152
6700SR Refrigerated Sampler
The persons stationed at the surface should
also function as guards to keep people and
vehicles away from the manhole opening. To
avoid a serious injury, a person should not be
lifted out of a manhole by his arm unless it is a
dire emergency.
“When more than one person must enter a
manhole, the first person should reach the bot-
tom and step off the ladder before the next one
starts down. When two men climb at the same
time, the upper one can cause the lower one to
fall by slipping or stepping on his fingers.
“5.
Traffic Protection
. In addition to traffic
cones, markers, warning signs, and barricades,
a vehicle or a heavy piece of equipment should
be placed between the working area and
oncoming traffic. Flashing warning signals
should be used to alert drivers and pedestrians.
Orange safety vests should be worn by person-
nel stationed at the surface when the manhole
is located in a vehicular traffic area.
“6.
Falling Objec
t. All loose items should be
kept away from the manhole opening. This
applies to hand tools as well as stones, gravel
and other objects.
“7.
Removing the Covers
. Manhole covers
should be removed with a properly designed
hook. Use of a pick ax, screwdriver, or small
pry bar may result in injury. A suitable tool can
be made from 3/4-inch round or hex stock. Two
inches of one end should be bent at a right
angle and the other end should be formed into
a D-handle wide enough to accommodate both
hands. Even with this tool, care must be exer-
cised to prevent the cover from being dropped
on the toes. The 2-inch projection should be
inserted into one of the holes in the cover, the
handle grasped with both hands, and the cover
lifted by straightening the legs which have
been slightly bent at the knees.
“8.
Other Precautions
. Other precautions
which should be taken when entering a man-
hole are:
•
Wear a hard hat.
•
Wear coveralls or removable outer garment
that can be readily removed when the work
is completed.
•
Wear boots or nonsparking safety shoes.
•
Wear rubberized or waterproof gloves.
•
Wear a safety harness with a stout rope
attached.
•
Do not smoke.
•
Avoid touching yourself above the collar
until you have cleaned your hands.
“9.
Emergencies
. Every member of the crew
should be instructed on procedures to be fol-
lowed in cases of an emergency. It is the duty of
each crew chief to have a list of emergency
phone numbers, including the nearest hospital
and ambulance service, police precinct, fire sta-
tion, and rescue or general emergency number.
“10.
Field Equipmen
t. The following equip-
ment will be available for use:
Blowers Gloves
Breathing apparatus Hard Hats
Coverall Harnesses
First aid kits Manhole irons
Emergency flashers Pick axes
Flashlight Rain slickers
Mirror Ropes
Gas detectors Safety vests
Gas masks Traffic cones
Waders”
Lethal Atmospheres in Sewers
The following is an article written by Dr. Rich-
ard 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 func-
tioning 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 procedures.
“It is less important to know just what the haz-
ardous components of sewer atmospheres are,
as safety precautions should in general be
broadly applicable, but there should be a rea-
sonable understanding of this subject. It is dis-
turbing to see statements in print that do not
reflect true conditions.
“One of the most common errors is the assump-
tion that people have died from a lack of oxy-
gen. The human body is able to function very
well with substantially reduced oxygen concen-
trations. 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.
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