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HEALTH AND SAFETY PROCEDURES FOR ENTRY INTO BORINGS
Down-hole geologic logging entails lowering a person into an uncased boring generally to gather information
on the stratigraphy of the soil. Descent in some cases may exceed 30 m. The boring is a confined space,
hence, hazards typical of confined spaces may be present. The major ones are oxygen deficiency, flammable
concentrations of gases or vapors, toxic concentrations of gas or vapors, and wall collapse. Because visual
inspection of the walls of the boring is essential to the logging process, the borings cannot be cased. These
guidelines are prepared for down-hole logging operations, sound and uniform health and safety procedures
that are in compliance with federal and state regulations.
These guidelines of the procedure are in full compliance with OSHA regulations contained in 29 CFR
1926.552, 29 CFR 1926,800 and incorporate more stringent regulations promulgated by Cal-OSHA and
described in Section 1542, Subchapter 4, and Article 108, Subchapter 7, Division 4, Title 8 of the California
Administrative Code (CAC). In all cases the local and state regulations regarding confined space entry and
shaft entry must be reviewed and provisions more stringent than those contained in this operating procedure
should be observed.
This procedure applies to down-hole logging operations associated with geotechnical projects where toxic
chemical releases are not known to have occurred. The procedure may be used for downhole logging
operations where toxic chemical releases have occurred, but only as an attachment to a site-specific
health and safety plan that assesses the exposure risks associated with the logging operation and
prescribes appropriate chemical-specific procedures for worker protection against the excessive
A.2.3 Responsibility and Authority
The field supervisor and/or the geotechnical engineer have overall responsibility for safe conduct of the
downhole logging operation and may not delegate that responsibility to another person.
A.2.4 Health and Safety Requirements
Some states, such as California, require permits for construction of shafts to be entered by personnel and
exceeding a certain depth (1.5 m in California). State and local government permit requirements shall be
reviewed and complied with before any shaft is constructed.
A qualified geotechnical specialist (engineer/geologist) shall be present a sufficient amount of time during
the drilling process to thoroughly inspect and record the material and stability characteristics of the shaft and
decide whether the walls of the shaft are stable enough so that it may be entered safely. Entry shall not be
permitted if, in the specialist's opinion, the walls could collapse.
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A qualified geotechnical specialist is an individual who has the following minimum qualifications:
Extensive hands-on experience in drilling and downhole geologic logging of uncased large-diameter
borings so that the person is considered an expert by peers.
Experience in performing down-hole inspection or logging in the local area where work is being
performed and/or experience in performing down-hole inspection/logging in other areas with similar
Prior training by other experienced geotechnical professionals.
Familiarity with the safe operation of the drilling and logging equipment being used, and the special
difficulties, hazards, and mitigation techniques used in down-hole geologic logging.
Surface Casing and Proximity of Material to the Shaft Opening
The upper portion of the shaft shall be equipped with a surface ring-collar to provide casing support of the
material within the upper 1.2 m or more of the shaft. The ring collar shall extend to 300 mm above the
ground surface or as high as necessary to prevent drill cuttings and other loose material or objects from
falling into or blocking access to the shaft. Drill cuttings, detached auger buckets, and other loose equipment
must be placed far enough away from the shaft opening or secured in a fashion that would prevent them from
falling into the shaft.
Prior to entry into a shaft, tests shall be performed to determine if the atmosphere in the shaft is not oxygen
deficient and does not contain explosive or toxic levels of gases or vapors. Testing shall continue throughout
the logging process to assure that dangerous atmospheric conditions do not develop. Monitoring instruments
shall include a combustible gas meter and an oxygen meter. Where toxic gases or vapors may be present,
a monitoring instrument equipped with a photoionization detector should be used for detection and
Ladders and Cable Descents
A ladder may be used to descend a shaft provided that the shaft is no deeper than 6 m. A mechanical hoisting
device shall be used with shafts more than 6 m deep.
Hoists may be powered or hand operated and must be worm geared or powered both ways. They must be
designed so that when power is stopped, the load cannot move. Controls for powered hoists must be the
deadman type with non-locking switch or control. A device for shutting off the power shall be installed
ahead of the operating control. Hoist machines shall not have cast metal parts. Each hoist must be tested
with twice the maximum load before being put into operation and annually thereafter. California regulations
require a minimum safety factor of 6 for hoists. Test results shall be kept on file at the geotechnical
engineer’s office and other offices as required by the agency engaged in the geologic logging procedure. The
hoist cable must have a diameter of at least 8 mm. Drill rigs may not be used to raise or lower personnel in
shafts unless they meet the requirements in this section.
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An enclosed covered metal cage shall be used to raise and lower persons in the shaft. The cage shall have
a minimum safety factor of 4 and shall be load tested prior to use. The exterior of the cage shall be free of
projections and sharp corners. Only closed shackles shall be used in cage rigging. The cage shall be certified
by a registered mechanical engineer as having met all the design specifications. The certificate and load test
results shall be kept on file.
In addition to the hoist or drill rig operator, an emergency standby person shall be positioned at the surface
near the shaft whenever there is a geotechnical specialist in the shaft.
A two-way electrically-operated communication system shall be in operation between the standby person
and the geotechnical specialist whenever the standby person and the geotechnical specialist is in a shaft that
is over 6 m in depth or when the ambient noise level makes unamplified voice communication difficult. A
cellular telephone at the drill rig is strongly recommended.
The geotechnical specialist must use the following safety equipment while in the shaft:
An approved safety harness designed to suspend a person upright. The harness must be attached to
the hoist cable through a hole in the head guard. Attaching the harness to the head guard or cage is
A steel cone-shaped or flat head guard or deflector with a minimum diameter of 450 mm must be
attached to the hoist cable above the harness.
Electrical devices, such as lamps, combustible gas and toxic vapor detectors, and electric tools, must be
approved for use in hazardous locations.
The storage and use of flammable or other dangerous chemicals at the surface must be controlled to prevent
them from entering the shaft.
The presence of water in the shaft must be determined before the shaft is entered. If the shaft contains more
than 1.2 m of water, the level of water must be reduced to less than 1.2 m before entry is permitted. If a shaft
is entered when water is present, the depth of the water must be measured periodically and the water level
kept below 1.2 m if work is to continue.
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NIOSH-approved supplied-air respirators (SCBA or airline) shall be available in the cage for use in the shaft
when oxygen deficient atmosphere or toxic gases or vapors are encountered. If an airline system is used, the
air pump or compressed air supply must be attended to by a person at the surface.
Light intensity in the portion of the shaft being logged must be at least 3 m center-to-center. Lighting devices
must be explosion-proof.
Time spent continuously in a shaft must not exceed two hours.
GEOTECHNICAL EQUIPMENT SUPPLIERS
SERVICE TESTING COMPANIES
Soil Sampling, Drilling Rigs, Augering, & Rock Coring:
Continuous Soil Sampling Methods
Flat Plate Dilatometer Test (DMT) for soils:
Cone Penetration Testing (CPT):
The CPT Site at: http://www.liquefaction.com
Pressuremeter Testing (PMT):
Dilatometers for Testing Rocks:
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