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Remediation Technologies Screening Matrix, Version 4.0 4.13 Landfarming
(Ex Situ Soil Remediation Technology)
  Description Synonyms Applicability Limitations Site Information Points of Contact
Data Needs Performance Cost References Vendor Info. Health & Safety
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Technology>>Soil, Sediment, Bedrock and Sludge

>>3.4 Ex Situ Biological Treatment (assuming excavation)

      >>4.13 Landfarming
Introduction>> Contaminated soil, sediment, or sludge is excavated, applied into lined beds, and periodically turned over or tilled to aerate the waste.

Description:

Figure 4-13a: Typical Landfarming Treatment Unit

  Landfarming is a full-scale bioremediation technology, which usually incorporates liners and other methods to control leaching of contaminants, which requires excavation and placement of contaminated soils, sediments, or sludges. Contaminated media is applied into lined beds and periodically turned over or tilled to aerate the waste.

Soil conditions are often controlled to optimize the rate of contaminant degradation. Conditions normally controlled include:

  • Moisture content (usually by irrigation or spraying).
  • Aeration (by tilling the soil with a predetermined frequency, the soil is mixed and aerated).
  • pH (buffered near neutral pH by adding crushed limestone or agricultural lime).
  • Other amendments (e.g., Soil bulking agents, nutrients, etc.).

Contaminated media is usually treated in lifts that are up to 18 inches thick. When the desired level of treatment is achieved, the lift is removed and a new lift is constructed. It may be desirable to only remove the top of the remediated lift, then construct the new lift by adding more contaminated media to the remaining material and mixing. This serves to inoculate the freshly added material with an actively degrading microbial culture, and can reduce treatment times.

Figure 4-13b:
Typical Land Treatment Unit  

Land Treatment is a full-scale bioremediation technology in which contaminated soils, sediments, or sludges are turned over (i.e., tilled) and allowed to interact with the soil and climate at the site. The waste, soil, climate, and biological activity interact dynamically as a system to degrade, transform, and immobilize waste constitutes. Wastes are periodically tilled to aerate the waste.

Soil conditions are often controlled to optimize the rate of contaminant degradation. Conditions normally controlled include:

  • Moisture content (usually by irrigation or spraying).
  • Aeration (by tilling the soil with a predetermined frequency, the soil is mixed and aerated).
  • pH (buffered near neutral pH by adding crushed limestone or agricultural lime).
  • Other amendments (e.g., Soil bulking agents, nutrients, etc.).

A Land Treatment site must be managed properly to prevent both on-site and off-site problems with ground water, surface water, air, or food chain contamination. Adequate monitoring and environmental safeguards are required.

Landfarming and Land Treatment are both medium- to long-term technologies.

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Synonyms:

Solid phase biodegradation.
DSERTS Code: H15 (Landfarming).

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Applicability:

Ex situ landfarming has been proven most successful in treating petroleum hydrocarbons. Because lighter, more volatile hydrocarbons such as gasoline are treated very successfully by processes that use their volatility (i.e., soil vapor extraction), the use of aboveground bioremediation is usually limited to heavier hydrocarbons. As a rule of thumb, the higher the molecular weight (and the more rings with a PAH), the slower the degradation rate. Also, the more chlorinated or nitrated the compound, the more difficult it is to degrade. (Note: Many mixed products and wastes include some volatile components that transfer to the atmosphere before they can be degraded.)

Contaminants that have been successfully treated using landfarming include diesel fuel, No. 2 and No. 6 fuel oils, JP-5, oily sludge, wood-preserving wastes (PCP and creosote), coke wastes, and certain pesticides.

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Limitations:

Factors that may limit the applicability and effectiveness of the process include:
  • A large amount of space is required.
  • Conditions affecting biological degradation of contaminants (e.g., temperature, rain fall) are largely uncontrolled, which increases the length of time to complete remediation.
  • Inorganic contaminants will not be biodegraded.
  • Volatile contaminants, such as solvents, must be pretreated because they would volatilize into the atmosphere, causing air pollution.
  • Dust control is an important consideration, especially during tilling and other material handling operations.
  • Runoff collection facilities must be constructed and monitored.
  • Topography, erosion, climate, soil stratigraphy, and permeability of the soil at the site must be evaluated to determine the optimum design of facility.
  • Waste constitutes may be subject to "Land-ban" regulation and thus may not be applied to soil for treatment by landfarming (e.g., some petroleum sludges).

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Data Needs:

A detailed discussion of these data elements is provided in Subsection 2.2.1 (Data Requirements for Soil, Sediment, and Sludge). The following contaminant considerations should be addressed prior to implementation: types and concentrations of contaminants, depth profile and distribution of contaminants, presence of toxic contaminants, presence of VOCs, and presence of inorganic contaminants (e.g., metals).

The following site and soil considerations should be addressed prior to implementation: surface geological features (e.g., topography and vegetative cover), subsurface geological and hydrogeological features, temperature, precipitation, wind velocity and direction, water availability, soil type and texture, soil moisture content, soil organic matter content, cation exchange capacity, water-holding capacity, nutrient content, pH, atmospheric temperature, permeability, and microorganisms (degradative populations present at site).

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Performance Data:

Numerous full-scale operations have been used, particularly for sludges produced by the petroleum industry. As with other biological treatments, under proper conditions, landfarming can transform contaminants into nonhazardous substances. Removal efficiencies, however, are a function of contaminant type and concentrations, soil type, temperature, moisture, waste loading rates, application frequency, aeration, volatilization, and other factors.

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Cost:

Ranges of costs likely to be encountered are:
  • Costs prior to treatment (assumed to be independent of volume to be treated): $25,000 to $50,000 for laboratory studies; and less than $100,000 for pilot tests or field demonstrations.
  • Cost of prepared bed (ex situ treatment and placement of soil on a prepared liner): Under $100 per cubic meter (under $75 per cubic yard).

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References:

Treatment Technologies for Site Cleanup: Annual Status Report (ASR), Tenth Edition, EPA 542-R-01-004

Innovative Remediation Technologies:  Field Scale Demonstration Project in North America, 2nd Edition

Remediation Technology Cost Compendium - Year 2000

Groundwater Cleanup: Overview of Operating Experience at 28 Sites, September 1999, EPA 542-R-99-006,

Potential Applicability of Assembled Chemical Weapons Assessment Technologies to RCRA Waste Streams and Contaminated Media, August 2000, EPA 542-R-00-004

Treatment Experiences at RCRA Corrective Actions, December 2000, EPA 542-F-00-020

Abstracts of Remediation Case Studies, Volume 4,  June, 2000, EPA 542-R-00-006

Guide to Documenting and Managing Cost and Performance Information for Remediation Projects - Revised Version, October, 1998, EPA 542-B-98-007

Seminars: Bioremediation of Hazardous Waste Sites: Practical Approaches to Implementation,  Environmental Protection Agency (EPA), May 1996, Land Treatment, pages 6-1 through 6-16; and

Remediation Handbook for POL-Contaminated Sites,  Headquarters United States Air Force Environmental Restoration Program, December 1993, Section 4.4, Treatment of Excavated Soil.

EPA, 1990. Bioremediation in the Field, EPA/540/2-90-004.

EPA, 1995. Remediation Case Studies: Bioremediation, Federal Remediation Technologies Roundtable, Report, EPA/542/R-95/002.

Norris, et al., 1994. Handbook of Bioremediation, EPA, RSKERL, Lewis Publishers, CRC Press, 200 Corporate Boulevard, Boca Raton, FL 33431.

Pope, D.F. and J.E. Matthews, 1993. Bioremediation Using the Land Treatment Concept, EPA Report EPA/600/R-93/164.

Sims, J.L., et al., 1989. Bioremediation of Contaminated Surface Soils, EPA, RSKERL, EPA Report EPA/600/9-89/073.

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Site Information:

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Points of Contact:

General FRTR Agency Contacts

Technology Specific Web Site:

Non Government Web Sites

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Vendor Information:

A list of vendors offering Ex Situ Biological Soil Treatment is available from EPA REACH IT which combines information from three established EPA databases, the Vendor Information System for Innovative Treatment Technologies (VISITT), the Vendor Field Analytical and Characterization Technologies System (Vendor FACTS), and the Innovative Treatment Technologies (ITT), to give users access to comprehensive information about treatment and characterization technologies and their applications.

Government Disclaimer

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Health and Safety:

Hazard Analysis

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