TIGF's natural gas storage at Lussagnet and Izaute is located roughly 500 m below ground, in an aquifer (water-impregnated porous rock stratum), known as a "reservoir", overlaid by impermeable rock strata, known as the "overburden".

TIGF continuously monitors the effects of its underground gas storage operations

In particular, the company monitors:

Full understanding of the implications of these readings is gained from monitoring, assessment (particularly in partnership with the geological and mining research bureau, BRGM), modelling and research (in particular with the University of Pau and the Pays de l’Adour, UPPA).

Storage authorisation is issued by official decree following a public inquiry. The main local and public authorities, associations and other organisations are invited to contribute their views regarding the application. Consultations also take place involving the CSHP (High Committee for Public Health) in France, the General Council for Industry, Energy and Technology, and the Council of State. The Ministry of the Economy, Finance and Industry and the Ministry of Ecology, Sustainable Development, Transport and Housing are also involved in the authorisation process.

Operation of TIGF’s storage facilities is subject to ongoing inspection by the DREAL (Regional Directorate of the Environment, Development and Housing), the Prefectures and national-level monitoring by: