Stability and Environmental Problems due to Groundwater Level Raising in the Abandoned Gavorrano Mine

摘要

The mine of Gavorrano, located in the South Tuscany,not far from the sea coast, has been mined for decades within a metallic sulphures orebody, on a difference in elevation of 500m, in a granitic embedding formation. The pirite orebody was interested in the lower part, by thermal groundwater, originally oursourcing from thermal springs at an elevation about few meters a.s.l. Ground water had been pumped down to less than 250 m below the sea level to allow the ore mining. After the closure of the mine, about 30 years ago, the water level has been taken into control, but now there is the need to let the water progressively raise. The mining method also adopted a cemented backfill of the voids. The paper describes this case ando refers in particular of possible instability problems, on the environmental consequences, on the evaluation of groundwater flow and characteristics, telated to the groundwater level rebound after closure, also on the basis of some monitoring techniques.