Mine water characterisation and monitoring borehole GGA05, UK Geoenergy Observatory, Glasgow

This report and accompanying data release describe the ‘as-built’ borehole GGA05 at the UK Geoenergy Observatory in Glasgow, as well as summarising hydrogeological testing and an initial geological interpretation. Mine water borehole GGA05 at the UK Geoenergy Observatory in Glasgow is screened across the Glasgow Main mine working void and overlying sandstone roof. The mine working is a water-filled void and initial hydrogeological indications from the test pumping are of a very high yielding borehole. Borehole GGA05 has ERT and DTS cables installed between the borehole casing and the rock wall and has a hydrogeological data logger installed within the borehole

Mine water characterisation and monitoring borehole GGA08, UK Geoenergy Observatory, Glasgow

This report and accompanying data release describe the ‘as-built’ borehole GGA08 at the UK Geoenergy Observatory in Glasgow. They also describe initial hydrogeological testing completed after borehole construction and provide an initial geological interpretation. Mine water characterisation and monitoring borehole GGA08 at the UK Geoenergy Observatory in Glasgow is screened across the Glasgow Main mine working and overlying sandstone roof. The mine working is interpreted as a roadway with a void, mine waste and wood encountered. Initial hydrogeological indications from the test pumping suggest borehole GGA08 is very high yielding. Borehole GGA08 has ERT and DTS cables installed between the borehole casing and the surrounding rock, and a hydrogeological data logger installed within the borehole

Mine water characterisation and monitoring borehole GGA04, UK Geoenergy Observatory, Glasgow

This report and accompanying data release describe the ‘as-built’ borehole GGA04 at the UK Geoenergy Observatory in Glasgow, as well as summarising hydrogeological testing and an initial geological interpretation. Mine water borehole GGA04 at the UK Geoenergy Observatory in Glasgow is screened across the Glasgow Upper coal and overlying sandstone roof. The borehole was drilled within an area of stoop (pillar) and room mine workings and is interpreted to have hit a coal pillar or partially collapsed pillar and a possibly fractured sandstone roof. It can be used for characterising and monitoring a fractured rock mass within a mine working area. Initial hydrogeological indications from the test pumping indicate that borehole GGA04 is high yielding. Borehole GGA04 has ERT and DTS cables installed between the borehole casing and the rock wall and has a hydrogeological data logger installed within the borehole

Mine water characterisation and monitoring borehole GGA01, UK Geoenergy Observatory, Glasgow.

This report and accompanying data release describe the ‘as-built’ borehole GGA01 at the UK Geoenergy Observatory in Glasgow, as well as summarising hydrogeological testing and an initial geological interpretation. Mine water borehole GGA01 at the UK Geoenergy Observatory in Glasgow is screened across the Glasgow Upper mine working and overlying sandstone roof. The mine working is interpreted to be filled with a loosely packed mine waste. Hydrogeological evidence from test pumping indicates that the borehole is very high yielding. Borehole GGA01 has ERT and DTS cables installed between the borehole casing and the rock wall and has a hydrogeological data logger installed within the borehole

Environmental baseline characterisation and monitoring borehole GGA06r, UK Geoenergy Observatory, Glasgow

This report and accompanying data release describe the ‘as-built’ borehole GGA06r at the UK Geoenergy Observatory in Glasgow, as well as summarising hydrogeological testing and an initial geological interpretation. Environmental baseline characterisation and monitoring borehole GGA06r at the UK Geoenergy Observatory in Glasgow is screened across a coarse sand and gravel in the superficial deposits. The borehole has proved to be low yielding on initial hydrogeological testing and has a hydrogeological data logger installed

Borehole GGA02, UK Geoenergy Observatory, Glasgow

This report and accompanying data release describe the ‘as-built’ borehole GGA02 at the UK Geoenergy Observatory in Glasgow, as well as summarising an initial geological interpretation. Mine water borehole GGA02 at the UK Geoenergy Observatory in Glasgow encountered the Glasgow Upper and Glasgow Ell mine workings and was screened across an interval interpreted as a completely collapsed Glasgow Main mine working and overlying sandstone roof. Unfortunately, grout entered the inside of the casing in the final stages of borehole construction, cementing up the screened section and resulting in GGA02 being repurposed as a cased, sensor testing borehole. New sensors can be tested inside the uPVC casing to 67.2 m drilled depth. Hydrogeological testing of GGA02 was not possible. Borehole GGA02 has a number of types of sensor cabling installed. Fibre-optic DTS cable is installed between the bedrock uPVC borehole casing and the rock wall with capability to work in passive (monitoring) mode to 72.65 m drilled depth. Fibre-optic cabling is also installed on the outside of the steel superficial deposits casing with the ability for use in active or passive mode. Electrical resistivity tomography cable with the deepest sensor placed at 85.58 m drilled depth is available for cross-borehole monitoring and imaging with the adjacent borehole GGA01

Environmental baseline characterisation and monitoring borehole GGB05, UK Geoenergy Observatory, Glasgow

This report and accompanying data release describe the ‘as-built’ borehole GGB05 at the UK Geoenergy Observatory in Glasgow, as well as summarising hydrogeological testing and an initial geological interpretation. Environmental characterisation and monitoring baseline borehole GGB05 at the UK Geoenergy Observatory in Glasgow is screened across a sandstone beneath rockhead, and thought to be around 5 m above recorded stoop and room mine workings in the Glasgow Upper coal. Initial hydrogeological indications from the test pumping suggest that borehole GGB05 is moderately yielding. There is a hydrogeological data logger installed in the borehole

Environmental baseline characterisation and monitoring borehole GGB04, UK Geoenergy Observatory, Glasgow

This report and accompanying data release describe the ‘as-built’ borehole GGB04 at the UK Geoenergy Observatory in Glasgow, as well as summarising hydrogeological testing and an initial geological interpretation. Environmental baseline characterisation and monitoring borehole GGB04 at the UK Geoenergy Observatory in Glasgow is screened across a sand and gravel unit in the upper part of the superficial deposits. Hydrogeological evidence from test pumping indicates that the borehole is very low yielding. There is a hydrogeological data logger installed in the borehole

Method and key observations from constructing a mine water heat subsurface observatory in Glasgow UK

The UK Geoenergy Observatories project (UKGEOS) is developing a subsurface Observatory in Glasgow for research and innovation in mine water heat and heat storage. This report provides an overview of the timing and tasks adopted in borehole construction and initial testing. It has been subdivided into three stages: planning/feasibility, exploration and appraisal. The fourth delivery or development stage, which is to construct the above ground infrastructure for mine water circulation and thermal perturbation, is ongoing in 2021 and is not covered in this report. Land availability, prior land use and environmental protection were key constraints in establishment of the Observatory, as well as subsurface geological factors. These are likely common to many mine water heat projects. Observations made during construction of the Glasgow Observatory are summarised to help to de-risk future mine water projects. These include difficulties associated with completing boreholes through sands and gravels in superficial deposits, and the challenge of identifying the type and size of mine workings during drilling. A key learning was the value of using a downhole optical or acoustic camera to better understand the nature of mine workings prior to screen installation

UK Geoenergy Observatories Glasgow : groundwater chemistry data collected during the borehole construction phase

The United Kingdom Geoenergy Observatory (UKGEOS) in Glasgow comprises 11 boreholes at the Cuningar Loop, South Lanarkshire and one seismic observation borehole in Dalmarnock in east Glasgow. Boreholes are drilled into superficial deposits, unmined bedrock and mined bedrock to characterise the geological and hydrogeological setting, and to provide access for baseline monitoring and mine water abstraction/ reinjection. The aims of the Observatory include de-risking key technical barriers to low-temperature shallow mine water heat energy and heat storage from groundwater in former coal mine workings; and providing environmental characterisation and monitoring to assess any change in ambient conditions. This report details baseline groundwater monitoring carried out during the construction phase of the Glasgow Observatory. It includes a description of the sampling methods and hydrochemical data for groundwater samples collected between December 2018 and December 2019. Eight groundwater samples and two mains water samples were analysed to determine the concentrations of selected chemical parameters at the British Geological Survey (BGS) and associated laboratories. The samples were collected to provide an initial indication of groundwater chemistry, primarily for water discharge purposes. The report accompanies the release of the construction phase groundwater hydrochemistry dataset. Sampling locations and methodology Groundwater samples were collected from the main Observatory borehole cluster at the Cuningar Loop, Rutherglen, South Lanarkshire from boreholes GGA02 at Site 1, GGA05 at Site 2, GGB04, GGB05 at Site 5, as well as from the seismic monitoring borehole GGC01 at Site 10 in Dalmarnock, Glasgow City. In the case of boreholes GGA02 and GGC01, they are the only groundwater chemistry samples that will be collected from these boreholes. Water was obtained from the Glasgow Upper mine working in GGA02 and Glasgow Main mine working in GGA05 by stopping the drilling at the mine working and retrieving a sample during and after purging. Groundwater from the bedrock and the superficial deposits was drawn from borehole GGB04 and borehole GGB05, respectively. Scope of analysis Groundwater samples were collected for analysis of major, minor and trace elements, Cr(VI), NPOC and stable isotopes (δ2H, δ18O, δ13C). In addition, field measurements of water temperature, pH, specific electrical conductance (SEC), redox potential (Eh) and dissolved oxygen (DO) were made. Total petroleum hydrocarbons (TPH) and polycyclic aromatic hydrocarbons (PAH) were analysed in samples from GGA02 and GGA05 only. Key Findings Both mine waters are net–alkaline with a near–neutral pH (Glasgow Upper pH 6.92 and Glasgow Main pH 7.12); they have a high alkalinity (as field-HCO3) (Glasgow Upper field-HCO3 609 mg/L and Glasgow Main field-HCO3 792 mg/L) and a high SEC of 1637 to 1723 µS/cm. Similarly, the bedrock and the superficial deposits waters have pH values of ~7.5 and alkalinity as field-HCO3 between 415 mg/L and 462 mg/L. The SEC is also high 1078–1183 µS/cm. All the waters belong to the bicarbonate (HCO3) type, with sodium (Na) as the dominant cation in the superficial deposits and bedrock groundwaters (Na–HCO3 waters), and Na, calcium (Ca) and, to a lesser extent, magnesium (Mg) in the two mine waters (Na–Ca–(Mg)–HCO3 water type). Water from all four lithologies ranges in sulphate (SO4) concentration between 165 and 302 mg/L. The chloride (Cl) range is 51–82 mg/L, with the highest value in the Glasgow Main mine working groundwater. Iron (Fe) concentrations range between 1.8 to 2.6 mg/L in the mine water and bedrock; a much lower concentration of 0.007 mg/L is measured in the superficial deposits groundwater. Chromium(VI), a known industrial contaminant in the area, was not detected above the lower limit of detection (LLD) in any samples. The stable isotope δ2H, δ18O values plot broadly on the global meteoric water line with no evidence of evaporation prior to recharge. The O-isotope values (δ18O -7.4 ‰ and -7.1 ‰) are all within the range of groundwater samples reported previously from Carboniferous sedimentary aquifers across the Midland Valley of Scotland. The mine waters have heavier δ13C (-9.9 and -10.8 ‰) than the bedrock and superficial deposits (-15.6 and -12.1 ‰). All lithologies’ groundwaters fall on the middle to upper range of the δ13C values from -22 ‰ to -10 ‰ of groundwater samples from other studies of the Coal Measures Group across the Midland Valley of Scotland. All samples are saturated with respect to calcite, dolomite, siderite, rhodochrosite, amorphous ferric hydroxide, gibbsite, and barite, and remain undersaturated with respect to gypsum, halite and jarosite. Water was also obtained during the installation of the GGC01 seismic monitoring borehole. However, given the sampling method (a bailer lowered to only a few meters from the top of the borehole) and evidence of dilution during flushing and residual contamination from the tracer/additive and drilling fluid, the chemical analyses of the groundwater samples from this borehole are not to be considered representative of the unmined Coal Measures aquifer(s) intercepting the borehole. Very high concentrations of boron (B) and dissolved organic carbon (NPOC) were found, which decreased between the two sampling dates, showing an increase in groundwater flowing into the borehole after drilling and flushing. The water was alkaline, and with a SEC of 310–650 µS/cm. Sodium was the most enriched cation, with HCO3 and Cl the most enriched anions. Chromium(VI) was not detected above the LLD in either sample. The δ2H, δ18O signature of the groundwater was similar to the samples taken in the four Cuningar Loop boreholes while the δ13C isotope signature was lighter