Scarborough’s troubled Accropode sea defences have suffered a new setback after sustaining abnormally high damage.
NCE this week discovered a significant number of badly damaged precast concrete Accropodes in the armoured revetment protecting 1.5km of Scarborough’s coastline.
Only completed in 2005, the troubled Castle Headland coastal defence project is showing a greater than normal level of damage for a scheme of this nature, according to one breakwater expert. “Along the seawall, a larger number of Accropodes than might be expected show direct evidence of collision damage [from tidal action],” he said. “Quite a few, again more than should be expected, also show clear signs of rough handling suggesting that the units might perhaps have been dragged across a hard rough surface during early handling.”
A spokesman for contractor Edmund Nuttall denied this saying: “The Accropodes were manufactured relatively close to Scarborough, and then they were stored on the beach, so there was minimal handling.” Scarborough Borough Council has denied any significant degradation at the town’s seafront saying that it had not picked up on anything that might be a concern.
But, when NCE visited the defences along the 100 year-old Marine Drive coastal road, there was clear evidence of damage to the revetment, with at least 20 armour units displaying considerable damage. Pictures taken by NCE show armour units at the top of the revetment exhibiting some of the worst examples of damage with some units broken or cracked. These elements are on a section of the sea defence which is least affected by coastal tides.
Construction of Scarborough’s coastal protection scheme began in 2002 with a budget of £28.6M, although the council later agreed increased costs with Nuttall of £46.5M, the extra £18M due to unforeseen ground conditions on the seabed (NCE 16 February 2006). Designer was consultant High Point Rendell. Even after these extra costs were agreed, the council and Nuttall remained locked in battle over the cost of repairing more than 50 of the mass concrete Accropodes. This dispute had been running since broken structures were discovered in the summer of 2004 (NCE 9 September 2004).
A council report in 2006 revealed that a budget of £100,000 had been set aside carry out laser scan surveys of the coastline to examine and track the damage. The scan was undertaken in 2007, along with aerial surveys and surveys by boat. Scarborough Borough Council’s head of engineering and harbour services John Riby said the surveys showed that the sea defence was fit for purpose.
However, Scarborough Council group engineer Neil Corrie admitted the whole of the revetment was still being monitored. “There’s nothing that’s been picked up that’s a concern, there’s not been a significant problem,” said Corrie. Commenting on the Accropodes, he said: “Of the number that were damaged during construction, the majority were replaced. “One or two were not because it wasn’t impinging on the integrity of the revetment itself.” Those that were not replaced are understood to have been strong enough to perform their function.
Riby added that he thought any damage was likely to have occurred when [the Accropodes] were in situ in the revetment rather than during construction. High Point Rendell was unavailable for comment.