The flood defence was breached when high tides combined with a tidal surge on 5 December 2013 to produce the highest water levels ever recorded in the Haven, flooding the landfill site and commercial properties on Riverside Industrial Estate.
Water was 6.08 above ordnance datum. Higher than the floods in 1953 and 1978.
The Environment Agency did an initial repair to the damaged defence in December 2013 using sheet piles and 2,000 tonnes of stone to plug a 45 metre gap to reduce the risk of further flooding.
Permanent repairs will now be carried out to the flood bank. The Environment Agency also plans to increase the width of the bank to 4 metres and the height to 7.3 metres above ordnance datum (the universal benchmark against which tides in Great Britain are measured).
Work to the flood defence is being carried out in agreement with the landowner FCC Environment.
Mark Robinson, Senior Coastal Advisor for the Environment Agency said:
This project is good news for Boston and we remain committed to working in partnership to reduce the risk of tidal flooding in the town and the surrounding communities.
Work is expected to take 8 weeks to complete. The sheet piles will remain in place in front of the defence to reduce the risk of flooding.