Method Statement: Casting Reinforced Concrete Water Tank Walls (General)

This generic method statement outlines the sequence, controls, and quality checks for casting reinforced concrete water-retaining walls. Use with your project’s drawings, specs, and ITP. Content and sequencing align with best practice distilled from approved method statements.

1. Scope

Provide materials, labour, plant, supervision, inspections, and tests to cast RC tank walls to the required dimensions, finish, and watertight performance. Includes setting-out, reinforcement, embedded items/sleeves, formwork, concrete supply/placement/compaction, curing, formwork striking, defect repair, and records. 

2. References (project-specific to be inserted)

• Approved construction drawings & bar bending schedules
• Project specs for structural concrete & water-retaining structures
• Relevant standards (e.g., BS EN 1992, BS EN 13670, BS EN 12350/12390)
• Project ITP, QCP, and HSE plan 

3. Responsibilities

• Project/Site Engineer: setting-out, coordination, inspections, records.
• QC Engineer: ITP compliance, material approvals, cube tests, NCR control.
• HSE Officer: risk assessments, briefings, permits, housekeeping.
• General Foreman: resources, sequencing, workmanship.
• MEP Coordinator: sleeves/openings verified before pour. 

4. Resources

• Materials: approved reinforcement & spacers, formwork materials, shutter release, concrete to specified grade/exposure, waterstops where required.
• Plant/Equipment: concrete pump, vibrators (primary + standby), total station/levels, lifting gear, curing equipment.
• PPE & HSE: as per task risk assessment and method statements. 

5. HSE & Site Controls

• Toolbox talk and permit-to-pour prior to each casting operation.
• Edge protection, working platforms, and safe access/lighting.
• Only competent operators on pumps, vibrators, lifting gear.
• Housekeeping to keep pour routes clear; emergency spill kit ready. 

6. Procedure

6.1 Setting-Out

• Confirm wall alignment, thickness, and levels from benchmarks.
• Verify kicker/keys and construction joints as detailed.

6.2 Reinforcement Fixing

• Install rebar per approved schedules; maintain cover using approved spacers.
• Clean substrate and reinforcement; remove laitance/debris from kicker.
• Provide waterstops at construction joints where specified.
• Raise Inspection Request (IR) minimum 24 hours before pour for rebar & formwork pre-close checks. 

6.3 MEP/Openings

• Fix sleeves/box-outs/inserts exactly to coordinated MEP/shop drawings.
• Raise separate IR for MEP penetrations and obtain clearance prior to shutter close. 

6.4 Formwork Erection

• Use modular/formwork system suitable for hydrostatic pressure of wall pour.
• Treat contact faces with approved release agent; ensure tight joints.
• Provide braces/ties as per system design; check plumb/line and stability.
• Close form with water-tight tie systems and seals; clean and blow out. 

6.5 Pre-Pour (Hold Point)

• Conduct pre-pour IR: dimensions, alignments, cleanliness, embedments, access, lighting, pump reach, vibrator availability, cube/testing plan, curing materials ready.
• Confirm concrete class, slump, max aggregate, and admixtures approved. 

6.6 Concrete Delivery, Placement & Compaction

• On arrival: verify temperature & slump; reject non-conforming loads.
• Place in layers ~300 mm; limit free drop to ≤1.5 m; avoid segregation.
• Poker vibrate each layer thoroughly; do not vibrate rebar directly; overlap zones to eliminate voids/honeycombs; avoid over-vibration.
• Maintain continuous pour to prevent cold joints; if unavoidable, form as detailed with waterstops/surface preparation. 

6.7 Finishing & Curing

• Close to finished level; seal around protrusions/sleeves as required.
• Begin curing immediately (membrane, wet hessian, or forms retained) to specified duration; protect from shock, vibration, and thermal extremes. 

6.8 Striking (De-shuttering)

• Observe minimum striking times and confirm sufficient in-situ strength.
• Never use crane to “break” cohesion—use proper wedges/pry bars; remove ties in sequence while maintaining stability; protect arrises. 

6.9 Defects & Repairs

• Inspect for honeycombs, fins, blowholes; repair with approved method/material after Consultant/QC agreement. Continue curing after repair. 

7. Quality Control & Tolerances

• Dimensional: section ±5 mm (≤400 mm thickness), verticality 1/500, position and level per project tolerances.
• Surface: free from voids, tie-hole treatment as specified.
• Testing: cubes/cores as per ITP (typ. one set per agreed volume or pour), plus slump/temperature records; water-tightness/hydrotest per spec. 

8. Inspection & Testing Plan (ITP) – Typical Hold/Witness Points

1. Rebar & Waterstop Inspection (HOLD) – cleanliness, cover, laps, anchors.
2. Formwork Pre-Close (HOLD) – alignment, pressure bracing, seals.
3. MEP Penetrations (WITNESS/HOLD) – locations, sizes, sleeves.
4. Pre-Pour (HOLD) – materials approvals, test plan, access & safety.
5. Concrete Tests (WITNESS) – slump/temperature/cubes per load/shift.
6. Post-Pour (WITNESS) – finish, curing, records.
7. Striking (WITNESS) – timing, stability, surface checks.
8. Defect Repair (WITNESS) – method & acceptance. 

9. Records & Documentation

• IRs, cube results, delivery tickets, calibration certificates (pump/vibrators), manpower/plant logs, as-built surveys, NCRs/CARs (if any), strike records, and curing log. 

10. Acceptance Criteria

• Dimensions and verticality within tolerance; surface sound and repaired areas accepted; test results meeting specified strength; watertightness confirmed by specified hold test (e.g., 24–72 h hydrotest or equivalent).