LAND APPLICATION REMEDIATION

Keystone Environmental Ltd. (Keystone) has assisted numerous clients in landfill and bioremediation applications. The key to a successful landfarming facility is the initial design based on the contaminant and site considerations. Keystone has professional engineers and geoscientists on staff that are knowledgeable of the applicable regulations and experienced in the design and construction of land application technologies.

Landfarming

Landfarming is a medium to long-term bioremediation technology which usually incorporates liners and other methods to control leaching of contaminants. Contaminated media is applied into lined beds and periodically turned over or tilled to aerate the soils. Soil conditions are often controlled to optimize the rate of contaminant degradation. Conditions normally controlled include:
 - Moisture content (usually by irrigation or spraying).
 - Aeration (soil tilling for aeration).
 - 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. Ex situ landfarming has been proven most successful in treating petroleum hydrocarbons.

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.
 - Dust control may be 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.

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, water-holding capacity, nutrient content, pH, atmospheric temperature, permeability, and microorganisms (degradative populations present at site).
 
On-line Resources

Government of British Columbia, Ministry of the Environment (MOE), Environmental Management Act, Hazardous Waste Regulation, Division 7 — Waste Piles, Surface Impoundments and Land Treatment Facilities
http://www.qp.gov.bc.ca/statreg/reg/E/EnvMgmt/EnvMgmt63_88/63_88.htm

Government of Yukon, Department of the Environment, Land Treatment Facilities (Guidelines for Construction, Operation and Decommissioning)
http://www.environmentyukon.gov.yk.ca/epa/landtreatment.html

U.S. Environmental Protection Agency (EPA) Landfarming webpage
The following description of Landfarming is an excerpt from Chapter V of OUST's publication: How to Evaluate Alternative Cleanup Technologies for Underground Storage Tank Sites: A Guide for Corrective Action Plan Reviewers.
http://www.epa.gov/swerust1/cat/landfarm.htm