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Working Smartly to Deal with the City's Rainwater

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Working smartly to deal with the city’s rainwater


We have devised a smart and sustainable way to deal with our city’s rainwater to guard against flooding and provide water for the plants and trees.

View looking south along the central path through the new Place de Brest, with solar canopies, new covered seating, lawned areas and planting

View looking south along the central path through the new Place de Brest, with solar canopies, new covered seating, lawned areas and planting

What is a SuDS and why is it important to include it in Armada Way?

We want to create a SuDS (sustainable urban drainage system) to manage all surface water which falls on Armada Way, mimicking where possible, a natural drainage system. This will involve the use of rain gardens and underground storage tanks which will fill with rainwater after being filtered through natural reed beds instead of using chemicals. The water will be recirculated around Armada Way through an ornamental stream which will run along the length of the proposed scheme. The water will be used to irrigate the trees day and night. Through this process, we will reduce the strain on the combined sewer system, clean our surface run off and reduce discharge events into Plymouth Sound.  The system is more climate resilient as it is designed to handle extreme weather events and is considered critical and best practice for handling urban water run off by the Environment Agency and South West Water.

What benefit will the SuDS bring?

The sustainable urban drainage system has a number of benefits for the proposed new trees, for the city centre and for Plymouth Sound. It: 

  • Reduces maintenance and watering costs: The system uses rain gardens which will be installed beneath the ground level, which combine with large underground storage tanks, and will retain rainwater that can be used to feed the plants and trees above the ground.
  • Reduces the amount of rain and foul water that ends up in the Sound: The system will ensure that rain and surface water will not go into the existing combined sewer system.
  • Frees up capacity in the existing combined sewer system: Reducing the risk of flooding in the city centre. 

Why can’t the old drainage system remain?

The old drainage system is showing its age. It is a post war combined sewer system – surface and foul water – that was never really designed to deal with the capacity it currently has to cope with, given the demands of modern plumbing in residential and commercial properties.

The SuDS system is not replacing the old drainage system but takes pressure off it as it is diverting rain and surface water away from the current drainage system. We will also be working with South West Water to help upgrade sections of their system in Armada Way at the same time.

The work will also entail the creation of an underground trench running the length of Armada to enable districting heating infrastructure to be retro fitted.

How will the SuDS be powered?

It will be powered by solar canopies that will be based at Place de Brest and on either side of the toilets. Power will be stored in huge batteries, underground.  The system also has an emergency ‘back-up’, linking to the main power-grid, in case not enough power is generated by the sun. The use of solar power will also help the Council with its Net Zero aspirations. 

The schematic of the proposed SuDS plan can be found on the final page of the Armada Way Tree Translocation Assessment document. This document can be found at the bottom of the Nature and Greenery page here