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Example ApplicationMetro & Tunnelling

Tunnel Construction Dewatering Treatment

This is an illustrative scenario showing how Reynolds & Bauhm equipment can be configured for this application. Every site has unique requirements — contact us for a solution tailored to your discharge consent.

Process Requirements & Constraints

A tunnel drive generates ~25 m³/h of dewatering water carrying 1,000–3,000 mg/L suspended solids, oil and grease from plant, and a high pH from cement and shotcrete contact. The discharge consent caps TSS, oil and pH tightly. The treatment plant has to ship in a 40ft container, mobilise fast, and move with the drive — making consent from day one.

Key Performance Targets
25 m³/h
Treatment flow
85–95%
TSS removal
<50
Outlet TSS mg/L
<15
Outlet O&G mg/L
6–9
Discharge pH
40ft
Single container

Treatment Approach

Step-by-step configuration from raw dewatering water to compliant discharge.

01

Coarse Screening

A drum/static screen removes grit and coarse debris that would blind the downstream plant.

02

Coagulation / Flocculation

Rapid mix and flocculation with coagulant (PAC/FeCl&sub3;) and polymer build settleable floc from the fine solids.

03

Lamella Clarification

Inclined-plate clarifier settles the floc in a compact footprint; clarified water passes to filtration.

04

Sand / Dual-Media Filtration

Auto-backwash media filter polishes the clarified water to the outlet TSS target.

05

pH Correction & Discharge

Acid dosing brings cement-driven pH back into the 6–9 consent window; settled sludge is dewatered (screw press) for disposal.

Equipment Configuration

The critical equipment that defines performance — not the full bill of materials.

Coarse Screen

Drum/static screen removing grit and debris ahead of treatment.

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Lamella Clarifier

SS 316L frame, PP plates; ~10 m² effective area in a compact footprint.

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Auto-Backwash Sand Filter

FRP vessel with backwash pump polishing the clarified water.

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pH & Chemical Dosing + Screw Press

Acid/coagulant/flocculant dosing and a screw press to dewater the sludge.

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Critical equipment shown, not the full BOM. For higher solids loads or on-site dewatering, the multi-stage (DAF + dual-media + screw press) system steps up the duty. The complete itemised BOM, P&ID and FAT pack are issued during detailed design.

Performance Achieved

Representative performance on 1,000–3,000 mg/L tunnel dewatering water.

85–95%
TSS removal
<50
Outlet TSS mg/L
<15
Outlet O&G mg/L
6–9
Discharge pH
25 m³/h
Treated flow
Relocatable
Moves with the drive

Related Treatment Processes

How this scenario connects to the wider tunnelling capability.

Apply This Configuration to Your Drive

Send us the water analysis, the flow and the discharge consent — we will pick the system class, size it and ship a factory-tested container.

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