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An ACAP Journey: Urban Stormwater Management in Action, Bailey Brogan (en anglais uniquement)

An ACAP Journey: Urban Stormwater Management in Action

Last month I had the opportunity to travel to the University of New Hampshire to visit the Stormwater Management Center to see innovative methods of dealing with stormwater using green infrastructure. The trip was part of the Building Regional Adaptation Capacity (BRACE) project funded by Natural Resources Canada and the New Brunswick Department of Environment and Local Government that strives to educate industry professionals about climate change adaptation. I traveled there with a diverse group of city planners and environmental NGO employees from across New Brunswick.When I was telling my friends and family about the reasons for this trip, I was met with confused looks and lots of questions. What is a stormwater management center? Why is this something you are interested in? How does this relate to climate change? Many people may be surprised to learn that stormwater can carry many pollutants as it runs across roadways, driveways and parking lots.  Any leaking fluids from vehicles, salt and sand to manage ice and snow, and even emissions from exhaust pipes can be deposited onto hard surfaces and run into nearby waterways during rain storms.  As our climate changes, rainfall events will become more intense (i.e. more volume of rain during a shorter period), which will create higher runoff volumes. Green infrastructure or low impact development (LID) promotes groundwater infiltration, filters pollutants and reduces the amount of stormwater flowing directly into aquatic habitats. As part of the Climate Change Adaptation Plan for the City of Saint John, I have been working on integrating LID into future planning and working with City employees to begin implementing green infrastructure projects throughout Saint John.The first part of the tour was in the Town of Dover, New Hampshire, where the University has worked with the Town to improve water quality in the Berry Brook Watershed. Berry Brook flows into the Cocheco River and then into the Gulf of Maine. Berry Brook was listed by the United States Environmental Protection Agency (USEPA) as a federally impaired waterway in 2006 due to high levels of e.coli and poor grades from biomonitoring surveys.  Since Berry Brook is considered a coldwater refuge for fish, improving the health of this ecosystem became a priority for stakeholders in the area. At this time, the impervious cover (i.e. parking lots, roadways, driveways) equalled 30% of the watershed area and contributed to a large amount of pollutants entering the brook.

Photo 1: Parking lot bioretention filter.

Photo 1: Parking lot bioretention filter.

Our group met up with Dr. Tom Ballestero, the Director of the Stormwater Management Center at the headwaters of the Berry Brook Watershed, or as it is now known, the Hannaford parking lot. The first site we visited was across the road from the Hannaford, where a former wetland turned dumping area had been restored into a subsurface gravel wetland. This wetland collects runoff from the nearby commercial buildings and parking lots and can treat runoff from one acre of impervious surface. A portion of this wetland was also “daylighted,” meaning that it was returned to its natural state before being filled in, and reconnected with Berry Brook. This area has become an area that locals now enjoy walking and bird watching. Tom said that the best compliment they received about this project was that a little girl wanted to have her birthday party in the field next to the wetland.

Photo 2: Daylighted portion of the wetland and subsurface gravel wetland.

Photo 2: Daylighted portion of the wetland and subsurface gravel wetland.

As we traveled through the watershed we saw many different techniques they employed to increase biofiltration such as bioretention swales, tree filters, and subsurface gravel filters.  Overall, 25 LID retrofits were installed in the watershed to reduce impervious cover from 30% to 13.4%. Tom mentioned that the municipal staff from the Town of Dover were committed to improving stormwater infiltration and this was one of the keys to their success. Staff are now thinking about how they will manage stormwater when new developments are built, or when roadway retrofits are completed. 

All of the systems installed measured water flow and pollutant levels that were collected and therefore diverted from waterways.  Pollutants that were monitored included total suspended solids, total phosphorus, dissolved inorganic nitrogen, total petroleum and hydrocarbons. It is amazing to see how multiple small LID installations removed approximately 19 tons of sediment, 710 lbs of nitrogen, and 127 lbs of phosphorus annually from the Berry Brook watershed.

Photo 3: Bioretention swale that collects water from a nearby roadway.

Photo 3: Bioretention swale that collects water from a nearby roadway.

For the afternoon portion of the tour, we traveled about 20 minutes to the University of New Hampshire Stormwater Center. The “Center” was technically stormwater management experiments that were installed throughout the University campus, but their main field site tests multiple stormwater management techniques simultaneously. This site is an area of low elevation next to faculty and student parking lots that collects runoff from paved surfaces and channels water into different systems.  This area tests three types of stormwater treatment systems: LID systems, product testing of manufactured systems and conventional structural systems, and has the ability to run up to 15 experiments at once. Other types of stormwater management infrastructure that was installed throughout the University campus includes permeable pavers, permeable asphalt, tree boxes and median swales in parking lots. One of the highlights was pouring water on the permeable asphalt and concrete to see how fast the water would disappear.

Photo 4: Field Test site.

Photo 4: Field Test site.

I found it incredibly useful to be able to see how these different systems worked and to actually see them embraced by a municipality as it was in the Town of Dover. I learned what types of infrastructure needed more / or less maintenance and what ones municipalities are more likely to use. I was surprised to learn that the staff from the Town of Dover seemed very receptive to using bioretention swales when they could be vegetated with grass, rather than flowers and shrubs.  When the swales are grassed, staff can continue their regular maintenance to mow the area, rather than weeding and removing the dead plants in the spring or fall. 

After a long day filled with countless site visits, we were all feeling a bit overwhelmed by the amount of information we received, but also excited and inspired to take this information back home to share with our colleagues and municipalities. I was blown away by the commitment to embracing LID shown by both municipalities we visited and wondered if this was because of the difference in regulations made by USEPA. Could green infrastructure be implemented at this level in New Brunswick without specific requirements for the quality of our stormwater runoff? Probably not, but through my own interactions with city staff in Saint John, I think that attitudes are changing toward using green infrastructure to reduce costs and adapt to climate change. 

Photo 5: Tree box filter.

Photo 5: Tree box filter.

I would like to thank Surahbi Sheth, BRACE Project Coordinator, for organizing this trip and Tom Ballestero, for giving us a great tour, and showing us that it is possible to manage stormwater on a watershed scale by integrating green stormwater management into urban landscapes.

Photo 6: Tour attendees and our guide Tom (middle) at the end of a great day!

Photo 6: Tour attendees and our guide Tom (middle) at the end of a great day!

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