Field services

Field services

Carbon Zero Consulting provide a full range of Field Services for Ground Source Heating & Cooling projects as well as supervision of drilling and testing boreholes for water supply, contaminated land and environmental monitoring;

  • In-situ measurement of soil thermal conductivity and closed loop borehole thermal response testing (TRT)
  • Supervision of borehole drilling from domestic scale to largest commercial water supplies for GSHC and water supply projects
  • Design and supervision of test-pumping programmes for GSHC and water supply projects
  • Water and soil sampling for contaminated land assessment
  • Installation of borehole, spring and river monitoring equipment for physical and chemical parameters
  • Field assessment of water and wastewater treatment systems including sampling and analysis of effluent and treated waters
  • Supervision and interpretation of all geophysical and CCTV surveys

Ground Water Services

Carbon Zero Consulting provide a full range of Field Services for the exploration, development, management and treatment of process water and groundwater.
  • Audit and risk assessment services for private water supply systems
  • Environment Agency liaison and field surveys to obtain consent to drill and test pump (Section WR32 applications and surveys)
  • Supervision of borehole drilling from domestic scale to largest commercial water supplies
  • Design and supervision of borehole testing programmes (to Environment Agency requirements) including provision of water level and water quality monitoring systems
  • Water sampling and analysis for ‘clean’ water supplies
  • Water and soil sampling for contaminated land assessment
  • Field assessment of water and wastewater treatment systems including sampling and analysis of effluent and treated waters

Thermal Response Testing

Carbon Zero Consulting operates a specially packaged, highly portable thermal response test (TRT) system for access to tricky or ‘tight’ borehole drilling sites.
A TRT provides in-situ measurement of site specific thermal properties of the ground into which a closed loop system is being installed. The measured values derived from a TRT are used to calibrate a design model and confirm the number (and depth) of boreholes required to meet your building heating/cooling requirements.
Testing might be completed in a pilot borehole prior to project commencement, or whilst the array boreholes are being drilled. In the latter case we are able to quickly update desk study design calculations and confirm total numbers of boreholes.
Good TRT practice requires accurate measurement and logging of flow and temperature to and from the test borehole. A reliable and consistent source of power (heat) must be available. We provide a suitable generator and fuel supply to allow testing for up to 72 hours.
Interpretation of the thermal response test is as important as acquiring good data. An experienced eye is required to identify when and where data is valid. We always aim to process and interpret the test data within 24 hours of test completion to provide our client with a reliable value for formation thermal conductivity and borehole resistance.

Soil Thermal Conductivity Testing

Carbon Zero Consulting provide a unique service to measure soil thermal conductivity in situ at the intended site of installation of pipework.

Procedures for thermal response testing (TRT) of vertical closed loop boreholes are well known and documented. Design simulation software or MCS ‘lookup’ tables for horizontal closed loop schemes also requires a representative value of soil thermal conductivity (λ) as input data. Databases of soil thermal conductivity data are not readily available or attributable to a particular soil type – especially as the installer is unlikely to have expertise in soil type recognition. As a result, many installers have little or no information with which to base their calculation of heat exchange pipe length to meet building heating loads.

The Soil Survey

We utilise a ‘Hukseflux FTN01’ Field Thermal Needle Probe System (see image below). The probe itself comprises a thermal needle of diameter 6.3 mm and 170 mm length, mounted on a 1.5 m long handle (Figure 1). The probe is pushed into the soil at the target depth, for example, at the base of a trial pit or at the base of a hand-drilled narrow auger hole. The probe is left for 5 minutes to equilibrate with the ambient soil temperature. The probe’s readout unit has a facility to detect whether the temperature has adequately stabilised prior to commencement of the heating test.

Soil Thermal Conductivity

During the test itself, a small electrical voltage is applied to a resistance element in the probe.

This results in a constant heat power being generated, which propagates radially into the surrounding soil. The temperature of the probe increases with time and this increase is monitored over a heating cycle of around 5 minutes. If radial heat conduction is assumed, the temperature should increase in proportion to the logarithm of time, according to a standard “line source” approximation.

Analysis of the rate of temperature increase provides a value of the surrounding soil thermal conductivity.

The determined thermal conductivity is representative of a cylinder of soil around 100 – 300 mm diameter around the probe. A representative assessment of a site’s “bulk” soil conductivity (i.e. a single value that can be used in design software) requires a number of individual determinations distributed across a site; normally 12 – 15 measurements for an ‘average’ domestic ground loop area.
A survey to obtain sufficient samples for a domestic application requires 1 day surveying in the field plus time for data analysis and reporting.

Call or email us to find out more. You can also download further information on the needle probe and our ‘Soilheat’ service.