In principle, three contamination paths of groundwater are possible. On the one hand, there is the theoretical possibility that hydraulic connections to water-conducting layers are created by the frac process and thus frac liquids could penetrate into groundwater near the surface. Due to the geological situation in northern Germany, this is considered extremely unlikely. In addition, failure of the cementation of the well wall could also cause the frac fluid to rise along the well. The greatest danger arises from improper storage, transport and handling of chemicals on the drilling site. In the event of a leakage, these can enter the subsoil near the surface and thus into the groundwater.
In general, all possible contamination paths are taken into account in the approval process. The relevant sections of the mining law, the Water Resources Act (WHG), the state water laws and, in the case of drilling in protection zones, the corresponding protection zone ordinances must be taken into account.
According to the WHG, it must be proven that the sinking of a deep well, the fracking and the production of natural gas do not adversely affect the water quality. Drinking water extraction plants as well as medicinal and mineral springs are subject to special further protection regulated by state laws. Protected area regulations regulate the use of water-polluting substances in protected areas.