Ground Control Highwall Safety

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Ground Control - Highwall Safety

• At Surface Mining Operations

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Correction of hazardous conditions30 CFR 56.3200

• Ground conditions that create a hazard to persons
  shall be taken down or supported before other
  work or travel is permitted in the affected area.
• Until corrective work is completed, the area
  shall be posted with a warning against entry and,
  when left unattended, a barrier shall be
  installed to impede unauthorized entry.

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Wall, bank and slope stability30 CFR 56.3130

• Mining methods shall be used that will maintain
  these stability's, in places where persons work
  or travel.
• When benching is necessary, the width and height
  shall be based on the type of equipment used for
  cleaning the benches or scaling the walls, banks
  or slopes.

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Pit or quarry wall perimeter30 CFR 56.3131

• Loose or unconsolidated material shall be sloped
  to the angle of repose, or stripped back for at
  least 10 feet from the top of the pit or quarry
  wall.
• Other conditions at or near the perimeter which
  create a fall-of-material hazard to persons shall
  be corrected.

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Examination of ground conditions30 CFR 56.3401

• Highwalls and banks adjoining travelways shall be
  examined weekly or more often if changing
  ground conditions warrant.

• Persons experienced in examining and testing for
  loose ground shall be designated by the mine
  operator.
• Designated persons shall examine and where
  applicable, test ground conditions in areas where
  work is to be performed prior to work commencing,
  after blasting and as conditions warrant.

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Activity between machinery or equipment and the
highwall or bank30 CFR 56.3430

• Persons shall not work or travel between
  machinery or equipment and the highwall or bank
  where the machinery or equipment may hinder
  escape from falls or slides of the highwall or
  bank.
• Travel is permitted when necessary for persons to
  dismount.

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Secondary breakage30 CFR 56.3400

• Prior to secondary breakage operations, material
  to be broken, other than hanging material, shall
  be positioned or blocked to prevent movement
  which would endanger persons in the work area.
• Secondary breakage shall be performed from a
  location which would not expose persons to danger.

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Berms and guardrails30 CFR 56.9300

• Berms or guardrails shall be provided and
  maintained on the banks of roadways where a drop
  off exists of sufficient grade or depth to cause
  a vehicle to overturn or endanger persons in
  equipment.
• Berms or guardrails shall be at least mid-axle
  height of the largest self propelled mobile
  equipment which usually travels the roadway.

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Dump site restraints30 CFR 56.9301

• Berms, bumper blocks, safety hooks or similar
  impeding devices shall be provided at dumping
  locations where there is a hazard of overtravel
  or overturning.

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Unstable ground30 CFR 56.9304

• Dumping locations shall be visually inspected
  prior to work commencing and as ground conditions
  warrant.
• Where there is evidence that the ground at a
  dumping location may fail to support the mobile
  equipment, loads shall be dumped a safe distance
  back from the edge of the unstable area of the
  bank.

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Fatalities Due to Ground Control Failure
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Fatalities Due to Failure to Recognize Ground
Control Hazards
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February 27, 1999, a 45-year-old co-owner of a
contract drilling company with 6 years drilling
experience was fatally injured at a crushed stone
operation. The victim had been contracted to
drill quarry blast holes. She was standing about
20 feet from the base of a 240-foot highwall
measuring a hole when a rock fell and struck her.

• Persons experienced in identifying loose ground
  should examine highwalls in the vicinity where
  work is to be performed, prior to the work
  commencing, after blasting and as conditions
  warrant throughout the shift.
• Ground conditions that create a hazard to persons
  should be taken down or supported before other
  work or travel is permitted in the affected area.
  
• Mining methods should be used that will maintain
  wall, bank and slope stability in places where
  persons work or travel. The width and height of
  benches should be based on the type of equipment
  used for cleaning of benches or for scaling walls
  banks or slopes.

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Ground Control Hazard Recognition
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Risk

• While ground control failures are often easy to
  explain after-the-fact, they are often very
  difficult to predict before-the-fact.
• Minimizing exposure to potential hazards is
  always the best policy.

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Risk Avoidance

• Use common sense
• Expect the unexpected
• Stay alert
• Never place yourself or others in a vulnerable
  position, no matter how good the wall or bank
  looks

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Energy of a Rock Fall
How much kinetic energy is released in a rock
fall? Suppose a 10 pound rock falls 50 feet from
a slope. In 50 feet, the rock will reach a speed
of about 57 feet per second. (Thats about 38
miles per hour.) KINETIC ENERGY is 1/2 mass
times speed squared. 1/2 10 57 57 16,000
foot-pounds of energy.
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Energy of a Rock Fall
How much kinetic energy is contained in a
speeding bullet? A 45 caliber bullet weighs
about 1/2 ounce or 0.031 pounds. Its muzzle
velocity is about 1000 feet per second. KINETIC
ENERGY is 1/2 mass times speed squared. 1/2
0.031 1000 1000 15,000 foot-pounds of
energy. Our falling rock had more
energy! Getting hit by a rock fall, even a small
rock fall, can do as much damage to your body as
a bullet!
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