Kildare By-Pass Decision
6th January, 2000
Kildare By-Pass Decision
The National Roads Authority and Kildare County Council are pleased to announce that clearance has been given by the Minister for the Environment and Local Government, Mr. Noel Dempsey, T. D., to complete the tendering process and to proceed with the Kildare Town By-Pass.
This project is of particular national significance. Traffic congestion and delays in Kildare Town have made the construction of a motorway by-pass an urgent necessity. The County Council, The National Roads Authority and a number of eminent and independent experts have contributed to the development of this important link in the national road system, and particular attention has been given to the protection of Pollardstown Fen.
The fen is a unique nature reserve, located some 4.5 kilometres from the in-cut section of the proposed new motorway. It is supplied with calcium rich waters from the Kildare Aquifer and is drained by the Milltown Feeder which flows into the Grand Canal. The fen is especially notable for the presence of a rare species of snail (the whorl snail) and a special type of spring (tufa springs).
Conditions imposed by the Minister for the Environment, when approving the motorway proposal in January 1996, included provision for a monitoring programme. This programme was intended to further evaluate groundwater conditions and dependent flora and fauna with a view to implementing any mitigation measures shown to be necessary. The evaluation carried out as part of the monitoring programme suggested that further mitigation measures were desirable in order to provide enhanced protection for the ecology of the area.
Due to the National Roads Authority’s and the County Council’s on-going appreciation of the environmental dimension of this project and the fact that hydrogeology was such an important factor in maintaining the fen's ecosystem an optimised engineering approach was developed, i.e. tanking. Though new in the context of Irish road construction, tanking has a proven track record in the Netherlands where it has been used in road and bridge building as a controlling mechanism for groundwater drainage. This decision of the Council and its senior technical advisers was made taking cognisance of the wealth of expert knowledge and experience provided by:
- Professor K. R. Rushton, Groundwater Specialist, Emeritus Professor of the University of Birmingham and Visiting Professor, Silsoe College, Cranfield University;
- Doctor Geert van Wirdum, Eco-hydrologist, Netherlands Institute of Applied Geoscience;
- Doctor Eric R. Farrell, Geotechnical Engineer, Lecturer at Trinity College, Dublin;
- Entec (UK Limited), who carried out groundwater modelling and prediction simulations;
- GeoDelft, Dutch Geotechnical Institute, Specialist Adviser on Tanking Construction Methodology.
The tanking alternative will involve placing an impermeable liner or membrane along a 3.5 kilometre section of the road in the cutting south of Kildare Town. As a further precautionary measure, the lining will be supplemented by a layer of impermeable boulder-clay, which will guarantee the long-term effectiveness of this approach. The tanking method will avoid the need for significant on-going de-watering of the aquifer in the vicinity of the road and will as a result minimise changes in groundwater levels at Pollardstown fen ensuring the protection of its natural habitat. The approach is entirely consistent with the Minister’s conditions relating to implementation of any remedial measures found to be necessary. It will also ensure that the motorway is constructed on the basis of the horizontal and vertical alignments approved by the Minister in 1996.
The expert evaluation made available to the County Council predicts that a maximum decrease of 4 cm. (1.5 inches) will occur in the groundwater level at the fen once the road is in place. This will have no significant impact on the fen’s ecosystem. The tanking approach has been extensively and rigorously evaluated from engineering, ecological and hydrogeological perspectives. These assessments confirm the engineering and environmental viability of the revised proposal and, on this basis, the Minister for the Environment and Local Government has determined that the project will not adversely affect the integrity of the fen site. This clears the way for Kildare County Council to proceed with the tendering process for the by-pass. The Council will, in line with the stipulation of the Minister, continue and enhance its monitoring programme in relation to groundwater, flora and fauna.
Traffic conditions through Kildare Town are continuing to deteriorate, giving rise to increased delays, notably at weekends, and the County Council is anxious to advance the motorway project as quickly as possible. The new by-pass will be of major benefit to road users, will greatly ease the serious congestion experienced in the area, and will also improve living and safety conditions for local residents. It will also form a vital link in the nation’s transportation network.
The main construction contract for the new motorway is expected to start this summer with completion in 2002 at an estimated cost of £70million. This includes in excess of £5million additional costs due to the tanking method of construction.