A Guide to Safe Field Operations
U.S. Geological Survey Open-File Report 95-777
Previous--Surface Water Activities
This section of the guide discusses safety issues that are common to most
of our ground-water activities. It includes procedures and guidelines to
avoid personal injuries when conducting well inventory, collecting
water-level data, instrumenting and repairing observation wells, drilling
observation wells, conducting aquifer tests, geophysical logging of wells,
and conducting surface-geophysical measurements.
Wells are the primary source of ground-water data. Well inventories,
either for project investigations or for basic data collection networks,
usually require an intensive search for a large number of wells in a
localized area. Data collection in most project wells are discontinued in
a few years upon completion of the project. Wells included in the basic
data collection network are selected to represent regional coverage and
various ground-water conditions and are usually operated for long periods
Private landowners, their dogs, and some of their livestock (bulls, horses,
certain breeds of cattle, buffalo, boar, hogs, etc.) must be recognized as
potential risks while conducting well inventories. Consider the following
- Contact property owners beforehand and obtain permission to access the
property. Obtain as much information as possible from the owner about
possible hazards. If the site will be visited regularly, make notes on
potential dangers so that subsequent field personnel will be
- Minimize disturbing livestock and fowl.
- Stay on roads or trails with vehicles to avoid damage to vehicles,
pastures, crops, etc. Catalytic converters can start grass fires. Leave
all gates as found (open or closed).
- Be careful of wells with pumps in operation and avoid contact with
moving parts and electrical wiring.
- Carry a clipboard as protection from small hostile animals and for
keeping data while at the field site. Carry a large crescent wrench or
walking stick to ward off larger hostile animals.
- Survey the site watching for snakes, animals, insects, water, and other
- List all the hazards on a hazard elimination log.
Collecting Water-Level Data
Fluctuations of water-levels in aquifers are obtained primarily from direct
measurements with a steel tape, battery powered electric tapes, air lines
equipment with pressure gages, and graphical or punch tape stage recorders.
In recent years, electronic pressure transducers and data recorders have
been used to measure water levels.
Collecting water-level data with a steel or electric tape is a relatively
safe activity, but a few simple procedures must be followed to minimize
personal injury and property damage. If the well is pumping, special
precautions must be taken.
- Determine as much as possible about the types of pumps you will be
working with and the position of the pump intake. Take care not to have
the tape pulled into the pump intake.
- Stay clear of unprotected rotating drive shafts or belt drives.
- Avoid using weights attached to tape. The weights could lodge in the
pump column or well casing. Be sure that the weights are attached with a
hook or wire mesh weak enough to be snapped off if it should become lodged
in the well.
- Watch for low doorways and beams in well houses. As you enter the well
house, check for rotten or loose floor boards, snakes, biting or stinging
insects, slick pump house floors, and inadequate lighting.
- If the pump is electrically driven, check for exposed wires, electrical
panels without protective covers and any other possible electrical hazards
which might be encountered while working near the pump.
- During measurement of non-pumping water levels, disconnect or open the
electrical switch on the pump motor to prevent the pump from starting
during the measurement. This will eliminate the chance of the tape
becoming pulled into the pump intake. Close the switch when measurement
Instrumentation and Repairing Observation Wells
Observation wells usually are equipped with digital, punched-tape recorders
and are used to monitor changes in water levels and to provide long-term
statistics for assessing the impacts of climatic and man-induced changes.
Another method uses a data logger with pressure transducers capable of
recording very frequent fluctuations of the water levels in wells. This
method is used for short-term projects such as measuring drawdowns during
Installing instruments and repairing observation wells are relatively safe
activities, but a number of procedures listed below must be followed to
avoid personal injury or infringing on someone's rights.
- Obtain permission and property access agreement from owner to access
site and to install instruments or repair observation wells.
- Read and follow instructions for materials to be used for
instrumentation or repairing the well.
- Prepare instrument shelter and attach all fittings in the shop so that
the shelter can be positioned into the well casing in the field. Be sure
to wear work gloves and goggles when operating power tools.
- Stay on roads or trails with vehicle to avoid damage to vehicle,
pasture, crops, etc., and to avoid getting stuck. Leave all gates as
found (open or closed)
- After arriving at well site, unload shelter by using proper technique
for lifting and moving heavy objects.
- If a generator and power tools are required, be sure they are operated
away from grass or brush to avoid a fire or away from water that could
cause an electrical shock to the operator. Install
Ground-Fault-Circuit-Interrupter (GFCI) when required to prevent shock.
- Clear vegetation, cut tall grass around the well site, and remove all
trash from site at each visit, or as needed, to discourage the nesting of
snakes, rodents, and insects.
- Be careful while using polyvinyl chloride (PVC) solvents and adhesives.
Avoid skin contact and breathing vapors.
Drilling Observation Wells
To obtain information on the subsurface and hydrology of an area, it is
often necessary to drill test wells, to collect drill cuttings of
formations penetrated by, or to make borehole geophysical studies involving
the use of specialized logging equipment. Field personnel assigned to such
projects are exposed to dangers when working around heavy machinery, and
must have a thorough understanding of the drilling equipment and its
operation. The following guidelines must be followed to avoid accidents
while working at well drilling sites.
- Obtain written permission for entry to land.
- Plan access to minimize damage to private property.
- Be familiar with the drilling equipment and its operation procedures.
- Drill rig should be fitted with an all around shut down switch bar.
- Before any drilling is started, a site must be selected that is free of
any overhead wires, underground cable, pipes, tanks, or buried wastes.
Research the historical use of a site and, if warranted, use surface
geophysical techniques such as resistivity or EM-31 profiling to indicate
potential problems from buried tanks or wastes.
- If it is necessary to set up a drilling rig on a public road, use proper
signs, reflectors, and/or flag persons to warn oncoming traffic.
- Be sure to wear the proper clothes and use safety equipment, such as
hard hats, gloves, safety glasses, steel-toed shoes.
- Never wear loose-fitting clothes that can be entangled in open rotating
gears or belt drives.
- One should be prepared for accidents by being trained on the principles
and procedures of first aid and fire fighting, and be equipped with
adequate first-aid kits and fire extinguishers.
- Keep the site clear of excess pipe, casing, tools, cables, and rope.
- Be aware of potential dangers such as pinching fingers between lengths
of pipe, casing, etc.; tangling hands and feet in ropes or chains,
slipping on drilling mud; and touching a hot compressor, generator,
- Never use equipment that is not safe. If a breakdown or problem arises
that constitutes a safety risk, the equipment must be shut down until
necessary repairs or changes have been made.
- Never allow a drill rig to be operated by only one person.
- Never do repair work on the equipment without first shutting it off.
- Allow a gasoline or diesel engine to cool before refueling.
- Clean up site after drilling and repair any damage to property.
- Drilling at hazardous waste sites such as air bases. Installation
Restoration Program (IRP) requires specific training and medical
surveillance of the personnel according to OSHA regulations.
- When lightning is observed, discontinue operation.
Conducting Aquifer Tests
Aquifer tests are routinely conducted as part of subsurface hydrologic
project activities. An aquifer test involves pumping a well at a constant
rate to stress the aquifer. The rate of water-level depletion is measured
in the pumped well and nearby monitoring wells and the data are used to
determine the hydraulic properties of the aquifer. The fluctuations in
water levels are measured either electronically, mechanically, or manually.
The hydraulic characteristics of the aquifer are determined graphically or
The following points need to be considered when conducting aquifer
Occasionally, project work calls for aquifer testing with a high-capacity
pump. A pump contractor is usually hired to install the pump, maintain it
in running condition throughout the test, and remove it when the test is
completed. The responsibility of the employees assigned to the site is
- Permission must be obtained from the agency, organization, or private
person owning or controlling the land. Remember to maintain cordial
relations and respect the right of the landowner. Be specific in your
communication about the purpose of work and locations where work will be
- Manpower and equipment must be able to reach the site safely.
- Protective gloves should be worn during pump installation and removal
because the discharge pipe may be slippery or the woven wire cable may be
- Protect against rotating shafts.
- If a portable generator is used, be sure to use caution when storing and
- In using electrical motors, care must be exercised to see that the motor
voltage, frequency or cycles and phase correspond with those of the power
lines. To ensure proper performance of the pump motor, have a licensed
electrician connect it to the service line.
- Transport the water away from the site to an area that will not be
damaged or flooded. This also will reduce the potential for electrical
- During long-term tests, schedule adequate personnel. Avoid extreme
fatigue; it can impair judgement and physical capability. Recuperate as
needed and maintain communications between personnel.
- After test is completed, clean up the site and repair any property
- Stand clear of the site while the pump is being installed or removed.
- Wear a hardhat at all times.
- Use earplugs.
- Insure that the contractor cleans up the site and repairs any property
Geophysical Logging of Wells
Geophysical logging sometimes provides the only means of obtaining
subsurface information. Geophysical logging can be used for determining
geologic formations, aquifer characteristics, and physical properties of
wells. Most geophysical logging equipment used by the USGS is permanently
mounted on heavyweight carryall trucks. The equipment includes a single or
multi-conductor cable and a pen and ink recorder and solid-state recorders.
Data are collected by lowering sensing devices in the borehole and
recording the data on a graphic chart and magnetic tape. The logger also
is useful for collecting water samples at different depths by lowering a
sampler into the well. The logger is generally powered by a generator, and
the cable is raised and lowered with a power winch.
To minimize the potential for accidents, consider the following
- Contact the well owner and request permission to log the well. Keep the
owner informed of your plans and schedule.
- Use common sense around logging equipment. Be aware that you are
working around water and 120 volts of electricity. To avoid electrical
shock, wear rubber boots.
- Check probes and generator before leaving office. Inspect cable and
connectors for rust and wear.
- Wear fitted clothing and stay clear of the winch and pulleys when probes
are being lowered or raised to avoid getting clothing caught. A helper
often must attend to the cable to work the probes past tight spots and to
clean the cable as it comes out of the hole.
- Handle cable with heavy gloves to prevent burns and cuts from cable.
- Tension on cables must be monitored at all times. Particular care must
be exercised when pulling probes out to avoid breaking line if tool
- When lightning is observed, discontinue operation and remove probes from
- Be aware of radiation risks and take the necessary precautions when
logging with a nuclear source. In order to operate a nuclear-source tool,
the operator must be trained and certified. The greatest danger may be to
an untrained helper who may get long-term exposure.
Surface Geophysical Measurements
Surface geophysical methods are often used to study the subsurface without
the expense of drilling wells. These methods include electrical
resistivity measurements, electromagnetic, seismic, magnetic and
ground-penetrating radar surveys, and gravity techniques. The electrical
resistivity, electromagnetics, and seismic methods are the most widely used
for ground-water exploration. Electrical resistivity measurements require
an electrode array to detect zones of high or low subsurface resistivity.
The seismic surveys use an energy source such as explosives or hammers and
an array of receivers to detect velocity difference between different earth
Personnel who conduct surface geophysical surveys must have a thorough
understanding of the equipment and its operation. General guidelines to
- Contact all property owners and obtain permission to conduct the
surface geophysical surveys. Keep owners informed of your plans and
- Make sure all equipment is in good operating condition. Check all
equipment and power source prior to leaving the office. Replace any
frayed, cut, or damaged cords or plugs.
- Follow all instructions when operating the equipment. Incorrect
connection of wires could be dangerous to the operator and the
- Respect the energy source and properly ground all instruments.
Discontinue use of any equipment that causes an electrical tickle or
shock. Use GFCI's in the lines.
- When working along roadways, use caution, place cones around work areas,
stay off the roadway if possible.
- Use special caution when operating equipment with high-voltage output.
Never tamper with the equipment during operation and only service it when
the unit has been properly discharged.
- Any use of explosives is potentially dangerous and requires special
training and preparation. Employees must not work around a site where
explosives are being used without receiving training on specific operation
and associated hazards. Check to see if permits are required from local
jurisdictions. Adequate communication between the explosives operators is
essential--they should be properly trained in use of hand signals and
Previous--Surface Water Activities
A Guide to Safe Field Operations
U.S. Geological Survey Open-File Report 95-777
h2o Webserver Team
Last Modified: 11:41 27June1996 ghc