Manchester, Chepstow Street Case Study

In 2012 Red Rose Forest (RRF) a partnership between six local authorities in the North West was looking for a tree planting solution that also considered surface water management. The project required the planting of 3 trees in a 16m permeable trench.

RRF with the support of the project funders INTERREG IVB and Viridor wanted to pioneer a tree planting specification in Greater Manchester that would demonstrate the value of the Geo-Cellular Raft System and permeable paving as a means for ensuring a good rate of oxygen, moisture, nutrient exchange from the surface to the tree roots below. The project also demonstrated the value of permeable paving in a city centre environment, prone to flash flooding, as a means for reducing surface water run-off.

Representatives from RRF and Manchester City Council worked together on this project to ensure that all aspects of water management and the tree’s healthy root development were considered from the beginning. Geo-Cellular Raft System CAD drawings were prepped for the 16m trench with the help of RRF. Each drawing was considerate of the hard landscaped environment and the proximity of the trees to the road.

Peter Stringer, Special Projects Manager for Red Rose Forest added:

‘Geo-Cellular Raft System’s load-bearing properties prevents compaction, the interaction between the nutrient rich soil mixture in the Geo-Cellular Raft System and the percolation of rain through the permeable block pavers provides a slow release feed system to the roots below. When the nutrients are washed through over a long period of time it will leave voids which when encountered by any tree root growth upwards will air prune their growth to arrest any further upward growth and subsequent damage to the paving above. This system will demonstrate the sustainability & long term cost savings of this approach in terms of tree welfare and eradicating root damage to pavements. ‘

Richard Wexham, gtspecifier’s Technical Specification Manager commented:

‘The project at Chepstow Street demonstrated the flexibility of the Geo-Cellular Raft System. Whilst on site we were able to make changes to the tree pits without returning to the drawing board or affecting the overall pit volume. The Geo-Cellular Raft System is designed to offer all the benefits of a healthy tree pit and an installation with minimal fuss or upheaval.’

After the tender was awarded, representatives from gtspecifier’s product specification team visited the site at Chepstow Street Manchester to assist the contractor (UPM Tilhill) with the installation of Geo-Cellular Raft System. Certain obstacles were overcome during the two-day installation, including proximity to sewers and disused caverns located underneath the tree pit. Due to the flexibility of the Geo-Cellular Raft System, the team was able to overcome all the issues whilst on site and the project continued without delay.

System Benefits