The four week project involved Seacore sinking six land holes of 102 mm diameter to depths of 15m, with rotary coring to 6m in rock using its new Italian Commachio rig with automated drill rod changing carousel.In addition Seacore brought its own modular in-house designed and built Skate 3 jack-up from a previous contract in the Dominican Republic, equipped with its own CR2 drill derrick and coring system to take samples from two crossings of the River Bann and from the seabed along the outfall route.

The Skate 3 jack-up's pontoons, components and associated equipment are designed around the container freight concept.

The pontoons, which can be quickly pinned together to suit the required deck area, also double as containers. They house the jack-up legs, power units and all other ancillary equipment, allowing costeffective international transport by road, rail or container ship.

The jack-up can be assembled and commissioned within a day of arriving on location.

Working the jack-up as a stable drilling platform, Seacore used Skate 3 to sink 13 marine holes to 16m below the seabed and up to 1,500m offshore in currents of up to 3 knots and in water depths ranging from 3 to 21m. There were also eight over-water cone penetration tests carried out into sands and clays. The CPT services were provided by Lankelma CPT Ltd, a specialist provider with whom Seacore have formed a jointly owned company, Lankelma Seacore Offshore Ltd.

For its rotary coring Seacore used the Geobore S triple barrel rotary coring system to extract and recover 102 mm diameter cores 1.5m long, which are pushed into a plastic sleeve within the core barrel to keep them intact and prevent drying out.

The combined land and marine site investigation at Portrush follows on from several other projects seacore has completed in Northern Ireland. These include the investigation and construction of marine outfalls off Cushendall, Cushendun, Glenarm and Kilkeel, and the installation of cased piles for a bridge widening project over the River Bann at Coleraine.

MJ Information No: 17840