Ex-situ remediation is more than just a shovel and a dump truck! Ex-situ remediation covers a variety of soil remediation approaches with one thing in common: cost-savings by avoiding offsite soil disposal costs.
Ex-situ remediation designs are tailored for each site and may include the following:
- Tilling of shallow soils,
- Excavation and construction of biopiles,
- Addition of amendments,
- Aeration or vapour control, and
- Leachate treatment.
Ex-situ remediation can be applied at sites with various contaminants including:
- Chlorinated herbicides
- Petroleum hydrocarbons (PHCs)
- Volatile organic compounds (VOCs)
- Metals, and
- Other recalcitrant contaminants of concern
Ontario Ministry of Environment and Climate Change (MOECC) recently developed new Excess Soil Regulations and other jurisdictions are following suit. Contact Vertex to find out if Ex-situ soil remediation is right for your site!
Tilling of Shallow Soils
Tilling is an ex-situ process for the mechanical agitation of shallow soils. Tilling is used in conjunction with the addition of amendments to promote treatment of the contaminants of concern. Tilling is typically applied in shallow soils for contamination down to 1 m below grade. Tilling is commonly used to address sites with pesticides and herbicide contamination.
Excavation and Construction of Biopiles
Excavation is required for ex-situ treatment of deeper soil impacts (i.e., more than 1 m below grade). The soils are excavated and placed into a biopile for treatment. Biopiles typically consist of an impermeable base with leachate and vapour controls and can range in size from 1 m3 to 10,000 m3 depending on site objectives. Once the soil is excavated and placed in a biopile, amendments can be added to promote treatment of the contaminants of concern. When the applicable standards are achieved, the soils can be removed from the biopile and re-purposed on the site.
Addition of Amendments
Addition of amendments is used in conjunction with either tilling or biopiles. The types of amendments are determined based on the contaminants of concern. For example, a pesticide site may require Daramend® to promote anaerobic treatment, whereas a PHC site may require addition of oxygen releasing materials to promote aerobic bioremediation. Each site receives a custom dosage of amendments based on the types and quantities of contaminants present.
Aeration and Vapour Control
Aeration and vapour control is a component of biopile ex-situ remediation and it can involve the addition of oxygen (i.e., aerobic treatment), the removal of oxygen (i.e., anaerobic treatment), or the capture and treatment of vapours prior to discharge into the natural atmosphere. Vertex has mobile ECA permits for aeration and vapour controls.
Leachate treatment is a component of biopile ex-situ remediation and it can involve the capture and treatment or disposal of leacheates from a biopile. Vertex has mobile ECA permits for the capture and treatment of biopile leachates.
Benefits of ex-situ treatment include:
- Sustainability: Improves soil health and reduces toxicity on site
- Environment: Reduce truck traffic to and from your site
- Amendment Contact: Ensures direct and immediate contact with amendments and ameliorate the unknowns of subsurface geology
- Costs: Save money by treating onsite
Limitations of ex-situ treatment include:
- Space: Onsite space is required to till soils (tractor access) or to build biopiles for treatment (excavator access)
Vertex has the permitting, equipment and experience to complete ex-situ remediation on your site. Over the past few years, Vertex completed various projects across South Western Ontario including:
- Soil tilling of a 100+ acres site with pesticide impacts at a former agricultural site
- Biopiling of 100,000 m3 of soils with petroleum hydrocarbon impacts at a former industrial site
- Development of stabilization technologies for lead and arsenic at a former shooting range