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Outdoor pile composting – Les Composts du Québec

Composting is a controlled, accelerated process of biologically transforming organic wastes originating from varied sources (municipal, commercial, industrial, agricultural). The end product is an organic soil amendment, known as compost.

A leader in the Canadian composting field, Les Composts du Québec has been operating since 1979. Now a subsidiary of GSI Environnement, the company uses two different technologies: outdoor composting in piles (sites located in St.Henri, Lachute and Bury) and indoor composting in channels (site located in L’Ange-Gardien, near Ottawa).

Description of the technology

Les Composts du Québec is a maker of composts and enriched mixes, with a plant at St-Henri near Quebec City, Canada. The company uses outdoor pile composting technology which allows it to produce and market a wide range of high quality composts, potting and top-soils at competitive prices. The raw material for its production consists of large quantities of selected organic wastes such as manure, yard wastes and leaves, and biosolids from paper-mills and from municipalities..

The system consists of mixing and piling organic wastes on an outdoor platform and then turning the piles on a monthly basis with a mechanical shovel, to aerate them. The time required with this simple composting method, to obtain a stable product ready for marketing, varies from 12 to 18 months, depending on the nature of the raw material. Composting time can be reduced by more frequent turning of the piles.

Steps of the composting process

  • Reception of raw materials
  • Preparation of the substrates for composting
  • Shaping the piles
  • Active exothermic decomposition phase (4 to 8 months)
  • Curing phase (8 to 10 months)
  • Screening
  • Finished product quality control

Additional steps for product marketing

  • Preparation of mixes
  • Bagging
  • Distribution


Outdoor pile composting is an easy to manage process with low operating costs. It has the advantage of using standard excavation machinery and is well-suited to situations where large quantities of organic waste need to be dealt with at moderate cost. Using this approach, Les Composts du Québec can annually compost about 20,000 metric tons of waste per hectare of platform; this is a higher output than that obtained by windrow composting systems.

Limits of application

Utilisation of outdoor pile composting technology:

  • Requires a leachate treatment system. Since the piles are exposed to precipitation, that creates leachates that need to be treated.
  • Since outdoor composting operations do cause certain impacts, including the emanation of odours, an adequate buffer zone must be maintained between the composting area and surrounding homes.

Installation and operation 

Construction of a composting yard includes the following elements:

  • Platforms: Compost platforms must be impermeable. Therefore, if the soil surface is not water-tight, it needs to be covered with asphalt or concrete. Leachates can thus be recovered and treated. The surface soil at the Saint-Henri composting facility is clay, with a degree of permeability which outstand applicable norms, thus ensuring adequate water-tightness and elimination of pollution risks.
  • Leachate treatment: In Quebec, under heavy precipitation, outdoor composting produces leachates. Consequently, drainage ditches are required to collect and carry these fluids to holding ponds for treatment before subsequent discharge to the surrounding milieu. At Saint-Henri, a treatment system with holding ponds, aeration and settling ponds was developed for an annual capacity of 50 to 60 million litres of leachates.
  • Machinery: Mechanical shovels, typically used for excavation can be used to turn the piles. Various types of loader can be used for moving materials around or for bulk loading of the finished product.
  • Compost storage platforms: It is preferable to store the finished product on an asphalt or concrete platform, to avoid contamination by gravel, sand or soil.
  • Supplementary systems: Production of bulk compost requires screening before completion. Preparation of special mixes and potting soils require more specialised equipment, such as hoppers suited to the type of material, silos for certain amendments, conveyors and storage bins. Different types of screen can be used to perfect the mixes.
  • Laboratory: In-house analytical services allow Les Composts du Québec to provide rigorous quality control and to conduct research projects. Growth chambers for conducting tests on plants constitute an additional peripheral infrastructure.

Bagging system: The end products can be sold in bulk or in bags. Les Composts du Québec sells several types of compost and enriched soil mixes for horticultural use. State-of-the-art automated bagging equipment is used, which can handle a variety of bag formats.


Pile composting on outdoor platforms represents the cheapest method of composting. Cost magnitude is directly related to the specific characteristics of a chosen site and to the characteristics of the wastes to be composted. This type of system represents the most economical method of composting.

Supplementary information

For over 25 years, Les Composts du Québec has, in conjunction with various organisations, undertaken important research projects on different types of waste and on new potential uses for the end product. The company remains open to partnerships and to strategic alliances which will help it to continue its mission and to remain a leader in the fields of composting, landspreading of organic matter on soil and production of specialised compost-based soils for horticulture.

Les Composts du Québec also operates a plant at Ange-Gardien in the Ottawa Valley since 1996. There, composting is accomplished in a closed factory facility with 4 horizontal channels in which the materials are turned daily by a highly mechanised system. Agitated channel composting is a compact solution, which provides more rapid transformation of wastes with efficient odour control by a biofiltration process. This composting plant can compost about 40 000 metric tons of waste annually per hectare of platform. Indoor composting facilities are particularly suited for odour-sensitive areas and for treatment of biosolids from various sources.

Les Composts du Québec inc.
M. Pierre Filiatrault, directeur général
415, chemin Plaisance C.P. 448
Saint-Henri, Québec, G0R 3E0

Phone :    (418) 882-2736
Phone :    1 800 463-1030
Fax :    (418) 882-2255
Email :    composts@composts.com
Web site :    www.composts.com