Municipal water supplies treated by public and private water facilities make water safe to drink and pleasant to taste. To produce water that is pure enough for human consumption, raw (untreated) water withdrawn from either surface or underground water supplies go through several processes.
The removal of fine solids and contaminants in sedimentation basins is one of these processes.
Periodic structural assessments of these water treatment facilities are intended to find conditions requiring repair and structural deficiencies. These assessments require water holding basins to be drained. Visual inspection of a public water treatment facility found numerous cracks and deterioration in adjoining basin’s concrete walls which allowed groundwater intrusion into basins and loss of water from other basins.
Structural assessment and repairs
Blackwell’s, Inc. was contracted to media blast the walls and floors of sedimentation basins at this public water facility to:
- Determine the extent of damage to the concrete walls
- Clean and profile the basin walls and floors for repair and recoating with modified cementitious material.
Media blasting basin walls and floors
Water treatment sedimentation basin wall showing three stages of cleaning and profiling after abrasive media blasting. To the right of the scaffolding is the wall before any cleaning or media blasting work was done to the wall. The center section of wall (behind the scaffolding) is after the initial soft washing with bleach. The left section (lighter color) shows the wall after profiling by media blasting. Note the plastic containment above the 16 ft. basin wall height.
Abrasive media blasting uncovered numerous deteriorating layers of concrete, structural wall cracks, exposed and corroded structural rebar, and earlier repair patches.
The deteriorated areas of the concrete walls exposed by the abrasive media blasting are being sounded out to determine the extent of the deterioration within the basin walls and any voids underneath the repair patches. The concrete in these areas will then be removed in preparation for the repair of the concrete. Cracks in the basin walls will be injected with hydrophobic polyurethane to form a tough flexible gasket to seal the cracks.
Blackwell’s, Inc. continues to clean and media blast basins
The Blackwell team will continue to clean and abrasive media blast the basins in preparation for concrete repair, injection of wall cracks, and profiling the basin walls in preparation for a new modified cementitious liner installation.
