Case Studies
Edgeworthstown Library, Longford
TEAM
Civil and Structural Engineering
Sector
Services Provided
Structural Engineering
Overview of service
Longford County Council (LCC) is the authority responsible for local government in County Longford. It operates at the centre of the local community. The ORS Civil and Structural Team works in partnership with LCC on several projects.
One significant project was constructing a three-storey library building, including a rear car park, an off-street plaza to the front, and all associated works. The site was brownfield and located off the main street in Edgeworthstown, County Longford.
The site was vacant for a sustained period before the development and required the design of significant level changes, retaining walls, stairs, and ramps. The lower ground floor level of the building was constructed below the main street level, with ground conditions being limestone bedrock at shallow depths.
The building structure was constructed of a mix of reinforced concrete, glulam and infill masonry blockwork. Vehicular access was provided from the rear, and a large car park was built to serve both the library and the main street shops. Ramp and stair access were provided to the main street level from the car park.
In the final constructed building, the main internal feature was an outstanding large atrium allowing views from the ground floor to the roof level. The exposed interior structure of the building at the first floor and roof levels are of glulam construction.
Project challenges
Working with a complex brownfield site
Level differences across the site and rock encountered at shallow levels presented challenges in the civil and structural design of the development. Prior to development, the site had been partially excavated for a previous retail unit development that never materialised. The ORS team designed reinforced concrete walls to facilitate the excavation of the lower ground floor level of the building. This was also important to protect adjoining properties with floor levels relative to the main street. The building was constructed on a raft foundation to minimise dig depths and ensure suitable structure onto the shallow rock.
Japanese Knotweed was identified on the site prior to the commencement of development. ORS, the design team and the client engaged with specialist consultants and contractors to develop a suitable treatment for this invasive species to suit both the development and the budget. The final solution entailed the removal of the Knotweed from the vast majority of the site and creating a sealed berm on a suitable strip of the site for further treatment over a 3 to 4-year period to eradicate the problem. The carefully coordinated solution allowed the development to proceed unhindered while ensuring the Knotweed was eliminated appropriately.
The ground floor structure required a significant transfer of structural loading whereby internal columns within the atrium do not carry down to the lower ground floor. The ORS team designed this transfer structure, constructed in a series of wide and shallow RC beams to ensure a relatively shallow structural zone could be achieved to maximise floor-to-ceiling heights.
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