Construction of a geothermal system

Geothermal collection systems include an energy well, earth circuit and water body.

In the urban and site plan area, an energy well is usually the only option as a heat source among ground heat collection systems. The space required by the district in a standard small house is approximately 1–000 square meters. Buildings cannot be built on top of the collection pipeline. An area that is plowed in the winter is also not suitable for the area of ​​the collection pipeline. Land may not be built in areas where groundwater is formed. The pipeline to be placed in the water system requires the permission of the owner of the water area and a water construction notification to the ELY center and possibly the permission of the regional administration agency.

The recommended minimum distances of the energy well borehole to different targets are shown in the table below.

¹ the distance depends on the quality of the soil, the depth of the trench and the pipes to be placed in the trench
² when drilling at an angle, see the environmental guide

• The distance of the energy well must be at least 7,5 m from the borders of the neighbors. With the written consent of the neighbor, the energy well can be built closer to the border. If the wells are built closer to each other than the recommended distances, an expert's opinion on the functionality of the wells must be submitted with the permit application.
• When drilling a diagonal hole that extends to the side of a neighboring property, it is recommended that, in addition to consent, the establishment of a property easement that secures changes of ownership. However, the slanted borehole must not extend into the street area or the public area.
• Before construction, it should be determined whether it is a groundwater or other special area.
• Before construction, the location of domestic water wells and other energy wells in the surrounding area should be determined.
• Before construction, it is necessary to find out whether there are possibly cables, caves or technical systems located underground (the responsibility of the person undertaking the project).
• Before starting the work, the neighbors must be informed sufficiently early about noise, dust and the estimated working time, among other things.

• Application form: the application must name a geothermal designer who must have sufficient experience and training in thermal management and construction.
• An explanation of the composition and quantity of the heat transfer agent and additives used in the collection pipeline.
• Statement on the ownership/management right of the construction site.
• Neighbor consultation forms from those property owners whose boundary is less than 7,5 m from the energy well.
• The consent of the city of Riihimäki, if the distance of the energy well is less than 4,0 meters from the boundary bordering the street area or the public area of ​​the lot.
• Station drawing (2 pcs), on which the distance of the energy well or wells is marked from the immediate boundaries of the plot, as well as the binding dimensions showing the location from a known point. In addition, the drilling angle is significant if the drilling angle of the energy wells deviates from the vertical. Domestic water wells of nearby properties must also be shown in the station drawing, if necessary. If an earth circuit is used for heat collection, its location and the length of the piping must be indicated in the station drawing.
• Map extract.
• Any other documents related to the procedure permit, such as a power of attorney and an extract from the minutes.

If the construction of a geothermal system also requires a permit other than the Land Use and Building Act, information about the documents needed to apply for them can be obtained from the authority granting the permit in question.

The operational permit decision regarding the construction of the geothermal system includes a condition for the completion of the final inspection. Order a final inspection from the building control authority during the validity period of the permit. The procedure permit is valid for three years after it becomes law.

At the latest at the final inspection, submit the implementation report of the energy well or underground pipeline to the building control authority, which must contain at least the following information:

• the location of the well or the plot of land, unless it is as stated in the application
• drilling contractor (energy well)
• the total depth and direction of the well and the length of the ground drilling (energy well)
• protection structures.

Attach the information about the energy well or the landscape to the property's operating and maintenance instructions.

When replacing the heat transfer medium of the geothermal system with a new one, the old heat transfer medium must be treated as hazardous waste.

If an oil tank that was previously in use is removed during the transition to a geothermal system, the rescue service must be notified and the regulations given in the oil heating regulation and the environmental protection regulations of the city of Riihimäki must be followed.

Coarse stone material and sludge formed by water and solid matter generated during the drilling of an energy well must be handled in such a way that it does not cause harm to the environment or neighbors. Aggregate or sludge must not be led as such directly into a body of water (stream, pond, lake) or into the general drainage network. If sludge is piped into the soil of the plot to be drilled, it must be done in such a way that it does not cause waterlogging of the neighboring plot or clogging of ditches. The aggregate must be stored during the work in such a way that it does not blow dust with the wind or spread uncontrollably into the environment as sludge with the rain.

As the heat transfer agent of the geothermal system, a substance that is as harmless as possible to the environment, such as ethanol, should be used. Possible leakage of heat collection pipes can cause groundwater pollution. To prevent the risk of pollution, compounds harmful to groundwater, for example ethylene or propylene glycol or methanol, should not be used as a heat transfer agent.

The direct access of surface water to the groundwater must be prevented by properly sealed well structures.

The transfer of possibly radon-containing air in the bedrock through the pipe penetrations from the energy well to the living spaces must be prevented by sealing the penetrations with suitable elastic sealants.