CARP Newsletter: Stormwater Special Feature
It’s raining, it’s pouring, and CARP staff are working!
Special Feature: Sustainable Stormwater Management
WHAT’S INCLUDED
What is stormwater?
Stormwater is water that originates during precipitation events (ex. rain storms) and snow/ice melts. Stormwater can soak into the soil (infiltrate), be held on the surface and evaporate, or runoff and end up in nearby streams, rivers, or other water bodies (surface water).
Current Stormwater Management (SWM) & the Issues
In natural landscapes such as forests, this cycle of infiltration, evaporation, and runoff manages and naturally filters stormwater.
Whereas, in developed environments (ex. Towns, Cities), stormwater is collected from roads, roofs, and other impermeable surfaces (surface you cannot get through) and transported through what we call grey infrastructure such as drains, pipes, culverts, and other water carrying systems. Stormwater in developed areas ends up carrying trash, sediment, bacteria, heavy metals and other pollutants from the landscape, which logically degrades the water quality of the receiving water bodies.
This water quality issue is then made worse because a majority of the stormwater grey infrastructure throughout southwest Nova Scotia leads to combined sewers. Combined sewers are piping systems that share pipes between the sewage systems and rainwater drains.
When there are heavy rainstorms and these sewers are overburdened by too much water our infrastructure experiences what are called Combined Sewer Overflows. This leads to raw sewage mixing with flooding water and ending up in surrounding watercourses and water bodies leading to major issues with E.Coli.
We also experience increases in E.Coli from excess nutrients picked up through overland runoff from agricultural land and livestock wading directly in water. Higher flows can also cause erosion and flooding in streams, damaging habitat, property and infrastructure.
Traditionally, stormwater management focusses mainly on collection and processing of stormwater without addressing all of these other issues and factors. Whereas, sustainable stormwater management aims to maintain the health of water bodies such as lakes and streams, prevent flooding and erosion, protect aquatic species, and sustain healthy sources of water for humans by mitigating the effects of urban development.
What does sustainable SWM look like?
There are 2 main methods that we typically refer to and use:
- Natural Infrastructure (NI)
- Low Impact Development (LID)
NI uses existing, restored, or enhanced ecosystems to generate infrastructure outcomes either on its own or in combination with built infrastructure (like LID).
NI can provide protection against a range of climate change hazards, such as coastal flooding, riverine flooding, extreme heat in urban areas, and drought, as well as generate co-benefits such as species habitat and recreational opportunities.
The following diagrams were developed by the International Insitute for Sustainable Development (IISD) to exemplify how Ni & LID can be implemented across our landscape:
CARP’s Previous Work in SWM:
Since the early 2000s, CARP has partnered with local businesses, organizations, communities, and municipalities to carry out sustainable SWM improvements such as:
- Rain barrel installation
- Tree planting
- Rain garden construction
- Cistern installation
- Wetland restoration
- Home assessment program
To successfully complete these projects, CARP collaborated with the following partners:
Coastal Action, Town of Digby, Bunchberry Nursery, Ragged Robin Farm & Nursery, Summerland Plant Nursery, Nova Scotia Community College (NSCC) Middleton, Sweet Fern Farm, Wayward Farm
NI Element Highlight: Rain Gardens
One of the most common forms of natural infrastructure are rain gardens. Rain gardens can be thought of as “engineered gardens”. A rain garden is a garden that allows stormwater to soak into the earth slowly, rather than flooding streets, entering storm drains, or going into nearby waterways. Stormwater runoff from streets and parking lots enters the rain garden through a gradual slope where it slowly seeps into the soil.
The stormwater slowly filters through the roots of water tolerant, or “water-loving” plants, where a majority of pollutants are removed. The water enters a secondary filtration level usually made of sand, gravel, or rock where it seeps into groundwater reserves below.
These engineered gardens are easy to implement, cost efficient, and aesthetically pleasing. For all of these reasons, the Clean Annapolis River Project has constructed multiple rain gardens throughout southwest Nova Scotia.
“Water-Loving” (Water Tolerant) Plants
When we construct rain gardens, plant bioswales, and implement NI, we typically choose a variety of vegetation that can tolerant a wide range of moisture conditions, from flood to drought. Emphasis is made on selecting native vegetation and plants that serve multiple purposes (ex. pollinator species). Check out the list below to discover some of our favourites!
- Red Osier Dogwood
- Bog Rosemary
- Blue False Indigo
- Daylilies
- Swamp Milkweed
- Blue Flag Iris
- Switchgrass
- Black Eyed Susan
- Common Yarrow
- Echinacea
LID/NI Element Highlight: Permeable Pavers
Permeable pavers are a great way to reduce impervious surfaces on your property without losing valuable footprint for other uses (ex. driveways, patios, walkways, etc…). Permeable pavers include a range of options, such as inter-locking paving blocks, permeable asphalt and cement, and vegetated cement grids. Permeable asphalt/cement have a porous binder, whereas inter-locking paving blocks have built-in spacing and a cement or stone grid with vegetation growing in a sandy soil medium between the guidelines.
Want to take it a step further?
Removing hardscape, or impervious surfaces, in sections can provide a point of access for stormwater to reach the ground below. This method also provides opportunities for greening up your neighbourhood, reclaiming natural landscapes, and improving overall aesthetics!
LID Element Highlight: Rain Barrels
NI Element Highlight: Wetlands
Wetlands are amazing forms of natural infrastructure. Wetlands are areas of land that are wet for all, or a portion, of the year. They tend to have soils that drain poorly and support water-loving plants such as cattails, sedges, rushes, blue flag iris, willows, and dogwoods.
Wetlands (preserved, restored, or constructed) play a critical role in sustainable design strategies to manage stormwater. They are integral parts of stormwater projects in both urban and open or undeveloped areas throughout our landscape due to the many services they provide to our communities and environment.
Wetlands recycle nutrients, filter certain pollutants, recharge groundwater, and provide habitat for fish and wildlife. They also reduce peak flows and flood damage, provide water storage, and mitigate erosion.
In addition to water quality and water quantity benefits, wetlands capture carbon. They are one of the most diverse and productive ecosystems in Canada.
Constructed or restored/preserved wetlands can also be combined with low-impact development to effectively manage stormwater in urban areas.
The wetland pictured above was restored through a CARP project spearheaded by Katie Mclean in the Town of Middleton.
Learn more about the Middleton Wetland Details!
In 2021, CARP secured funding through Environment and Climate Change Canada’s EcoAction Community Funding Program to further conduct stormwater management work. We are currently partnered with the Town of Digbyand Beacon United in Yarmouth to implement natural infrastructure, low impact development, and advise on sustainable stormwater management for future projects.
This fall we constructed two rain gardens behind the Digby General Hospital, each over 80 square meters and comprising of over 500 plants. In addition, we consulted on future implementation of natural infrastructure to be incorporated into the park’s design.
We also constructed a 50 square metre rain garden at Beacon United in Yarmouth, planting over 350 “water-loving” plants, to improve drainage on site, as well as procured two 1000L cistern totes to improve collection and redirection of stormwater on the property. CARP is also advising on future improvements for the property and its ability to manage stormwater sustainably with the support of Snow Owl Consulting.
For both projects, we received support and generous donations from local businesses and members of the community.
Special thanks to Acadian Seaplants Ltd, Gini Proulx of the Clements Garden Club, David Trefry Excavating Ltd, and Keir Anthony Ltd.
Coastal Action – Project Partner Update
Our partners, Coastal Action, have also been hard at work this fall installing a rain garden in the Town of Bridgewater. This included removing impermeable pavementfrom a section of no longer used parking lot at a local community space. This location, the Bridgewater Memorial Arena, is where the community gathers for their weekly Farmer’s Market.
Once the area was depaved and prepared with absorptive soils, Coastal Action then hosted a TD Tree Days event and welcomed 30 volunteers to help plant approximately 250 native trees, shrubs, and herbaceous perennials!
TD staff, members of local garden clubs, and community members all came together for a wonderful afternoon of improving stormwater management within the town. The finished installation is the second rain garden at this site and compliments another rain garden installed in 2022. These two natural infrastructure installations work together to filter and absorb nearly 7,000 m³ of stormwater runoff every year!
To check out Coastal Action’s current initiatives and find out more about their upcoming projects, visit their website www.coastalaction.org, or follow them on Instagram and Facebook @coastalaction!
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