A multi-occupancy development of offices in the mature landscaped grounds of a former mansion house. Housing over 2000 people, the 20-acre site is in a Conservation Area and a tree preservation order protects most of the trees.
In 2016, we advised a risk-based approach to the management of tree safety on the site using our Quantified Tree Risk Assessment method. First taking an overview of the trees and the land-use (people and property) upon which trees could fail, we considered the relationship between trees, infrastructure, site users, neighbours, and the public. Using our bespoke CWSurveys data collection software, the trees were then assessed and recorded in fourteen groups with ten trees individually plotted.
A schedule of inspection records was produced in a spreadsheet format and the groups and individual trees were plotted on a drawing. Using a colour-coded traffic light system to identify levels of risk, both on the drawing and in the schedule, enabled the client to identify risk distribution across the site at a glance. Our findings and options for future management of the trees were recorded in the schedule and the more significant findings were discussed in a short report that, without dictating to the client, guided their decision making and allocation of resources.
Significantly elevated risks considered to be unacceptable were mitigated. However, in line with current good practice (National Tree Safety Group, 2011) where elevated risks were identified , the benefits of retaining the hazard, e.g. the dead tree or damaged branch, were considered and balanced against the risk, and in many cases hazards were retained providing the risks were within tolerable limits.
Since our initial assessment and inspection of trees, the site has been reviewed annually. Our management advice covers not only the issue of risk from falling trees and branches, but also their relationship with infrastructure, with recreational space and neighbouring gardens. Our management advice considers the long-term continuity of tree cover on the sites and the multiple benefits the trees provide, not only to site users, but to the local community, ecology, and the wider environment.
Over time and at reasonable cost, we have built a robust approach to the management of trees and woodland that can be implemented within the wider context of the client’s risk management policy.
Cheshire Woodlands use of Quantified Tree Risk Assessment has proved invaluable. It has helped us to retain trees that were condemned by another advisor. They have used measurable data to provide us with a valid tree risk assessment.