Surface layer improvement system and methods for on-site remediation of contaminated sediments

1 . A surface layer improvement system for on-site remediation of contaminated sediments at a water bottom floor, the surface layer improvement system comprising:

a stabilizer spray unit that performs underwater spraying of a stabilizer to a remediation target region; and

a disturbing and mixing unit that induces bioturbation by mixing the stabilizer with the contaminated sediments in water,

wherein the stabilizer spray unit includes:

a stabilizer storage in which the stabilizer is stored,

a stabilizer supply pipe in which the stabilizer is transferred and guided from the stabilizer storage, and

stabilizer spray pipes which are connected to the stabilizer supply pipe and through which the stabilizer is sprayed to the remediation target region,

wherein the stabilizer supply pipe has a distribution vane which partitions an inner channel of the stabilizer supply pipe into a plurality of channels, and

wherein the stabilizer spray pipes are arranged radially about the stabilizer supply pipe and are formed to rotate about the stabilizer supply pipe, have respective angle adjusters which adjust an arrangement angle with respect to the stabilizer supply pipe, and enable a spraying range of the stabilizer to be adjusted by adjusting a rotation speed or an arrangement angle.

2 . The surface layer improvement system according to claim 1 ,

wherein the stabilizer spray unit and the disturbing and mixing unit are supported by a workboat and a crane on the water to be maintained at an underwater location, and

the stabilizer includes a pellet or solid particle stabilizer.

3 . The surface layer improvement system according to claim 1 ,

wherein each of the stabilizer spray pipes has a discharge chute at an end region from which the stabilizer is discharged, the discharge chute being formed in a shape having an open upper surface.

4 . The surface layer improvement system according to claim 1 ,

wherein the disturbing and mixing unit includes

a rotation shaft driven rotatably about an axis in a longitudinal direction, and

a plurality of disturbing and mixing wheels which are provided about the rotation shaft and disturb and mix the stabilizer with the contaminated sediments.

5 . The surface layer improvement system according to claim 4 ,

wherein each of the disturbing and mixing wheels includes

a rim that is fastened to the rotation shaft, and

a plurality of blades arranged apart at predetermined intervals in a circumferential direction along the rim.

6 . The surface layer improvement system according to claim 5 ,

wherein each of the blades has a plurality of fixing holes formed in a longitudinal direction to enable a length to be adjusted depending on a pile thickness of the contaminated sediments, and a bent end portion formed at an end portion separated from the rim.

7 . The surface layer improvement system according to claim 4 ,

wherein each of the disturbing and mixing wheels is disposed at a position different from a position of another adjacent disturbing and mixing wheel according to a rotation direction.

8 . The surface layer improvement system according to claim 1 ,

wherein a barrier structure isolates the remediation target region from other underwater regions and accommodates the stabilizer spray unit and the disturbing and mixing unit inside during on-site remediation.

9 . The surface layer improvement system according to claim 8 ,

wherein the barrier structure is formed having an open bottom and a curved upper surface or side surface.

10 . The surface layer improvement system according to claim 9 ,

wherein the barrier structure is formed to settle and be installed on the water bottom floor with a self-weight or a predetermined additional weight.

11 . The surface layer improvement system according to claim 9 ,

wherein the barrier structure has a guide roller at a front end or a rear end to assist movement of the barrier structure or a curtain made of a flexible material including geotextiles.

12 . The surface layer improvement system according to claim 9 ,

wherein the barrier structure is formed to have a plurality of divided blocks and enables the plurality of blocks to be assembled and separated from each other with a joining line.

13 . The surface layer improvement system according to claim 9 , comprising

a sensor unit that monitors an on-site remediation operation,

wherein the sensor unit includes one or more of a camera sensor, a position sensor, a turbidimeter, and a flow velocity sensor.