European Space Agency, Harwell

GROUND SOURCE HEAT INVESTIGATION SITE INVESTIGATION

Terra Firma (South) has extensive experience of ground source heat investigation in order to obtain the necessary soil parameters to allow appropriate design.

CASE STUDY: EUROPEAN SPACE AGENCY (ESA), HARWELL

Terra Firma (South) acted as site investigation contractors for the construction of the new European Centre for Space Applications and Telecommunications (ESCAT).

In order to obtain relevant soil parameters a test borehole was sunk to a depth of 120m. Due to the depth of the borehole, various geological starta was encountered including the Lower Chalk, Upper Greensand and Gault Clay.

The sites close proximity to the adjacent Diamond Light Building meant that the drilling had to be vibration sensitive. This was overcome by our experience of drilling at reduced speed and using polymer flush.

Due to possible UXO, an appropriate specialist was present during shallow drilling. No anomolies were encountered and therefore drilling was able to progress.

Due to groundwater issues, the Environment Agency (EA) requested that the uppermost unconfined groundwater horizon was cased out from creating a pathway to the middle confined chalk. In addition, groundwater testing of a VOC suite was also required.

Upon reaching the required depth the borehole was then grouted using a thermal condutive grout. Following a ‘setting’ period, a Thermal Response Test (TRT) was undertaken to determine the appropriate design parameters, which showed good agreement with various published data for the strata encountered.

Terra Firma (South) was able to manage the vibration restrictions, difficult drilling conditions and environmental sensitivity of this project to deliver.