, it is essential to remediate the water as soon as possible.

How is groundwater remediated?

Remediation can take place either in-situ (on-site) or ex-situ (off-site). In-situ is where it is cleaned in place, instead of transferring it to another location to be treated, this is generally cheaper and quicker. On the other hand, ex-situ is the process of taking it to an external location to be treated or disposed of. This method is particularly useful as it removes all possibility of further damage being done, however, it takes longer and is more expensive than in-situ practices.

The type of remediation that is best is evaluated on a case-by-case basis and numerous factors are taken into account such as the pollutant in question and how much water has been impacted.

Most common methods of groundwater remediation

There are several different methods of remediating groundwater, some of the most common being:

• Extraction and disposal: where the impacted groundwater is removed from the site and taken elsewhere to be disposed of safely
• Pumping and treatment: this involves pumping out the contaminated groundwater using a vacuum pump and purifying the groundwater using materials to absorb the contaminants
• Chemical oxidation: a process that involves treating the water and sometimes the surrounding soil with natural, specialist synthetic or man-made products
• Air sparging: this is typically used when fuel, oil or hydrocarbons need to be removed, this is done via pumping air through the water
• Soil vapor extraction: a process used to remove odors from contaminated soil or groundwater. This method is usually used in conjunction with other remediation methods

Find out more about the different methods of remediating groundwater in depth with our dedicated guide.

How long does groundwater remediation take?

The length of a groundwater remediation project varies greatly depending on the contaminants in question and the size of the area that has been impacted. It is not uncommon for a project to take years as after each phase of cleaning, sampling is required to check if the water meets certain criteria and regulations. A project is only considered to be complete once it meets stringent standards which are set by the local government.

Now you know what groundwater remediation is and why it takes place, find out about environmental remediation next and how it plays a vital part in protecting the environment.