How is it possible to heal a gaping wound right in the middle of a city like Montreal, while at the same time producing electricity from old rubbish, transforming new waste into compost and creating an immense park?
The four-letter answer: CESM.
In French, it stands for the Complexe Environnemental de Saint Michel, or the Saint Michel Environmental Complex.
Located in the neighbourhood of Saint Michel, the complex started out as a quarry. Since the giant hole - measuring 2 sq km - was converted into a garbage dump in the late 1960s, it has taken in over 40 million tonnes of waste, all of which will be completely covered by soil a few months from now.
This place has become an example of successful repurposing in an urban environment.
"The Saint Michel Complex, a garbage dump in the middle of the city with thousands of homes a few hundred metres away, is, in fact, unique in the world," says Mr Eric Blain, division chief of technical and infrastructure support for the city of Montreal.
Each year, up to 16,000 tonnes of green waste - mostly autumn leaves - are transformed into compost. Most is used to cover the mountain of waste, which is 70m high in some places, and to meet the city's horticultural needs.
Two years from now, the city will open a composting centre, which will treat 29,000 tonnes of compostable material, extracting biogas in the process.
When it is burnt, biogas turns water into steam to power turbines - thus enabling a nearby power plant to produce around 7 megawatts of electricity, enough to power 4,000 homes. In winter, this steam also provides heat for a nearby "green" building.
Even the strong winds that blow over this large area are exploited: Four wind turbines power surveillance equipment in the pipes channelling the biogas, which are often damaged by ground movement.
In 2017, there will be a new 1.5 sq km park that official documents say is "the biggest environmental rehabilitation project ever undertaken in the City of Montreal". Essentially, a 2m layer of sand, a geotextile membrane and soil is being placed over the waste at CESM, turning the dump into a sweep of hills and small woods.
This new park will feature a lake - one of three retention basins - and visitors will be able to stroll through a wooded area or over the wind plain, or attend performances in an amphitheatre dug into the ground.
"It will be magnificent, one of the most beautiful parks in Montreal," promises Mr Blain.
Audrey Ruel-Manseau contributed to the reporting of this article.