Professor, Department of Civil Engineering and Cross-appointed Professor, School of Urban and Regional Planning, Queen’s University, Canada
Professor, Department of Landscape Architecture, School of Architecture, Tianjin University, China

Speech Title: Regional planning and public participation for successful green infrastructure and low impact development (LID) implementation

Abstract: In the ‘modern’ city, it can be argued that traditional water servicing, i.e. provision of potable water through treatment and distribution, and collection/treatment/disposal of municipal wastewater, is generally doing a good job of protecting public health and ecosystem health. As urban populations continue to grow, it is expected that city managers and utilities operators will continue to focus on these fundamental water services, and strive for continuing improvement to meet current and future needs.

At the same time the third conventional water service required in the modern city, stormwater management, typically does not enjoy the same level of design, operation and oversight as those other services (nor can it reasonably be expected to, given the flows generated), and this continues to present threats to our source water protection aspirations. The typical stormwater management system can be termed ‘grey infrastructure’, comprised of drainage and discharge components with some rudimentary treatment applied (generally described as beneficial management practices, BMPs, and commonly taking the form of stormwater management ponds with simple settling and detention functions). The discharge of partially or untreated stormwater runoff (and/or untreated agricultural runoff from rural portions of urban areas) into local waterways represents the largest on-going threat to source water protection, as evidenced in recent years by the occurrence of harmful algae blooms (HABs) in lakes around the world, the continuing presence of persistent and toxic contaminants in source waters, and the emerging threat of hypoxia (low or zero oxygen zones in major lakes). Many scientists point to diffuse sources of pollution as the cause of these issues since we have improved the quality of point source discharges through wastewater collection and treatment applications; stormwater runoff from the hard surfaces of the developed urban area therefore continues to be one of the main sources of contaminant flows into our surface waters.

The recent and growing focus on the application of ‘green’ infrastructure (also called low impact development, LID in some applications), is a promising approach to true source control of stormwater contaminants, through the application of on-site systems like wetlands, green roofs, infiltration installations and other vegetated techniques to provide enhanced treatment and retention of stormwater close to the source. The resulting discharges from these systems have been evaluated to be of higher quality and lower quantity, which provides enhanced source water protection. It has also been suggested that this retained water could be an excellent alternative water supply for non-potable uses (irrigation, fire flow, toilet flushing, etc.), thereby reducing the demand on the potable water supply system for non-consumptive water. This may become more important in future as cities face the costs and challenges of continuing improvement of water supply/distribution in the face of climate change. Having an alternative water supply derived from the application of green infrastructure for stormwater management, at the individual lot level or at the community level, seems to be a natural outcome of this movement, as long as some fundamental aspects of the green infrastructure are first addressed. Two such aspects are the need for an urban watershed-based approach to green infrastructure implementation, and the inclusion of the public as active stakeholders in the planning and application of the systems being installed in the public domain (as a new kind of PPP approach).

There are many good current examples of research and demonstration of green infrastructure at the individual lot level in Canada and China (part of the ‘sponge city’ initiatives) but it is felt that with these systems generally being applied in an ad-hoc manner by individuals, groups and/or organizations, they remain disconnected from each other within the urban watershed, and they are not fulfilling their full potential. We can propose that one of the most important aspects of green infrastructure is the reconnection of urban systems that have been fragmented by typical hard surface development, e.g. reestablishing/reconnecting wildlife corridors and previously existing vegetated ecosystems; reconnecting surface water systems and flows; and reconnecting surface- and groundwater systems for recharge and the maintenance of base flow of surface rivers/streams. This can be thought of in the same way that current stormwater management seeks to reestablish pre-development water flows (based on the storm flow hydrograph). If this is the case, it can be suggested that the best way to establish these reconnections is through a more comprehensive regional planning approach, expanding the very successful lot-level green infrastructure applications into neighbourhood-scale approaches and beyond. This may also help address the challenges faced by green infrastructure designers/proponents when considering the differences and ease (or difficulty) of implementation of these reconnections in densely developed areas as opposed to ‘greenfield’ developments in suburban areas.

One organization involved in this kind of approach worth noting is the Credit Valley Conservation Authority (Mississauga, Ontario, Canada) which in partnership with other organizations has launched a ‘grey-to-green’ planning, design and implementation program to serve as a guide for the urban watershed-based restoration approach to green infrastructure. This program is an excellent template for the approach that can be taken to successfully implement green infrastructure, and is echoed by a recent study in our research group which modeled both a neighbourhood and a ‘sewershed’ approach to green infrastructure implementation. That study indicates that LID installations at both those scales provide small but measurable benefits in terms of stormwater management, with increased benefit for the smaller, more frequent storm events. Optimization of the installations at these scales could be easily incorporated into the future development and maintenance plans of the municipality, to realize the full benefit of the green infrastructure.

In parallel with this new approach, it is felt that green infrastructure application must also involve and encourage strong public participation to be fully successful. This may seem obvious at the lot-level and for such LID applications as rain barrels and storage cisterns and even for end-of-driveway permeable pavers. Use of increasingly common stormwater utility approaches (wherein homeowners pay for the discharge of stormwater runoff from their property) might be seen as public participation as well, since many stormwater utilities will offer relief from the cost of drainage for homeowners who demonstrate flow reductions (most probably through use of green infrastructure). However, in expanding these installations to the neighbourhood or larger scale it can be suggested that the public needs to be actively involved in the process (which may include the installation and the longer-term maintenance and operation of the systems). Two examples from our research program highlight the importance and mechanism of public participation: one involved full public participation at the neighbourhood scale through detailed surveys to identify issues and preferred green infrastructure options, and assessment of willingness-to-participate in the active maintenance of the installed systems; and the other involved direct neighbourhood level participation in the construction and installation of a large-scale integrated LID system. The willing participation of the residents in both examples allowed the relevant municipal authorities to incorporate those view points and desires into creating systems that fulfilled most of the goals of green infrastructure, and these can serve as excellent examples of true partnering, public education and public engagement for the municipal common good.

Both aspects of the proposed ‘optimized’ green infrastructure installation and management will be illustrated in this presentation with relevant current examples from our research program and from collaborating organizations. These examples will be useful to our Chinese colleagues as they move forward with ‘sponge city’ activities, both in terms of municipal planning and use of the technologies available to achieve optimal green infrastructure systems.