Executive
Summary
(Version
français)
Urban agriculture
is an important emerging field because of its positive implications
for urban food security, community development, and urban environmental
conditions. However, community groups pursuing urban agriculture face
many obstacles. Soil contamination is a major barrier to potential agriculture
projects in urban areas, as most urban soil is below agricultural soil
standards, and food cannot be grown in contaminated soil because of
the associated human health risks. Unused, contaminated lands in urban
areas known as 'brownfields' have great potential as sites for urban
agriculture if remediation can be successfully undertaken. Though many
soil remediation techniques exist, they are of varying practicality
for community groups attempting the remediation of brownfields for urban
agriculture.
The goal of this project is to evaluate several physical and biological
soil remediation techniques for use by community groups using the following
criteria: accessibility, cost, time, ability to bring soil up to agricultural
standards, and environmental effects. Our specific research questions
were as follows:
- What are the initial
steps a community group should follow before beginning a remediation
project?
- What are the various
soil remediation techniques that can be used to achieve these soil
quality requirements?
- What are the pros and
cons of available remediation techniques for use by community groups
for the purpose of urban agriculture?
- What can we learn from
case studies of past remediation attempts undertaken by community
groups for this purpose?
The research
team consulted academic journals, sources from the Quebec, Canadian,
and US government, and conducted interviews with academics, Montreal
city officials, representatives from remediation companies, and community
group members to answer these questions. It was determined that although
soil standards exist at several levels of government, community groups
should follow the most stringent ones, as they are liable for any contamination
of the food produced in their gardens. The research team also explored
resources available for determining the land use history of a proposed
garden plot and for soil testing, which will enable a community group
to determine the levels of contamination present in the soil. Sources
of subsidies were also researched.
Four physical remediation methods were evaluated: excavation, geotextiles,
soil washing and soil vapor extraction. Of these methods, excavation
was determined to be the most appropriate option for community groups,
as it can ensure complete contaminant removal in a very short time frame.
Other techniques were deemed too technical and costly for use by community
groups, and had negative environmental consequences. Of the biological
remediation techniques (microbial remediation, phytoremediation, fungal
remediation, and composting), microbial remediation was selected as
most effective for community groups, as it has very low associated costs
and can be effective in a relatively short timeframe. Other techniques
were less accessible, took longer to implement, and had varying degrees
of effectiveness in bringing soil up to agricultural standards. It should
be noted that these are only general conclusions; selection of a remediation
technique must be done on a case-specific basis, since variance in the
level and spectrum of contaminants in the soil, the soil's properties,
and the available timeframe and budget will all determine the appropriateness
of each technique for the urban agriculture project.
Finally, the research team recognizes that the field of soil remediation
for urban agriculture is quite young, and some techniques that are not
presently applicable may have a promising future.
©
2002 McGill School
of Environment
McGill University
3534 University, Montreal, Quebec, Canada H3A 2A7
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