4220 Flow Meter
Appendix D General Safety Procedures
“10. Field Equipment. The following equipment will be available for use:
Blowers | Gloves | Traffic cones |
Breathing apparatus | Hard Hats | Coveralls |
Harnesses | First aid kits | Manhole irons |
Emergency flashers | Pick axes | Flashlights |
Rain slickers | Mirrors | Ropes |
Gas detectors | Safety vests | Gas masks |
Waders” |
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D.2 Lethal Atmospheres in Sewers
The following is an article written by Dr. Richard D. Pomeroy, and published in the October 1980 issue of Deeds & Data of the WPCF. Dr. Pomeroy is particularly well known for his studies, over a period of nearly 50 years, in the field of the control of hydrogen sulfide and other odors in sewers and treatment plants. He has personally worked in a great many functioning sewers. In the earlier years he did so, he admits, with little knowledge of the grave hazards to which he exposed himself.
“It is gratifying that the subject of hazards to people working in sewers is receiving much more attention than in past years, and good safety procedures are prescribed in various publications on this subject. It is essential that people know and use correct pro- cedures.
“It is less important to know just what the hazardous compo- nents of sewer atmospheres are, as safety precautions should in general be broadly applicable, but there should be a reasonable understanding of this subject. It is disturbing to see statements in print that do not reflect true conditions.
“One of the most common errors is the assumption that people have died from a lack of oxygen. The human body is able to function very well with substantially reduced oxygen concentra- tions. No one worries about going to Santa Fe, New Mexico, (elev. 2,100 meters), where the partial pressure of oxygen is equal to 16.2% (a normal atmosphere is about 21%) oxygen. When first going there, a person may experience a little ‘shortness of breath’ following exercise. People in good health are not afraid to drive over the high passes in the Rocky Mountains. At Loveland Pass, oxygen pressure is 13.2% of a normal atmosphere. At the top of Mt. Whitney, oxygen is equal to 12.2%t. Many hikers go there, and to higher peaks as well. After adequate acclimation, they may climb to the top of Mt. Everest, where oxygen is equal to only 6.7%.
“The lowest oxygen concentrations that I have observed in a sewer atmosphere was 13 percent. It was in a sealed chamber, near sea level, upstream from an inverted siphon on a metro- politan trunk. A man would be foolish to enter the chamber. Without ventilation, he might die, but not from lack of oxygen.
