NON-CONFORMANCE REPORT (NCR) - Water Tank – Leakage / Ponding Test Failure)

Project: [Project Name], Structure: Make-Up Water Tank / Water Retaining Structure

Location: [Site Location], NCR Reference: NCR-CIV-WT-..... Date Issued: [Date]

Issued By: [Consultant / Engineer] Issued To: [Main Contractor]

1. Description of Non-Conformance

During the 24-hour water ponding / leakage test conducted on the Make-Up Water Tank, visible water seepage and damp patches were observed along the wall–base construction joint and selected wall surfaces.

The test results did not comply with:

Project Specifications, Approved Method Statement for Water Retaining Structures, BS EN 1992-3 / BS 8007 (Water-retaining structures)

2. Immediate Action Taken

Ponding test was stopped and water level safely reduced, Affected areas were marked and recorded, Structural Engineer instructed detailed inspection to identify leakage paths

3. Root Cause Analysis

Based on site inspection and review of construction records, the following root causes were identified:

Technical Causes - Inadequate compaction of concrete at construction joints

Poor bonding at wall base joint due to laitance presence, Improper installation of waterstop (misalignment / insufficient embedment)

Execution & Supervision Causes - Insufficient supervision during base-to-wall concreting works, Failure to strictly follow approved joint treatment method statement, Lack of pre-pour joint inspection and approval

Root Cause Summary:

Leakage resulted from poor joint workmanship and ineffective quality control during construction of water-retaining elements.

4. Corrective Actions Implemented

Leakage paths traced and marked, Affected joint areas exposed and cleaned

Chemical injection (PU/epoxy) carried out at leaking joints, Surface cracks sealed using approved waterproof repair mortar, Curing completed as per manufacturer’s recommendations, Repeat ponding test conducted for 48 hours

Result: No leakage observed Status: Satisfactory

5. Preventive Actions

To prevent recurrence, the following measures were implemented:

Mandatory joint inspection checklist prior to concreting, Strict verification of waterstop installation, Enhanced supervision for water-retaining structures, Toolbox briefing on water-tight concrete and joint treatment, Increased curing duration and monitoring

6. Risk Assessment Review

The Contractor has reviewed and updated the Risk Register to include:  Increased risk severity for joint leakage

Additional mitigation controls for water-retaining works

7. Conclusion

The non-conformance has been satisfactorily rectified. Corrective and preventive actions have been implemented and verified. The Consultant recommends closure of this NCR.

NCR Status: Closed Verified By: [Name / Designation] Date: [Date]