In our series A New Approach to Storm-Water Management and Flood Reduction, about Low Impact Development (LID) and Sustainable Drainage Systems (SuDS), there are many examples of ways to encourage rainwater and storm-water infiltration into the ground in order to reduce run-off and the resultant costs and other negative implications of storm-water management.
The legislation and regulations supporting SuDS and LID / Green Infrastructure, however, largely focus on future developments aimed at reducing the ongoing impacts and cumulative costs of storm-water management. But what of the pre-existing situation?
Asphalt, concrete and tarmac dominate the urban landscape of many cities, often driven by a desire amongst many property owners to reduce costs associated with maintaining gardens. There is a sea-change in progress, however, with a growing number of residents realizing that, especially in the public realm, this tendency leads to an uglier, less friendly, and more dysfunctional environment. And while it may be considered overstepping the mark to try to tell a private homeowner what they can or can’t do with their front yard, there is a growing movement in the United States towards changing the public landscape in many cities.
The movement has been spearheaded by a voluntary, non-profit group, Depave, based in Portland, Oregon, which started as a neighbourhood initiative in 2008.
Depave is now recognized as an influential organisation whose activity has been reproduced in many cities across the United States and Canada, as well as in Australia and the UK, with representatives from several other countries attending Depave courses.
New York urban planner, Mike Lydon, who coined the term of ‘Tactical Urbanism’, and a group of other ‘young urbanists’ who compiled the open source publication ‘Tactical Urbanism: Short-term Action, Long-term Change’ in 2011, subsequently released a second, expanded edition, to include another 12 tactics, including depaving – “a Portland-born volunteer project to improve storm water treatment by removing unneeded driveways and concrete ground cover”.
The first official Depave event took place in Portland, Oregon, in June 2008, having grown out of an idea that germinated when a homeowner asked a friend to help him demolish his garage and concrete driveway – he didn’t own a car – so he could plant fruit trees instead. That first event, at the corner of Fargo Street and North Williams Avenue in North Portland, kicked off the ‘International Towards Carfree Cities’ conference held in the city that year, and introduced the volunteer-driven initiative which pulls in local residents to remove areas of excess tarmac and concrete in underutilized parking lots, in order to create rain gardens, food forests and community parks.
The definition of ‘depaving’, as found in Wikipedia, is to “undo the act of paving; to remove pavement so as to restore the land to a more natural state”. According to the Depave publication ‘How to Depave: The Guide to Freeing your Soil’, this “will reduce stormwater pollution and increase the amount of land available for habitat restoration, urban farming, trees, native vegetation, and beauty…”
In its first five years, Depave co-ordinated the removal of some 94,100 square feet (8,742 square metres) of unnecessary paving by over 700 volunteers, diverting an estimated 2,221,115 gallons (8,407 kilolitres) of storm-water.
Preparation and Collaboration
Depave events require a massive amount of preparation, including identifying a potential site, researching for possible underground utility lines, obtaining any necessary permits, sourcing sponsorship, communicating with the local community, collecting and delivering tools, arranging for transport of materials to and from the site, scheduling tasks and training volunteers.
Projects typically take up to a year to plan, fund and implement, and can involve as many as 100 or more volunteers in each of the four to six events per summer season. Depave works with a wide variety of community groups and organisations with the aim of creating new green spaces that will benefit neighbourhoods as a whole, rather than improving individual residential properties, although they will consider apartment complexes.
Eric Rosewall, executive director of Depave, notes that the projects work best at a specific urban scale and necessitate a ‘fairly unique’ property owner or user, and that “a property owner that is willing to give up that (paved) surface for a more maintenance-intense application – in tandem with a community connected to the site that will help create the green space and take care of it over the long term, is harder to find than many people realize.”
St Mary Ethiopian Orthodox Church
Rosewall mentions the depaving exercise at St Mary Ethiopian Orthodox Church in Portland, Oregon, as one of his favourite projects, “due to the collaboration of groups, the lasting bonds formed, and the impact the new green infrastructure has had on the church, solving a flooding problem.”
St Mary’s is a small immigrant church on the east side of Portland, near the Johnson Creek. A drywell system in its parking lot proved insufficient for the amount of water filling the parking area even after moderate rainfall, making access to the building difficult. With the church having little finance to apply to the problem, it was suggested by the Portland Bureau of Environmental Services that public funding was available for stormwater remediation projects, and that a portion of the parking lot could be ‘depaved’ to form a rain garden.
Depave was called in to assist with site preparation, soil testing, volunteer recruitment and permitting. On September 28, 2013, after 2,500 square feet of the church parking lot had been cut into manageable squares, more than 80 volunteers removed the blocks by hand. After the underlying soil had been rehabilitated, volunteers again arrived to get the site landscaped and planted, helped by Green Lents, who designed the new green space.
The area hasn’t flooded since – “all the rain just comes and sinks into the rain garden,” says Tadele Gelagay of the St Mary’s board of trustees, “this project makes our property a more beautiful place for the entire community.”
National and International Model
The model has outgrown Portland and there are now depaving groups in numerous cities, mainly in the USA and Canada, but also in Australia and the UK. Green Communities Canada provided finances in 2014 for five centres around the country to receive funding, in support of its ‘Depave Paradise’ initiative.
Unfortunately, in the case of Sutton Hill in Telford, UK, the local council engaged contractors to undertake its ‘depaving’ exercise, which took place over a period of a week in February 2016, and seems to have seen little or no community involvement, despite advertising and the support of the local wildlife trust. Nevertheless, Depave UK is up and running and one can expect to see more events taking place there in future.
Whether the depave exercise is a state funded program or a voluntary initiative, community involvement needs to be strongly emphasized, as it increases a sense of local ownership of the project, thus improving its chances of sustainability. Although the depaving activity itself typically takes place during a single day, planting and care of the vegetation on the site requires a longer term commitment, for which community involvement is crucial.
After the actual depaving event, the ground needs to be rehabilitated; this may require the top layer to be scraped off and removed, then the layer below to be loosened for aeration, fresh topsoil to be brought in, and an irrigation system to be installed. While volunteers may be involved, some of this work will require contracted machinery, for example, to remove the compacted, polluted soil. Only after this has been completed can planting of vegetation take place – this is usually done in the fall season to allow plants time to adapt to their environment before new growth occurs.
Each depaving project costs in the region of US$10,000 for equipment, asphalt and soil disposal (some of the asphalt can be recycled), new soil, plants, and all the associated administrative and technical requirements. While the organisation receives some sponsorship, funding is still the biggest ongoing challenge for Depave in Portland, says Rosewall. Although it is a grassroots group, he notes, it actually functions as a professional (but ‘charitable’) organisation that requires staff to plan and implement projects, run the administration to support them, engage contractors and source appropriate plantings.
“What we do is not all that far from what any (landscape) construction firm would do, we just add in a super fun and unique element, and engage tons of volunteers in the process of transformation,” says Rosewall, in order to “deliver on our mission and help those seeking it.”