In September 2010, a 48-year-old male worker (Victim I) employed by a village Department of Public Works (DPW) and a 51-year-old male volunteer firefighter (Victim II) of the village Fire Department (FD) died after entering a sewer manhole. The manhole was located behind the firehouse. The Fire Chief and a firefighter were called in by the DPW general foreman (GF) to unlock the firehouse and move the fire truck so it would not be blocked by the DPW utility truck while working at the manhole.
Victim II also arrived to offer assistance. The manhole was five feet in diameter and 18 feet deep with an opening 24 inches in diameter (see photo). Victim I started climbing down the metal rungs on the manhole wall wearing a Tyvek suit and work boots in an attempt to clear a sewer blockage. The DPW GF, the firefighter and Victim II walked over to observe. They saw Victim I lying on the manhole floor motionless. They speculated that he had slipped and fallen off the rungs and injured himself. The Fire Chief immediately called for an ambulance. Meanwhile, Victim II entered the manhole to rescue Victim I without wearing any respiratory protection. The firefighter saw that Victim II fell off the rungs backwards while he was half way down and informed the Fire Chief. The Fire Chief immediately called for a second ambulance and summoned the village FD to respond. The FD responders arrived within minutes.
The Assistant Fire Chief (AFC) donned a self-contained breathing apparatus. He could not go through the manhole opening with the air cylinder on his back. The cylinder was tied to a rope that was held by the assisting firefighters at the ground level. The AFC entered the manhole with the cylinder suspended above his head. He did not wear a lifeline although there was a tripod retrieval system. He secured Victim II with a rope that was attached to the tripod. Victim II was successfully lifted out of the manhole. The AFC exited the manhole before a second rescuer entered the manhole and extricated Victim I in the same manner. Both victims were transported to an emergency medical center where they were pronounced dead an hour later. The case of death for both victims was asphyxia due to low oxygen and exposure to sewer gases.
CONTRIBUTING FACTORS
Contributors to the DPW worker’s death:
- DPW no-entry policy for permit-required confined spaces was not enforced
- DPW permit-required confined space program was not implemented
- Employees were not trained on confined space hazards, and proper entry and rescue procedures
Contributors to the firefighter’s death:
- Firefighters were not trained in confined space rescue procedure
- FD confined space rescue protocol was not followed
- Standard operating procedure (SOP) was not established for confined space rescue
INTRODUCTION
In September 2010, a 48 year-old male worker (Victim I) employed by a village Department of Public Works (DPW) and a 51 year-old male volunteer firefighter (Victim II) of the village Fire Department (FD) died after entering a sewer manhole.
Victim I started working for the village DPW as a highway/road maintenance worker in 1980. He was promoted to a road maintenance foreman in 2005 supervising approximately 20 workers with another foreman. The DPW maintains highway and village roads, catch basins and sanitary and storm water sewer systems, including approximately 500 manholes. The DPW has two high water pressure jet trucks for clearing sewer blockages. The smaller jet truck was purchased in 1993; it has a 500 foot long hose and 400 gallon water tank. The bigger jet truck that was purchased in 2005 has a 1,000 gallon water tank and 350 foot long hose as well as a vacuum with a 12
inch diameter vacuum hose. These jet trucks deliver a high pressure water jet up to 1,500 pounds per square inch through a steel nozzle (jet head). The jet head can be lowered and guided into the sewer pipe with a rope and a tool with a long handle at the ground level (no worker has to enter a manhole to place the jet head). Once inside a sewer pipe, the jet head and jet stream pound, loosen and clear the sewer line. The DPW purchased both trucks with the intention of preventing workers from entering manholes. The DPW developed a permit-required confined space program in the 1990’s but stopped implementing it in 2004 when the last trained employee retired. On April 26, 2007, the DPW provided an 8-hour permit-required confined space training that was conducted by a safety consulting firm. Seventeen highway workers including Victim I attended the training. The DPW purchased a four-gas (oxygen, hydrogen sulfide, carbon monoxide and combustible gases) monitor and a retrieval tripod to be used during the training. According to the village and DPW management, a permit-required confined space program was never developed because the DPW policy prohibited workers from entering a manhole.
However, the no-entry policy was not enforced. Numerous incidents of workers entering manholes were confirmed by employee interviews conducted by the PESH investigation.
Victim II joined the village FD as a volunteer firefighter in 1977. The FD is comprised of all volunteer firefighters; it has six fire companies and responds to fire and carbon monoxide alarms, vehicle fires, as well as extrication and rescue calls. The firefighters received training on first aid and cardiopulmonary resuscitation (CPR), Hazardous Waste Operations and Emergency Response and Essentials of Fire Fighting.
The FD did not have a permit-required confined space rescue program and the firefighters did not
receive training on permit-required confined space rescue procedures. The neighboring town has a TRT that was specialized in high risk rescue operations including confined space rescues. According to the agreement between the village and the town, in case of an emergency rescue beyond the FD trained capability, the FD would summon the TRT to conduct the rescue.
INVESTIGATION
At approximately 4 p.m. on a holiday afternoon, the DPW highway crew was dispatched to respond to a homeowner’s call reporting a sewer backup in his basement. The DPW GF called Victim I and another worker to assist. The GF met up with Victim I and the worker who drove the bigger jet truck to the site. They were to trace the sewer line downstream from the homeowner’s basement and run the high pressure water jet to clear the blockage.
The first manhole downstream was full to the top. They proceeded to the next two manholes and jetted the sewer line, but could not clear the blockage. They then drove to the firehouse where the next three manholes were located: one was in the front, one was inside and the other was in the back of the firehouse. The DPW crew first worked on the manhole in front of the firehouse using the jet truck.
Meanwhile the GF, who was also a volunteer firefighter, called the Fire Chief to unlock the firehouse so that they could work on the manhole inside the building.
The jet truck ran out of water while the DPW crew was jetting the first manhole. Victim I and the DPW worker drove the jet truck to a nearby fire hydrant to fill its water tank. At this point, the Fire Chief and a firefighter arrived; they unlocked the firehouse and drove the fire truck out so that it would not be blocked. Victim II, who was not officially dispatched, also arrived at the firehouse to offer assistance.
The GF inspected the manhole inside the firehouse; it was still clogged. He then proceeded to the manhole that was behind the firehouse (the incident manhole) accompanied by the firefighter and Victim II. The incident manhole was built two years ago. It was located on a hill approximately five feet from the firehouse and fifty feet from the street. The manhole cover was covered with brush which the firefighter cleared with a shovel. The GF considered calling for the small jet truck with a longer hose for a better access to the manhole. The GF, firefighter and Victim II were sitting at a picnic table that was approximately fifteen feet from the manhole when Victim I came back from filling the jet truck. The GF was calling for the small jet truck on his cell phone. Victim I walked to the manhole and opened the cover with the shovel.
The manhole was five feet in diameter and 18 feet deep with an opening of 24 inches in diameter.
Two sewer pipes were connected at opposite sides of the vertical manhole wall in 180 degrees near the bottom. An 8 inch diameter half pipe that was cemented into the manhole floor connects the two sewer pipes. There were metal access rungs mounted on the manhole wall; all rungs were sturdy and intact. Victim I examined the manhole and commented to the others that it was clogged and he did not smell any odor. He was wearing a Tyvek suit and work boots; he was not wearing any respiratory protection.
With a shovel in his hand, he started climbing down the metal rungs. The men who sat at the picnic table including the GF all saw that Victim I was entering the manhole. They all got up and walked over to the manhole to observe. As soon as they got to the manhole, they saw victim lying on the manhole floor motionless. At this point, they speculated that Victim I had slipped and fallen off the rungs and injured himself. The firefighter immediately suggested to the GF that he would go down the manhole to rescue Victim I; the GF answered “no”. The GF asked the Fire Chief to call for an ambulance. At 6:36 p.m., the Fire Chief called 911 and requested an ambulance and summoned the firefighters to respond.
The firefighter brought boots, ropes and a four-gas monitor from the fire truck to the GF who started tying the gas monitor with a rope. Meanwhile, Victim II retrieved his fire boots from his pickup, put them on, went to the manhole and started climbing down the rungs while the GF and the Fire Chief were looking on. The firefighter who was standing next to the manhole saw Victim II looking up with his eyes rolled back and falling off the rungs backwards while he was half way down. The firefighter immediately notified the Fire Chief and the GF. At 6:41 p.m. the Fire Chief placed another 911 call to request a second ambulance and summoned a full FD and TRT response. He also gave the order that no one was to enter the manhole.
The GF lowered the four-gas monitor to the bottom of the manhole and the alarm went off. The GF said that the monitor was reading 14% oxygen, while the firefighter thought the reading was 11.4%. Normal atmospheric oxygen content is 20.9%. The concentrations of hydrogen sulfide, carbon monoxide and combustible gases were not measured.
The village FD responders arrived at the scene approximately five minutes following the alarm. An exhaust fan was placed on the manhole opening facing down to ventilate the manhole while the
firefighters were setting up for the rescue operation. A retrieval tripod was set up. The Assistant Fire Chief (AFC) donned an self-contained breathing apparatus (SCBA) mask. The manhole opening was too small for him to enter carrying the air cylinder on his back. A 30-minute air cylinder was tied to a rope and the rope was held by the assisting firefighters at the ground level. The fan was removed from the manhole opening to make room for the AFC to enter the manhole and the manhole air was not monitored before the entry. The AFC entered the manhole with the air cylinder suspended above his head. He did not wear a lifeline that was secured to the tripod.
The firefighters attached an oxygen bottle with a face mask to a rope and lowered it into the manhole. A third rope for lifting the victims was secured to the tripod. Upon descending to the bottom of the manhole, the AFC first put the oxygen mask on Victim II, secured him with the rope that was attached to the tripod and then signaled for lifting. Victim II was successfully lifted out of the manhole. The AFC exited the manhole before the second rescuer, the Fire Captain entered the manhole and extricated Victim I in the same manner. Both victims were in traumatic cardiac arrest. When the TRT arrived at the site at 7:18 p.m., both victims were en route to an emergency medical center where they were pronounced dead an hour later. The cause of death for both victims was asphyxia due to low oxygen and exposure to sewer gases.
Upon arrival, the TRT immediately established a unified command with the representatives of all
responders on-site: the village police department (PD) and FD, the neighboring town PD and the county HAZMAT team. It was noted by the TRT that several firefighters were in dangerous proximity to the incident manhole with numerous fire ignition sources including cigarettes and non-intrinsically safe lighting sources. The TRT quickly cordoned off a safe zone and secured the site.
Three four-gas monitors were used to monitor the exterior atmosphere and the air inside the manhole. The TRT noted that they took extreme caution to prevent fire and explosion when removing the incident manhole cover that had been replaced prior to the TRT’s arrival. Urethane tubes were attached to all three monitors that were lowered into the manholes. The readings were taken from top to bottom incrementally. All three monitors recorded nearly identical safe readings of oxygen, carbon monoxide, hydrogen sulfide and combustible gases both inside and outside the incident manhole according to the TRT report.
The village administrator contacted the neighboring town DPW to provide assistance in clearing the sewer blockage. The town DPW was advised to use extreme caution and conduct all work at the ground level. The town DPW worked on an adjacent manhole north of the incident manhole and unplugged the sewer line hours later.
The TRT continued monitoring the air inside the incident manhole while the town DPW was clearing
the blockage. Two elevated hydrogen sulfide readings were recorded: 18 parts per million (ppm) taken approximately ¾ down the shaft and 25 ppm taken at the bottom of the manhole. The OSHA acceptable ceiling concentration (ACC) limit for hydrogen sulfide is 20 ppm.1 According to OSHA, an employee’s exposure to hydrogen sulfide should not exceed 20 ppm at any time during an 8-hour shift (with an exception of 10 minute maximum peak exposure of 50 ppm). The concentration that is immediately dangerous to life and health (IDLH) is 100 ppm. The incident manhole was continuously ventilated and monitored until the sewer obstruction was cleared and all four-gas monitors showed safe readings. The TRT response ended at 10:45 p.m.
After the fatal incident, the village administration contracted an occupational safety and health consulting firm to conduct a complete hazard assessment of the job duties assigned to the DPW workers and develop a permit-required confined space program. All DPW employees received permit required confined space entry training. A contractor was hired to conduct all confined space work until the training was completed. The DPW will perform annual program review and provide refresher training following the initial training. While all members of the village FD received confined space awareness training, a select group of firefighters received training in confined space rescue. This group of firefighters will assist the TRT in conducting a confined space rescue. The confined space awareness training was also provided to both the Police Department and the Parks and Recreation Department.