Site Investigation

The company’s Ground Engineering section carries out full geotechnical investigations of soils and rock strata as well as investigations of mine workings and mine shafts in coal, oil shale, chalk, salt, limestone, ironstone and sandstone. Site Investigation work is managed by our own qualified and experienced geotechnical engineering staff .

• Rotary percussive probing
  
• Rotary open hole
  
• Coring & core logging
  
• Simultaneous casing methods
  
• Shell and Auger (soils) boreholes
  
• Recording depths of superficial fills, mining voids, hydrological data and rock quality data.
  
• Installation of temporary or permanent casing for monitoring, down hole surveys, and sampling
  
• Installation of stand pipes & peizometers
  
• Installation of ground water level monitoring and control systems
  
• Installation of instrumentation e.g. extensometers
  
• Installation of permanent packers
  
• Undertaking a range of in-situ tests including:
  
  • In-situ hydrological tests (modified falling head, pumping and single packer tests)
    
  • Discrete water sampling
    
  • SPT/CPT
• Excavations and trial pits
  
• Sampling, logging (to ISRM standards) and testing
  
• Investigation of contaminated sites
  
• Production of factual reports.

In addition a range of specific survey and testing techniques can be provided through our links with specialist geotechnical service providers:

• CCTV and ultrasonic cavity surveys
  
• Geophysical surveys including optical televiewer, borehole caliper surveys wireline geophysical surveys (natural gamma, dual neutron and fluid temperature conductivity), resistivity and microgravity surveys, high pressure dilatometer

We are also fully qualified to carry out site investigation work on Network Rail infrastructure, possessing a Principal Contractors Licence as well as all necessary Link-up accreditations.

The company’s specialist in house drilling resources allows the full range of Site Investigation drilling to be carried out using differing drilling and flushing techniques.

Examples of specialist drilling equipment include:

• Casagrande C6S/M9 Dual head drill rigs, allowing simultaneous casing of drill holes enabling one pass drilling through unstable ground, worked seams and voids without loss of flush and artesian water or gas conditions The installed steel casing can be immediately used to allow monitoring, groundwater sampling, down hole surveys, and installation of instrumentation or it can be replaced with permanent plastic casing.
  
  • The dual head units and cutting collection systems have been adapted when drilling has been required in artesian conditions or in salt mine investigation to enable sealing off wet rock head and to provide blow-out protection.
    
  • Similar adaptations have been made for investigation work for coal bed methane extraction where one-pass fully cased boreholes have been drilled to 380m to investigate gas productive coal seams, and facilitate gas protection during drilling.
    
• Klemm KR701 Mini Rigs with dual head capability allowing drilling in areas of restricted access, working space or weight limits. The rigs have a weight of approximately 2.5 tonnes and have a separate towable diesel/hydraulic power pack. These rigs come with powerful single or dual rotary drilling heads and have extendable masts up to 3m working height. The tracks are retractable and the rig can pass through a 700mm opening. The rig also includes sophisticated kinematics which allows a multi-angling drilling facility.
  
• Klemm KR904 Geotechnical Drill Rigs with multi-functional rotary/rotary percussive head. These versatile tracked rigs occupy a small footprint enabling operation in limited working space.
  
• All of our rigs are track mounted giving a stable drilling platform which is essential for site investigation work. In addition the majority of our 25 drilling rigs offer multi-angling mast positioning which gives additional flexibility in hole positioning with potential reduction in disruption for site investigation work in residential and sensitive locations.
  

We also undertake site investigation works by excavation, trial pitting and trenching, by hand or excavator, for location and identification of utilities and services, investigation of existing underground assets as well as investigation of ground conditions—it is easier to understand the immediate and temporary engineering properties of soils, rocks and groundwater in pits and trenches that can be inspected for the behaviour of the materials and the likely requirements for excavation support, assessment of groundwater inflow, instability, excavatability etc.

This extends to investigations on contaminated and derelict sites to determine the extent of structures and foundations, the area and degree of contamination in soils & groundwater, sampling and testing of soils and groundwater.