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Hesselberg Hydro

River Blackwater – Southern Sections

OSA repair to damaged Essex block revetment

River Blackwater

3 sections of seawall along the southern side of the river Blackwater in Essex were identified as requiring maintenance.

Existing damaged revetment

River Blackwater

Hesselberg Hydro proposed solutions mainly comprising of LSA & OSA to replace the failed blocks, plus a section of grouted rock and some Elastocoast repairs for two remote patches. These alternatives to the specified design of using Canewdon Blocks were accepted and the works were delivered on time and in Budget with minimal disruption to the existing seawalls.

LSA filter layer

River Blackwater

Rather than replace the whole revetment, we only removed the failed blocks, generally in the zone between neap & spring high tide levels. The existing toe was left undisturbed where it was sound and there was minimal risk of undermining (prevented disturbing the important foreshore habitat), and the upper rows of blocks were left in place (prevented disturbing the established vegetation including rare species)

Completed OSA repair

River Blackwater

Repairs after 6 months

River Blackwater

Bradwell Wick existing damage

River Blackwater

Bradwell Wick LSA/OSA repair

River Blackwater

Maylandsea existing damage

River Blackwater

Maylandsea LSA/OSA repair