For systems with geothermal probes, the distances between the probes should be as large as possible to minimize mutual interference. If several geothermal probes are installed, they should be arranged as perpendicular as possible to the direction of groundwater flow.
direction of groundwater flow.

The VDI guideline specifies the following minimum distances:

• 0.70 m from supply and disposal lines
• 2.00 m from buildings
• 6.00 m between two geothermal probes
  (for depths > 50 m and depending on the soil material)

This means that a minimum distance of 3.00 m must be maintained from the neighboring boundary so that the neighbor can also use his heat potential accordingly without the systems interfering with each other too much. According to the VDI guideline, it is even advisable to maintain a minimum distance of 10 m from the neighbor's system. If the property allows it, the systems should therefore be installed far away from the property boundary and at a large distance from each other.

After inserting the geothermal probe, the borehole must be properly grouted in accordance with the manufacturer's instructions and the specifications of the VDI guideline. Aggressive carbon dioxide is likely to rise throughout the Bonn city area. This can destroy the grouting materials. Conventional grouting agents are therefore not sufficient. To protect the groundwater and your system, only materials that are permanently resistant to attack by aggressive carbonic acid (clay pellets) are therefore permitted for deeper boreholes (> 40m). Proof of this must be provided. If a larger carbonic acid deposit is drilled into, the borehole may have to be sealed again, with the result that the planned depths cannot be implemented at this location.

In the protected area of the two medicinal springs in the south of Bonn (Bad Godesberg/Pennefeld area), geothermal drilling is permitted to a maximum depth of 20 m, whereby no geothermal drilling is possible in designated areas.

Water-water systems usually consist of two wells. When planning, care must be taken to ensure that these are far enough apart and that the direction of groundwater flow is taken into account. For small systems (single-family homes), distances of ≥ 10 m are usually required.

The groundwater is extracted from one well, fed via a closed circuit and reintroduced via the second well. The temperature of the groundwater may only be changed by the operation of the system. In most cases, a temperature difference of ΔT = 3 to 5 K between the extracted groundwater and the groundwater reintroduced after use can be permitted in the Bonn urban area. The discharge temperature must also lie within the temperature range between + 5°C and + 18°C. If the system is also used for cooling purposes, an even energy balance over the year must generally be ensured so that the groundwater is not heated excessively. It must also be taken into account that neighboring systems must not be significantly impaired by operation. You can find out whether such systems already exist in your neighborhood,
can be obtained from the Lower Environmental Authority.

After receiving the permit, the client must ensure that the companies carrying out the work are aware of and comply with the content provisions (conditions) and ancillary provisions of the permit and, in particular, that the minimum distances are observed.
Expert construction supervision is required.

Geothermal probes are supplied in one piece and must not be welded on site. Once the probe has been inserted into the borehole, subsequent pressure testing with water and proper grouting of the surrounding annular space from bottom to top are extremely important, as this is the only way to ensure optimum heat transfer and prevent damage later on. The pressure test and grouting must be recorded.

The drilling contractor is obliged to record the local ground conditions for each borehole and to present them in a stratigraphic log. After completion of the work, these must be submitted to the approval authority together with a determination of the position of the drilling points and the pressure test and grouting logs. Experience has shown that the points listed here for groundwater protection and plant safety are observed and complied with by qualified specialist companies and their drilling contractors.