Mobile Concrete Batching Machine Safe Work Method Statement

Mobile concrete batching machine operation does not require specific licensing under national plant licensing schemes as these machines are not classified as high-risk plant under the WHS Regulations. However, operators must be trained to competency by the employer under the WHS Act 2011 which requires persons operating plant to be adequately trained, assessed as competent, and supervised appropriately. Training should cover machine components and operation, concrete technology including mix design interpretation, hazard identification and control measures, emergency procedures, and quality control requirements including slump testing. Many employers use manufacturer-provided training programs ensuring operators understand machine-specific features and safety systems. Operators also require general construction induction (White Card) for work on construction sites. For machines with integrated weighbridge systems, operators may benefit from trade training in batching plant operation although this is not legally required. Employers must maintain training records documenting each operator's training content, dates, assessment results, and authorized equipment.

Crystalline silica is a component of cement and aggregates with workplace exposure standard of 0.05 mg/m³ (8-hour TWA) due to carcinogenic and respiratory hazard properties. Control hierarchy starts with elimination through substitution which is not feasible as cement is essential to concrete production. Engineering controls include dust extraction systems on cement silos capturing dust during pneumatic loading, silo vent filters preventing dust release during filling, enclosed conveyor systems containing dust during aggregate transfer, and water spray systems at transfer points suppressing aggregate dust. Administrative controls include work procedures minimizing dust generation, limiting worker time in high-dust areas through job rotation, and conducting air quality monitoring using personal dust monitors measuring actual exposure. Respiratory protection using P2 or P3 disposable respirators or powered air purifying respirators (PAPR) is essential final control particularly during cement loading when dust generation is highest. Respirators require fit testing ensuring proper seal, training in correct donning procedures, and clean-shaven faces where seal contacts skin. Health monitoring through periodic medical examinations including chest X-rays may be implemented for workers with sustained silica exposure documenting baseline lung function and detecting early signs of silicosis.

Mixer drums meet confined space definition under AS 2865 as they have restricted entry and exit, are not designed for continuous human occupancy, and present hazards including engulfment from material release, atmospheric hazards from cement dust or oxygen displacement, and entrapment from unexpected drum rotation. Confined space entry requires formal entry permit documenting hazard assessment, atmospheric testing, isolation verification, and authorized entry personnel. Before entry, drum must be completely isolated from energy sources through electrical disconnection, hydraulic pressure release, and mechanical locking devices preventing drum rotation. Test atmosphere for oxygen content (acceptable range 19.5-23.5%), flammable gases (must be below 5% LEL), and toxic gases including carbon monoxide. Provide continuous mechanical ventilation during entry maintaining fresh air circulation throughout drum interior. Assign standby person maintaining constant visual or communication contact with entrant and capable of initiating rescue without entering space. Equip entrants with full-body harness connected to retrieval system enabling extraction without entry by rescue personnel. Maintain entry permit throughout entry period with standby person verifying ongoing safety of entry conditions. Limit entry duration considering environmental factors including heat buildup in enclosed drum space. Emergency rescue equipment must be immediately available including retrieval systems and communication devices.

Concrete quality control during mobile batching follows requirements of AS 1379 Specification and supply of concrete and project specifications. Primary quality test is slump test measuring concrete workability performed per AS 1012.3.1 at frequency typically every 10 cubic meters, hourly, or when concrete appearance suggests variation from specification. Target slump values typically range from 80mm for low workability concrete to 160mm for highly workable mixes with tolerance of ±20mm. Additional testing may include density determination per AS 1012.3.4 verifying proper material proportioning, making compression test cylinders per AS 1012.8.1 for strength testing at 7 and 28 days, and air content measurement for air-entrained concrete per AS 1012.4.1. Operators conduct visual inspection of each batch assessing consistency, aggregate distribution, and absence of segregation. Batching computer provides weight records for each material documenting actual quantities loaded versus target quantities with tolerances typically ±2% for cement and ±3% for aggregates per AS 1379. Calibration verification of weighing systems should occur monthly using certified weights verifying accuracy within ±1% across operating range. Maintain comprehensive production records including batch tickets, test results, calibration records, and material delivery documentation providing traceability of concrete properties and compliance with specifications. Non-conforming concrete should not be placed and must be rejected documenting reasons for rejection and disposal methods.

Securing mobile batching machines when not operating prevents unauthorized access, vandalism, theft, and inadvertent operation by unqualified personnel. Implement lockout procedures isolating electrical power through main disconnect switch in locked-off position with personal locks applied. Apply lockout tags identifying person who applied locks and date of application. Lock control cabin preventing access to operating controls with keys stored in designated secure location. Secure storage hoppers and access hatches with locks or padlocks preventing access to materials. Install security fencing around machine and material stockpiles if operating in unsecured site areas. Consider security systems including motion sensors, cameras, or site security patrols for high-value equipment in remote locations. Drain water systems in freezing conditions preventing ice damage to pumps and piping. Cover exposed equipment protecting from weather particularly control panels and electrical components. Document equipment condition at shift end through photos or inspection records establishing baseline for next shift comparison. For long-term storage between projects, implement comprehensive preservation procedures including lubricating all moving parts, draining all water systems completely, covering exposed surfaces, and disconnecting batteries to prevent discharge. Position machine considering security, drainage, and access for maintenance during storage period. Maintain insurance coverage throughout storage period as equipment value remains high and weather damage risk exists.

Concrete washout water has pH typically exceeding 12 due to cement alkalinity and contains suspended solids from cement and aggregates making it unsuitable for discharge to stormwater systems or waterways. Environmental regulations under state Environmental Protection Acts prohibit discharge of contaminated water causing environmental harm with significant penalties for violations. Establish designated washout area with containment preventing uncontrolled discharge. Common methods include excavated washout pit lined with impermeable membrane, portable washout bins specifically designed for concrete waste capture, or mobile water treatment systems neutralizing pH and settling solids. Collected washout water should be allowed to settle with clear water potentially reused for dust suppression or future washdowns reducing water consumption. Settled solids form sludge requiring disposal as solid waste at licensed facility. For large operations, consider pH neutralization using acid injection systems or carbon dioxide bubbling reducing pH to acceptable discharge range of 6.5-8.5 before discharge subject to regulatory approval. Never discharge washout water directly to ground, stormwater drains, or waterways as alkalinity kills aquatic life and suspended solids smother waterway beds. Maintain washout records documenting quantities generated, treatment methods applied, disposal destinations, and waste tracking documentation. Design washout systems considering daily washout volumes typically 500-1000 liters per machine ensuring adequate capacity throughout project duration. Inspect containment systems regularly ensuring integrity maintained preventing leaks and overflow particularly after heavy rain.