Teretek® Re-Levels Wash Plant Slab & Restores Drainage Performance

The approximately 150 m² slab supporting Wash Plant No. 1 and its water tank had settled unevenly, creating low points that prevented water and slurry from draining effectively towards the catchment pits.

The loss of effective drainage was causing water and slurry to continually accumulate throughout the active wash plant area. In addition to creating an ongoing operational issue for the facility, the trapped water was saturating the supporting soils and contributing to further settlement beneath the heavily loaded slab.

Site investigations identified pockets of voiding below the slab. The reinforced concrete slab also varied considerably in thickness across the treatment area and became substantially thicker near the adjoining water pit, adding complexity to the drilling and injection works.

Injection points were installed across the treatment area at approximately 1.2 m intervals. Teretek® expanding polyurethane resins were injected at depths of up to 3.5 m, with deeper injections concentrated beneath the areas of greatest settlement.

As the resin expanded, it filled voids, displaced trapped subsurface water and compacted the surrounding soils to improve ground bearing performance. Once support had been re-established, controlled injections continued to lift the slab and restore the required drainage falls.

Movement was continuously monitored using laser levelling equipment and receivers positioned on the slab and tank support columns. Before the final injection stage, the water tank was refilled, enabling Mainmark to assess the slab’s response and complete the treatment while the structure was under its operational load.

Measurements taken beneath the tank support columns recorded localised lift of up to approximately 68 mm. The final injections were completed with the water tank at full capacity, allowing the treated area to be assessed under operational load.

The works improved slab alignment and restored effective drainage falls towards the drainage area, reducing water and slurry ponding around the wash plant. The existing infrastructure remained in place throughout the works, avoiding the disruption and cost associated with removing the tank or reconstructing the reinforced concrete slab.