Rain Gardens, Swales, and Permeable Paving: Sustainable Solutions for Managing Stormwater

Sustainable drainage systems, often shortened to SuDS, is a term for a set of environmentally friendly techniques that are designed to help manage and control surface water runoff, particularly in urban areas. SuDS are vital for managing urban water runoff in an environmentally friendly way.

Why are SuDS important?

They reduce flood risks, improve water quality, and promote groundwater recharge by encouraging natural infiltration and water filtration. SuDS also boost biodiversity by providing habitats while helping to mitigate the effects of urban heat islands by using green infrastructure. In addition to playing a key role in climate change adaptation, they offer social and aesthetic advantages by incorporating green spaces into cities. SuDS are often more cost-effective and sustainable compared to conventional drainage systems. 

In natural environments, rain falls on permeable surfaces and soaks into the ground; this process is called infiltration. In urban areas, where many surfaces are sealed by buildings and paving, natural infiltration is limited. The aim of a Sustainable Drainage System is to mimic natural water management processes by allowing water to infiltrate into the ground, evaporate away, or be stored again for later use, rather than immediately diverted into traditional drainage systems. SuDS are a practical part of urban planning and an aspiration for a greener approach to construction and living. Rural SuDS on the other hand are tools that help maintain and manage the provision of good water quality. They provide a vital role by intercepting run-off and trapping soil before it leaves the field. 

What are the key components of SuDS? 

Infiltration, filtration, and storage are key components of SuDS that play distinct but complementary roles. Infiltration allows water to percolate through the soil, replenishing groundwater and reducing surface runoff. Filtration, on the other hand, involves the removal of pollutants and sediments from water as it passes through soil or engineered media, improving water quality before it reaches natural water bodies. Storage is essential for temporarily holding excess stormwater during heavy rainfall, preventing overwhelming of drainage systems, and reducing the risk of flooding. Together, these processes enhance water management by mimicking natural hydrological cycles, promoting environmental sustainability, and protecting urban infrastructure and ecosystems from the adverse effects of uncontrolled stormwater. 

Designing rain gardens and bioswales 

Rain gardens collect and absorb rainwater, typically from rooftops or driveways. Bioswales, on the other hand, are built to manage and treat runoff water from more expansive areas, like car parks or alongside roads.  

The most important consideration when planning a rain garden is site selection. Ensuring to choose a location between two impervious surfaces, for example, a roof, a lawn, and a street is imperative. Examine where the rainwater pours off the roof via downspouts and watch how it flows to any grass area to see where the runoff water enters the street. Choose a natural, rounded shape for a rain garden, like an oval, teardrop, or kidney shape. A rain garden will create a channel to an artificial depression or will serve as an artificial depression, where water will be able to collect and enter the ground slowly. When installing a rain garden, you are not creating a pond; ideally, the garden should drain within 24 hours after a storm. 

Bioswales function similarly to rain gardens but are designed to capture significantly more runoff from larger impervious surfaces, such as streets and car parks. They incorporate more complex design elements, including layers of engineered soil, gravel, perforated pipe underdrains, and overflow structures to manage excess water from heavy storms. Like rain gardens, bioswales rely on native plants to enhance water absorption and reduce erosion. Due to their advanced design, collaboration between an engineer and a landscape architect is typically required to ensure the bioswale is properly constructed and performs efficiently. 

Benefits and applications of permeable paving 

Permeable paving surfaces are made of either a porous material that enables water to flow through it or nonporous blocks spaced so that water can flow between the gaps. Permeable paving can also include a variety of surfacing techniques for roads, parking areas, and pedestrian walkways. 

Permeable paving offers several environmental advantages, including: 

• Reduces stormwater runoff: Permeable paving catches and slowly drains water into the soil rather than allowing puddles to form and flow into drains. 

• Reduces pollutants: Permeable paving provides natural filtration where the rainwater is returned to the earth and passes through the sub-base of the pavement which can eliminate pollutants in a few ways. One method of elimination is created physically where the pollutants get trapped in the pavement or soil. Another method is created chemically whereby the pollutants are broken down by toxin consuming bacteria and microorganisms.  

• Reduction of Urban Heat Islands: Urban heat islands are created through heat absorption through concrete and tarmac which causes a temperature increase in the earth below. Permeable paving allows the earth beneath to breathe which reduces this heat absorption. 

• Increases energy efficiency: Permeable pavers absorb less heat than traditional pavement, which helps lower the surrounding air temperature, resulting in less demand for building cooling systems.  

• Reduces water demand: Water can flow directly into garden beds, tree plantations and entire ecosystems through porous surfaces. The filtered water provided by pervious and porous surfaces is also ideal for organic material replenishment.    

Features of Tobermore Hydropave permeable paving range 

Tobermore offers a high-end range of permeable concrete paving products that create beautiful hard landscaping with environmentally friendly properties.  

Tobermore’s Hydropave range plays a vital role in reducing flood risks by serving as an effective component of Sustainable Urban Drainage Systems (SuDS). The Hydropave range offers the perfect balance of durability and visual appeal, ensuring long-lasting performance without compromising aesthetics. A standout feature of the Hydropave range is its ability to seamlessly integrate permeable and impermeable areas, maintaining design continuity throughout a project. Additionally, each product in the range comes with independently verified Environmental Product Declarations, reflecting Tobermore’s commitment to sustainability and environmental responsibility. 

For more information on how your project can benefit from SuDS, get in touch with our technical team today!