Combined Phase I And Phase II Ground Investigation

Residential Development – St Peter’s Road, Kings Lynn

JPP Geotechnical and Environmental Ltd were appointed to undertake a Phase I and Phase II geotechnical and geoenvironmental investigation. The site comprised a parcel of reclaimed land adjacent to the River Great Ouse. It was proposed to redevelop the site into a residential development with associated infrastructure.

Our Phase I desk study assessment identified two historical channel features on site and that the land had been infilled and reclaimed from salting’s. The site had subsequently been developed into a commercial depot, which had recently been demolished. A site-specific risk assessment of the potential sources of both onsite and off-site contamination was produced. This enabled a targeted scope of site investigation to be designed, to assess the identified contaminative and geotechnical risks.

The targeted ground investigation comprised cable percussive boreholes for pile design parameters, trial pitting to assess ground conditions in regard to both geotechnical design parameters and potential to encounter on site sources of contamination. In addition, a series of windowless sampler boreholes were drilled across the site to target potential sources of onsite contamination identified in the conceptual model and to allow for the installation of land gas and groundwater monitoring wells. A second phase of intrusive investigation comprising  plate bearing tests was undertaken to assess compressibility of the ground as part of a settlement assessment.

Following the intrusive investigation works, a range of soil and groundwater samples were tested for potential contamination. These were associated with the sites historical land use and included heavy metals, metalloids, PAHs, petroleum hydrocarbons, VOCs and asbestos.

During our monitoring visits, groundwater samples were collected for contamination testing and land gas monitoring was undertaken to ascertain the site-specific gas screening value for the site to help determine the need for any land gas precautionary measures in the new development.

Our detailed assessment of the site allowed the key risks associated with the site’s historical usage and underlying ground conditions to be identified at an early stage. The subsequent targeted ground investigation works enabled a more cost and time effective investigation of the site to be undertaken. This helped to reduce the risks to our client whilst delivering the work within the required timescales and budget.

Our interpretive assessment of the ground investigation findings enabled both remedial and geotechnical design recommendations to be provided, which were tailored to the development proposals.