Client: Office of Public Works
DBFL provided civil, structural and transportation engineering services to The Office of Public Works (OPW) for the new Walter Scott House development on Military Road, Dublin. The significant new development replaces the An Garda Síochána premises on Harcourt Street and houses several units of An Garda Síochána including the Garda National Bureau of Criminal Investigation (GNBCI), Garda National Drugs and Organised Crime Bureau (GNDOCB) and the Garda National Cyber Crime Bureau (GNCCB). As well as the new building, the project included the assessment, protection, stabilisation, and refurbishment to the protected eighteenth-century Laundry Building, a remnant of the Royal Infirmary of the Royal Hospital Kilmainham.
Walter Scott House consists of a three superstructure blocks springing from a podium spanning over a 2-storey partially buried basement. The six and four storey blocks form the main office accomodation of 11000sqm. A separate single storey block houses large services. The basement is a 12000sqm carpark and utility area holding 220 carpark spaces, and utility rooms.
DBFL designed all building elements and siteworks including footpaths, drainage, and water supply. The main structure is a reinforced concete frame typically supported on shallow foundations at the base of the double basement. There are local areas of transfer at podium level to allow for vehicle circulation. The two storey basement was constructed by an excavation inside a secant pile wall, allowing for maximising useable space in the restricted city center site.
A large naturally ventillated atrium is provided in the middle of the building. Steel framed walkways and stairs span across the atrium, covered with a long span trussed roof, while precast concrete façade panels clad the structure above podium level.
DBFL assessed the flood risk to the site given the close proximity to the nearby Camac River. Options were reviewed to protect the building and limit disruption in case of a flood event and to maximise the developable area of the site. The solution adopted was to use a flood wall to protect the basement, which is below the level of a significant flood. The structural design of the flood wall incorporates it into the fully waterproof basement structure, and continues it through to the access ramps on either side of the building. Flexible waterproof joints have been detailed to allow for differential movement at the joints.
DBFL designed the temporary works to stabilise the protected Laundry building located directly adjacent the new pole wall. The Laundry Building was monitored through the piling, excavation and basement construction process. Once the permanent works basement was completed, DBFL designed the sympathetic permanent remediation works for the Laundry Building.
The construction period for the project presented various challenges. The original tight programme was challenged by Covid-19, Brexit, and the hyperinflation of construction materials. The collaborative working relationship between the design team and the contractor directly contributed to the successful delivery of this project on time and within budget, in adherence with the Public Works Contract Form #1 for Public Works Designed by the Employer.
The space between the six and four storey blocks houses a naturally ventilated atrium to help reduce building life-cycle energy use. The structural design facilitated this design, following the lack of commercially available plenums of a suitable size. DBFL provided for the use of Reinforced Concrete plenums and below the podium slab to draw in fresh air from the sides of the site, and openings in the atrium floor to discharge this to the atrium. The long span steel atrium roof structure was detailed as a system of deep trusses to both allow space for large active louvers to control the airflow, and provide for a materially efficient design.
The civil design incorporated a number of Sustainable Urban Drainage Systems (SuDS), including a green roof above the four-storey and single-storey blocks and a suspended attenuation tank above the B1 carparking area. Significant effort was put in to remove the need for pumping of the surface and foul water discharge system. Through careful coordinate of pipe routes under the podium, most of the water leaving the building is through a gravity system. Pumps have been used to facilitate discharge originating in the basement, which is already below the level of the roadway sewers. The DBFL civils team considered these elements at an early design stage and liaised with the design team to fully coordinate these items into the building design.
Project Director
