PURPOSE: To simply remove slime accumulated on the bottom of a trench without disturbing the trench bottom or causing deep excavation by a method in which a bucket having an erected pipe on its bottom plate is settled on the bottom of a trench filled with a stabilizer liquid, and after the lapse of a given period of time, the bucket is pulled up.

CONSTITUTION: A trench 1 is excavated, a stabilizer liquid, e.g., bentonite solution, etc., is packed into the trench 1, and immediately after the excavation, a bottomed cylindrical bucket 3 of a size matching the trench 1 is settled on the bottom of the trench 1 through a rope and allowed to stand for a given period of time. Slime 5 being dispersed in the stabilizer liquid 2 sediments in the bucket 3, and is removed when the bucket 3 is pulled up by the rope 4. Since the stabilizer liquid 2 flows through the pipe 7 and window 10 provided to the bottom plate 13 of the bucket 3 when settling and pulling up the bucket 3, the bucket 3 quickly goes down or up. Since a cover 9 is also provided at the upper part of the pipe 7, the slime 5 does not drop to the lower part of the bucket 3.