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Soil Erosion Problems and Solutions

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Soil Erosion in the United States

The United States is one of the top producers of food products worldwide. According to ShareAmerica, the U.S. shipped over $139 billion worth of agricultural products just in 2018. Those are astonishing numbers since U.S. farmers struggle to feed the world despite harsh winters, torrential rains, and hot summers which all contribute to soil loss and erosion.

Why Is Soil Conservation so Important?

Over the last decade, the United States has seen radical changes in weather patterns that are resulting in massive flooding in the Midwest and California where most food crops are grown. Excessive water can compact the soil as well as cause the topsoil to wash away. Hot, dry summers sear the soil, and strong winds carry nutrient-rich topsoil away. 

Without topsoil, food crops can’t be grown, which could spell disaster for farmers trying to feed the population. The nation needs to stop the rapid loss of soil and take actionable steps towards soil conservation so farmers can continue growing much-needed food.

What Is Soil?

Soil covers all of the Earth and is comprised of thousands of components that create a dynamic ecosystem. Without soil, we could not grow food, and trees and plants that provide oxygen and clean the air would not exist. Earth would be an inhospitable place to live without soil. 

Soil is made up of decomposed minerals, water, gases, organic matter, and tiny microorganisms. For soil to support life, it must be porous enough for air and water to filter through so the microorganisms that break down organic and non-organic compounds can survive.

What is Topsoil?

Topsoil is the upper layer of soil between 3-9 inches deep and is rich in organic matter. The topsoil is where the microorganisms live and where most of the biological activity takes place. Decomposed organic matter and minerals are nutrient rich and can be found in the upper layer of soil. Microorganisms help with the decomposition and also help to fix nitrogen which is essential for plant growth. In addition, topsoil is home to worms and beetles that help to keep the soil aerated. 

Topsoil that is dark in color and has a deep earthy smell has the greatest concentration of nutrients available to plants so they can grow and thrive. In addition, rich topsoil has better water availability for plants to access. Keeping and managing topsoil from eroding is vital for agriculture and many farmers today understand the importance of managing topsoil to reduce their dependence on chemical fertilizers and nutrients.

The Importance of Soil Structure

Soil structure and texture help to determine the water holding capacity that soil has. The finer the particles of the soil and the more organic matter there is in the soil, the better the soil water availability is. If there is too much sand, water drains away, and if the soil is made primarily of dense clay, then too much water gets trapped. Soil structure needs the perfect balance of fine and dense for plants to thrive.

What Is Soil Erosion?

Factors that contribute to soil and topsoil erosion are wind, water, reduced amounts of organic matter, poor drainage of the soil, poor soil structure, and overuse of chemicals. Salinization can also be a contributing factor. Topsoil erosion is of great concern because this is where the plants receive nutrients to grow.

Not only does soil erosion take away the nutrients for the plants, but erosion can also have a negative impact on the surrounding environment. When wind or water carries topsoil away, it may end up clogging adjacent watercourses and wetlands which can restrict the flow of water and kill off food supplies to wildlife.

Soil Erosion in the  United States

According to a study by Cornell University, topsoil is disappearing at a terrifying rate in the United States, nearly 10 times faster than it can be replaced. The study states that almost two billion tons of farmland are lost to soil erosion every year resulting in loss of food crops and income.

The majority of food grown in the United States comes from the Midwest or the central valley of California, and both of these areas are seeing massive changes in weather. The loss of soil in the prime agricultural parts of the U.S. could become catastrophic if actionable steps are not taken soon to stop soil erosion.

What Are the Best United States Soil Conservation Service Organizations Available?

Fortunately, there are several organizations that provide a wealth of information about soils, soil erosion, and soil conservation.

The United States Department of Agriculture’s (USDA) website, Natural Resources Conservation Service, has a lot of great information about soil diversity and soil conservation.

For information and education about soil use and conservation of the nations natural resources, the Natural Resources Conservation Service (NCRS) works with private landowners to help create healthy ecosystems.

The National Association of Conservation Districts’ mission is to promote responsible use of all lands, and this includes soil conservation. The organization works with soil dynamics within a specific district of the United States.

Ways to Help Reduce Soil Erosion

There are several ways that farmers large and small can help with soil conservation and the prevention of soil erosion. 

One way is by not plowing, which is often called no-till farming. When a field is tilled after harvest, the topsoil gets turned over. Tilling removes plant matter and destroys beneficial microorganisms. Tilling also kills worms and insects that help to aerate the soil. No-till farming also allows the soil structure to remain intact, helping with its water holding capabilities.

Adding soil amendments, such as coir, can help improve soil’s ability to retain water, especially in soil that is heavily compacted. Coir and other soil amendments can help to loosen dense soils and help improve drainage. Adding amendments also helps to improve nutrient uptake for plants and reduce or eliminate dependency on chemical fertilizers.

Soil conservation, as well as education, are vitally important in reducing and stopping soil erosion in the United States. By helping to conserve the nation’s topsoil, the United States can continue to provide essential food crops to the world.

Soil Amendments and the Impacts of Soil Erosion

In theory, you could go into your backyard, dig up a section, and plant a tomato plant seedling. Over time, that tomato plant would grow more prominent, develop yellow blossoms, and those blossoms would become tomatoes that you can harvest. It doesn’t always work out. Your seedling may not do well because its root system cannot expand due to a soil that has a lot of clay in it. You may have blossom end rot because there is a lack of calcium in the ground. There are many different scenarios for why your garden isn’t able to grow vibrant plants.

When your soil doesn’t have everything that a plant needs to grow, you’ll need to make additions to the ground so that it will be ready. This scenario is where soil amendments come into play. Learn more about what soil amendments are and how you can make the most of them. 

What is Soil Amendment?

A soil amendment is something that you add to the dirt to make it more suitable for growing plants. Soil amendments can be used to address issues with aeration, nutrients, pH, and more. Each soil amendment has its own positives and negatives, so it’s often beneficial to determine what problem needs to be fixed before deciding on the proper amendment that you need to use. 

Soil Erosion and Amendments

Soil erosion can take away much-needed minerals, nutrients, and other characteristics that make up fertile soil. The wind and other agents of erosion remove dirt from your garden, and this removal of the topsoil can negatively impact the makeup of the land. If you believe that your garden may have been adversely affected by soil erosion, it is time to look into the use of amendments.

Testing Your Soil

After you’ve noticed that your soil isn’t performing as it should, it’s time to determine what is wrong. It can be very beneficial to test your soil to see what is missing or in overabundance. Some gardeners think that adding a lot of fertilizer amendments are always a good move, but too much can be just as big an issue as not enough in the soil. That’s often why it’s better to start out testing the dirt before making any changes with the amendments. 

There are testing kits that allow you to test your soil yourself to see what needs to be addressed, but you can also have it sent out to a lab to test. Once you’ve learned the cause behind your poor soil, you can choose what amendment you should use to fix it.  

How Much Soil Amendment Do I Need?

The question when it comes to how much soil amendment you need will depend on a few factors. The most important factor is what are you using the amendment to address. For instance, if you are looking to change the pH value of your soil because it’s too acidic, you’ll add lime. Too much lime and your soil’s pH can be just as problematic as soil that’s too acidic. Not enough lime and your soil’s pH won’t change enough. In some cases, it can be a delicate balancing act to get the right amount added. 

The instructions that come with the amendment can be essential in not going overboard with it. These instructions will typically tell you how much of the amendment you should add to a particular sized area. It will also tell you the specific way that you should apply it to get the most benefit from the amendment.   

What is the Best Soil Amendment?

There are a large variety of soil amendments that can work wonders on an underperforming garden. You can find topsoil, garden soil, coconut coir, compost, compost tea, fertilizers, peat moss, manure, mushroom compost, lime, gypsum, and more. 

The best soil amendments are the ones that will fix the issue that you’ve noticed. It can depend on the circumstances. For instance, container gardening does better with lighter soil compositions, so you may find that adding coconut coir to garden soil will give you the benefits from the coconut coir without weighing down the container.    

Organic Soil Amendments

Organic soil amendments are any amendments that you add to the soil that don’t contain any human-made chemicals in them. They are entirely natural, and for many, believed to be a safer option. Farms and gardens that are deemed organic can only use organic amendments. Some examples of organic amendments include manure, leaf mold, mulch, compost, and bat guano.   

Soil Amendments for Clay

Clay soil can be a real issue for gardeners. It often retains too much water, making proper drainage an issue, and can be too heavy for roots to grow into the soil thoroughly. This problem can usually be addressed by adding in an amendment to remove the negative impact that the clay can have on a garden.

Peat moss and coconut coir are two excellent amendments for dealing with soil that features a lot of dense clay. These amendments provide a couple of benefits. One is that they both help to add aeration to the dirt when mixed into the soil. It helps the earth have more air spaces for water to drain and roots to grow. It also can add mass to the land that allows it not to compact down easily. Another is that they help to retain moisture in the soil and slowly release it as needed for the plants growing. 

You’ll want to mix a decent amount of coconut coir or peat moss into the soil before planting your crops for the upcoming growing season. Continue adding the amendment until you get to the point where the clay is no longer an issue. You may also consider adding some additional topsoil in equal parts if you’re working in a large area with a lot of clay.

Your garden can only perform as well as the soil it is growing in. Sometimes, the plants need a helping hand to get them to where they could be with the perfect conditions. Gardeners that want the biggest blooms on their roses or a big crop of vegetables should look into adding soil amendments when needed. These additions to the soil can make a world of difference for how well a garden will grow.

Understanding Soil Stabilization

Soil stabilization is a term that denotes the physical, mechanical, biological, chemical, or combined method of changing natural soil for a specific purpose.

Soil may need to be stabilized in order to increase its weight-bearing capabilities or improve its tensile strength. Understanding the various types of permanent and temporary soil stabilization methods is essential for improving load-bearing capacities to support building foundations, road pavements, and other engineered structures.

The Importance of Soil Stabilization

Natural soil doesn’t always have the properties necessary to support construction projects. Unless the soil is stable enough to support a road or building, the structure can easily be washed away by flowing water, especially during a flood or torrential rainfall.

Soil that hasn’t been stabilized tends to contain larger particles than stabilized soil. These larger particles allow the soil to sink, which can result in literal sinkholes due to the soil’s inability to bear the weight of traffic.

With stabilized soil, the particles are crushed into smaller sizes, resulting in a compact soil that holds up well to manmade structures.

Types of Soil Stabilization

There are many materials and methods utilized in stabilizing soil, including:

  • Electricity.
  • Geotextiles.
  • Cement.
  • Lime.
  • Bitumen (asphalt).
  • Chemicals.

Electrical Stabilization

When electricity is used in soil stabilization, a direct current is sent through the soil in order to drain and discharge water. Draining the soil strengthens it, lowers the soil’s water table, creates an anti-seepage curtain, and provides stability to slopes, allowing construction to take place in slide-prone areas, trenches, pits, and quarries.

Electro-osmosis, however, is only used in soil stabilization when no other method is suitable. That’s because the process requires highly sophisticated and specialized equipment along with a high amount of electricity to achieve the desired result.

Geotextile Stabilization

Various types of geotextiles are frequently used in soil stabilization efforts. High-quality geotextiles like coir have been used to control soil erosion, support roads, improve drainage, and promote quick vegetation.

If you’re looking for a natural, eco-friendly method to stabilize soil, these versatile, permeable soil stabilization products are effective, low-cost options. Coir is a geosynthetic made from coconut fiber that can be synthesized for specific applications, allowing it to meet a variety of requirements.

Soil Cement Stabilization

Cement is often used as a low-cost means of preparing foundations for parking areas, highways, residential streets, and airport runways. The technique involves mixing soil with cement and water to form a strong soil-cement. Also known as a cement-treated aggregate base or cement-stabilized base, soil-cement can involve any type of soil and gravel rock combination.

Prior to construction, it’s important to perform laboratory tests to establish the soil’s water requirements, cement content, and compaction.

Testing ensures the soil-cement stabilization mixture has enough durability and strength to last. Soil-cement is made in a central mixing plant or on-site depending on the project, but there are always four steps involved:

  • Spreading cement.
  • Mixing.
  • Compaction.
  • Curing.

Curing is important for preventing water evaporation and ensuring maximum strength. In most cases, a light coating of bituminous material is used to prevent moisture loss.

Lime Soil Stabilization

Mixing lime with soil can significantly improve construction sites. When the right amount of lime is added to a reactive soil, the soil stabilizes and gains strength through a process called pozzolanic reaction. This chemical reaction converts a silica-rich soil with no cementing properties into a calcium silicate with excellent cementing properties.

In fact, the pozzolanic reaction was the main reaction involved in creating Roman concrete, which was used to build not only ancient roads but also impressive structures like the Pantheon.

Today, lime continues to be used as a trusted method of stabilizing soil via pozzolanic activity. The key is using a reactive soil along with a good mix design protocol to improve the soil’s strength and long-term durability.

Bituminous Soil Stabilization

Bitumen is a black viscous mixture used mainly in roofing and road surfacing. Most people know it as asphalt. The concept of bituminous stabilization is similar to soil-cement. Essentially, a controlled amount of bituminous material is added to soil and mixed to increase its load-bearing capacity and make it water-resistant.

Bitumen is sticky by nature, which helps it hold the compacted soil particles together. The result is a strong layer that prevents groundwater from being absorbed. As such, bitumen is excellent for waterproofing. 

Chemical Soil Stabilization

Chemical soil stabilization involves altering the soil’s properties via chemicals like chrome lignin, polymers, sodium chloride, sodium silicate, calcium chloride, and other chemicals. Chemical reactions can cause the soil’s structure to change, removing space between the particles and making it more compact, leaving no room for air or water to penetrate it.

Polymer soil stabilization is a popular chemical technique for geotechnical engineering, agricultural, and construction projects. Adding various polymers to soil can reinforce roadbeds, reduce erosion, support soil structure, increase soil shear strength, and improve water retention.

Soil Stabilization Equipment

Once you know which soil stabilization method to use, you’ll need to invest in the right equipment. Soil stabilization machines are designed with different approaches in mind, and each technique requires different equipment and machinery to get the job done. While your needs may vary, these are some of the most widely used soil stabilization machines.

Integrated Mixers

On sites where dust may pose an issue, an integrated mixer spreads a controlled amount of lime, cement, or other material directly in front of a mixing drum. The binding agent is immediately mixed with the site’s soil, eliminating dust issues and creating a stabilized soil on the spot.

Spreaders

Spreader units are either self-propelled or tractor-towed, but their purpose is to spread all sorts of dry binding agents. Although they’re often called cement spreaders, they can spread large quantities of fly ash, lime, cement, and similar materials with minimal dust.

Cold Planers

Cold planer machines are a low-cost option designed to grind asphalt. Also known as asphalt milling machines, cold planers feature rotating drums that remove and grind surface asphalt. The pavement can then be loaded on a conveyor and removed from the site or mixed with soil.

Reinforcing the soil provides the perfect foundation for a variety of engineering feats. When you choose the proper soil stabilization technique, you can rest assured your construction project will stand the test of time.

Sources:

https://www.civil-engg-world.com/2008/12/electrical-stabilization-of-soil.html

https://www.popsci.com/roman-concrete-can-withstand-seawater

http://article.sciencepublishinggroup.com/pdf/10.11648.j.ijtet.20170302.12.pdf

http://scholarsmine.mst.edu/cgi/viewcontent.cgi?article=3360&context=icchge

https://crrc.unh.edu/sites/crrc.unh.edu/files/media/docs/Workshops/liquid_asphalt/concawe_bitumen.pdf

https://www.mdpi.com/2073-4360/10/3/287/htm

http://asphaltzipper.com/how-it-works/road-repairs/soil-stabilization

https://www.wirtgen.de/en/technologies/application/recycling-soil-stabilization/soil-stabilization/bodenstabilisierung.php

http://precisioncoldplaninginc.com/services/soil-stabilization

Need to Know: Soil Degradation

The soil is a crucial component of agriculture and forestry, and degradation leads to a partial or total decline of its productive capacity. Due to natural hazards or human mismanagement, the soil can lose one or more of its potential ecological functions, leading to a steep decline in its capacity to be used in the production of goods and services.

Defining Soil Degradation

A 2004 report by the U.N. Department of Economic and Social Affairs described soil degradation as a process that occurs when “the balance between the attacking forces of climate and the natural resistance of the terrain against these forces has been broken by human intervention, resulting in a decreased current and/or future capacity of soil to support life”.

Soil degradation is primarily attributed to mismanagement or misuse of the land in domains such as agriculture, industry, or urban planning. Due to its major impact on food growth and consumption and on the environment as a whole, soil degradation causes have been a constant topic of research and concern throughout the 20th and the 21st centuries.

Causes of Soil Degradation

Throughout the world, soil degradation is usually caused by one or more of these three factors:

  • Physical factors represent the loss of the soil’s life-sustaining qualities due to natural physical forces, mainly water or wind erosion. These physical forces affect the structure of the soil mainly by damaging its top layer and subsequent organic matter, where the nutrients necessary for sustaining growth are found. Long-term exposure to massive rainfall, winds, floods, surface runoff, or any other powerful physical factors leads to the slow decline in the respective soil’s structure and quality. According to Volume 11 of the publication “Advances in Soil Science,” physical degradation can include:
    • Compaction and hardsetting, causing densification of soil due to the elimination or reduction of its structural pores, and also increasing soil’s bulk density as a result of natural and manmade factors.
    • Desertification caused by erosion and sedimentation due to constant exposure to wind and water.
    • Laterization, meaning the desiccation and hardening of plinthitic material.
  • Chemical factors are the alterations of the soil’s chemical properties that lead to it losing nutrients. University of Chittagong professor Khan Towhid Osman’s book, “Soil Degradation, Conservation and Remediation,” states that chemical degradation of soil can be caused by a number of factors, such as a rise of alkalinity or acidity levels, or simply the oversaturation of the respective soil with water. The result is usually either a buildup of salt or the hardening of the soil, with soil nutrients being irreversibly lost in the process. More than half a billion acres of land are affected by chemical soil erosion throughout the world. 
  • Biological factors refer to human activities or plant growth that cause degradation of soil quality by accentuation compaction, erosion, water runoff, anaerobiosis, nutrient depletion, reduction in SOC pool etc., as described in the book “Soil Degradation in the United States: Extent, Severity, and Trends.” An overaccumulation of fungi or bacteria can, for example, cause biochemical reactions that will drastically reduce the soil’s capacity to grow proper crops. Poor farming practices and overfarming also have the potential to diminish the fertility of the soil by depleting it of nutrients. These farming practices can be excessive cultivation, improper manuring, misuse or overuse of fertilizers, or excessive irrigation, among others. 

There are also other factors that can lead to soil degradation. Deforestation will dramatically alter the soil’s composition by removing the vegetation that binds it together. Mining and other industrial activities release toxic substances into the soil, making it poisonous and completely unusable. Also, urbanization will unavoidably affect the soil quality by covering the soil with concrete and with the inevitable rise in pollution levels.

Effects of Soil Degradation

The most significant effect of soil degradation is the loss of a land’s life-sustaining qualities. Throughout the world, more and more land becomes unusable because of factors like soil pollution, contamination, and erosion.

The overuse of fertilizers also keeps the affected land from regenerating, polluting both the land and water in the area and dramatically decreasing land value.

Another major effect of degradation to the soil is its contribution to droughts and the occurrence of arid conditions in certain areas. Soil degradation reduces the biodiversity in the area, leading to desertification and the inevitable drought and aridity that come with it.

The University of Sheffield’s Grantham Centre for Sustainable Futures estimates that approximately 40 percent of the world’s agricultural land is unusable because of the loss of soil quality caused by degradation and overuse of agrochemicals. These practices make agriculture impossible, and therefore make the respective land useless.

Due to the alteration of the degraded soil’s physical attributes, one of the consequences is the affected land’s inability to hold massive amounts of water, leading to increased chances of floods occurring.

How Big is the Range of Soil Degradation Observed Between Continents?

Soil degradation is a big issue all over the world, but Africa is by far the most-affected continent. Throughout the African continent, it is estimated that 28 percent of the land is affected by degradation.

This costs the continent as much as 56 billion euros every year. It’s usually manmade, with the lack of fertile land being compensated by mass deforestation, leading to massive soil degradation. It can be reversed, though, with massive state programs and policies that train communities to take better care of the land. 

Other areas of the world gravely affected by the degradation of soil are Southeast Asia, Northern and Central Australia, China, and parts of the boreal forests in North America and Siberia. 

Solutions for Soil Degradation

The reduction and reversal of soil degradation typically lie in the elimination of manmade causes. Chief among these causes is massive deforestation, and the trend can be reversed by educating populations and governments about the dangers of reckless deforestation. Improving the land’s organic composition and restoring its mineral matter can also reverse soil degradation.

Prevention is also crucial to reducing the amount of land that is affected by soil degradation. Reducing over-irrigation, improving overall irrigation efficiency, and preventing land salinization are all significantly more cost-effective than restoring soil that has already been affected by degradation.

Soil degradation is an issue that affects the entire world in numerous ways. It increases the odds of famine and poverty in already impoverished countries. It also increases the cost and human labor that’s necessary to grow food throughout the world, massively influencing the price and quality of the food that we eat.

Other side effects, from dramatic rises in pollution levels to socio-economic effects like mass migration, also contribute to soil degradation’s status as a major global issue.

Sources:

Advances in Soil Science Vol. 11, Soil Degradation

Soil Degradation, Conservation, and Remediation, Khan Towhid Osman

Soil Degradation in the United States: Extent, Severity, and Trends, Rattan Lal, Terry M. Sobiecki, Thomas Iivari, John M. Kimble

Introduction to Soil Remediation

When nature and human activities clash, it’s practically inevitable that pollution and toxins contaminate our soil, sediment, groundwater, and surface water. Sadly, soil contamination has serious, long-term effects on property and eco-systems, even resulting in massive animal die-offs.

What Is Contaminated Soil?

Contaminated soil is defined by significant harm to the health of living organisms or interference with ecological systems, which usually involves significant pollution to either the soil itself or nearby water.

Environmental contaminants are not only harmful to nature, but they can also negatively impact human health. In fact, people can get permanently ill from soil contamination.

One high-profile example of environmental contamination that made people sick involved Erin Brockovich, who helped build a case against the Pacific Gas and Electric Company in 1993. PG&E had allegedly allowed hexavalent chromium to contaminate the drinking water in Hinkley, California.

The case was settled in 1996, resulting in the largest settlement ever paid in a direct-action lawsuit in the United States. The incident was the focus of the 2000 film “Erin Brockovich,” starring Julia Roberts.

Given how devastating the effects of environmental contamination can be, remedial action is often necessary to address contaminated soil and water. That’s why numerous regulatory requirements have been legislated over the years, helping maintain standards by which government agencies and environmental remediation services must abide.

What Is Soil Remediation?

Soil remediation is a term applied to various processes used to decontaminate the soil. The goal is to treat contaminated soil by removing and converting pollutants into less harmful products.

Some of the pollutants that soil remediation addresses include:

  • Heavy metals
  • Cyanides
  • Pesticides
  • Creosote
  • Semi-volatiles
  • Petroleum and fuel residues

Removing these pollutants from the soil prevents them from seeping into the groundwater, surface water, agricultural crops, and wild flora. In cases where they’ve already affected water sources, additional land remediation techniques are required.

Types of Soil Remediation

There are four main techniques used for soil remediation, each of which takes a distinct approach to removing pollutants. These techniques are:

  • Thermal Soil Remediation
  • Air Sparging
  • Encapsulation
  • Bioremediation

It’s important to choose the right soil remediation technique for each situation, as each method has an indicated best use.

Thermal Soil Remediation

Thermal soil remediation is an in-situ technique that involves heating contaminated material in a Primary Treatment Unit (PTU) to the point where hydrocarbon impurities and water evaporate. Polluted materials are typically treated at temperatures ranging from 650 to 900 degrees. Think of the PTU as a massive oven that bakes the soil.

Once heated, the materials are transferred from the PTU into a cooling unit such as an auger or mixer. At this point, water is added for additional cooling and dust control. Once cooled, the material is moved from the cooling unit via a conveyor system and is then tested and recycled.

Thermal soil remediation is best used for soil that has been polluted by either contaminated water or hydrocarbon compounds like petroleum products. Since thermal remediation methods are performed without excavating the contaminated zone, they are great for hard-to-access locations such as between buildings and around buried utilities.

Air Sparging

Another soil remediation method is called air sparging, which involves injecting large amounts of air into a contaminated soil stratum to force organic vapors outwards where they can be treated by carbon filtering. Unlike other methods, air sparging has to be applied directly to the soil instead of being used on extracted soil in a treatment unit.

Air sparging is commonly used for removing hydrocarbon pollutants, but it’s best used in cases where the soil can’t be removed from the site.

Encapsulation

Encapsulation is an interesting remediation soil technique because it separates contaminates instead of filtering them. Essentially, encapsulation ensures that the pollutants can’t spread any further than they already have, so it acts similar to a medical quarantine.

The contaminant source is covered with layers of lime, concrete, clay caps, or synthetic textiles that limit precipitation’s infiltration, thereby preventing the leaching and migration of contaminants away from the isolated zone. The process isolates the polluted soil and prevents it from coming into contact with the surrounding soil.

Unfortunately, although the technique is effective, it doesn’t treat and recycle the soil to be used in cultivation. Instead, encapsulated soil will never be used to grow anything ever again, which makes encapsulation a sort of “last resort” technique.

Bioremediation

Bioremediation is a soil remediation technique that uses a biological mechanism rather than mechanical means. The contaminated soil is treated at the site with aerobic and anaerobic bacteria that have been engineered specifically to consume and break down pollutants. Once the contaminate has been taken care of, the microbes die off.

While bioremediation is the most natural technique of soil remediation, it’s most successful when the soil maintains a temperature of 70 degrees with sporadic rainfall to optimize the moisture levels. As such, bioremediation isn’t always possible, especially in extreme climates. In colder climates, the soil must be covered and insulated prior to the bioremediation.

NJDEP Soil Remediation Standards

In 2017, the New Jersey Department of Environmental Protection (NJDEP) updated the residential and non-residential soil remediation standards for 19 contaminants listed in the United States Environmental Protection Agency Integrated Risk Information System database. The updates reflected recent revisions made to existing toxicity data.

Overall, the standards to remediate soil increased (became less stringent) for 11 contaminants and decreased (became more stringent) for six contaminants. One contaminant will no longer be regulated and one remained unchanged.

Of the six contaminants for which the standards become more stringent, three stood out as having their remediation standards decrease by an order of magnitude:

  • 1,1-Biphenyl
  • Cyanide
  • Nitrobenzene

Thallium is the contaminant no longer being regulated by NJDEP soil remediation standards.

How Much Does Soil Remediation Cost?

Historically, soil contamination has had far-reaching economic impacts, but remedial action aims to minimize those adverse effects. Soil remediation costs vary depending on the technique, but the NJDEP has released an estimated soil remediation cost per acre-foot that can provide a glimpse into the economic impacts.

For example, consolidating and covering on-site soil with roads or other structures costs around $1000 to $2000 per acre-foot. Blending contaminated soil with clean soil can cost up to $15,000, while treating soil with innovative treatment technologies can range from $50,000 to $100,000 per acre-foot.

Remediating soil isn’t necessarily easy or cheap, but remediated soil prevents long-term, detrimental effects on our ecosystem. Taking responsibility for man-made contaminants goes a long way toward ensuring a healthy planet for future generations.

Sources:

https://www.nj.gov/dep/srp/guidance/srra/srwmp_implementing.pdf

https://www.nj.gov/dep/special/hpctf/final/costs.htm

https://centerjd.org/system/files/MB08_Enviro2.pdf

http://www.terratherm.com/pdf/white%20papers/paper3-11-6-09.pdf

https://clu-in.org/download/toolkit/sparge_o.pdf

https://pdfs.semanticscholar.org/6bff/82c2c20de69c1892915f4ee46f60f50c5f2a.pdf