Code of practice for safety precautions to be taken when entering a sewerage system
1987 Edition

Overview of IS 11972: Scope and Essential Requirements

Scope:
This standard specifies safety precautions for personnel entering sewer systems, addressing hazards such as physical injuries, chemical and radioactive exposures, infections, toxic gases, and oxygen deficiency.

Highlights from Clause 2.1.1 and Appendix A

• Medical Fitness:
  Regular medical re-evaluations are required, tailored to the worker's age and responsibilities.

• Worker Selection:
  Procedures for choosing suitable personnel for sewer tasks, prioritizing safety and health.

• Occupational Risks:
  Includes dangers from physical trauma, hazardous substances, infectious agents, explosive or harmful vapors, and lack of oxygen.

• Safety Equipment and Instruction:
  Mandatory use of appropriate protective gear and comprehensive training on risks and equipment usage.

International System of Units (SI) Applied

Workflow Diagram: Safety Process Overview

flowchart TD
    A[Worker Selection] --> B[Medical Evaluation]
    B --> C[Safety Training & Equipment Handling]
    C --> D[Use of Protective Gear]
    D --> E[Entry into Sewer System]
    E --> F[Ongoing Monitoring & Re-assessment]

Additional Notes

• IS 11972 is a Code of Practice, not a design specification.
• It supplements other IS standards by focusing on worker health and safety.
• Adhere to local laws and treat this code as a baseline for safety protocols.

For complete procedures and equipment details, consult the full IS 11972 document.

IS 11972: Guidelines on Selecting Sewermen

1. General Instructions (Clause 2.2 & Appendix A)

• Selection depends on the nature of tasks:
  • Tasks not involving confined space entry (Appendix A-1)
  • Tasks requiring confined space entry (Table A-2, Clause 2.1.1)
• Medical re-assessment intervals vary based on age and job responsibilities (A-2.1.1).

2. Medical and Safety Obligations

• Periodic health evaluations ensure suitability for hazardous sewer activities.
• Adherence to safe working systems as outlined in Clause 1.1 is mandatory.

3. Units & Symbols (SI Units)

4. Summary of Selection Factors

• Expertise & Experience: Matched with task type.
• Health Status: Determined through medical re-examinations.
• Training: Required for confined space operations and safety protocols.

flowchart TD
    A[Identify Task Type] --> B{Is Confined Space Entry Required?}
    B -- No --> C[Select per Appendix A-1]
    B -- Yes --> D[Apply Table A-2 Standards]
    D --> E[Medical Evaluation]
    C --> E
    E --> F[Safety Training & Procedures]
    F --> G[Deploy Selected Personnel]

For exact medical criteria and detailed guidance, refer to Appendix A and Table A-2 of IS 11972.

IS 11972: Gas Hazard Safety in Sewer Operations

Important Safety Measures (Clause 3.1)

• Prohibit smoking and open flames; avoid spark generation.
• Install warning signage around work zones.
• Employ explosion-proof electric lighting or reflective mirrors.
• Conduct atmospheric testing for toxic gases and oxygen levels; stir scum to release trapped gases.
• Entry only with safety belt and at least two standby personnel above.
• Perform gas checks every 3 minutes throughout the task.
• If hazardous gases persist, use hose masks, non-sparking tools, and approved safety lights.
• Inspect ladders meticulously; maintain at least two men ready for rescue.
• Use portable ventilation blowers (diesel-powered, flameproof, weatherproof) positioned ≥2 meters away on the leeward side.

Entry and Work Process (Clause 5.1)

Ventilation and Equipment Details

• Use forced ventilation with blower and flexible ducts.
• Blower must be diesel-driven, flameproof, and weather-resistant without spark plugs.
• Position blower ≥2 meters from manhole on leeward side.

Summary Table: Gas Testing and Safety Protocols

flowchart TD
    A[Prepare for Sewer Entry] --> B{Gas Test Result}
    B -- Safe --> C[Enter with Safety Belt & Two Men at Surface]
    B -- Hazardous --> D[Activate Ventilation Blower]
    D --> E{Re-test Atmosphere}
    E -- Safe --> C
    E -- Hazardous --> F[Delay Entry or Use Protective Gear]

IS 11972: Essential Safety Gear for Sewer Entry

Primary Protective Items (Clause 4.1)

• Helmet fitted with explosion-proof cap lamp
• Safety belt and securing ropes
• Protective gloves
• Heavy-duty waterproof attire (overall or heavy coat)
• Safety boots (knee or thigh-high with toe guards and spark-resistant studs)
• Gas masks and breathing apparatus
• Eye protection gear
• Portable lighting devices
• Non-sparking hand tools
• Portable ventilation blowers
• Gas detection instruments: safety candle lamps, Davy lamps, lead acetate papers, electronic detectors
• First aid supplies

Safety Protocols Summary (Clause 5.1)

1. Pre-operation: Inspect equipment and identify hazards.
2. On-site: Mark roads and ventilate manholes.
3. Entry: Conduct gas tests, secure safety belt, examine ladders.
4. Inside Sewer: Monitor gas levels every 3 minutes; keep communication active.
5. Post-operation: Remove tools, restore manhole covers, clear signage, notify supervisor.

SI Units Reference

Gas Testing and Emergency Preparedness

• Employ safety candle and Davy lamps, lead acetate paper, and electronic gas detectors.
• Continuous atmosphere monitoring is compulsory during sewer entry.

flowchart TD
    A[Pre-operation: Equipment Inspection] --> B[On-site: Marking & Ventilation]
    B --> C[Entry: Gas Testing & Safety Belt]
    C --> D[Inside Sewer: Continuous Monitoring & Communication]
    D --> E[Completion: Tool Removal & Site Notification]

Summary: IS 11972 mandates comprehensive protective gear, strict entry protocols, and ongoing gas surveillance to safeguard sewer workers, requiring explosion-proof and non-sparking equipment in all operations.

IS 11972: Step-by-Step Procedure for Sewer Work

Required Safety Gear (Clause 4.1)

• Helmet with explosion-proof cap lamp
• Safety belt and ropes
• Protective gloves and waterproof heavy-duty clothing
• Knee or thigh-length boots with toe protection and anti-sparking studs
• Gas masks, breathing devices, and eye protection
• Portable lighting and spark-resistant tools
• Portable air blowers and gas detection devices
• First aid supplies

Sequential Work Procedure (Clause 5.1)

Gas Hazard Response

• Always test atmosphere before entry; avoid entry if unsafe.
• Use continuous gas monitors or safety lamps.

Safety Monitoring Flowchart

flowchart TD
    A[Prepare Equipment & Check Hazards] --> B[Set Up Site & Ventilation]
    B --> C[Gas Testing & Safety Checks]
    C --> |Safe| D[Enter Sewer with Safety Gear]
    C --> |Unsafe| E[Do Not Enter]
    D --> F[Conduct Work with Gas Monitoring]
    F --> G[Complete Work & Remove Equipment]
    G --> H[Restore Covers & Clear Site]
    H --> I[Notify Supervisor & Hygiene Measures]

Important: Always comply with minimum ventilation and gas detection standards to avoid accidents in confined sewer spaces.

IS 11972: Procedures for Gas Emergency Situations

Safety Actions (Clause 5.1)

• Before Departure: Verify all safety gear; identify potential risks.
• Upon Arrival: Set up road markers; ventilate manholes (working and upstream).
• Entry: Test atmosphere; use safety belts and ropes; keep emergency equipment at hand.
• Inside Sewer: Monitor gas levels every 3 minutes; maintain communication between inside workers and surface personnel.
• After Work: Remove tools; replace covers; clear the site; notify supervisors.

Gas Emergency Response (Clause 6.1)

• Immediate Measures: Don breathing apparatus (escape sets) and sound the alarm.

First Aid for Gas Victims (Clause 6.4)

• Quickly move the affected person to fresh air.
• Position the casualty comfortably, avoiding water contact.
• If the victim wears a gas mask and breathes, ensure a rescuer remains nearby to prevent choking.
• If breathing has stopped, apply artificial respiration preferably with oxygen, or mouth-to-mouth if oxygen is unavailable.
• Keep the casualty lying down until ambulance or emergency services arrive.

Reference Units (SI Units)

Emergency Response Flowchart

flowchart TD
    A[Gas Emergency Detected] --> B[Don Breathing Apparatus]
    B --> C[Raise Alarm]
    C --> D[Evacuate Personnel]
    D --> E[Administer First Aid]
    E --> F[Contact Emergency Services]

Reminder: Maintain constant gas monitoring and communication as per IS 11972 guidelines during confined space operations.

IS 11972: Sewermen Selection Guidance

Key Aspects from Clause 2.2 & Appendix A

• Selection Based on Task: Personnel are chosen depending on whether their duties require confined space entry.
• Medical Fitness: Periodic medical examinations are compulsory for those entering confined spaces, considering age and job nature (Clause 2.1.1).
• Safe Work Practices: Emphasis on following safe methods for sewer operation.

Simplified Selection Criteria Table

Relevant Units & Definitions (SI Units)

Recommendations Summary

• Refer to Appendix A for detailed task-based guidance.
• Ensure workers are medically fit for confined space operations.
• Provide adequate training based on task requirements.
• Maintain safe work systems as stipulated by IS 11972.

flowchart TD
    A[Worker Selection Process]
    A --> B{Task Type}
    B --> C[No Confined Space Entry]
    B --> D[Confined Space Entry]
    C --> E[Basic Safety Training]
    D --> F[Medical Evaluation + Confined Space Training]

This framework guarantees safe and effective sewer operations in compliance with IS 11972.