Excavation and trenching - Massachusetts

Massachusetts operates an OSHA-approved State Plan covering only state and local government workers. Private sector employers and their workers are covered by federal OSHA.

Notice of excavations to public utility companies

Excavators in Massachusetts must provide notice of proposed excavations to the underground plant damage prevention system (defined in ALM GL ch. 164, § 76D) so that the system can give notice to public utilities companies to mark their underground utilities to prevent accidental damage, interruption of service, or injury to excavation workers. The rules governing the notice and marking requirements are found at ALM GL ch. 82, §§ 40 – 40E.

Open trenches and excavations

An excavator must not leave an open trench unattended without first making a reasonable effort to eliminate any recognized safety hazard that may exist because of leaving the open trench unattended.

Permit required

No person may, except in an emergency, contract for the making of or make a trench, in any public way, public property, or privately owned land until a permit is obtained from the appropriately designated person within the city, town, or public agency that is authorized to issue the permit.

Definition of “trench”

A “trench” is an excavation which is narrow in relation to its length, made below the surface ground in excess of 3 feet below grade and the depth of which is, in general, greater than the width, but the width of the trench, as measured at the bottom, is no greater than 15 feet.

Landowner to erect barriers around excavations

The owner of any land which abuts a public way and on which an excavation has been made within 50 feet of said way must erect a fence or other barrier not less than five feet in height at the street line of such way. The fence or barrier must not be removed until the area abutting the public way has been made level with the public way for 50 feet from the street line.

Installations of gas pipes under a road

These rules apply only to the layout or construction of any street, place or way over, across, or along that portion of high-pressure gas mains located within a right of way held by the gas company in fee simple or by easement.

• Construction method:
  • Excavation. Excavate trench sides as nearly vertical as practical. Make trench width at least 12 inches, but not more than 24 inches wider than the diameter of the pipe (where practicable).
  • Bed fill. Place, compact and shape the bed fill. Locate the bed so that the pipe will lie in the center of the trench.
  • Pipe. Lay pipe on bed.
  • Side fill. Fill both sides of the pipe simultaneously in six-inch lifts. Compact each lift.
  • Top fill. Place the top fill at the same time the last lift of side fill is placed. Do not compact top fill for first six inches over pipe.
  • Back fill. Place in six-inch lifts and compact above six-inch layer.
• Compaction:
  • The bed side and top fill must be compacted by any one of the following methods:
    • Three-inch lifts and two coverages with a hand tamper weighing from 15 to 25 pounds having an area of tamping face 50 to 90 inches.
    • Four-inch lifts with two coverages of a pneumatic compactor or a jackhammer fitted with a plate six to eight inches in diameter.
    • Six-inch lifts of fill with two coverages of a rubber-tired roller or the wheels of a rubber-tired earth-moving equipment.
  • The backfill must be placed in six-inch lifts with each lift being compacted by at least one coverage of a mechanical compactor or of construction equipment. That portion of the backfill within the subgrade and base of a road or railroad must be compacted to the standard specified for the particular base or subgrade.
• Fill Materials:
  • Bed, side and top fill. Use a natural granular soil (concrete sand, asphalt course base sand) having the following size characteristics:
    • 100 percent finer than 3/4 inches.
    • 30 to 90 percent finer than No. 10 sieve.
    • 10 to 40 percent finer than No. 40 sieve.
    • Less than 10 percent finer than No. 200 sieve.
  • Backfill. Use a soil having:
    • No particles larger than 12 inches.
    • No concentrated organic matter.
  • Backfill. Within the depth of road, subgrade and base must meet the specifications in force for the particular base or subgrade.
  • No person or municipality may uncover, disturb, change or otherwise alter or interfere with the safety of any high-pressure gas main or portion thereof subject to the provisions of 220 CMR 111.00.
  • Any person or municipality laying out or intending to construct a street, way, or place over, across or along a high-pressure gas main subject to the provisions of 220 CMR 111.00 must notify in writing the Department and the owner of the high-pressure pipeline at least 30 days before undertaking the construction.

Replacement of cast-iron pipe – Gas distribution

These cast-iron pipe replacement rules apply to every gas company, municipal gas department or other person engaged in the distribution of gas in Massachusetts.

Replacement of cast-iron pipe at trench crossings. Cast-iron pipe, eight inches or less in nominal diameter, which is exposed and undermined by a trench crossing the pipeline must be replaced immediately:

• When there is less than 24 inches of cover; or
• When there is 24 inches or more of cover and the trench widths set forth in 220 CMR 113.06, Table 1 are exceeded.

The trench width must be determined by the distance along the centerline of the exposed pipe.

The minimum length of the replacement must be equal to the trench width plus twice the distance from the top of the pipe to the bottom of the crossing trench, extending equally on both sides of the crossing trench.

When cast-iron pipe is intersected by a trench and the pipe must be replaced, the pipe must be surveyed daily for gas leakage and monitored daily until the pipe is replaced.

At the operator's discretion, cast-iron pipe does not have to be replaced when a pipe segment is exposed and undermined in a shallow trench crossing, provided that:

• The backfill supporting and surrounding the pipe is thoroughly compacted for the full trench width and for a distance equal to 1/2 of the trench width on both sides of the centerline of the pipe;
• The backfill is free of objectionable material or debris, such as, but not limited to, pavement, frozen soil, trash and rocks; and
• The backfilling techniques used are included in the operator's operating and maintenance plan.

Replacement of cast-iron pipe adjacent to parallel excavations. These rules apply to every gas company, municipal gas department or other person engaged in the distribution of gas in Massachusetts.

Cast-iron pipe, eight inches or less in nominal diameter, which is adjacent to parallel excavation must be replaced immediately, provided that the excavation exceeds eight feet in length and a condition listed below exists:

• Shallow trench. A low-pressure cast-iron pipe that is parallel to a shallow trench excavation must be replaced if:
  • The pipe is exposed and undermined; or
  • A least 1/2 of the pipe diameter lies within the angle of influence; and
    • The bottom of the excavation is below the water table; or
    • The excavation is in soft clay.

• Deep trench. A low-pressure cast-iron pipe that is parallel to a deep trench excavation and lies within the angle of influence must be replaced if:
  • The pipe is exposed and undermined;
  • The pipe is totally, or in part, within three feet of the edge of the trench and sheeting that may have been used is not left in place; or
  • The operator determines that the strain on the pipe caused by, but not limited to, excessive ground movement or inadequate pipe support shall exceed 0.05% (500 microstrain).

• Shallow or deep trench. A high-pressure cast-iron pipe that is parallel to a shallow or deep trench excavation must be replaced if:
  • The pipe is exposed and undermined; or
  • At least 1/2 of the pipe diameter lies within the angle of influence, and sheeting that may have been used is not left in place.

When cast-iron pipe is adjacent to a parallel excavation and must be replaced, the pipe must be surveyed daily for gas leakage and monitored daily until the pipe is replaced.

Any pipe that replaces cast-iron pipe must extend a safe distance, determined by the operator, beyond the point where parallel excavation terminates.

Installation of underground conduit systems

Key term. A "conduit" is a structure containing one or more ducts; and "conduit system" is the combination of conduit, conduits, manholes, handholes, and/or vaults joined to form an integrated whole.

Excavation and backfill requirements.

• Trench. The bottom of the trench should be undisturbed, tamped, or relatively smooth earth. Where the excavation is in rock, the conduit should be laid on a protective layer of clean tamped backfill.
• Quality of backfill. All backfill should be free of materials that may damage the conduit system.

Recommendation: Backfill within six inches of the conduit should be free of solid material greater than four inches in maximum dimension or with sharp edges likely to damage it. The balance of backfill should be free of solid material greater than eight inches in maximum dimension. Backfill material should be adequately compacted.

Special requirements for excavating machines, including backhoes and front-end loaders

Prior to any excavation, Dig Safe and other utilities not covered by Dig Safe must be notified. The operator must have a Dig Safe permit number, start date, and time.

Protection of operators. Where the operator of an excavating machine may be exposed to the elements or overhead hazards, a suitable equipped cab for protection against such conditions must be provided.

Operation. Excavating machines must be operated by a licensee, temporary permit holder, or an apprentice licensee under the direct supervision of a duly licensed operator. In addition:

• SAE hand signals must be used with excavating machinery.
• No person except the operating crew or apprentice licensee operating under the direct supervision of a duly licensed operator may be permitted on an excavating machine while it is in operation.
• No person other than the pitman and excavating crew may stand within the full working radius of an excavator or backhoe while the shovel or backhoe is in operation.
• Excavating machinery may not straddle an open trench.

Protection of the general public

Generally. Wherever an unattended trench exists, the operation must be secured in a safe manner and suitable protection for the general public must be provided. The Excavator must secure the unattended trench to prevent unauthorized entry when work is not in progress.

Trenches on public ways. Access to unattended trenches opened during construction on a public way must be restricted by covers or barriers.

• Covers. Where covers are used, they must be comprised of steel metal plates no less than 3/4 inch thick, or equivalent. Covers must be placed over the trench. Such covers must be level and physically secure to prevent the creation of a hazard by inadvertent movement.
• Barriers. Where barriers are used, they must comply with the following provisions:
  • A continuous barrier not less than six feet in height must surround the unattended trench.
  • All barriers must be of adequate strength and supported in a manner that will allow them to be seen by the motorist and provide a stable support not easily blown over by the wind or traffic.
  • Trench barriers adjacent to high-speed traffic may include traffic control barrels ballasted by sandbags or temporary pre-cast concrete barriers as components.
  • Trench barriers comprised of multiple sections must allow not more than four inches between each section. Adjacent sections must be securely fastened to each other.
  • Any openings between the ground and barrier must not exceed four inches. Openings greater than four inches may be protected by solid guards of suitable materials, including plywood or wood planks.
  • Barriers must be at a sufficient distance from the trench to be unaffected by changing conditions of the trench site.

Trenches at fixed work sites other than on a public way. Access to unattended trenches opened during construction at a fixed work site on public or private property must be restricted by covers or portable barriers.

• Covers. Where covers are used, they must be comprised of steel metal plates no less than 3/4 inch thick or equivalent. Covers must be placed over trenches. Such covers must be level and physically secure to prevent the creation of a hazard by inadvertent movement.
• Barriers. Where portable protective barriers are used, barriers of a height not less than six feet must be constructed surrounding the entire perimeter of the trench.
  • Barriers comprised of multiple sections may allow not more than four inches between each section. Adjacent sections must be securely fastened to each other.
  • Openings between the ground and fence must not exceed four inches. Openings greater than four inches may be protected by solid guards or suitable materials, including plywood or wood planks.
  • Fence-type barriers must be adequately secured by vertical support members. Fencing spaces must not exceed four inches when measured as mesh size or between slats.
  • Solid barriers must not contain holes or indentations larger than four inches.
  • All horizontal support members must be located on the trench side of the barrier.
  • The wall of a dwelling or other permanent structure of a height of not less than six feet may serve as part of the barrier, provided it complies with all of the provisions of 520 CMR 14.04.
  • Gates and other means of egress must:
    • Comply with the size and strength provisions of 520 CMR 14.04(3)(b);
    • Be securely fastened to adjacent barrier components;
    • Allow not more than four inches between gates and barrier components; and
    • Be securely locked with a padlock, combination lock, or other suitable locking device.
  • Barriers must be clearly marked on all sides with signs indicating "Danger - Do Not Enter", "Authorized Personnel Only" or equivalent warning.
  • Barriers must be placed at a sufficient distance from the trench to be unaffected by changing conditions of the trench site.
• Continuous personal monitoring. The provisions of 520 CMR 14.04 may be substituted by continuous personal monitoring of the unattended trench by the permit holder or by person(s) under the control and direction of the permit holder.
• Backfilling while unattended. The provisions of 520 CMR 14.04 may be substituted by backfilling the work site while unattended.
• Additional site-specific provisions. The permitting authority may require any additional, site-specific provisions it deems necessary to protect the general public as a condition of any permit issued.