Page 587 - Fair, Geyer, and Okun's Water and wastewater engineering : water supply and wastewater removal

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14.16 Safety and Hazards Prevention 543

Connection point of new
line to existing line 3,000 ft
1 2
3
Direction of flow

30˝ by pass line
New line under construction
(66˝ |D)
Existing line
to be abandoned

# Manholes
Pump
Approx. Loc. of “down” workers
Rescue entry points (Not to scale)
Figure 14.22 Plan for Laying the Sewer. Conversion factors: 1 ft 0.3048 m; 1
1 in. 25.4 mm

During this time, sewage seeped/flowed past the dike and extended approximately 480 ft
(146.3 m) into the newly constructed line. This sewage had to be removed before the con-
tractor could proceed with grouting the pipe joints.
The contractor replaced the sandbag dike with a steel plug to eliminate further seep-
age. A gasoline engine–driven pump was placed upstream of the plug so that the existing
sewage could be removed from the pipe. The pumping procedure required a laborer to
enter the new line at manhole 2, walk downstream approximately 1,200 ft (365.8 m) to the
pump, fuel the gasoline engine, start it, and exit back through manhole 2. This procedure
was performed on a 3-day cycle. At no time was the atmosphere in the pipe tested prior to
entry, nor was there mechanical ventilation to remove air contaminants.
This procedure was not removing the sewage quickly enough and it was decided to in-
crease this cycle to three times per day. On the day of the accident, the labor foreman and
one worker (his son) followed the procedure of starting the pump. The two workers re-
turned to manhole 2 to repeat the procedure of refueling the pump. However, manhole 2
had been covered with plywood and framed over in order to have concrete poured the fol-
lowing day. So the two had to enter the pipe from the point of construction. Each carried a
flashlight and the worker carried a can of gasoline. They began walking the 3,000-ft (914.4-m)
distance to the pump. After passing manhole 3, they took a short break and proceeded past
manhole 2 toward the pump. Approximately 750 ft (229 m) past manhole 2, the two came
to the board used to mark the water line. While the foreman was moving the board and
counting the pipe length to determine how far the water had receded, the worker went on
ahead to fuel the pump and start it. After noticing haze in the sewer, the foreman told the
worker to keep talking so he could tell if anything was wrong. Shortly the foreman heard
the worker attempt to start the pump four times and then say, “I feel dizzy.” The foreman
ordered the worker out of the pipe. The worker started to leave, dropping his flashlight and
stumbling in his unsuccessful attempt. By the time the foreman reached the worker, the
worker was down and unresponsive. After failing to carry the worker out, he propped him
up out of the water and told him he was going for help. The foreman walked, crawled, and