Carbon Monoxide (CO)
The acute effects produced by carbon monoxide in relation to ambient concentration in parts per million are listed below:
35 ppm – Headache and dizziness within 6 to 8 hrs of constant exposure
100 ppm – Slight headache in 2 to 3 hrs
200 ppm – Slight headache within 2 to 3 hrs; loss of judgement
400 ppm – Frontal headache within 1 to 2 hrs
800 ppm – Dizziness, nausea, and convulsions within 45 min
1,600 ppm – Headache, tachycardia, dizziness, and nausea within 20 min; death in less than 2 hrs
3,200 ppm – Headache, dizziness and nausea in 5 to 10 min. Death within 30 min
6,400 ppm – Headache and dizziness in 1 to 2 min. Convulsions, respiratory arrest, adn death in less than 20 min
12,800 ppm – Unconsciousness after 2 to 3 breaths. Death in less than 3 min
1 ppm – Slight symptoms after several hrs of exposure
10 – 15 ppm – Irritates throat
30 ppm – Causes coughing
40 – 60 ppm – Dangerous in 30 min
1000 ppm – Fatal in a few breaths
Chlorination Safety Precautions & Facts:
If you have a leak in a cylinder, rotate the leak so gas and not liquid is escaping.
One volume of liquid chlorine yields approximately 450 volumes of vapor.
Never throw a leaking chlorine cylinder into water or hose it down. This will increase the size of the leak and worsen the situation.
Use new lead gaskets when installing chlorine cylinders.
Turn the chlorine valve on and right back off, test for leaks.
Never open the cylinder valve more than one turn.
Chlorine gas is about 2½ times heavier than air.
Is highly flammable and may form explosive mixtures with air.
The explosive range of methane is 5-15%
Methane is violently reactive with oxidizers, halogens, and some halogen containing compounds.
Methane is also an asphyxiant and may displace oxygen in an enclosed space.
Several hazards exist when performing excavations in the collection system. Some of these are listed below.
All work in an excavation must be supervised by a qualified person.
Remove hazards to employees, trees, boulders, poles, etc
Inspect excavation after rain, freeze/thaw or anytime you suspect a problem.
Shoring or step-back any trench over 5 ft deep.
Spoil pile: move spoil pile far enough away so it won’t fall back in the hole. At least 2 ft away on one side only, for excavations over 5 ft.
Use a ladder for access for trenches 4 ft + every 25 ft is required, don’t climb on shoring.
Don’t jump across trenches install a crossing.
Don’t excavate under an existing structures foundation without shoring bracing or underpinning.
Use no existing retaining walls or structure as a retaining wall for the excavation.
Barricade or tape off all potentially hazardous areas.
Use diversion ditches, dikes or other measures to keep water out of the excavations.
Use additional bracing on the shoring if near a road, railroad or other sources of vibration or external load.
Sloping and Benching
If no shoring is used the side walls of the excavations should be sloped at ¾ horizontal to 1 vertical.
Benching is used for deeper excavations, starting at 3.5 feet in depth the typical bench is 2 feet wide for each 2 feet of additional depth.