Inside the 32-hour operation to contain Mumbai–Pune Expressway gas leak

PUNE: The 32-hour-long operation to neutralise a leaking propylene gas tanker on the Pune–Mumbai expressway threw a harsh spotlight on the lack of preparedness, specialised manpower, and equipment within the state's hazardous materials (hazmat) response system, disaster management experts said.

The long-winded series of events began around 5pm on Tuesday evening, when a tanker carrying nearly 21,000kg of highly flammable propylene gas overturned near the Adoshi tunnel.


Bhalchandra Chavan, director of the state disaster management department, told TOI, "We could not operate at the site as we did not have the capabilities and trained personnel to operate in such an environment. We were totally dependent on private agencies that eventually helped us. To tackle such emergencies, we will take the necessary steps and train our personnel."

A senior official from state disaster management added, "As multiple agencies were on board and since the gas was highly inflammable, we took extra precautions to ensure the safety of commuters and personnel involved in the operation. This took extra time since the operation was in the ghat section and there was huge traffic congestion. So, it hampered the operation and thereby consumed extra time."

Despite the gravity of the situation, specialised response teams did not reach the site for several hours. Officials confirmed that the operation eventually stretched to over 32 hours not because of the complexity alone, but due to delays in mobilising trained hazmat experts and appropriate equipment.

Technical intervention was finally led by a private agency, Mec Elec Industrial Services, whose team reached the site only on Wednesday morning. By then, propylene continued to escape the tanker. "This was not a conventional fuel spill. Propylene is a compressed, highly volatile gas. Any wrong move could have triggered a massive blast," said a senior disaster management official, pointing out that most state agencies lacked hands-on experience in such scenarios.

ZN Gawade, technical director of Mec Elec Industrial Services (MEIS), Thane, a private agency which played a crucial role in the operation, told TOI that the situation on the ground was extremely volatile and critical.

"All three top-mounted ball valves on the tanker were damaged in the rollover and were leaking. Liquid propylene was discharging from every connection, forcing authorities to stop traffic in both directions. Lower Explosive Limit readings were alarmingly high even 500m from the site, underscoring the severe explosion risk," he said.

Working under life-threatening conditions, the response team managed to arrest two out of three leaks — one liquid and one vapour valve. The third valve, however, posed a formidable challenge. Bent sharply during impact, its handle jammed against the weld cap, making operation impossible while liquid propylene continued to escape, officials said.

Gawade reached the site on Wednesday morning, travelling against traffic flow in a police-escorted ambulance. After a detailed technical assessment, the team opted for a high-risk decanting strategy — transferring the tanker's contents through the single operable vapour valve into multiple empty propylene tankers.

"The objective was to reduce the liquid level inside the damaged tanker until the leaking valve began releasing vapour instead of liquid, significantly lowering the hazard," he said.

"By around 4.30pm, specialised transfer hoses were connected and liquid transfer was initiated using pressure differential, with receiving tankers carefully depressurised. The process was repeated thrice, each transfer conducted with extreme caution due to loosened valves and mechanical instability," said Madhav Divekar, director of MEIS.

Once the leaking valve began venting vapour — indicating the liquid level dropped below roughly 50% — authorities prepared for the next critical phase: lifting the overturned tanker. The operation was carried out with extensive multi-agency support, including the police, NDRF, fire brigade, and other state and local agencies. Four cranes and multiple fire tenders were deployed, and the plan was rehearsed in detail before execution, Divekar said.

"As anticipated, the leak briefly intensified when residual liquid contacted the damaged valve via the dip pipe. The response team swiftly arrested the final leak, preventing escalation at a critical moment. At around 1.30am on Thursday, the tanker was escorted through the ghat section under strict safety supervision," he said.

"Despite still containing a significant quantity of propylene, another delicate operation was undertaken, partially opening the bent liquid valve to decant additional product into a fourth tanker. The tanker was finally transported to the Khalapur tanker testing station, reaching the facility at around 5am. By then, the technical team worked continuously for almost 36 hours, navigating one of the most complex and hazardous compressed-gas response operations witnessed on an Indian highway in recent years," Divekar added.

What needs to be done immediately

• A clearly defined, legally binding SOP must be put in place for responding to chemical and gas tanker emergencies
• It should spell out roles of oil companies, district administrations, police, fire brigades, and disaster response teams, along with strict response timelines
• Petroleum companies, gas refineries, and chemical manufacturers must be mandated to deploy dedicated rescue and recovery vans, equipped to handle compressed gas leaks
• These units should be strategically stationed along major highways and industrial corridors to ensure rapid response
• Movement of highly hazardous gas tankers should be restricted to designated time windows — preferably during low-traffic hours — to minimise public risk and allow quicker isolation of accident sites if required
• Drivers transporting hazardous materials must undergo compulsory training in emergency response
• Each tanker should carry a basic emergency kit capable of addressing minor leakages, along with real-time communication systems to alert authorities instantly
• State govts need to invest in specialised training for fire services, police, and disaster management personnel to handle hazardous material emergencies
• Regular mock drills on highways and near industrial hubs must be institutionalised

Growing risk on highways

• The scale of hazardous material movement across the country is staggering
• Nearly 1,000 propylene gas tankers travel daily from refineries in Kochi, Visakhapatnam, Chennai, and Jamnagar, supplying industries across India
• In addition, around 4,000 ammonia tankers originate from Maharashtra's industrial hubs such as Taloja and Chembur, moving to southern states and other regions
• Experts warn that while propylene is highly flammable, an ammonia leak would be far more dangerous, releasing toxic gases that could make containment virtually impossible in densely populated or high-traffic areas

Expert Speak
India has thousands of hazmat tankers moving daily. Therefore, it is essential to have designated routes for transportation of ‘dangerous goods' across highways to prevent incidents like this

— Amit Bhargava | Co-founder & CEO of Canada-based EnviroApp (hazmat shipping solutions company)