CIGPE history of engineering in Guernsey
It is intended that this part of the web page will expand to include reports on a number of local projects. To get things started, here are a couple of reports kindly provided by Alan Hill. Alan is the principal engineer of the Harbours and Airports section of Guernsey's Department of Engineering and was closely involved with both the Queen Elizabeth II Marina and the Longue Hougue Reclamation Site.
If you would like to contribute a write-up for this page please contact one of the branch secretaries.
Longue Hougue Reclamation Site
Interest in reclaiming all or part of Bellegreve Bay was revived by the Island Development Committee’s Outline Development Plan, published in 1967, which suggested that even if the whole project was far too costly the area lying between White Rock and Salerie Point would be a "most valuable site".
At that time there was no thought of a marina. The scheme for reclaiming 30 acres at North Beach at an estimated cost of £2.4 million was seen as helping the Island’s waste disposal, water storage and traffic problems and providing land for developments such as hotels, flats, industrial sites and even possible for a leisure centre.
No progress was made on the proposals until 1980 when the scheme was back before the States of Deliberation but this time in quite a different form as a means of enabling St Peter Port Harbour to grow. With the creation of the ever popular Victoria and Albert Marinas the scope for development within the harbour had been virtually exhausted and the Board of Administration investigated ways to enlarge the facility.
It was decided that it was more advantageous to extend to the north. Bellegreve Bay and the offshore islands provided good shelter, construction from the foreshore would be comparatively easy, the site was on the right side of the harbour for a container and Ro-Ro marshalling area and with 60% of the Island’s population living north of the Weighbridge the reclamation would provide valuable car parking in the best place. In addition a marina to accommodate over 950 vessels would be provided.
The development was authorised by the States of Deliberation in November 1983 and work commenced early in 1984 and was substantially completed five years later at a cost in excess of £17 million. The main elements of the contract were:-
- Construction of rubble mound breakwater to protect the area. Almost 260,000 tonnes of locally quarried stone was used.
- Excavation of "North Beach" for marina development. Almost 40,000 cubic metres of material was excavated and used as fill material including 15,000 cubic metres of rock which required drilling and blasting.
- Dredging of St Peter Port Harbour to provide fill material for the reclamation areas. Over 220,000 cubic metres of material were removed and an additional 40,000 cubic metres imported from offshore.
- Provision of navigation gates.
- Provision of pontoons complete with water and electricity services.
- Surfacing and drainage to reclaimed areas.
The development which was the largest civil engineering contract undertaken by the States of Guernsey this century was officially opened by Her Majesty Queen Elizabeth II on 23 May 1989.
Alan Hill, Department of Engineering, Guernsey, January 1999.
LONGUE HOUGUE RECLAMATION SITE
The Longue Hougue Reclamation Site at St Sampson, Guernsey serves a dual purpose for the Island. It provides a site for the long term disposal of the Island’s inert waste and also provides the first phase for a major deep water extension to St Sampson’s Harbour.
The site covers an area of over twelve hectares and is enclosed by a rubble mound breakwater one kilometre in length. The total tonnage of stone, ranging in size from five kilogrammes to four tonnes, in the breakwater is in excess of 555,000 tonnes.
Ronez Ltd, who now operate the only working quarry on the Island, was unable to provide this tonnage and stated that the maximum tonnage available from local resources would be 150,000 tonnes. It was obvious therefore that the balance would need to be imported from elsewhere.
The successful contractor for the work Fairclough Civil Engineering Ltd (now part of the Amec group of companies) had hoped that a coastal quarry at Cachaliere in Alderney could be reopened to provide the additional material requested however this proposal was strongly opposed by the people of Alderney and the contractor had to look elsewhere. Sites in Cornwall, Eire and France were considered but finally the French quarries were used.
Three quarries in the Cherbourg area provided the stone. The quarries were at L’Ouest, Brix and Montebourg and these supplied over 400,000 tonnes of material. Stone was stockpiled at a disused quay in the port of Cherbourg and shipped to Guernsey using two flat bottomed barges each carrying approximately 4,200 tonnes. Although production of stone at the quarries commenced in October 1990 shipments did not commence until late January 1991. The 130,000 tonnes of material stockpiled on the quay thereby avoided any delays other than weather restrictions, to shipments. As weather conditions improved late April - to end of July a barge load of material was received almost on a daily basis.
At a time when construction was falling behind programme a self-discharge side stone dumping vessel was used together with the barges. The vessel which was highly manoeuvrable had a carrying capacity of 2,000 tonnes of stone.
The Contractor had taken possession of the site in September 1990 and the contract was substantially completed in October 1991. The total cost of the contract including variations in price, pilotage fees and harbour dues was £9.9 million. The main elements of the works included:-
- Core Stone Imported 361,000 tonnes
- Local 116,000 tonnes
- Armour Stone Imported 45,000 tonnes
- Local 34,000 tonnes
- Deliveries of imported stone totalled 103 No.
Alan Hill, Department of Engineering,Guernsey, January 1999.