It is possible to prevent iron ochre deposits, either before or after the construction.
Before the construction
One must keep vigilant when tell-tale signs appear such as the presence of reddish waters, after a rainfall, in ditches or on the ground surface.
During the construction of a property, it is recommended to enquire, with the neighbours and the municipality, about any history of iron ochre formations in the area.
A professional evaluation of the current conditions should also be made before proceeding with the construction. This evaluation should determine:
- The type of soil;
- The pH of the soil;
- The presence of iron or iron bacteria in the soil;
- The annual variation of the level of the water table.
The results of this evaluation will enable the contractor to adapt his building strategy in order to avoid the effects of iron ochre formations.
Such adaptations may be as follows:
- Location of the basement concrete slab above the water table level;
- Selection of the weeping tile (diameter, size and locations of openings, material);
- Location of the geomembrane;
- Type of granular backfill.
If the location of the construction site remains at risk, it is recommended to fit up two vertical cleaning conduits to enable the cleaning-up of the drain as needed.
After the construction
Keep vigilant in the presence of tell-tales signs such as a high humidity level in the basement, a recent flood event, or the presence of reddish waters in ditches or on ground surfaces after a rainfall.
The possible remedial actions with existing buildings in order to alleviate the symptoms of iron ochre deposits will vary with the locations. Such actions may require:
- A change to the grade;
- The sealing of the junction between concrete walls and slab;
- The installation of vertical cleaning conduits;
- The draining system under the slab;
- The installation of a waterproofing coating;
- The installation of a watertight membrane;
- The uplifting of the basement slab;
- Condemning the basement.
Example of remedial action from the outside
Example of remedial action from the inside