Hydrorock Tree Pit Solution to Solving Flooding

Retrofitting a Hydrorock Natural Aquifer buffering, infiltration and irrigation system in combination with 78 tree pits to prevent flooding in an urban location

System information

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System datasheet

System design brief

The existing old rain water sewage system was failing and damaged which resulted in flooding of the area during continuous or short bursts of heavy rain. Local authorities needed an innovative solution in which the existing sewage system could become obsolete, flooding would be solved, and a greener appearance with trees and scrubs would improve the streets image.

The local Council required a scheme to deal with both issues and the proposed Hydrorock Natural Aquifer SuDS system was adopted. Each subsystem was required to buffer and infiltrate/irrigate the rainfall on a 75m² section of road and to buffer and infiltrate 30mm rainfall within one hour. Giving a volume to buffer of 2.25mᶾ in an hour per tree pit.

Why the Hydrorock Natural Aquifer SuDS System?

The Hydrorock SuDS system provided the council with a very cost-effective solution which is capable of effectively dealing with a large rain event, without any need to connect to a sewerage system. The Hydrorock system created tree pits, where the water is stored and utilised to irrigate trees and shrubs.

£562 per tree pit

Previously the only solution was to drain the area and take the water into the overburdened sewers. Hydrorock provided the council with the only solution to buffer the rainwater and irrigate trees in a completely green way. Like many which are environmentally-conscious, the council was strongly against placing large volumes of plastics in the ground, due to contamination of the nearby sea with micro plastics.

The Hydrorock solution filtered run off from the road, and the Aquifer Blocks chemically bound some pollutants, cleaning the water before it finally infiltrated into the soil.

Installation and Spec

The project could be undertaken with minimal disruption with sections of the road being dealt with at a time. The trees were located between the existing parking spaces and the system was installed around these trees and underneath the spaces to avoid root disturbance.

Because the area was not subject to heavy vehicular traffic, standard-density blocks were able to be used, which have a lower cost per litre than the high-density blocks. These were placed with 300mm of over burden, allowing a loading of 3000Kg per m².

For each sub array, three BD 340 blocks were used at a depth of 1300mm, arranged to the side of the tree under the parking spaces and one directly in front of the tree. The blocks were connected to ensure fast filling of the sub array.

Download our case study PDF for more details and cost implications

Hydrorock Benefits

By selecting Hydrorock, the drainage engineers were able to design a SuDS solution for the project that:

  • Prevents rainwater flooding

  • Retains all infiltrated all rainwater on site, using a dispersed aquifer system

  • Is 100% green, using a natural substrate

  • Minimal maintenance and lasts a lifetime

  • Modular design meant that installation caused minimised disruption

  • Only required two men to install

  • The installation could work around existing underground infrastructure

If you have any questions regarding this case study, any projects that you wish to discuss or any other questions about the Hydrorock Natural Aquifer SuDS System, please get in touch from the details below.

Hydrorock Water Infiltration

HydroRock System Used

To provide a fully integrated green SuDS solution that harvests, buffers and irrigates rainwater and runoff, before infiltrating all site water within the confines of the site, our Hydrorock Aquifer Water Infiltration System was integrated.

Aquifer Water Infiltration System

Our range of Hydrorock Aquifer Blocks are configured for each specific site allowing for far faster infiltration of rainwater. Our HD range of Hydrorock Aquifer Blocks gives a new, cost effective infiltration system that has many advantages over current solutions.

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