Investigating Underground Hazards

Land Affected by Mining or Natural Cavities

Assessment And Investigation Services

At JGP, we specialise in comprehensive assessments of land and property affected by subsurface voids, whether naturally occurring (e.g., caves, karstic solution features) or man-made (e.g., historic mining). Our expertise lies in delivering reliable, data-driven assessments that identify potential stability risks, allowing us to recommend the most appropriate solutions tailored to the specific needs of each site.

In areas like Devon and Cornwall, where historical mining activity and naturally occurring voids are common, Planning Authorities may require pre-development stability assessments to address geotechnical risks associated with underground surface voids. With JGP’s proven expertise in investigating underground hazards, we ensure land and properties affected by subsurface voids are thoroughly evaluated.

In addition to assessments, JGP provides comprehensive remedial design and construction support. Our geotechnical engineering team develops tailored remediation solutions to address instability risks, including void filling, grouting, and ground stabilisation. We work closely with construction teams throughout the implementation phase, offering technical supervision and long-term monitoring.

Historic Mine Workings

Abandoned historic mining activities, including both metalliferous and non-metalliferous mining, often leave behind a complex legacy of issues, such as:

JGP brings extensive experience in investigating and addressing ground instability and contamination associated with historic mining voids and quarries. Our expertise spans the entire project lifecycle, from initial assessments and ground investigations to the design and implementation of remedial measures. We also specialise in drainage relief schemes to mitigate flooding and ground instability associated with mine workings.

Our services for historic mine workings include:

We use historical mining records, geological data, and digital terrain modelling to map underground features.

We use non-invasive geophysical methods, such as ground-penetrating radar and seismic refraction, to map subsurface voids and fractures.

We conduct borehole drilling, trial pits, and core sampling to directly assess soil and rock conditions.

We assess mine water levels, flow, and composition to identify flooding risks.

Our confined-space-trained engineers use rope access to perform hands-on inspections of mine shafts and tunnels, ensuring precise assessment of hazardous or hard-to-reach areas.

We provide remediation appraisals to develop cost-effective solutions for mine voids, contamination, and ground stability.

We offer shaft capping and stabilising solutions for mine openings to prevent collapse of surface ground.

For contaminated sites, we provide soil treatment and water purification to neutralise contaminants, manage risks from acid mine drainage and protect groundwater systems

Ground Stability and Groundwater

JGP has engineered solutions to some of the largest and most complex ground stability and groundwater problems associated with the deterioration of historic mine workings across Devon, Cornwall, and the Southwest of England. With extensive experience in the metalliferous mining areas of the region, we have tackled significant challenges related to subsidence, mine-related contamination, and hydrogeological issues. Our tailored solutions ensure that developments in these areas remain stable and compliant with environmental regulations and safeguarding properties/infrastructure.

Natural Cavities

Natural cavities such as karstic voids and fissures in limestone and chalk present both geotechnical and drainage problems. Karst limestone landscapes are characterised by underground natural drainage conduits, caves, sinkholes, dry valleys, thin soils and bare rock outcrops.

Karstic Terrain and Solution Features

One of the most common issues with karstic terrains is the presence of solution features. At the rockhead (surface), weathered rock can cause fissures and pinnacles, making strip footings problematic. Below the surface, subsurface voids can collapse, resulting in sinkhole formation and migration to the surface. These features can create significant stability risks if not properly assessed before development. Additionally, changes to the natural surface water and drainage systems during development can exacerbate instability due to the washout of void infill or solution enlargement.

Our Services for Natural Cavities Include:

We use geophysical techniques like GPR and electrical resistivity to detect voids and fissures. Borehole drilling and trial pits provide further detail on subsurface conditions to ensure accurate assessments.

We design customised foundation and drainage systems to prevent sinkhole formation and manage risks from subsurface drainage systems in karstic areas.

We stabilise sites affected by subsidence or crown hole formation using techniques like backfilling and foundation reinforcement to prevent further collapse.

We assess the impact of surface water on subsurface stability and design water management systems to prevent erosion and void enlargement.

Karstic Ground Conditions

JGP has extensive experience in addressing karstic ground conditions across Devon, Cornwall, and the Southwest of England. We have conducted numerous ground investigations using both geophysical and intrusive methods to accurately identify voids. Our Ground Engineering and Civil Engineering teams have designed and implemented effective foundation and drainage solutions for both private and commercial developments over karstic terrain. We have also engineered remedial schemes to rectify subsidence and stabilise sites prone to crown-hole formation and total collapse, ensuring long-term safety and stability.

Contact Us

If you’re facing issues related to subsidence, historic mine workings, or natural cavities, JGP is here to help. Our expert Geotechnical Engineering and Ground Investigation teams offer tailored solutions for ground stability, remediation, and risk management. We specialise in site investigations, remedial designs, and environmental assessments to ensure your property or development remains safe and compliant.