The company was appointed by the client to carry out the installation of an open-loop ground source energy system to provide 300 kW of heating demand for an existing development of 95 council and private flats. The works were part of a larger scheme to modernise the residential blocks as part of  council’s ambitious target to reach net zero carbon emissions.  Renewing the heating and hot water system using groundwater-source heat pump will provide a more efficient heating system producing less carbon emissions, improving local air quality and delivering 5,309 tonnes of CO2e savings over 25 years – the equivalent of growing around 87,000 trees.  

THE WORKS
Our works involved an initial pumping test on a borehole drilled into the shallow gravel deposits below the site to a depth of 10 m. Pumping tests showed that the gravel borehole was not sufficient to deliver the flow required for the building. The final system comprised 2 No. 90 m deep chalk wells, one for abstraction and one for re-injection of the groundwater, operating at a flow rate of 15 l/sec. Boreholes were drilled with our compact rotary rig on a space-constrained site within the grounds of the building. 

Boreholes were acidised to improve the yield from the Chalk.  A series of pumping tests were carried out as part of the trail, including step tests, constant rate tests and reinjection tests to allow Environment Agency approval for the scheme.