Excavation and Trenching Safety

Caliber Construction Alaska LLC Excavations and Trenching Safety Plan and Policy

Procedure / Operating: 

The Superintendent shall control all trenching and excavation work performed at the job site. All surface obstructions that are located that may create a hazard to employees shall be removed or supported, as necessary.  Utility installations may be expected to be encountered during excavation work, locates must be called prior to excavation. Any necessary permits shall be obtained prior to digging. When excavation operations approach the estimated location of underground installations, the exact locations shall be determined by safe and acceptable means. While the excavation is open, underground installations shall be protected, supported or removed as necessary.  Two working days before any excavation activities take place, Alaska Dig Line shall be contacted at:

▪ 811 or (800) 478-3121 or (907) 278-3121 or online at 811ak.com  Employees and subcontractors shall not work in areas where excavation equipment and/or material may injure a person. While equipment is being operated, workers shall stay clear. If the equipment operator cannot see the excavation, there shall be a designated person to spot to ensure that personnel are not within the danger zone. The excavation contractor is responsible to ensure excavation and trenches are constructed within OSHA standards. 

▪ A rescue plan must be in place for dirt work. 

▪ Workers shall not enter a trench without a trench box. 

▪ Overburden soil pile shall be 2 feet from edge of trench. 

▪ If water is being accumulated in an excavation, a competent person shall control the removal of water. Workers shall not work in excavation where there is water accumulation that is not actively being pumped out. 

▪ Excavations over 20 ft. shall be designed by a professional engineer. 

▪ When mobile equipment is operated adjacent to an excavation, or when such equipment is required to approach the edge of an excavation, and the operator does not have a clear view of the edge, a warning system shall be utilized such as barricades.  Soil Classification

▪ Stable rock: natural solid mineral matter that can be excavated with vertical sides and remain intact while exposed. 

▪ Type A: Cohesive soils such as clay, silty clay, and/or sandy clay. 

o Soil is NOT Type A if any of the following are present:

▪ Soil is fissured or significantly cracked (will be classified as Type B).

▪ Soil is subject to vibration from heavy traffic or pile driving.

▪ Soil has previously been disturbed (will be classified as Type C).

▪ Soil is part of a sloped, layered system (will be classified as Type B) 

▪ Type B: Angular gravel such as: silt loam, sandy loam and/or dry rock that is not stable.  

▪ Type C: Granular soils such as: gravel, sand, sandy loam, and/or submerged rock that is not stable. Access and Egress A stairway, ladder, or any other safe means of egress shall be located in trench excavations that are 4 feet or more in depth as to require no more than 25 feet of travel for employees. 

 

Inspections 

Daily inspections of excavations and protective systems shall be made by a competent person for evidence of a possible cave-in, failure of protective systems, hazardous atmospheres and other hazardous conditions. The competent person shall conduct an inspection at the start of shift, and as needed throughout the shift. Where there is evidence of a situation that could cause hazardous conditions, exposed employees shall be removed from the hazardous area until necessary precautions have been taken.

 

Protective Systems

Each employee in an excavation shall be protected from cave-ins by an adequate protective system, except when excavations are less than 4 feet in depth and examination of the ground by a competent person provides no indication of a potential cave-in, or it is made entirely of stable rock.  Protective systems shall have the capacity to resist, without failure, all loads that are intended, or could reasonably be expected. All pits, shafts, or steep-sided excavations shall be covered or guarded with standard guardrail on all open sides during non-working hours.  Walls and faces of trenches 4 feet or more in depth, and all excavations in which employees are exposed to danger from cave-in, must be guarded by shoring or sloping to the proper angle.

▪ Slopes will change if the soils report states that onsite soil is classified as either “A” or “C.” 

▪ All simple slope excavations 20ft or less in depth shall have a maximum allowable slope of 1.5:1. 

▪ All benched excavations 20ft or less in depth shall have a maximum allowable slope of 1.5:1. 

▪ All excavations 20 feet or less in depth, which have vertically-sided lower portions, shall be shielded or supported to a height at least 18 inches above the top of the vertical side. All such excavations shall have a maximum allowable slope of 1:1.