For the last three years The Ecology Consultancy has worked closely with DP World London Gateway Port in their development of the UK’s newest deep-water port and one of Europe’s largest logistics parks.
The DP World London Gateway site, located on the north coast of the River Thames Estuary in Essex, includes road and railway linkages to London and the rest of the country, and will be able to handle the largest container ships in the world, using the latest technology available. This includes the creation of two new managed realignment mudflat sites, known by their working titles “Site A” (located directly west of the development) and “Site X” (located across the Estuary in Kent). This creation of compensatory mudflats is a requirement of a Mitigation, Compensation and Monitoring Agreement (MCMA).
New Seawall Creation
The construction of the first new area of mudflat at Site A was completed in July 2010, with a controlled breach of the seawall, following completion of ecological and archaeological works and the excavation of surface soils to ‘mudflat depth’, for the creation of a new seawall. Site A has now been fully developed into ‘Stanford Wharf Nature Reserve’, and includes new footpaths, bridleways and information boards.
The compensatory mudflats at Site X are undergoing construction at their location on the Cooling Marshes in Kent, opposite the DP World London Gateway site. By the end of 2015, following an extensive operation to lower ground levels and to construct a new sea wall, a 52 hectare area will be ready for inundation by sea water. Construction work will comprise the removal of a 900m section from the existing seawall, to allow the estuarine waters to flood in and out with the tide, to create the mudflat habitat.
To enable the creation of Site X, since 2012 The Ecology Consultancy has worked with the DP World London Gateway Environment Team to establish an ecological baseline and to carry out mitigation in advance of the construction works.
The habitats within Site X were dominated by grazing marsh and associated ditch systems, a significant resource for breeding and wintering birds, and an extensive population of water-voles. With work well underway at Site X, our ecologists are working closely with the client and their contractors on a rolling mitigation programme, particularly to minimise the risks and constraints to works from ground nesting birds. The approach to mitigation was based on a combination of an ecological constraints map, daily checks for nests and precautionary systems of work.
Compensation and Enhancement Measures
Working with local farmers, as well as DP World London Gateway teams, The Ecology Consultancy provided detailed design and implementation of additional compensation and enhancement measures. These included arable reversion to wet grassland, the creation of a 1.5ha wader scrape, and the construction and/or restoration of 3.5km of drainage ditches, for the benefit of aquatic plants, invertebrates and water voles.
The newly created ditches were dug using a unique digger attachment specially designed to create a deep central channel and high berms for emergent vegetation. Some ditches were left to colonise naturally. Others received transplanted local flora, including nationally scarce aquatic plants, such as brackish water crowfoot, as well as communities of sedges, rushes and reeds, from other ditches that were to be lost at Site X. In consultation with the Bumblebee Conservation Trust we also recommended a bespoke wildflower seed-mix to be sown on the extensive new sea wall for the benefit of rare bumble-bees and other species.
Our ecologists will continue to monitor the ecological health of the newly created habitats and their wildlife at both Site X and in the adjacent compensation land. It is anticipated the site will become a natural haven, complementing and extending the existing important wildlife areas of the north Kent coast and becoming a resource for both humans and wildlife alike.
Published 12th August 2015