Work is under way to remove massive boulders which have hindered a multimillion-pound flood scheme in the centre of Inverness.
Highland Council’s River Ness Flood Alleviation Scheme was disrupted in October when contractors installing sheet piling on Bank Street found large obstructions underground.
It later emerged that these were armour rocks, thought to have been placed there during a scheme to widen Bank Street in the 1970s.
Piling work was switched across the river to Huntly Street while engineers tried to come up with a solution.
Now the £8.5million work has recommenced in Bank Street following the festive break.
While contractors can excavate some large rocks, others cannot be removed and a different scheme has been drawn up. Sam MacNaughton, Highland Council’s head of transport and infrastructure, said that where the rocks could be removed, sand and gravel will be used to backfill the holes and sheet piling installed.
In areas where it is not possible to remove the boulders, a “gravity wall” will be created.
This method involves building a retaining wall underground to hold back the floodwater.
Mr MacNaughton said that the wall was being used in areas on Bank Street where trees are planted, so as not to disturb their roots.
Work will continue on the scheme until February, when there will be a break because of the Kessock Bridge resurfacing.
The second phase of the bridge roadworks is expected to cause major disruption to traffic.
It means that Bank Street will be reopened to traffic, removing the need for long detours.
The River Ness Flood Scheme is designed to protect around 800 homes and 200 businesses in the city centre.
The second phase, between Friars Bridge and the harbour, is expected to start later this year and will not be completed until 2015.