Gas Build-ups in Industrial Sewer Lines, A Critical Operational Risk

Toxic gas accumulation in industrial sewer networks is an overlooked threat. It affects safety, plant continuity, and most importantly, surrounding communities.

Gas forms as a result when wastewater and sludge degrade without oxygen in confined or stagnant segments of these networks. Among the most common gases produced from such reactions are Hydrogen Sulfide and Methane, and such gases can pose life-threatening risks when they combine with low pH discharge or heavy industrial load.

The Extent of the Issue

The Giaspura gas leak incident in Ludhiana on April 30, 2023, resulted in the deaths of 11 people, including children. Hydrogen Sulfide had escaped from a sewer line near an industrial area, and investigators identified acidic industrial effluent and blockages as factors that played a role in the incident.

While this occurred in a mixed residential and industrial locality, the underlying failure mechanism is the same. Inside plants, sewer systems still run below the ground or in hard-to-observe locations, and monitoring continues to be limited. Gas accumulation, in particular, as was the case in the Giaspura incident, does not always present warning signs before exposure occurs.

What Plant Managers Need to Consider

Considering the stakes of such hazardous outcomes, it’s key that those with the responsibility of ensuring the safe operations are ahead of the curve, predicting such build-ups rather than reacting to them. That’s why they should know that:  

• Gas formation risk increases where sludge accumulates, flow is restricted or pH levels drop.

• Hydrogen Sulfide and Methane can displace oxygen, leading to sudden collapse during manual entry or cleaning.

• Corrosion from gas can also weaken pipelines, chambers and equipment, increasing downtime and unplanned repair.

Among the other common telltale signs of gas build-up are persistent odor near access points, repeated manual cleaning needs, sediment accumulation in chambers, and inconsistent gas readings without an identifiable cause.

The Operational Takeaway

Sewer networks are critical infrastructure within a facility, but it’s hard to know what’s going on in them, let alone predicting the same. That’s why treating them as secondary systems introduces risk, which can be prevented with the right approach.

Giving network assessments the due they deserve, keeping a close watch on high-sediment zones, and adhering to comprehensive confined-space entry protocols can go a long way in bolstering the safety of sewer networks from gas build-ups.