2 Storey Basement Construction

Beasly Street Hotel

Introduction• We have recently completed the construction of a 125 bedroom

hotel in Beasly St, Cork and successfully carried out the 2 storey basement phase of these works.

•  The basement construction posed a number of engineering and logistical challenges .

The Challenges• The city centre site is located some 50m from the river Lee and

subject to a high tidal water table.• The site is bounded by several listed buildings . The buildings are

founded on poor ground and sensitive to vibration.• The site is confined and access is restricted

The Requirements• The site needed to be dewatered for the duration of the basement

construction• Excessive water table drawdown needed to be avoided underneath

neighbouring properties• Ground movement and vibration needed to be kept below set limits.

The Method • Installation of perimeter secant pile wall to rock level (approx 25 m

deep)• Design and installation of a perimeter dewatering system

discharging to the river. A recharge system to maintain the water table tables underneath the adjoining buildings.

• 7 day working during the critical excavation phase• Temporary propping to minimise deflection of piles during

excavation

The Result• The excavation phase was completed in a 3 week period.• The reinforced concrete works including basement, mezzanine and

ground floors were completed in 12 weeks• Monitoring of vibrations ,water levels inside and outside the site,

deflection of piles and possible movement of adjoining buildings were all carried out during the construction

• All measurements were maintained within set limits