Navigating the Hazards of Hydrogen Sulfide

Understanding the Hazard

Hydrogen sulfide (H2S), one of the main components of what is commonly referred to as “sewer gas,” is an inevitable byproduct of domestic wastewater. Recognizable by its distinct smell of rotten eggs or burnt rubber at low concentrations, H2S presents challenges and dangers within wastewater systems. While minor household encounters with H2S—such as from a dried-out P-trap—are not life-threatening, its presence in confined spaces within collection systems and treatment plants can be lethal.

H2S exposure is measured in parts per million (ppm), with OSHA guidelines setting strict limits to protect workers’ health. The permissible exposure limit (PEL) is 20 ppm, not to be exceeded during an eight-hour shift—except for brief exposures up to 50 ppm for no more than 10 minutes, provided no other measurable exposure occurs.

High concentrations of H2S can cause olfactory fatigue, making the gas undetectable by smell after 100 ppm and increasing the risk of fatal exposure without warning. This makes H2S one of the leading causes of occupational fatalities in the wastewater industry.

Dangers of H2S

• Low Concentrations (0 ppm – 20 ppm): Can cause irritated eyes, nose, throat, and respiratory system, including eye tearing, coughing, or shortness of breath. Effects may be delayed.
• Moderate Concentrations (20 ppm – 100 ppm): Can cause severe eye and respiratory irritation, coughing, and difficulty breathing, possibly accompanied by headaches, dizziness, nausea, and vomiting.
• High Concentrations (100 ppm – 1000 ppm): Can lead to shock, convulsions, inability to breathe, rapid unconsciousness, coma, and even death within a few breaths—or a single breath—depending on the concentration.

Filling a Critical Industry Need

Despite its dangers, H2S is unavoidable in wastewater management. It’s found in collection systems, pump stations, and treatment plants, all of which require regular inspection, maintenance, and flow monitoring to ensure efficiency. These tasks demand specialized equipment, strict safety protocols, and a workforce ready for high-risk environments.

GBA’s Omaha office specializes in high H2S collection system inspections and flow monitoring. Since 2010, we’ve partnered with the City of Omaha’s sewer maintenance teams to perform quarterly equipment testing, calibration, cleaning, structure inspections and repairs. This long-standing partnership reflects our commitment to safety, technical excellence, and client service in high-risk wastewater operations.

Rigorous Training and Safety Protocols

Working in H2S environments requires comprehensive safety training and adherence to regulatory standards.

Supplied Air Respirator (SAR) and Self-Contained Breathing Apparatus (SCBA) operations require comprehensive training to ensure safety and compliance. This includes:

• 10-Hour OSHA Construction and OSHA Standards Confined Space Entry training
• Proficiency in OSHA 1910.134 respiratory protection protocols
• Hands-on SAR/SCBA training with annual in-house re-certification
• Training in SAR/SCBA setup, disassembly, equipment operation, and emergency response
• Annual medical evaluations to confirm fitness for respiratory protection equipment

At GBA, our team not only meets these requirements but continuously trains to stay prepared for H2S risks, ensuring safety for themselves and those around them.

Specialized Equipment for High-Risk Environments

Our approach to H2S-related work includes advanced safety equipment tailored to field conditions:

1. 1. Blower Systems (Allegro Industries COM-PAX-IAL Blower): Ventilates confined spaces, exhausting contaminated air or supplying fresh air to maintain gas concentrations within OSHA’s PEL.
   2. SAR/SCBA Setups: Includes compressors, pre-filters, breather boxes, air cylinders, and full-face respirators. SAR/SCBA entries require at least three trained team members—one diver and two attendants—to manage equipment, monitor safety, and maintain communication.
   3. Personal Protective Equipment (PPE): Depending on H2S concentration, team members may use Tyvek suits, ENVIRO diving suit, coveralls, harnesses, and respiratory protection to reduce exposure risks.

Our equipment protocols include redundancies and adaptability, allowing rapid response to changing site conditions and hazards.

A Culture of Safety and Excellence

GBA Omaha’s team has developed the skills, training, and equipment necessary to manage high-risk environments effectively. Our experience ensures we can support essential wastewater infrastructure safely and reliably, helping communities maintain critical systems while protecting the health and safety of all involved.