Sewer Pipe Relining Case Study in Melrose Mine

Client Challenge

The mine infrastructure team responsible for a process-water and stormwater route in Melrose, Johannesburg needed a repair option that avoided unnecessary excavation. The reported issue was recurring blockages after heavy water use, with the main operational risk being road crossings, production access and safety exclusions.

The affected route was located under a road crossing. That made open trench replacement more disruptive than a controlled diagnostic and trenchless rehabilitation approach.

CCTV Inspection Findings

HydroTrace would first verify the pipe internally before recommending relining. In this scenario, CCTV inspection indicated fine root mats entering through displaced joints and holding solids in the invert. The host pipe was recorded as 525 mm asbestos cement, with approximately 52 m requiring close assessment.

The inspection focus included pipe grade, deformation, connection points, water holding, silt deposits, joint condition and whether the host pipe was suitable for a liner or coating system.

Existing Pipe Details

• Pipe material: asbestos cement
• Internal diameter: 525 mm
• Assessed length: 52 m
• Access restriction: under a road crossing
• Failure mode: root intrusion at pipe joints

Recommended Rehabilitation Method

The selected approach was UV-cure CIPP liner. This method involves glass-reinforced liner pulled into position and cured under controlled UV exposure. It was selected because it could reinstate the internal pipe surface while limiting demolition, downtime and reinstatement cost.

Preparation included mechanical cutting, high-pressure cleaning and CCTV verification before lining. Preparation is critical because relining should never be installed over loose scale, grease, silt or unverified obstructions.

Installation Process

1. Confirm access points and isolate the working section.
2. Perform CCTV inspection and mark the affected distances.
3. Clean the pipe using jetting, descaling or mechanical cleaning.
4. Reinspect the pipe to confirm readiness for rehabilitation.
5. Install the UV-cure CIPP liner to the measured section.
6. Allow the system to cure or set under controlled conditions.
7. Carry out post-installation CCTV and flow verification.
8. Issue a technical report with findings, photos or video references where available.

Project Outcome

The intended outcome was to restore flow, reduce water ingress, seal the damaged pipe wall and avoid unnecessary excavation around the process-water and stormwater route. The estimated working window for this scenario was 6 days, depending on access, cleaning difficulty and curing requirements.

For similar sites in Melrose and Johannesburg, HydroTrace would recommend combining CCTV inspection, cleaning and post-repair verification so the client receives a defensible technical record instead of a guess-based repair.

Related HydroTrace Services

FAQs

Why was pipe relining considered instead of excavation?

Relining was suitable because the damaged section was accessible from existing inspection points and excavation would have disrupted the site, finishes or operations.

Was CCTV inspection used before the relining decision?

Yes. CCTV inspection is used to confirm pipe condition, locate defects, measure distances and verify whether the line can be cleaned and rehabilitated internally.

Can this method work below concrete or paving?

Yes, where the host pipe still has enough structural profile and access is available, trenchless lining can rehabilitate sections below concrete, paving, roads or buildings.

Is pipe cleaning required before lining?

Yes. Jetting, descaling or mechanical cleaning is required so the liner or coating bonds against a prepared internal pipe surface.

What confirms that the repair worked?

Post-installation CCTV, flow verification and where applicable pressure or water testing are used to confirm the result.