Project Sheet: North Road, Ponciau



  • Mr G Jones

Works Undertaken

  • Site investigation
  • Desk study
  • Chemical analysis of soil samples to enable a contamination risk assessment to be undertaken
  • Geotechnical recommendation
  • Solutions to treat the mine shaft on site

Description of Project

Mr G Jones proposed the development of a single detached house on North Road, Ponciau. Following the planning application, a condition was imposed requiring a land contamination assessment. GroundSolve Ltd was required to carry out this assessment. This involved identifying the extent of contamination on site, remedial solutions, and post development monitoring.

The site had previously been occupied by a coal yard, a fuel tank and a repair kit. According to a report obtained by the Coal Authority, there were also three mine entries on or within 20m of the site boundary.

The site investigation, supervised by GroundSolve Ltd, comprised the excavation of six machine dug trial pits. Samples were taken to the laboratories of Alcontrol for chemical analysis. The results were compared to human health critical values for initial screening purposes. The trial pit excavated below the old service pit exceeded the guidelines for residential end-use in both the arsenic and lead tests.

Another area was excavated in search of the mine shaft. It was identified at a depth of about 2.15m, measuring approximately 3m in diameter, the shaft had been backfilled with made ground.

Following these findings, a hazards assessment was made. It stated that all excavated material should be disposed of at a suitably licensed landfill facility and a cover system installed in garden areas.

Geotechnical recommendations by GroundSolve Ltd included the creation of a suitably reinforced concrete cap over the top of the shaft. A concrete plug was also recommended to be placed in the top of the shaft. This work had to be approved and overseen by the Coal Authority. The above works were designed and supervised by GroundSolve Ltd.

Concrete cap over the top of the mine shaft
Concrete cap over the top of the mine shaft
One of the 6 machine dug trial pits
One of the 6 machine dug trial pits