An advisory engagement proposed automated CO2 pH correction for highly alkaline shotcrete and grout wash and seepage water, with the control philosophy and calculations provided.
Shotcrete and grouting operations produced wash and seepage water at pH 11–12.5 that could not be discharged and threatened the receiving water.
On a metro or tunnelling project, a water challenge of this kind translates straight into cost and programme risk — constrained sites, peaky dewatering flows, tight discharge limits and a heavy regulatory burden. The reliable route is to measure the actual water first, understand what is really driving the problem, and only then size the treatment. That diagnostic discipline is where Reynolds & Bauhm began this engagement.
Reynolds & Bauhm was engaged as the consulting engineer. Working alongside the project team, we characterised the water and proposed a solution sized to the measured duty, with the supporting drawings, specification and calculations handed over. The recommended approach combined several coordinated measures:
Reynolds & Bauhm acted in an advisory capacity — assessing the problem, proposing and sizing the solution and providing the documents and calculations. This is a representative scenario; figures are typical of the technology proposed and every project is validated against the project’s own data.
Each stage was selected against the water analysis and sized with a sensible design margin, then set out as a process flow diagram, functional design specification and sizing calculations for the project to take forward. Reynolds & Bauhm defined the duty, the equipment selection and the control philosophy, and identified the interface and consent risks to resolve before implementation — including a commissioning, sampling and validation plan so the plant could meet its targets and its discharge consent from start-up.
| Parameter | Before | After (target) |
|---|---|---|
| pH | 11–12.5 | 6–9 |
| Reagent overshoot | risk | eliminated |
| Consent | fail | met |
Beyond the headline figures, the proposed approach targets reliable discharge compliance on a constrained construction site and a treatment footprint that fits the works — the combination that keeps the tunnelling programme moving.
The proposed train is built around real water data, not an assumption — the single biggest determinant of whether a construction-water plant succeeds.
Each stage earns its place against the measured load and the site footprint, avoiding both under-treatment and over-engineering.
Drawings, specifications and sizing calculations make the result provable, auditable and ready for the regulator.
The approach suits constrained, fast-moving tunnelling sites — compact, containerised and re-deployable.
Reynolds & Bauhm can assess feasibility and propose a validated, sized solution for your metro & tunnelling application, with the supporting documents and calculations. Send us your flow, ground/water data and target consent and we will scope it.
Our expertise spans multiple industries with sector-specific water treatment solutions.