PROJECT OUTLINE

Construction of approximately 2.3km of paved greenway between Cruagh Wood estate and the Ballyogan Road in Stepaside, Co. Dublin. The 4m wide greenway provides a safe and comfortable pedestrian/cycle link to public transport on Ballyogan Road and services adjacent.

The site is located on Park Development lands, bordered by an ESB substation, residential properties, a former landfill site and a golf course. Hedgerows and trees form its southern and northern boundaries in the vicinity of the Ballyogan Stream in the eastern part of the site.

At commencement of the project, the vicinity of the stream was overgrown, and an extensive floodplain present. There were also several smaller watercourses running through the site and the potential for areas of soft ground.

“With widespread public support and goodwill, it’s very rewarding to work on the delivery of a sustainable greenway that connects communities and protects biodiversity,” said James Donnelly, Contracts Manager with Murphy Ireland.

KEY CHALLENGES

Underground 220Kv high voltage and 38Kv medium voltage cable were a significant risk factor on this project, located within the site area below the greenway.

Where excavations were within 2m, ESB supervision was required. Hand digging was the only method of excavation acceptable in the vicinity of the underground cables. A combination of tracing equipment and trial holes were used to locate all services in advance of the works.

To protect fishery habitats, instream works could not be carried out between September and April. With works due to start in early September, piling across the Ballyogan Stream for construction of the steel bridge was another key challenge. Murphy held regular site meetings with Dún-Laoghaire-Rathdown County Council, the project ecologist and Inland Fisheries Ireland to ensure an appropriate methodology was devised. The process commenced with a redesign of the piles by our subcontractors, Terradrive. A 50-tonne piling rig was then brought in to carry out the works and the 24 precast piles were installed ahead of schedule.

The 80m boardwalk structure (prefabricated in-house by the Murphy steel fabrication facility at Newbridge, Co. Kildare) spans the Ballyogan Stream and associated floodplain.

Water Pollution Prevention Controls were integral to ensuring our Never Harm policy, due to the sensitive nature of the location. Sedimentary water from pumping operations were carefully controlled. All land drains were identified and marked so they could be blocked off in the event of an environmental incident or emergency situation. Materials with potential to generate run-off were not stored within 50m of any water course. Murphy Environmental Adviser monitored the watercourse for any siltation or other pollutants for the duration of these works.

Archaeology was known to be present on the adjacent Park Development lands and significant excavations had taken place. The possibility of finding related archaeological material on the greenway site was high and as such, all groundworks were monitored by a suitably qualified archaeologist.

PROJECT DELIVERY AND INNOVATIONS

Earthworks included excavating the greenway to formation level and battering back the work area. Excavations up to 2m were required with the use of sheet piles in the vicinity of the Ballyogan stream. Works required removal of existing trees, fencing and trimming back overgrown vegetation.

Public lighting, ducting and columns were installed for the extent of the scheme. Cannon bollards and catch pits were installed, and gullies relocated. All manhole lids were raised or lowered to keep in profile with the greenway surface. Bespoke pedestrian parapets were designed, certified, fabricated, supplied and installed. Signage, planting and grass seeding followed by a maintenance period provided finishes to the greenway verges.

There was a strong focus on ecology and sustainability in the undertaking of works on this project. Murphy were in regular communications with the project ecologist and committed to ensuring no negative impact on the environment.

WORKS INCLUDED
  • Site clearance
  • Provision of a new paved shared surface and associated green verge which is to be constructed over the existing alignment of an underground 220Kv ESB cables and crosses a 110kv ESB cable
  • Provision of an elevated boardwalk
  • Provision of public lighting and associated services
  • Provision of temporary and permanent timber post and rail fencing
  • Alterations to existing services and utilities
  • Earthworks including excavation, disposal and importation
  • Trimming of existing hedgerows and removal of trees
  • Provision of road markings and signage
  • Provision of new greenway entrance detail at Cruagh Wood Estate entrance location
  • The establishment of all necessary traffic management to complete the works safely

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