Portlaoise, Republic of Ireland
Introduction:
As part of a UK and Ireland ground investigation framework, we delivered a phased investigation consisting of a desk study and exploratory investigation which satisfied geotechnical design requirements and discharged Local Authority conditions to achieve planning consent. The works were delivered within the projected programme, budget and to the satisfaction of our Client.
Details:
The site involved the demolition and replacement of an existing place of worship.
A desk based review indicated no obvious former contaminative uses, however it had been previously devleoped for residential purposes.
The site was indicated to be underlain by glacial soils followed by Carboniferous Limestone bedrock of the Allenwood Formation.
The main potential hazards included:
- Potential asbestos and other contamination from demolition of historic buildings and Made Ground.
- Volume change of fine grained glacial soils and weathered bedrock.
- Ground dissolution within the limestone bedrock.
Investigation points were spread across the site to obtain a general overview of the ground conditions present. Locations were positioned to maximise the information that could be obtained:
- Windowless sampling was undertaken at the proposed structure location to inform the foundation design.
- Shallow hand excavated trial pits were undertaken in the remainder of the site to assess the contamination status of the shallow soils.
- Dynamic cone penetrometer testing was undertaken in areas of proposed car parking.
Whilst generally low levels of contamination were noted, localised asbestos contamination was identified at low levels and advice for further assessment/remedial action was provided. Low risks were proven to be posed to environmental receptors (e.g. Carboniferous Limestone aquifer).
Design recommendations for shallow strip foundations, a ground bearing floor slab and pavement design were provied with precautionary advice related to shrinkage and swelling and anomolous conditions associated with ground dissolution. The investigation undertaken was sufficient to identify the key ground issues at the site.
Summary of services provided by ESP:
- Desk study review of published information to establish initial Conceptual Ground Model and preliminary assessment of geoenvironmental and geotechnical hazards and risks.
- Windowless sampling, hand excavated pits and dynamic cone penetrometer (DCP) testing in accordance with BS5930.
- Quantitative risks assessment of human health risks.
- Provision of foundation, floor slab, pavement and drainage design advice and recommendations for inspection during construction, further assessment of asbestos risks and mitigation measures.