emcus logo
geotechnical investigation image

Project 1 - Geotechnical Investigation & Assessment

Working with a firm of Architects and English Heritage, Emcus Ltd. carried out the Geotechnical investigation and assessment to determine the likely cause of cracking and displacement observed in the eastern end of a church building in a former mining village near Swadlincote, Derbyshire.

The investigation initially comprised thorough geotechnical desk study including an appraisal of the historic usage of the site, which had seen several phases of development, including an 11th Century monastory; an assessment of the geology and recorded coal mining activities beneath the site and the surrounding area; and interpretation of the results from a programme of structural monitoring.

Following an assessment of the desk study information, several phases of intrusive investigation were carried out at the site. The intrusive investigation was undertaken using restricted access plant and minimal disturbance techniques and comprised:
• The excavation of hand dug pits to inspect the foundations of the church building.
• The investigation of the near surface ground conditions at the site by window sampling and in site Standard Penetration Testing.
• The laboratory analysis of representative samples of the cohesive strata recovered from the site for moisture content and plasticity index determinations.
• The drilling of rotary boreholes to a maximum depth of circa 20m bgl and the proof grouting of the boreholes using a cement / pfa grout to investigate potential unrecorded mine workings in the shallow coal seams identified by the desk study beneath the church.

rotary drilling of boreholes

The investigation identified the cracking and displacement observed in the church building was likely to have initially been caused by compression / consolidation of the Made Ground identified directly beneath the church foundations. This settlement was exacerbated by ground movements associated with the former deep long wall mining in the area of the site and the local heave / swell of the cohesive strata beneath parts of the church from the seasonal water demand of mature trees in the church yard. Working with the Architects, Emcus Limited provided outline remediation solutions to stabilise the foundations of the church.