CASE STUDY: ROCK ARMOUR

Location: Isles of Scilly

August – October 2008

Scope of works:

Supply, deliver and place 1200 tonnes granite armour stone of size range 4-9 tonnes per stone for protection of new quay constructed by Nuttall John Martin Construction Ltd. Location: Porth Conger, St Agnes, Isles of Scilly; Granite foreshore accessible by sea only.

KML directors personally sourced appropriate granite from the historic De Lank quarry on Bodmin Moor in Cornwall, in Victorian times the supplier of dimension stone to James Douglass’s nearby Bishop Rock lighthouse. Following requests from KML, IMERYS minerals kindly reopened the Port of Par, near St Austell, and the stone was road-hauled to Par and shipped onward to Scilly by KML’s 600t flat-top barge and tug.

At site, bagged local granitic clay sourced from a quarry operated by a KML group company was installed by divers and workboats. The landing craft docked down on the temporary beach to unload a 45 tonne Komatsu excavator, which made its way across the intertidal rocks.

The flat top barge was berthed onto a four point mooring at high water and the rocks discharged with KML’s 33 tonne long reached excavator aboard the barge. At low water the Komatsu machine was used to install the armourstone to client engineering specification. Three barge loads were made and on final completion the shore machine was again removed by landing craft and temporary beach.

On time and on budget, the project was a great success, meeting with full client approval, and its local sourcing and engineering challenges generated considerable media interest.