• 20 March 2018

Clifden Community School

Along the world famous Wild Atlantic Way’s scenic coastal route, located at the foot of the Twelve Pins Mountains and in the heart of the beautiful Connemara region, travellers driving north will now be greeted by the ambitious €8m redevelopment of Clifden Community School, originally built in 1979.

The new school was completed in October 2017, as part of a €100 million investment initiative to upgrade older school premises to meet modern day standards. It has greatly improved educational facilities for this western seaboard community.

Located in one of the most picturesque towns in Ireland, the Community School sits close to the winding roadway, making a bold statement with its white mica-speckled render, against the imposing surrounding landscape.

The existing school has been fully operational throughout the entire construction of the new premises, which will cater for 500 students. Our team in Dublin provided civil and structural engineering services for the new school building.

A combination of two and three storeys offering more than 3,900m² of teaching and ancillary space it has also been designed to include a new school entrance, internal access roads, parking spaces, landscaping, drainage works, sports facilities and an on-site waste water treatment plant. The moment the new school was completed, the project moved onto demolition of the existing school buildings at the rear of the site.

Dip in the rock horizon

The southern, western and northern edges of the site comprise rock faces, up to 9m in height, carved out of the hill to accommodate the new school. The rock is a competent schist which is extremely resistant to break out. It also transpired that the mass of rock belies the most difficult issue encountered in the construction of the entire school – when the rock was needed, it was nowhere to be found!

While most of the new school building is supported on strip foundations formed on cleaned and levelled rock faces, under the centre of the new building footprint there was a localised sharp dip in the bedrock. The new building could not be founded on the alluvial clay overburden, as the foundation loads would certainly cause long term consolidation of the deep saturated clays. It was critical to reach the bedrock, and we had to be sure that it was indeed bedrock that the building was being founded on.

We achieved this by designing for piled support for the new building, utilising thick-walled steel tubular piles driven to bedrock. This solution enabled the use of high impact driving forces to break through rock fragments in the clay matrix and ensure bearing on competent rock. The piles installed ranged in length from 1.2m to 28m.

Protecting the deep-water salt lagoon

As the school site is located within the Connemara Bog Complex Special Area of Conservation our team prepared an Environmental Impact Statement, incorporating careful mitigation measures to avoid any detrimental impacts on the surrounding environment.

One of our biggest challenges was to minimise the impact of foul and surface water discharges on a sensitive deepwater salt lagoon in front of the school. The lagoon has an extremely diverse specialist lagoonal flora and fauna. We designed and constructed a pumping station and a tertiary treatment plant, including UV sterilisation, to ensure that the Salt Lake salinity and the ecosystems would be entirely protected from foul or surface water discharges.

Offsite construction reduced the overall programme

As the existing school was in full operation throughout the construction, offsite construction was adopted to minimise the overall programme. Precast concrete was used throughout, with walls, floors and lift shafts all cast under factory conditions, transported to site and erected in place. Waterman’s team had overall responsibility for the preparation of coordinated drawings for the precast manufacture. We designed fully detailed and coordinated drawings at an early stage in the process to ensure the factory had everything required to manufacture the individual precast units.

Richard Osborne, Director of Waterman Moylan, commented: “We are pleased to have been responsible for provision of civil and structural engineering services on this technically and logistically challenging project, and we are delighted with how well the final build has turned out.”

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