Installed stations and instrumentalization

The XEGCat of Girona, Salt and Vilablareix has 22 active points located in the urban and peri-urban area of Girona.

The network is divided into two sub-networks:

• Primary sub-network:11 measurement stations corresponding to 11 boreholes carried out between 2019 and 2020 (5 boreholes completed as closed or cemented points with a geothermal probe and 6 open boreholes equipped with a 100 meter long piezometric tube) that have been equipped with temperature sensors according to different configurations and piezometric level sensors.
• Secondary sub-network: 11 control points corresponding to pre-existing piezometers and wells in which a temperature and groundwater level sensors have been installed and where temperature profiles are periodically carried out.

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Situation maps of the 22 points of measurement and control of the XEGCat of Girona, Salt and Vilablareix

In relation to the geothermal stations of the primary network, these can be open borehole or closed borehole.

The stations corresponding to open boreholes are equipped with a 114 mm diameter PVC piezometric tube (114/104 mm). Inside the piezometric tube, temperature sensor strings have been installed, configured for each survey depending on the characteristics of the subsoil. In addition, groundwater level and punctual temperature sensors have also been installed.

The stations corresponding to closed boreholes were equipped with a geothermal probe (heat exchanger) with the following characteristics: PE100 40,0 x 3,7 mm in simple U. Afterwards, the stations were cemented directly in place using a thermo-active mortar with a density between 1,1 y 1,35 g/cm³ and a minimal thermal conductivity of 2 W/(m·K). These probes have allowed to perform thermal response tests (TRT) that permit the obtention of thermal conductivity from the perforation. The reports resulting of these analyses can be downloaded in PDF format. Temperature sensors have also been installed at different depths in these stations.

All the stations of the primary network have been equipped with a telemetry system for the acquisition and automatic transmission of data. The data is stored in a temporary data record to later be automatically sent to the spatial database of the NetMon© system (the measurement and control station monitoring system of the ICGC).

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Downloading of data in a point in the secondary sub-network is being performed. Fully-equipped station in the city of Girona. Construction scheme of the open piezometers in the geothermal stations of the primary network. Insights to the inside of a monitoring station showing the instruments used for the collection of data and its ending to the main network.

The following table shows a summary of the characteristics of the 22 points included in the XEGCat of the Girona, Salt and Vilablareix urban and peri-urban areas. Lithologic logs and the reports for the TRTs can be downloaded. The temperature and piezometric level data of each of the sensors in depth can be visualized and downloaded in the ICGC Geoíndex - XEGCat.