STAFF BLOG
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.
Photo 1: Parking lot bioretention filter.
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.
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.
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.
Photo 3: Bioretention swale that collects water from a nearby roadway.
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.
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.
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.
Photo 5: Tree box filter.
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.
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!
Protect, Accommodate, Retreat
The 2019 flood: the second major flood event in New Brunswick in the past year, the third in the past 11 years. As of May 2019, approximately 639 households have registered with the Red Cross for flood relief support. The response from last year’s “once in a century flood” was major, individuals and communities came together to help one another through this natural disaster. People were comforted by the thought that this probably wouldn’t happen again for another ten years, but the reality is, as the climate changes these events will become a more common occurrence. After two floods in a row, people are already feeling the fatigue that recurring events can bring. When recovering from back to back flooding events many people want to know, what can they change so that this doesn’t happen to them again?
Essentially there are three options that people living in flood prone areas can choose to adapt: protect, accommodate or retreat. With each option, comes its own set of costs and challenges. Whichever option you choose (or combination of options) will be the one that makes the most sense with your physical location, available resources and time.
(Natural Resources Canada, 2016)
Protect: This method includes setting up an either temporary or permanent structure between a waterway and infrastructure that will hold back flood water. While sandbagging can be an effective flood protection measure, it is time consuming and physically demanding work. Many volunteers made themselves available to help sandbagging in 2018 and 2019, and the military provided assistance in 2019. After floodwaters recede, homeowners are then left with wet, heavy and potentially contaminated sandbags that need to be disposed of in the landfill.
Sandbags holding back floodwater (Eastern Ontario Network, 2018)
Other temporary protection devices include “Water Gates,” Water Inflated Property Protectors and interlocking flood barriers. These structures are reusable and can be easy to install. Investing in alternative kinds of flood barriers may save time and reduce the amount of manpower needed for protection.
Photo: Interlocking flood barriers, (Design 1st, 2018).
Other ways to protect your home from flooding is to move appliances and furniture to upper floors of your home, install a sump pump, and seal and cracks in your foundation or gaps around basement windows. Follow this link for more resources about flood preparedness.
Accommodate: The method requires altering infrastructure to be more resilient to flooding. This includes jacking up houses, adding basements or height to foundations, building homes on stilts, raising road levels (like Ragged Point Road, Saint John), redesigning basements to be able to withstand flooding, or restoring wetland habitat. If you qualify for Disaster Financial Assistance you may use up to 15% of the allocated funds for mitigation of flooding on your property.
Flood proofing is especially important if you use petroleum products for home heating or cooking. Ensuring vents and fill pipes for aboveground and underground storage tanks are above the 1 in 100 year flood line will avoid contaminating flood waters and causing further post-flood cleanup headaches. The province of New Brunswick has provided a Petroleum Product Storage Tank System Flood Protection Checklist to guide homeowners with home heating oil or propane tanks.
Retreat: Moving infrastructure away from risk zones. This method can be very costly, but will ensure that you will likely not be impacted by future flood events. Currently if 80% of the value of your home has been damaged by flooding, the Province of New Brunswick will buy out a home or property (Seventy-eight properties were bought out after the 2018 flood). Recently, the Government of New Brunswick bought three properties on Darlings Island and sold the homes with the requirement that they are moved out of the flood zone. Buyouts were also used in 2012 in Perth Andover after devastating flooding.
A fourth option for dealing with flooding is to avoid building in flood risk areas altogether. For this option to be successful, action will need to be taken at a policy level. Guidelines for floodplain management and updating flood hazard mapping will help governments make informed decisions when allowing new development. Individuals can keep this in mind as well when choosing where to build or if considering buying a new home that is within the flood zone. There are resources available on the GeoNB website that shows the 1973 and 2008 flood zones - this can be used as a guide for the public when searching for a new home or land.
We have learned many lessons over the past year and will continue to learn from this flood. As climate change progresses, floods in New Brunswick will become more common, so considering your options to protect, accommodate, or retreat can help to increase our resiliency to flooding events in the future.
Have you tried any methods to adapt to flooding? Leave us a comment or contact office@acapsj.org to share your story.
Kennebecasis Drive, 2019.
Sources:
Admin, E. (2018). “New Brunswick flooding to continue for ‘at least’ 5 days, state of emergency not ruled out” Eastern Ontario Network Television.
CBC Information Morning Fredericton (2019). “Province offers financial aid to owners of flood-damaged buildings. CBC News New Brunswick.
https://www.cbc.ca/news/canada/new-brunswick/jeff-carr-cottage-owners-flood-1.5121368
Campbell, A. (2012). “N.B. to spend up to $8M to relocate Perth Andover homes.” CTV News Atlantic. https://atlantic.ctvnews.ca/n-b-to-spend-up-to-8m-to-relocate-perth-andover-homes-1.980575
Design 1st (2018). 5 New Flood Prevention Products. https://www.design1st.com/5-innovative-flood-prevention-products-replace-sandbags/
Lemmen, D.S., Warren, F.J., James, T.S. and Mercer Clarke, C.S.L. editors (2016). Canada’s Marine Coasts in a Changing Climate; Government of Canada, Ottawa, ON, 274p. https://www.nrcan.gc.ca/sites/www.nrcan.gc.ca/files/earthsciences/files/pdf/NRCAN_fullBook%20%20accessible.pdf
New Brunswick Emergency Measures Organization (NB EMO) (2019). Disaster Financial Assistance Frequently Asked Questions. Government of New Brunswick. https://www2.gnb.ca/content/dam/gnb/Departments/pa-ap/pdf/Report_Damages/dfa_faq.pdf
NB EMO (2019). 2019 Freshet by the Numbers. Government of New Brunswick. https://www2.gnb.ca/content/dam/gnb/Departments/pa-ap/River_Watch/pdf/2019_freshet-e.pdf
New Brunswick Department of Environment and Local Government (2016). Petroleum Product Storage Tank System Flood Protection Guidance Checklist. Government of New Brunswick. https://www2.gnb.ca/content/dam/gnb/Departments/env/pdf/Flooding-Inondations/PetroleumProductStorageTankSystemFloodProtectionGuidance.pdf
Service New Brunswick (2019). GeoNB Map Viewer. Government of New Brunswick. http://www.snb.ca/geonb1/e/index-E.asp
Smith, C. (2019) “Province clears houses from Nauwigewauk flood zone”. CBC News New Brunswick.
Planning for Sea Level Rise in Saint John
Recently ACAP Saint John worked with the New Brunswick Environmental Network to host a Sea Level Rise Workshop at the Saint John Free Public Library. The workshop’s goals were to educate the public on sea level rise concepts, identify areas and infrastructure that may be at risk, and to discuss tools and approaches for adapting to the effects of climate change.
Flood risk maps were shown to participants and depicted water levels at four different stages:
Higher High Water Large Tide (HHWLT) (4.6 m) represents the impact of storm surge on higher tides associated with the new moon or full moon cycles. This figure is determined by the average large tide over a 19 year period.
HHWLT + 1 m (5.6 m) which depicts sea level rise of 1 m, the approximate height predicted to occur by 2100.
HHWLT + 2 m (6.6 m) Saxby Gale Type Event. The Saxby Gale was a hurricane that made landfall during a perigean (extreme high) tide in 1869 and resulted in a storm surge of approximately 1.7-2.1 m high, the highest ever recorded in the Bay of Fundy.
1 in 100 year storm surge in 2100 (6.8 m). Flooding scenarios are generally modeled for return periods (the average time between events) ranging from and annual event to a one in 100-year event. For example, a 100-year event is predicted to have a one in 100 (1%) chance of occurring in any given year.
Participants were able to visualize what areas may be at risk to sea level rise and discussed some actions that could be taken to prevent damage to coastal assets.
Workshop participants discuss sea level rise in Saint John.
Most coastal infrastructure is built to withstand storms and flood events based on a specific return period (i.e. 1 in 100 year storm). Return periods are calculated based on current weather, and does not include changes in future climate; therefore, in the future a 1 in 100 year event could become a 1 in 50 year event due to increased severity and frequency of storms. To further illustrate this, consider that a 1 in 100 year storm (1% probability) today could create a storm surge of 5.5 m (0.9 m above the current HHWLT). By 2050, this same storm surge level will be a 1 in 2 year event (50% probability) and in 2100 the annual storm surge event is projected exceed the current 1 in 100 year event by 0.8 m. When infrastructure is designed to withstand today’s 1 in 100 year events, it may only do the bare minimum by 2100. Will these predictions be factored into building planning and design? How do we accommodate this moving target?
Now that we have identified what areas may be at risk, we can start to think about adaptation. By making changes to how and where we build, we can be better prepared for climate change impacts.
Adaptation to sea level rise and coastal erosion can be achieved in three ways: protection, accommodation and retreat/avoidance. Examples include:
Protection: hard/soft armouring beaches and coastal infrastructure, dykes, sea walls, restoring beaches/coastal wetlands, reinstating vegetation.
Accommodation: flood proofing buildings, changing building design guidelines, protection of coastal wetlands and restricting use in coastal areas.
Retreat/Avoidance: either abandoning or relocating infrastructure out of low lying areas restricting development in low lying areas.
Depending on the risks and costs associated with each strategy, no single approach can be applied to every situation. A combination of adaptation strategies would provide a more holistic approach to dealing with sea level rise.
Feedback from the workshop participants on the community needs included:
Better access to local information on climate change, sea level rise, etc.
More public consultation on new developments, especially in at risk areas.
Motivated and committed elected officials that will make adaptation a priority.
The Province of New Brunswick is developing flood risk maps that will depict coastal and inland flooding risks. These will be available to the public within the next few years. Community climate change adaptation planning is in the works at ACAP, along with Asset Management and Resilience studies that are being conducted by the City of Saint John. Community consultation on these projects will continue throughout the fall, including a Resilient Community Workshop which will take place on September 13.
If you have any questions about ACAP's climate adaptation work or are interested in participating in upcoming community consultation please contact office@acapsj.org
References
Daigle, R., 2017. Sea Level Rise and Flooding Estimates for New Brunswick Coastal Sections, 2017. R.J. Daigle Enviro. Prepared for New Brunswick Department of Environment and Local Government.