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STELLA (SubTErranean Low Level Assay) is the ultra low background facility of the Gran Sasso National Laboratories (L.N.G.S.) in Italy. It is mainly devoted to material screening and rare events physics due to its very low radioactive background. Nevertheless, also environmental samples are measured within the collaboration with the ERMES (Environmental Radioactivity Monitoring for Earth Sciences) project. After a short description of the facility some on-going applications within the ERMES project will be briefly presented. The usefulness of doing environmental radioactivity measurements in a deep underground laboratory will be shortly discussed.

Monitoring of chemical and physical groundwater parameters has been carried out worldwide in seismogenic areas with the aim to test possible correlations between their spatial and temporal variations and strain processes. It is shown in this paper that uranium groundwater anomalies, which were observed in cataclastic rocks crossing the underground Gran Sasso National Laboratory (LNGS), can be used as a possible strain meter in domains where continental lithosphère is subducted. Moreover, whereas at the Gran Sasso National Laboratory only the natural radioactivity in the rock, the concrete, as well as the induced part coming from interaction of cosmic ray muons with the rock or the detector materials itself were considered as possible sources for the neutron flux background, the water-rock interaction and its spatial-temporal variation induced by the hydrological pattern of the Gran Sasso aquifer must be taken into account. Water must be considered not only as moderator in concrete, but also as additional source for neutron flux modulation due to its variable concentration and its radioactivity.