To develop a large park today requires a balance of public benefit with financial viability. New models are needed that complement public and private investment with alternative sources of revenue and material resources, particularly as parks confront the realities of climate change – an especially urgent challenge for waterfront cities. We might consider the coastal park in terms of a new urban paradigm of resilience. Toronto is a telling example. Much of the city’s historic network of rivers, streams, and deltaic landscapes was buried in the processes of urbanisation and industrial development. Only relatively recently has the city recognised the ecological and social value of its lakefront, despite, or perhaps because of, expanding impermeable surfaces, accelerating erosion and pollution in waterways, and the essential dredging of navigable channels for commercial shipping. Typically viewed as a practical maintenance operation, dredging presents an opportunity to close a material loop. Rather than treating dredged sediment as waste, how can it be transformed into a valuable resource? Through remediation and processing, dredged material could support the ecological restoration of disturbed landscapes while introducing a more productive conception of the urban park. In this sense, public parks can embody principles of industrial ecology, making cities not only more livable but more responsive to environmental change. A pilot project at Kalaeloa in Hawaii transformed de-watered dredged material from Pearl Harbour into a fertile growing medium through the addition of organic matter, bioremediation and phytoremediation, resulting in strong water retention, healthy vegetative cover and fertility equal to or greater than that of local natural soils. 4 Similar examples, below, indicate that dredged material can regain productive value with minimal external inputs.
industrial ecology in the Great Lakes region The Great Lakes Basin, the largest freshwater system on earth, edged by major urban centres: Toronto, Hamilton, Kitchener-Waterloo, London, St Catharines, Windsor, Oshawa, Duluth, Milwaukee, Chicago, Detroit, Toledo, Cleveland, Buffalo, Rochester and Syracuse; home to between 35-40 million people, and an epicentre of industrial production. In ‘Designing dredge: engaging the sediment landscapes of the Great Lakes Basin’, Sean Burkholder writes that it is time that sedimentation in the Great Lakes be managed differently than it would be in other coastal or riverine conditions. 5 The physiological composition of the lakes makes them ‘act like a sink’ where material cannot simply be transported away by ocean currents, making the integration of sediment with urbanised and freshwater ecologies imperative.
The dredging and filling of the Toronto waterfront, circa 1921, showing Toronto Port Authority
Luca Bertolotti
above: The Salins d’Aigues-Mortes in France serve as a precedent for integrating industrial production, ecological processes and recreating in a single landscape. right: the IJsseloog is a Dutch confined disposal facility in the middle of Ketelmeer lake. top : construction in 1996, and below: in service in 2015
4 Kornuc, John. ‘Treating Dredged Sediments for Beneficial Use’, Currents , 2013, pp. 18–21 5 Burkholder, Sean. ‘Designing Dredge: Engaging the Sediment Land- scapes of the Great Lakes Basin’, Journal of Landscape Architecture , vol. 11, no. 1, 1 Feb. 2016, pp. 6–17.
Dutch Ministry of Infrastructure and the Environment
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on site review 49 :: shorelines
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