Parafintank

Hei, In my garden, it has 2 big parafintanker in underground. i wanna check with you if you can remove them and how much do they cost? i have no idea how long they hage been here or used or any oil left in the tanks. So probably you hage to empty the tanks as well. i´ve owned the house since last year. Inside the house, we cant find any place or pipe that connected to the tanks. Probably you can check as well. Thank you very much. Mvh