The Geological Service of the State of Geneva requested DROPSTONE to drill a borehole in Carouge (Geneva) in order to replace a former one that was damaged with the years. The purpose of the work is to allow a continuous monitoring of the underground water quality. The former borehole, used since 1976, was a historical site for observing the Arve aquifer in an area close to industrial sites. The Arve aquifers provides large amounts of drinking water to the canton of Geneva.

The challenges were to drill just near the Carouge tunnel and also to make minimal damages to the agricultural field, privately owned. The works lasted five intense days and were just successfully finalised last week. The total thickness of the aquifer, constituted of gravel and sand, was drilled down to 80m, until reaching the basal impervious layer. The borehole has allowed confirming the geological hypothesis, known only indirectly through electricity surveys.