Excess stormwater runoff can lead to flooding and can impact water quality, either by moving across surface land and picking up contaminants which are then discharged into streams and waterways, or by overwhelming combined storm sewer and sanitary systems and resulting in a sewage outflow to surface waters. Traditional engineering solutions are aging, frequently at capacity, and expensive to retrofit. Alternatives to such traditional approaches can be found in green and blue infrastructure projects.
- Green infrastructure: Mimics natural processes to treat, restore, and manage the water on site preventing it from entering the sewer system and providing natural benefits locally. Examples include stream daylighting, rain gardens, bioswales, constructed wetlands, retention and detention basins, and green roofs. These methods provide improvement in flood risk mitigation, water quality treatment, and community enhancement. While green infrastructure plays an important role in stormwater management, the space requirements for this solution often pose a challenge in densely developed environments.
- Blue infrastructure: Implements technological systems to reduce the impacts on the traditional infrastructure, especially in areas where more natural methods are limited due to space constraints. While some refer to the water component of green infrastructure as “blue”, i.e. ponds, basins, or surface waterbodies; here we are referring to blue infrastructure as technology based, compact solutions that are used to enhance the efficiency of the green and gray systems – for example through improved filtration, maintenance, or treatment. They are particularly well suited to retrofit into existing gray systems, increasing the efficiency or diverting excess flow from one treatment option to another, and prevent downstream flooding.
Through the development of a comprehensive, strategic stormwater management plan which incorporates grey, blue, and green infrastructure and involves all stakeholders, communities can maximize the efficiency of stormwater system. This should include incorporation of the water management plan into planning documents, the zoning code, infrastructure management, facilities development and capital plans.