Soil remediation is a way of purifying and revitalizing the soil. It is the process of removing contaminants in order to protect both the health of the population and the environment. In short, the goal of the process is to restore the soil to its natural, pollution-free state.
What exactly causes contamination in your soil?
Soil contamination—also known as soil pollution—is caused by the presence of manmade chemicals in the natural soil environment. It is often caused by some form of industrial activity, agricultural chemicals or the improper disposal of waste. The most common chemicals involved in soil pollution are petroleum hydrocarbons, pesticides and lead and other heavy metals. Soil contamination can also happen as a result of underground storage tanks rupturing or the leaching of waste from landfills. Mining, fertilizer application, oil and fuel dumping and a multitude of other environmental issues can also cause pollution of the soil.
What are ways that you can test your soil to determine what is contaminating it?
A sure fire way to find out what exactly is contaminating your soil and to what level it is polluting, is through soil sampling and soil analysis. In order to retrieve soil samples, first a test pit must be dug to the depth where you believe the contaminants have settled in the soil. After digging the test pit to the appropriate depth and width, soil samples must be taken from the appropriate wall and finally sent off to a lab for testing.
After you know what is contaminating the soil, how do you remediate the soil?
There are three main soil remediation techniques: Soil washing, bioremediation, and thermal desorption.
Soil washing is a process that uses surfactants and water to remove contaminants from the soil. The process involves either dissolving or suspending pollutants in the wash solution and separates the soil by particle size (Center for Public Environmental Oversight, www.cpeo.org).
Bioremediation involves the use of living microorganisms, such as bacteria and fungi, to break down organic pollutants in the soil. In thermal desorption, heat is used to increase the volatility of contaminants, so that they can be separated from the solid material. The contaminants are then either collected or destroyed.
Thermal desorption is the most proven and successful technology used for hydrocarbon contamination, and typically direct fired plants have been used for low levels of contamination. Lately, indirect fired units are more commonly used because of their versatility and their ability to recapture the hydrocarbons. A typical thermal desorption unit consists of two main processes. In the first, contaminated solids are heated to the boiling point of the contaminants. The volatized contaminants are then pumped to the second part of the process, where the vapor is either destroyed by a thermal oxidizer or condensed in a vapor recovery unit (VRU).
Another popular method of remediating soil known as (load’n go), consists of digging out all of the contaminated soil, and then loading it onto end dump trucks to have it shipped to a landfill for proper disposal.
What are the proper ways to dispose of contaminated soil once it’s been removed?
The most common method is to have it picked up and transported to a landfill to be disposed of. This method essentially takes the contaminated soil right off your hands, there are however other on site treatments that can be used for the contaminated soil.
Solidification/stabilization work has a reasonably good track record but also a set off serious deficiencies related to durability of solutions and potential longterm effects. In addition CO2 emissions due to the use of cement are also becoming a major obstacle to its widespread use in solidification/stabilization projects.
Stabilization/solidification (S/S) is a remediation/treatment technology that relies on the reaction between a binder and soil to stop/prevent or reduce the mobility of contaminants.
Vitrification permanently traps harmful chemicals in a solid block of glass-like material. The process uses electric power to melt the soil and trap the contaminants.
Vitrification doesn’t make economic sense for large-scale applications that would be needed at this site. In-place vitrification results in a sterile, impermeable soil on which nothing can be grown and no water can infiltrate.
The result would be ponded water in places where it never did before, increased runoff into storm drains, increased runoff water temperatures, potentially more polluted storm water without the filtering effects of vegetation, and more.
At the yard-soil level, electrical currents coursing through the soil would pose a significant risk to the landowner’s water and sewer pipes, wells, fences and foundations. Vitrification is a risky choice for landowners and agencies.
Now why is it important to take your contaminated soil seriously?
The U.S. Environmental Protection Agency (EPA) and other agencies regulate the levels of contamination in order to protect the environment. Superfund is the common name for the Comprehensive Environmental Response, Compensation, and Liability Act that was passed in 1980 to deal with abandoned hazardous waste sites. Through Superfund, the EPA finds those responsible for the contamination—known as potentially responsible parties (PRP)—and requires them to clean up the polluted soil or pay the cost of cleanup. The penalties for failure to clean up the contamination vary, but the law authorizes the EPA to seek up to $37,500 for each day of non-compliance (EPA Superfund Compliance and Penalties, www.epa.gov).
How can Mantis help you?