Mackley is part way through an 11-week project to improve protection for an Environment Agency asset on the River Thames at Coldharbour on the Isle of Dogs.
The Coldharbour Flood Wall Remediation and Foreshore Protection Works are being carried out under a 10-year Environment Agency framework called TEAM2100. This involves looking after the Environment Agency’s assets on the tidal section of the Thames, from Teddington in Middlesex out to the Kent and Essex coasts. Mackley are the principal subcontractor working for Balfour Beatty on this project.
Due to constrained access from the landside the works are being carried out from the river, with materials delivered to the opposite, south bank and a short distance upstream where access is easier. Materials are then transported by a barge to the foreshore as required.
Due to the tidal nature of the site, and with a tidal working window of just two hours, works have to be strictly timetabled to ensure progress is on-going.
The barge is anchored at the works site each day, and supported by a safety boat which is present at all times when work is taking place. When equipment needs to be very close at hand, the barge can be positioned within six inches of the front of the works area.
The existing sand bags at the base of the wall have been removed, along with the horizontal timbers and any others that required replacement, and the timber piles on the foreshore were cut off for recycling.
27 new three metre piles were placed at low tide at a rate of 10 per hour. A small vibration piling hammer was used to reduce noise and disturbance to people living in adjacent properties. With the piles in place, concrete infill was pumped into the space behind the piles, filling the void. The concrete was pumped through the adjacent properties’ gardens and over the wall in a single day.
The foreshore protection works involved the placement of Kyowa rock filter bags at the foot of the river wall. The Kyowa system is designed to give protection from scour damage to riverbanks, shorelines, bridges and other structures, while at the same time benefitting the surrounding environment. The system comprises mesh net and rocks, and creates the ideal environment for small fish and plants to live in the interspace within it.
The new timber fenders were then installed, with reclaimed beach groynes used as the material for these.
Brickwork remedial works have involved pointing and replacing some bricks. To maintain the aesthetic appeal of the river wall, the team sourced imperial measure bricks of a similar type to the original, from a local reclamation yard. Further works to the downstream adjacent wall are currently taking place.
When the project is complete the site will be cleared and any remaining waste removed for recycling