Probe drilling and ground grouting return water laden with drilling fines, bentonite and high-pH grout. Dedicated treatment clears and neutralises this difficult stream before it joins the main flow.
Probe drilling ahead of the face and pre-excavation grouting both return water that is among the most difficult on a tunnel: heavy with drilling fines and rock flour, often carrying bentonite, and strongly alkaline from cement and chemical grouts. It arrives in concentrated slugs during drilling and grouting cycles. Treating it as a dedicated stream — or buffering it into the main train — keeps the rest of the plant stable and the discharge in consent.
Handling Fines, Bentonite and Grout
Probe and grout return water needs robust solids removal, coagulation tuned to bentonite and drilling fines, and reliable high-pH neutralisation. We buffer the cyclic slugs, dose coagulant and polymer calibrated to the actual return, clarify with lamella plates, and correct pH with CO² or acid. The thickened solids go to dewatering, and the cleared, neutralised water rejoins the main treatment or is reused.
Buffer volume flattens the concentrated drilling and grouting cycles.
Dosing tuned to bentonite and drilling fines for reliable settlement.
CO² or acid neutralises the strongly alkaline grout return.
Heavy solids thickened for economical dewatering.
A Concentrated, Variable Stream
This stream combines high solids, bentonite, high pH and slug delivery — the hardest combination on the drive.
High solids and bentonite need robust, tuned coagulation.
Cement and chemical grouts push pH to 12+.
Drilling and grouting return arrives in concentrated bursts.
From Return Water to Clean Stream
Cyclic return is buffered to a steady feed.
Cleared water rejoins the main train or is reused; sludge to dewatering.
Plant We Build Into This Stage
Hydrocyclones strip abrasive excavation sand to protect pumps and media.
View EquipmentCoagulant and polymer dosing grows settleable floc from colloidal fines.
View EquipmentHigh-rate inclined-plate settlers cut suspended solids in a compact footprint.
View EquipmentAutomated acid or CO² dosing neutralises high-pH cement-affected water.
View EquipmentSediment and suspended-solids removal for tunnel construction water.
View EquipmentPre-assembled, road-transportable treatment trains that relocate as work advances.
View EquipmentWhy Choose Reynolds & Bauhm
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