Kilkenny Motorway Scheme

Kilkenny Motorway Scheme

Kilkenny Motorway Scheme

Client: Kilkenny County Council

Project: N9 N10 Powerstown Co. Carlow to Knocktopher Co. Kilkenny road scheme phase 4, with the construction of over 40km of motorway and 60 major structures including 3 river crossings.

Contract Value: €217million

Handover date: September 2010

Habitat Protection and Preservation - This project involved work within designated Special Area of Conservation (SAC) sites protected by national and European law.  The 3 rivers crossed were the River Barrow, and River Nore (both SACs), and the Kings River (itself a tributary of the Nore).  These rivers support large stocks of salmonids, with brook lamprey, and have potential for river and sea lamprey, crayfish, freshwater pearl mussel, otter, and kingfisher.  The bridges were designed with consultation of the Southern Regional Fisheries Board (SRFB) and the National Parks and Wildlife Service (NPWS).  Mitigation measures included fencing off habitat areas, compensatory planting of specified species such as locally sourced acorns and shade resistant flora, providing flight lines and boxes for bats, reusing soil salvage to retain the native habitat and species. The main challenge of river bridge construction was stabilisation and maintenance of river banks during works.  Sheet piling was not an option due to the impact it would have on destabilisation of the river bank, so willow wattle protection was carried out.  The wattle system comprised of approximately 2 to 2.5m length full rounded natural timber posts which were set along the river bank and driven at approximately 300mm centres. The posts protruded approximately 300 above the ground. These posts where driven along the river bank and woven with willow stems. The stems where woven in pairs around the posts alternating between the bank and river side of the posts. On completion of the wattle the space between the wattle and the existing bank was loosely backfilled with salvaged soil.  Willow wattle acted to stabilise the river bank, introduce connectivity along the river bank, and introduced a habitat for wildlife during and after construction.