A Guide to Safe Field Operations
U.S. Geological Survey Open-File Report 95-777
Previous--Specific Procedures and Safety
Procedures and guidelines to avoid personal injury during wading
measurements, bridge measurements, cableway measurements, boat
measurements, measurements under ice cover, indirect flood discharge,
maintenance of streamgages, and scuba diving are discussed in this
Discharge measurements using current meters are best made by wading.
Wading measurements have a distinct advantage over measurements made from
bridges, boats, or cableways in that it is usually possible to select the
best available cross sections for the measurement. However, wading
measurements represent one of the greatest potential sources of accidents
in the Division. The wide range of conditions, combined with the
relatively large number of measurements made by wading, creates the high
potential for accidents. Constant awareness of wading dangers and weather
conditions needs to be maintained to avoid accidents and potential injury.
Listed below are some safety guidelines that need to be observed:
- Review the field folder to determine the best section for making wading
measurements. Also determine if any potential risks are noted and the
maximum velocity and depths that may be encountered.
- Determine whether the river stage is rising or falling. Beware of rapid
rises in river stage when wading and anticipate and allow for changes in
flow conditions at the end of the measurement. It is a good idea to
select an object (rock, stump, mark along bank, etc.) that is just above
water surface and keep watching it to determine if the river stage is
rising or falling.
- Always probe the stream bed ahead with a rod when moving from bank to
bank. Keep your feet spread apart and alignment of legs parallel to the
flow for better stability.
- If the velocity becomes too great for safe wading do not turn around,
because when the greater area of the front or back of the body is exposed
to the current, you may be swept downstream. Back out carefully, bracing
yourself with the wading rod.
- Don't try to break the station discharge record for the maximum wading
- Wear a PFD when wading and conducting discharge measurements. Tie the
tagline securely so that you may pull yourself out, if necessary.
- Don't wear boots or waders that are too tight or too loose.
- Beware of sand channels where pot-holes, quicksand, and scour can be
- Beware of slick, steep banks, and swampy areas.
- Watch for debris and ice drifting.
- Beware of streams with partial or thin ice cover and especially of
ice-covered streams at the time of incipient breakup. To venture out on
such ice, tie yourself to some stable object ashore or overhead, if
available. Otherwise, stay off and return on another day.
- At controlled or regulated streams, consult recorder or instruction for
pattern of regulation. Contact dam, reservoir or gate operators before
Bridges are often used for making discharge measurements of streams that
cannot be waded. Equipment needed in making bridge measurements differs
from that used in wading measurements in that a portable metal crane is
often used to mount a reel and suspend the meter, sounding weights, and
cable over the bridge. Power equipment, which may be mounted on vehicles,
is used for large rivers. Some bridges are not adaptable for cranes, and
bridge boards must be used. On some foot bridges a special rod or handline
Bridges are inherently dangerous because of vehicular traffic. The
following safety procedures are recommended when making discharge
measurements from a bridge:
- Review field folders to determine any hazards that are noted and maximum
depths and velocities that have been observed.
- Know how to use the equipment. Make a dry run with new equipment or
unfamiliar equipment at the office with someone who knows how it
- Check the operation of the equipment before leaving the office to make
sure that cranes, meters, reels, and motors are in good operating
condition. Perform a visual inspection of batteries used with power
cranes. Replace if unusual wear or cracks in the casing are observed.
- Follow the procedures outlined in the Traffic Control Plan (TCP) for each
bridge site for placing traffic control devices, and keep a copy in the
field folder. The plan must meet Federal standards as a minimum, or State
or local standards, whichever prevails.
- Park the vehicle on the shoulder and use colored, revolving beams and
emergency flashers on vehicle to warn oncoming traffic, as stated in the
- Set "caution" signs and plastic cones around work area and assign a
person, when necessary, to watch for traffic and debris in the river and
shout warnings as appropriate.
- Wear an orange-colored PFD and work gloves.
- Using a reel and crane, either hand operated or power, can be dangerous
because of the possibility of getting fingers caught under the cable or
having the cable break and fly wildly. If at any time you lose your grip
on the hand crank, make no attempt to grab the handle. Let it go! The
flying handle can severely bruise an arm or even break a bone.
- When measuring at night, use adequate lights, especially if drift is
- Keep a sharp look-out for drift when measuring. Have a pair of heavy
duty wire cutters handy to cut loose if drift is snagged.
- Work from upstream side of the bridges if at all possible, so that
debris can be spotted moving downstream.
- Provide some device to alert boat operators that a cable is in the
- When working from a bridge that has hazardous power lines, provide a
permanent warning sign on some part of the bridge directly above or below
the hazard to alert the field person of the danger.
Cableways have been used for many decades by the Division in making
discharge measurements. Cableways provide a track for the operation of a
cable car from which the hydrographer makes a current-meter measurement.
Cable cars also support the sounding reel and other necessary equipment.
Cable cars are moved from one point to another on the cableway by means of
cable-car pullers. Power-operated cable cars are available for extremely
Properly constructed and maintained cableways and properly operated cable
cars are dependable and convenient. The following safety procedures are
recommended to be followed when making cableway measurements:
- Review and adherence to the new manual "Streamgaging Cableways" (USGS
Open-File Report 91-84 (1991) and WRD Memo No 9142 ("Plan for Insuring the
Safety of Cableways") for information on construction, inspection, and
maintenance of cableways.
- Review field folder and note any special conditions or procedures to be
used at the site.
- Before starting to assemble measuring equipment in the cable car
undertake a close inspection of A frames, all cables, cable connectors,
and all bolts at both banks, if possible. It is
especially important that all cable cars be equipped with the necessary
safety equipment, such as car pullers, and braking system, and that towers
or A-frames supporting the cable should be provided with suitable means of
access to the cable such as ladders, climbing bolts, and landing
- Inspect all areas of the cable car for weak or missing parts, also check
operation and condition of the braking system.
- After completing cableway inspection, proceed with setting up necessary
measuring equipment in the cable car. When carrying sounding reel and
weight, use proper lifting techniques. Caution must be taken in climbing
A-frames and towers and getting into the cable car to avoid falling.
- Avoid personnel working under cableway platform when assembling
measuring equipment in cable car.
- The cable car, when not in use, must be locked to the cable support by a
bar hook. Then the car can be unlocked from the platform without danger
of its getting loose. Once the field person is aboard, the car can be
easily released without danger.
- A cable-car puller must fit the cable which is positive in its action
and grip and which will release the cable readily and without undue
- Before departing the bank where cable car is parked, inspect and take
inventory of safety and operational equipment and inspect car for insect
nests and cable for fishing lures.
- Wear PFD, hard hat, and work gloves. Carry extra cable-car puller,
heavy duty cutting pliers for emergency cutting, sounding reel, insect
repellent, and necessary tools for repairing measuring equipment.
- Keep your hands off the cable when the car is moving to prevent possible
- If the river is used by boats, some warning device must be used to alert
the boat operators that there is a cable in the water ahead.
Measurements made from boats require special equipment not used for other
types of measurements. Generally, a cross-piece reaching across the boat
is clamped to the sides of the boat and a boom attached to the center of
the cross-piece extends out over the bow. The cross-piece is equipped with
a guide sheave and clamp arrangement at each end, to attach the boat to the
tag line and make it possible to slide the boat along the tag line from one
station to the next. Power-operated equipment, which may be mounded on
boats, is used for large rivers. The following safety procedures are
necessary to prevent accidents or damage to equipment:
The essence of boating safety is keeping out of trouble rather than getting
out of trouble after you get into it. The operator of the boat is
responsible for knowing all equipment requirements and safety procedures
for the craft. Employees are referred to U.S. Coast Guard Auxiliary (1986)
for detailed boating information and regulations. Some general boating
safety guidelines are:
- Review field folders to determine potential risks and maximum depths and
- Select the proper boat and motor for the particular job and maintain
them in good, workable condition.
- Follow all safety precautions during trailering, towing, and launching
- After arriving at boat measuring site, locate launching area for the
boat. Check this area for snakes and clear any brush.
- Unload boat from top of truck or trailer. Remember to use proper
- At least two people on board and one on bank
- Boat trailer must have lights rather than reflector
- Operators of boats must be trained in CPR and have completed an approved
boating skills and seamanship course.
- Assemble all equipment associated with the boat measurement. Carry
spare paddles, horn, cutting pliers, bailing devices, PFD's, and water
- Stretch a tagline (with white or red flagging attached) across the river
and secure it to a tree or stake with a cable grip. Wear a PFD, work
gloves, and be observant for boat traffic. Provide an advanced warning to
the boaters such as a compressed air horn, buoys, or flashing lights.
Warning devices should be positioned 1/4 mi upstream and downstream of
tagline. Remember, the only practical way to avoid tagline accidents is
to engage a tagline release person and provide them with equipment to
release the tagline quickly.
- Avoid or take special precautions in the vicinity of canal siphons,
pumping intakes, bridge piers, docks, locks, and dams.
- Distribute weight evenly when loading your boat.
- Know emergency procedures and distress signals.
- In addition to the equipment required by law, carry a first aid kit,
flashlight, distress flares, paddle or oars, extra shear pins, bailor or
bucket, extra anchor and plenty of anchor line, mooring lines, a good tool
kit, compass, reserve fuel and extra spark plugs, emergency water and
food, and a transistor radio capable of receiving on the marine band.
- Call for weather report for the area you will be in prior to each trip.
Beware of weather, currents, and tide conditions.
- Know and obey state and federal rules.
- Leave a float plan.
- Follow all safety precautions when fueling the craft. Portable fuel
tanks should be lifted out of the boat and placed on the dock to be
fueled. Don't forget to secure the tank and wipe up and wash down any
- Pay attention to your boat's handling characteristics and know its
capabilities for all types of weather conditions.
- Keep clear of fixed objects and watch out for overhead power lines.
- Keep the boat in good condition.
- Where possible, have the boat safety checked by U.S. Coast Guard.
Discharge Measurements Under Ice Cover
Current-meter measurements, made under ice cover require special equipment
for cutting holes in the ice through which to suspend the meter. Holes of
6-inch diameter are most often cut with a power ice drill. Where
impossible to use an ice drill, ice chisels are used to chop the holes.
The most dangerous task of ice measurements is determining whether or not
the ice is strong enough to support the hydrographer and the equipment. If
the ice thickness is questionable for safety, no measurement will be made.
Discharge measurements under ice cover are usually made under conditions
that range from uncomfortable to severe.
A few reminders that might prevent accidents or damage to equipment are:
- Review field folder and study previous available field notes on hazards
experienced at the measuring sites.
- Use appropriate ice drilling and measuring equipment. Power augers must
have a dead man switch to stop the auger when the operator lets go. Be
sure to have enough sharpened blades for ice drill that could be replaced
- A minimum of two people must be assigned to make a measurement under ice
cover. Especially, when testing the strength of the ice, they should work
as a team and observe all safety precautions. PFD's will be worn at all
times during the measurement.
- After arriving at the site, first select the cross section that is most
suitable for existing flow condition. This will require crossing the
stream; the hydrographer should test the strength of the ice with solid
blows using a sharp ice chisel.
- Ice creepers, strapped on the shoes of boots or waders, are especially
recommended for use on steep or icy streambanks.
- After selecting a cross section, stretch a tag line across the stream.
Start cutting holes with an ice drill. Be careful, avoid hitting rocks or
- Dress according to the weather conditions; always carry extra clothing
- After holes are cut, start discharge measurement. The meter should be
exposed as little as possible to the cold air so that its operation will
not be impaired by the formation of ice on exposed parts. When taking
velocity counts from hole to hole, avoid slipping on freshly formed glazed
Indirect Flood Discharge Measurements
The measurement of flood discharges at field sites may be impossible or
impractical, due to road conditions or high streamwater velocities.
Fortunately, technology exists that enables hydrologists to measure peak
flood discharges after the fact by indirect methods. These methods require
the field surveying of water-surface profiles, from flagged high-water
marks, and the geometry of the stream channel which carried the flood.
The field surveying is performed in a timely manner after the flood peak
occurrence, and is performed under commonly difficult field conditions.
The high-water marks are generally flagged within 24 hours of the crest,
when seed lines are fresh. Field conditions can be hazardous and require
extreme caution by field people. These conditions can include dead and
decaying animals, broken sewer lines, foul humid air, downed power lines
and trees, and snakes up in trees. Additional information can be found in
Benson and Dalrymple (1967) or Rantz and others (1982).
Some WRD programs require that biological information on fish be collected
to help assess the water quality of a stream. A technique which is
commonly used by biologists to collect fish is electrofishing (EF). In
this method, an electrical charge in the water stuns the fish so they can
be captured and examined.
Electrofishing is an inherently hazardous activity in which safety is the
primary concern. The electrical energy used in EF is sufficient to cause
electrocution. To protect the safety of the employees involved in EF, the
WRD has issued Memorandum 93.19 ("Requirements for WRD Personnel Performing
Electrofishing") that presents policy on training, immunization, and
procedures and responsibilities.
Construction, Repair, and Maintenance of Streamgaging Stations
There are many hazards associated with the construction and repair of
streamgaging stations. By using common sense and by taking proper
precautions, most accidents can be prevented. This can be accomplished by
reading instructions and asking questions related to the job, including
planning of work, research for information in field folders, and reading
previous field notes of adjacent sites. The type of structure or repair
that is needed should be determined and, if necessary, detailed plans for
the construction or repair of gages must be prepared. Construction permits
and inspections may be required and you must consult your local building
department for up-to-date information. On occasion, contractors may be
required to complete the work.
The maintenance of gages needs to be conducted on a regular basis. If
maintenance is scheduled and carried out properly, it will result in fewer
safety risks and less costly repairs. All manufacturer's recommendations
must be closely followed when servicing or trouble-shooting equipment.
Instructions associated with equipment operation in the field must be filed
in the field folder. All specific information related to the maintenance
of the gage must be available prior to technician's departure to the field.
The following safety procedures relating to gaging stations are
- Identify all potential hazards before the construction or repair of the
gage. Assemble the list of hazards from hazard elimination logs, and
provide it to the field crew.
- Clear away the brush, vegetation, or debris from around the structure
using a brush hog, keeping a sharp eye out for poisonous snakes. Hip
boots or high-top leather shoes provide some protection against snake
- During construction of gage houses, the excavation must be properly
shored to eliminate any danger of cave-ins. Scaffolding should be well
constructed and checked before using.
- Before any excavation is started, the location of underground utility
lines must be identified. These
lines include electric, oil and gas,
telecommunications, water, and sewer.
- When doing construction or repair work on the gage structure,
precautions must be taken against falls. Portable ladders used to gain
access to the roof of a gage house must be well positioned to prevent
- When doing construction or repair work to the gage structure attached to
bridges, precaution must be taken to insure employees safety as well as
the safety of the motoring public while working from the bridge. Wear
PFD's at all times. Check atmosphere in well before entering and have an
assistant and retrieval system available for emergencies.
- When working in a well, be sure that tools are in a safe place where
they cannot be knocked into the well. When buckets are lowered or raised,
the person below, should wear a hard hat and stand in the farthest side
from the trap or well door.
- When entering a well (confined space), proper ventilation in the well is
necessary. Some wells may have little or no oxygen. Use a gas monitoring
instrument to check for the presence of harmful gases and low oxygen
levels. Do not strike a match in a well because of the danger posed by
the possible presence of explosive or flammable vapors. Do not work in
the well until the deficiency is corrected.
- Carry plenty of rope and complete set of bridge traffic control safety
equipment to warn motorists.
- The walkaways, steps, etc., to the gage houses must be checked
frequently. Any parts that are decayed, broken, loose, etc. must be
replaced promptly. Never paint a wooden walkaway, use a wood
- Flooring, trap doors, and shelves within the gage house must be checked
frequently for safety. Wooden parts will often become weakened by decay
and must be replaced.
- Ladders and ladder rungs must be properly secured to and spaced from the
gage house walls. Those under water can rust so badly that they become
unsafe. When descending or ascending ladders, employees should make sure
of their footing and always have one hand gripping the siderails.
- Check for evidences of rodents as a prevention of hantavirus and other
infectious diseases. Respirators must be worn during removal of rodent
nests and excreta. The inside of the gage house must be sprayed with a
chlorine solution (1 cup Chlorox to 1 gallon of water). Access holes for
rodents must be found and plugged.
Gage Inspection and Records Removal
It is required to visit the streamgaging stations at scheduled intervals
for record removal and discharge measurement. The field folders provide
the specific pertinent information associated with each station. All
instructions and notes that are related to the particular station must be
left in the field folder and transferred from year to year. Hazards must
be well documented in a log and made available to anyone that visits the
Upon arrival at the station, one should clear away the brush, vegetation,
or debris from around the structure, keeping a sharp eye for poisonous
snakes before beginning the inspection and records removal. Open the gage
house door carefully and look for unusual conditions that might exist
inside. If the station was vandalized, equipment in the gage house may be
left in a dangerous condition. Also, look for insects that could be a
hazard to you during your work inside the gage house. Brace the door or
lid of the shelter so it will not close by strong wind while you are
working inside of the gage house. In gage houses with wells or equipped
with monitoring manometers, check if there is a supply of oxygen and
maintain proper ventilation. The house door should be kept open for at
least a few minutes before servicing the equipment. This is because
mercury vapor may be present even in ventilated houses.
Do not work inside a gage house with the door closed. Gage house doors are
often targets for gun practice. People may not be aware that someone may
be behind the closed door.
Share information on any hazard that you discover by leaving a note in the
field folder and inside the gage house, and list all hazards on a hazard
elimination log. Any problem that field personnel encounter in the field
must be corrected immediately, if possible. A problem left unresolved
could become a serious hazard.
Keep the inside of the gage house clean.
Occasionally it is necessary for Survey personnel to conduct scuba diving
activities in support of data collection and environmental studies. Scuba
diving is a potentially high risk operation and therefore requires special
control and procedures to protect employees from accidents. Compliance
with OSHA regulations is required as specified for scientific diving. No
scuba operations are permitted without meeting every requirement of the
Safety considerations include:
- Always dive with another person; use the buddy system. Stay together
- Avoid decompression, dive within your limits.
- Make the deepest dive first.
- Control buoyancy; don't overweight yourself.
- Always display the dive flag while diving.
- Avoid strong currents and begin dive against current.
- Equalize pressure early and often.
- Develop and use methods to communicate underwater.
- Limit depth to 100 feet or less.
- Breathe regularly and be aware of the hazards of breath holding.
- Stay aware of air supply while diving.
- Ascend carefully and slowly.
- Leave water when shivering, tired, or injured.
- If diving in an area where gates are being moved using electrical power, coordinate the dive with the gate tender to avoid movement of the gates while the diver is in the water.
Previous--Specific Procedures and Safety
A Guide to Safe Field Operations
U.S. Geological Survey Open-File Report 95-777
h2o Webserver Team
Last Modified: 11:26 27June1996 ghc