Jackson Geo Services was contacted by Rhondda Cynon Taff County Borough Council to carry out an extensive ground investigation at a former colliery spoil tip near Dinas, Tonypandy. The site raised concerns due to its historical use for mining and the risk of slope instability which could potentially impact nearby infrastructure and residential properties. The primary goal was to evaluate the site’s geotechnical conditions and monitor potential ground movement to ensure the safety of the surrounding areas.
The investigation involved dynamic sampling with follow-on coring to collect subsurface samples for both geotechnical and geoenvironmental testing. Open hole drilling was used to install monitoring equipment, including standpipe piezometers, and vibrating wire piezometers to assess groundwater levels and monitor slope stability. Additionally, a series of in-situ tests, such as standard penetration tests and variable head permeability tests were performed to evaluate the strength and permeability of the ground.
The findings revealed that the site consisted largely of colliery spoil, including sand, gravel and coal fragments. Geotechnical analysis identified areas of uncompacted material, presenting moderate risk of ground movement. Groundwater monitoring indicated fluctuating water levels, which could exacerbate slope instability if not correctly managed.
Based on these findings Jackson Geo Services recommended several mitigation measures, These included slope stabilisation techniques such as installing drainage systems to control groundwater and reduce pore pressure as well as ongoing monitoring of ground movements. Contaminated soils were identified for remediation in areas with elevated hydrocarbon levels to ensure environmental safety and compliance with regulations.
