Site Investigation Services

 Site Investigation Services

Nicholls Colton Group offer a comprehensive scope of ground investigation techniques, ranging from simple hand excavated trial pits to more sophisticated deep rotary drilled boreholes with specialist in situ testing and instrumentation.

Our team of experienced Geotechnical and Geo-Environmental Engineers can advise on suitable investigation techniques for your site that will provide technically robust site assessments, minimising risk to the project development, meeting regulatory requirements and providing you with value for money.

Services Include :

Phase 1 Desk Study
The initial phase of most site investigations is to undertake a desk study in order to asses the risks posed to the site by previous and current development and contaminative land uses. The desk study involves collating and reviewing historical O.S maps, geological, hydrogeological and environmental data for the site and includes information from the Environment Agency, the British Geological Survey and Local Authorities. The desk study data assists with the design of the Phase 2 intrusive investigation and can identify potential constraints to the proposed development at an early stage.

Trial Pits
Trial pits are a rapid and cost effective method for allowing assessment of the shallow soil profile and groundwater conditions at a site. Trial pits can be excavated by hand digging techniques for the purpose of confirming shallow foundation construction of existing buildings, for locating existing utilities or for sampling the near surface soils. Machine excavated trial pits can be utilised for investigation of the shallow soil profile down to depths of approximately 4.00m (with standard excavation plant). Soil samples can be obtained from the trial pits for subsequent geotechnical and contamination laboratory testing (all in our in-house *MCERTS and *UKAS accredited testing laboratory).

Window Sampling & Dynamic Probing
Window sample boreholes can be carried out using either hand held pneumatic sampling methods or tracked percussive samplers.

The highly portable hand held window sample system drives sampling tubes into the ground using a hydraulic hammer and is particularly useful for sites where access for a conventional window sample drilling rig is not possible. Long hydraulic hoses can be used to allow the power supply to be situated away from the working area when working internally within buildings or within basements to alleviate problems associated with exhaust fumes or when working on embankments.

A track mounted window sample drilling rig can sample the soil profile to depths of approximately 6.00 to 8.00m (depending on the ground conditions) and this method of investigation is particularly useful on sites with restricted access and where disturbance needs to be kept to a minimum. Window sample boreholes can be utilised for geotechnical and geo-environmental investigations, installing gas and groundwater monitoring installations and for undertaking Standard Penetration Tests (SPTs).

The track mounted window sample rig is capable of carrying out dynamic probe testing which allows the relative density or strength of the soils to be assessed to depths of around 10m.

Cable Percussion Boreholes
Cable percussion boreholes are a common method of site investigation and are also regularly referred to as “shell & auger” boreholes. Cable percussion boreholes can investigate the soil profile to much greater depths than window sample boreholes, but are limited to cohesive or granular superficial soils or weak weathered solid geological deposits. The boreholes are typically drilled in 6” diameter, but the drilling rigs also have the capability of drilling larger daimeter holes and reducing the diameter with depth to aid the drilling progress.

These boreholes are used for obtaining undisturbed cohesive soil samples, for undertaking in situ testing (SPTs) and for various permeability tests. The soil samples are logged by Nicholls Colton Group’s experienced engineers and selected soil samples tested in our *MCERTS and *UKAS accredited geotechnical and contamination testing laboratory. The boreholes can be used for the installation of a wide range of gas, groundwater and geotechnical instrumentation.

Rotary Boreholes
Rotary drilling techniques are used to drill through rock quality deposits and can be either rotary open hole drilled (where only the cuttings are returned to the surface as fine rock chippings) or rotary core drilled (where solid rock cores are recovered).

Rotary rigs available include relatively small and mobile tracked rigs up to much larger truck mounted rotary drilling rigs that are capable of accessing most development sites.