Himalayan balsam remediation on Exeter Flood Defence Scheme

Following a competitive tendering process, we were awarded the Himalayan balsam remediation package by BMMJV (a joint venture between BAM Nuttall and Mott MacDonald), for works on the Exeter Flood Defence Scheme Phase II.

The £32m Exeter Flood Defence scheme for the Environment Agency will involve the construction of flood defences on both banks of the River Exe from Cowley Bridge to Countess Weir.

The defences will include walls, banks, demountable weirs, gates and glass panels with extensive landscaping and habitat creation also taking place.

As part of our works scope, we were contracted to carry out the following:

  • Mechanical clearance of 7 hectares of Himalayan balsam along the River Exe using a combination of brushcutters and an excavator-mounted flail. Care was taken to ensure that the Himalayan balsam was cut below the lowest growing node
  • Application for Environment Agency herbicide spraying permissions
  • Spraying 7 hectares of re-growth along the banks with herbicide
  • Providing advice and input into fortnightly environmental progress meetings

We used our bespoke interactive mapping service –TIM, so that the client and the project team could track progress and see the areas where Himalayan balsam was or had been present. This is important because it means that any future works involving interfaces with contaminated areas can be properly planned.

“Thomson Habitats have assisted us from the early pre-tender stages of this project. We asked them to carry out the initial Himalayan Balsam clearance works due to their prior knowledge of the site, and their extensive experience in carrying out invasive species works. From the outset, they have worked pragmatically and effectively, and have become part of the wider project team. The site team worked hard to ensure that the Himalayan Balsam clearance works were undertaken on time and in accordance with best practice. Their TIM software in particular, has proved to be of huge assistance – particularly in our monthly environmental progress update meetings. We look forward to continuing our working relationship with Thomson Habitats on site.”  Marcus Hargreaves, BAM Nuttall

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