Executive Summary:
An embankment by the Lancaster canal in Garstang had become greatly overgrown after years of neglect. Heavy bramble and other vegetation made it impossible for surveyors to get close enough to make accurate assessments of the embankments structural integrity, test the water’s oxygen level or carry out ecology reports etc.
We were tasked with clearing all of the embankment and creating multiple paths through thick vegetation and fallen trees from the edge of a neighbouring estate to the water’s edge, allowing the appropriate parties to inspect the relevant areas when required (Fig 1).
Upon arriving on site to scope out the work we
discovered a great deal of himalayan balsam (Fig 2)
across the embankment and throughout the desired locations for the paths. This meant we would be required to think and act carefully so as not to disturb the invasive species in a way that could cause it to spread further afield.
Himalayan Balsam:
Originating from the Indian subcontinent, Himalayan Balsam (Impatiens glandulifera) was introduced into the UK in the early 19th century as a garden plant, with wild recordings first made in 1855. Preferring moist and semi-shaded damp places, you are most likely to find this particular non-native invasive species on River banks and damp woodlands. The area we were carrying out our work falls under both of these umbrellas, and so it was no surprise to find such dense amounts on site.
The effects of the non-native plants across the country are significant, with native plants unable to compete for space and nutrients.With other vegetation suffering as a result, it leaves effected river banks vulnerable to erosion, meaning the embankment where we were working would be all the more in need of surveying from a safety and risk point of view, but the build up of vegetation itself making this impossible.
With the usual equipment of choice for a job of this nature being hedgecutters, strimmers and chainsaws, it was imperative that we find a way to clear pathways without making contact with the Himalayan Balsams the spread itself is caused by its seed pods exploding upon touch and attaching spores to a host such as operatives or equipment in order to spread elsewhere. We also had to ensure that a system was put in place to adhere to the Department for Environment, Food and Rural Affairs (DEFRA) approved Check, Clean and Dry campaign.
Work Methodology:
The operatives arrived on site and surveyed the area to locate and log the densest affected areas so that they could be avoided entirely. Six paths were then marked out based on the smallest amount of contact that would be made with the invasive plant from beginning to end of each section of devegetation.
We established that the best practice for handling the himalayan balsam would be to remove it by carefully pulling it up from the base, and gently placing it on existing patches. So before any strimming began, the mapped out paths were walked along and the plants removed by hand, gently laid to the side on top of undisturbed but affected areas.
The team were also provided with a biosecurity kit to take with them to site, this included:
- Industrial disinfectant wipes
- A spray bottle
- Scrubbing bushes
- Rubber protective gloves
This would allow the operatives to scrub down all equipment and Personal Protective Equipment (PPE) before leaving site, before returning to the yard where we have a purpose built warm area to dry everything out after use.
It was decided that we would use the fence bordering the adjacent estate as a baseline starting point for around 300 metres before being stopped by a particularly heavy section of Himalayan Balsam. Then we began removing the overgrown bramble and saplings from the embankment’s edge so that it was also clear in the areas that could be without disturbing areas heavily impacted by the invasive plant.
Now we had a clear indication of where the paths could begin and end, we mapped out the six paths as per the plan, We also kept in mind making sure each path was a metre and a half wide so that it was plenty of space for people to walk down without disturbing the nearby plants, and that they were each around 10 metres apart so that each path could be easily seen from that neighbouring one.
After each path had had the balsam removed, a second operative would walk ahead of the strimmer to ensure the area was free of the invasive plant prior to contact with the equipment (Fig 3).
For work in which fallen trees had to be tackled to make the paths clear (Fig 4) chainsaws were used to perform a slowed fell so that minimum impact was made and other operatives on the ground were able to steer the limbs away from the himalayan balsam. They were then cut up and neatly stacked into a habitat pile (Fig 5).
We knew that further treatment of the paths was necessary as the area was the perfect habitat for vegetative growth. During the planning stage it was discussed whether we use chip from the fallen limbs to cover the path to slow down the growth. We decided that as the paths were within sight of an estate, a wood-chipped path may appear inviting to the public. With the area not being a public footpath, the uneven nature of the terrain, and the large amounts of non-native invasive species present, it was decided a public invitation to use the paths was not a wise decision.
We instead opted to spray glyphosate over the paths created to increase the length of time that the vegetation would re-grow up to a further 200+ days. We ensured that no spray was laid down within 20 metres of the embankment edge.
All of our Operatives have completed up to and including Module 3 in the NNSS Biosecurity E-learning, each holding a certificate of competency. This gives them sound knowledge of the subject, as well as an understanding of its importance. After completing the spray, the operatives used the Biosecurity Kit to scrub down on site to treat all the equipment and themselves, ensuring they checked thoroughly for any foreign agents that could be carried offsite, scrubbed themselves and the equipment from top to bottom, and sealed all PPE in a bag, ready to bring back to the yard and place in our dedicated drying room.
Job Completion:
Engineers have since been able to visit the site to inspect the structural integrity of the river’s edge. It was critical that these checks were carried out due to the neighbouring estate, and our effective clearance of vegetation allowed this to happen in a safe and controlled manner. The client was satisfied with the results and operationally, we were also very pleased with how the work was planned, carried out and the site left with minimal impact on the existing Himalayan Balsam.
