Dealing with contaminated soil at your construction site can create legal liabilities, cleanup costs, and delay your project. That's because contaminated soil can cause havoc on the environment and impact human health. Contaminates can seep into the water supply system, affecting our food supply chain and air quality.
That's why there are rules and regulations, and cleanup procedures that require your attention. You'll need to know the implications of dealing with contaminated soil, how to determine the contamination level, and the cleanup options.
Watch the webinar below for more details:
What are the common soil contaminates?
Apart from nuclear waste, common soil contaminates include the following:
| Metals | Hydrocarbons | Solvents | Pesticides | |
|---|---|---|---|---|
| Type | Arsenic, barium, cadmium, chromium, mercury, lead, and selenium are widespread metal contaminants. | Petroleum: Benzene, ethylbenzene, toluene, and xylene... Polycyclic aromatic hydrocarbons (PAHs): Coal, gas, wood, garbage & other organic substances. | Military, Industrial or commercial chemicals that may have been spilled or disposed of improperly. | Atrazine and carbaryl (often sold as Sevin®) are commonly used in lawn and garden areas. |
| Source | Naturally accruing & industrial, manufacturing, gasoline, paint, coal, plumbing, electrical... | Commercial and industrial areas like gas stations. PAHs are formed during the incomplete burning of coal, oil, gas, wood, garbage, or other organic substances. | Former dry cleaning or machine shop sites. | Industrial and commercial areas where they were stored or mixed. |
How to know if your site is contaminated?
The first indicator for a contaminated construction site is the historical land use. If the land or adjacent areas have ever been used for agriculture, industry, mining, military, waste disposal, or gas dispensing, then there may be a lingering soil contamination problem.
The only sure way to find out is to conduct a soil analysis. Engage a certified local soil engineer or professional testing lab to get surface and deep soil samples for testing.
The soil analysis can help you determine the level of contamination.
| LOW | HIGH | HAZARDOUS | |
|---|---|---|---|
| Contamination | Any type of contaminants that have a very low level of PPM | It is measure per PPM depending on the type of contamination in the soil | Corrosive, ignitable, infectious, reactive, and toxic and hazardous wastes, I.e., creosote, PCB, PCP... |
| Source of Contamination | Commercial or natural occurring | Industrial, commercial, Gas Station, and construction sites | Military and industrial waste, paints, oils, and solvents to acids, sludges, and pesticides.... |
| Common Teatments | Soil Washing Evaporation Landfill |
Excavation & treatment on-site or off-site In-situ Capping Chemical Oxidation |
Thermal Oxidizer Secured Landfill |
How to treat contaminated soil?
Some of the standard soil contamination cleanup methods include:
Excavation: After contaminated soil has been identified, it may be removed from the property and transferred to a landfill for disposal or treatment. New topsoil is tested, trucked in, and distributed throughout the property to replace the old soil. Contaminated soil can be sent to disposal sites for treatment or landfill depending on the level of contamination and the type of contaminants.
Soil Blending: Contaminated soil is mixed with fresh soil to reduce the level of contamination to meets local guidelines for acceptable pollutant levels.
Bioremediation: Bioremediation is a biological process to degrade, break down, transform or remove contaminants from soil. The technique relies on bacteria, fungi, and plants to alter contaminants. These organisms carry out their everyday life functions.
Soil Washing: Soil washing removes contaminants from soils by dissolving them in the wash solution. It is a chemical manipulation of pH levels in the soil. Soil washing can also include sorting and shifting soil through particle size separation, gravity separation, and attrition scrubbing, similar to techniques used in sand and gravel operations.
Capping: Capping involves the coverup of a contaminated site to avoid the spread of contamination. Some areas require a top cover and underground lining to prevent leaching in the underground water level system.
Thermal Oxidizer: Thermal Oxidize removes heavy and hazardous organic wastes from the soil, sludge, or sediment by heating the VOCs to high temperatures (1000 degrees). The oxidation process breaks down the harmful particulates into carbon dioxide and water. It has an air pollution control that decomposes hazardous gases. The chart below created by Sonia Shoukry shows the time to vaporize organics of average soil matrix and organic concentration at operating temperature for HT – High-Temperature Thermal Oxidizer (Kiln Temp.) and TD – Low-Temperature Thermal Desorption (Kiln Temp.)
Best Practices
Dealing with contaminated soil is serious business. Regulations for soil contamination vary based on country, province/state, cities, and municipalities.
That's why you always need to consult your local government and environmental agency websites for details on cleanup procedures in your area.
Always consult with a local legal and land remediation specialist before signing or negotiating any deals related to contaminated soil.
Once you own a contaminated site, you'll be responsible for the cleanup even regardless of who was responsible for the contamination.
That's why at Fill Connect, we always encourage all our clients to test any soil or any other fill material before accepting it on their land. And always make sure you have a permit to receive new material on your sites.
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