LAND QUALITY SITE INVESTIGATION AT FLOOKBURGH, CUMBRIA

15.08.18

REC provided Geo-environmental and Geotechnical consultancy support to the developer for their proposed scheme in Flookburgh. The investigation was aimed at providing information to assist in the development of a proposed 3 storey residential care-home apartment block with associated car-parking areas, soft landscaping and infrastructure.

Background

REC initially performed a Phase I geo-environmental assessment on the site.  This desk study enabled REC to detail the background of the site’s environmental risk and any geotechnical constraints.

Following this, an initial Phase II site investigation entailing 12 no. window sample boreholes was undertaken, in order to establish baseline conditions at the site and confirm the findings of the Phase I report.

A Geo-environmental assessment of soils was progressed together with a gas risk assessment to establish the gassing regime at the site. REC was, as a result, able to establish any potentially significant risks by undertaking a Tier II Quantitative Risk Assessment.1

Due to the presence of superficial clay deposits with a variable strength and  high cobble content, 3 no. deeper boreholes were required in order to establish deep strata conditions and the depth to rockhead.

REC undertook a review of all available drilling techniques, concluding that high cobble content excluded standard techniques such as cable percussion drilling. REC therefore advised that sonic drilling techniques would be most appropriate. This allowed for rapid progress establishing sandstone rockhead at depths at around 15.50m bgl far quicker and more economically than standard techniques would allow.  As a result, a geotechnical assessment and therefore foundation design was able to be recommended to the client.

Site Constraints

The main constraints on site were access due to the narrow nature of a track and the gate leading to the site.  REC informed the drillers and the client, then planned and arranged the safe access to the site of the drilling equipment, including the widening of the gate and reinstatement following the works. Access was blocked off onto site following completion of each day using the forklift in an aim to secure of the site (see photo below).2

Outcome and Next Steps

The Phase I Desk Study and Phase II Geo-environmental Site Investigation identified no elevated concentrations of contaminants, however the site is within an area where full radon gas protection measures are required. The geotechnical data derived from the ground investigation identified the most suitable foundation solution to involve piling to rockhead with a suspended floor slab due to the clay deposits being of a variable nature with high to low plasticity.