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, which involves looking after the agency’s assets on the tidal section of the Thames, from Teddington in Middlesex out to the Kent and Essex coasts.
Mackley’s contract is with Balfour Beatty who is working as part of CH2M, a delivery partner on the framework.
Mackley reports that 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 ongoing.
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, Mackley said.
According to the company, 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.
Mackley also added that 27 new three meter piles were placed at low tide at a rate of 10 per hour. A small vibration piling hammer was used to reduce noise. 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 benefiting 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 system has previously been deployed by Mackley on a scheme of works on the lower reaches of the River Mole in Surrey.
The new timber fenders were then installed, with reclaimed beach groynes used as the material for these.
When the project is complete the site will be cleared and any remaining waste removed for recycling.