- 7th December 2018
- Posted by: Joanne Woodhouse
- Category: Projects
Topsham Lock separates the historic Exeter Canal from the Exe Estuary. It has become structurally unstable and is currently leaking water from the canal into the estuary.
Existing sheet piling installed in the 1970s to secure the lock is at risk of complete collapse. The lock is located within the Exe Estuary special protection area (SPA), Ramsar and sites of special scientific interest (SSSI) designated site, which is protected under European Law for the assemblage of wading birds it supports.
We were approached by Exeter City Council to provide ecological support for repairs and sheet piling works to Topsham Lock in order to stabilise it.
Our ecologists conducted a Preliminary Ecological Appraisal to identify potential ecological constraints on the site. An assessment of the stone walls of the lock for bat roost potential was conducted from a boat using an endoscope by a licensed bat ecologist.
The team of ecologists then worked with Exeter City Council and the piling engineers to deliver a suitable engineering solution without compromising the integrity of the protected Exe Estuary site. Our ecologists also coordinated a Habitat Regulations Assessment (screening and appropriate assessment) and SSSI consent. This demonstrated to Natural England that the works would not damage the interest features of the Exe Estuary, which was required to gain legal permission to work on the Lock.
As part of the mitigation for the works, the team provided an ecological clerk of works three times a week for the duration of the work on site. They observed bird behavior, species and numbers in the adjacent estuary and worked to see that no disturbance to the protected bird populations occurred as a result of the repair work.
The piling works were completed successfully, and Topsham Lock is now projected to be secure for another 40 years. As a result of the ecological support we provided, there were no significant negative impacts on the Exe Estuary protected site.
Many of the wading birds that use the estuary spend the summer abroad and only migrate to the UK for winter. By working collaboratively with the engineers and Exeter City Council, our ecology team were able to ensure the works were completed by the end of October, before most of the birds had even arrived, thereby minimising any potential effects.