Landfarming may include:
- mobilization, site access, and the establishment of temporary installations;
- preparation of the treatment area (waterproofing, water and leachate management and treatment system, if applicable, vapour emissions management and treatment system, if applicable);
- excavation of contaminated soils, including stripping of topsoil and its temporary storage, control of slope stability, dewatering of excavations, protection of structures to be saved;
- loading and transport of soils to the treatment area;
- soil mixing using specialized equipment;
- the addition of fertilizers and/or additives;
- backfilling and surface restoration (grading, paving, hydroseeding or planting).
Materials and Storage
On-site storage may include amendments, geomembranes, drainage pipes, fuels, lubricants and other site materials required for the operation of machinery or equipment for the process. Piles of treated soils may also be temporarily stored on site, awaiting replacement in the excavations.
On-site storage is generally limited to small quantities of fuel and lubricants (daily refuelling is often done from a mobile tank) and small quantities of various site supplies required during construction of the landfarming area.
Typically, a starting amount of fertilizer and/or bulking agent is plowed, mixed, or sifted into the soils. Fairly small amounts of fertilizer may be retained on site for addition to, for example, irrigation water over time.
The technique is performed using traditional methods and equipment readily available for civil engineering work (including excavators, bar screens, rotary screeners), using specialized equipment and/or agricultural equipment.
Treatment cells can use imported aggregates, overlay or protective geomembranes, perforated drainage pipes.
Soils can be amended with texture or swelling agents (such as alfalfa, wood chips, shredded cardboard, or rice hulls) and/or by controlling pH (usually with lime).
Residues and Discharges
Treated soils can be reused as backfill material if they meet site conditions and are therefore not considered waste. Materials such as geomembranes and other materials used to construct the treatment area should be managed at the end of the treatment.
Vapours, leachate and runoff may be generated during treatment. These releases are usually captured by appropriate management and treatment systems.
Dust transported by air, from excavations, soil treatment areas, or soil spread on the ground by equipment wheels or tracks, can also be deposited on surfaces located in the wind direction.
Composed by : Magalie Turgeon, National Research Council
Updated by : Jennifer Holdner, M.Sc., Public Works Government Services Canada
Updated Date : March 1, 2015
Latest update provided by : Nathalie Arel ing., M.Sc., Frédéric Gagnon CPI., Sylvain Hains ing., M.Sc., Golder Associates Ltd.
Updated Date : March 24, 2022