Considering their options to lower both their outgoings and their carbon footprint, they decided to employ us to drill and test a borehole for an open loop ground source heating scheme.

Drilling test boreholes to determine flow and yield

A test borehole was required to predict peak groundwater flow rates and ascertain sustainable groundwater yield.  It was estimated that a yield between 10l/s and 20l/s would be achievable, and that this would support the client’s ambitions to create a clean, green source of renewable heating.

Depending on the results of this phase of works, a decision would then be made to proceed with one or more additional boreholes to complete the ground source heating solution. 

Igne - considerate contractors

We began by drilling a single abstraction borehole and one reinjection borehole for the proposed ground source heating system.  We mobilised a rotary drilling rig and implemented a clean site system to prevent mess and to protect the sewer network which had a very limited capacity of no more than 3l/s. 

As the borehole was being drilled in an urban area, every precaution was also taken to minimise disruption and noise.

The drilling risks considered were the possibilities of:

• Contaminated land
• Artesian flow
• Coal mining
• Metalliferous mining
• Borehole instability
• Caves, fissures and faults

How we drilled boreholes for ground source heat

We installed suitable steel, welded casing to a nominal depth of 20m and grouted to surface.  In total we drilled to 110m, taking samples every 2m for logging.  There after we airlifted to clear all drilling mud and drill cuttings from the borehole.  

A geophysical survey consisting of CCTV, temperature, conductivity and caliper was produced for the client.

The test pumping consisted of a short (<1h) calibration pumping test to ascertain pumping rate, drawdown and injection characteristics, and a constant-rate test over a period of 48h at a rate of approximately 10 - 15l/s from one borehole to the other.

The reinjection borehole was capable of being pressured during injection testing.  On-site monitoring of water level, flow rate and suspended solids measurements was provided.

Following successful development pumping, a temporary submersible pump was supplied to supply a flow rate of at nominal 15l/s - at an assumed maximum pumping head of 6bar.  The pump was installed on plastic rising main and the system calibration tested to the satisfaction of the client.

The test pump was removed on completion of pumping in readiness for installation of a permanent wellhead, borehole chamber and permanent pumping system.

Delivering on the decarbonisation ambitions of our clients

In other words – the entire project was a complete success – from survey to installation.  Now Crystal Leisure has achieved its decarbonisation ambitions and we’re proud to call them our client.

If you would like to discuss ground source heating, decarbonisation or boreholes, we’d be delighted to hear from you!  Contact Igne on 01544 267 980 for a no obligation exploration of ideas and options.