Excavation and trenching - Louisiana

Louisiana is under federal OSHA jurisdiction which covers most private sector workers within the state. State and local government workers are not covered by federal OSHA.

Underground utilities

Louisiana’s excavation and trenching laws require excavators to notify a regional notification center before starting any excavation or demolition. The center then notifies operators of underground utilities and facilities so that they can located and mark their utilities and facilities and thereby prevent damage, injury to workmen, and the interruption of essential services. The law does not apply to activities by operators or landowners excavating their own underground facilities or utilities on their own property. The rules can be found at La. R.S. 40:1749.11 to 40:1749.27.

Plumbing excavation, trenching, and backfill requirements

Piping support. Buried piping must be supported throughout its entire length.

Open trenches. All excavations required to be made for the installation of a building drainage system, or any part thereof within the walls of a building, must be open trench work and must be kept open until the piping has been inspected, tested and accepted.

Mechanical excavation. Trenches must be properly graded and tamped to support the load of the pipe installation.

Backfilling. Adequate precautions must be taken to ensure proper compactness of backfill around piping without damage to such piping.

Tunneling. Where necessary, pipes may be installed by tunneling, jacking, or a combination of both. In such cases, special care must be exercised to protect the pipe from damage either during installation or from subsequent uneven loading. Where earth tunnels are used, adequate supporting structures must be provided to prevent future settling or caving. Pipe may be installed in larger conduit which has been jacked through unexcavated portions of the trench.

Single trench prohibited. Water service pipes or any underground water pipes must not be run or laid in the same trench as the building sewer or drainage piping, except as provided for in LAC 51:XIV.601-629 and LAC 51:XIV.701-735.

Standards for installation of utilities on highways

General. All excavations within the limits of the right-of-way must be backfilled and tamped in layers to the density of the adjacent undisturbed soil. Where sod is removed or destroyed, it must be replaced. Where it is necessary to make excavations in the shoulder, the top six inches of backfill must be with like shoulder material. Existing soil materials declared unsuitable for backfill by the Department of Transportation and Development (DOTD) must be disposed of by approved methods and replaced with select material as needed.

Pipeline standards – Bury rules. The critical controls for bury on a pipeline crossing are the low points in the highway cross-section. Usually these are the bottoms of the longitudinal ditches or drain lines. In establishing the depth of bury below an unpaved ditch, consideration should be given to potential increases in ditch depth resulting from scour, ditch maintenance operations, or the need to increase the capacity of the ditch. On parallel installations, the critical controls for bury are the depths of lateral drainage facilities, landscaping, buried utility lines, bridge bury of pipelines.

• The minimum bury for parallel installations is 24 inches.
• The minimum bury under pavement or surfacing is 4 feet for cased crossings and 5 feet for uncased crossings.
• The minimum bury under ditches and drainage structures is 24 inches for cased facilities and 36 inches for uncased facilities.
• Protection, in the form of a concrete slab or other acceptable method, must be provided invulnerable locations, such as below ditches, if the minimum bury cannot be practically obtained.

Pipeline installation – Trenching. All trenched installation must be approved by the engineer. Trenches must be cut to have vertical faces, where soil and depth conditions permit, with a maximum width of outside diameter of pipe plus two feet. They must be shored where necessary.

Pipeline installation – Backfilling:

• Backfill placed under the roadway prism must equal or exceed the quality of the existing material and be compacted to a density equal to or in excess of the density of the existing undisturbed roadway embankment.
• Backfill inside the highway right-of-way, but not under the roadway prism must be compacted to a density at least equal to the density of the surrounding undisturbed soil.
  • This must be accomplished by the use of tools, methods and materials approved by the engineer.
• The required compaction of the backfill throughout the utility's installation within the limits of highway right-of-way must be satisfactory to the engineer who may make or cause to be made such density tests that he may consider appropriate for the circumstance.
• In some instances, the DOTD may require that backfill and/or paving be performed by its own forces or under its direction at the expense of the utility when considered necessary by the engineer for the protection of the traveling public and/or the highway itself.
• The pavement structure must be restored in appropriate layers utilizing materials at least equal in quality and layer depths to the original construction.
  • There will be additional removal of base and surfacing to minimize later development of sag in the grade of pavement over the ditch.

Installation of fiber-optic cable

All excavations within the limits of the right-of-way must be backfilled and tamped in six-inch layers to the density of the adjacent undisturbed soil. Where sod is removed or destroyed, it must be replaced within one week of the original disturbance. Where existing spoil material is, at the discretion of the department, unsuitable for backfill, select material must be furnished in lieu thereof, and the existing material must be disposed of by approved methods.

Repairs beneath the roadway will not be allowed if such repairs necessitate open cutting (open trenches) the highway. If a problem occurs with a line crossing, the utility company must install a new crossing. The utility company must bear the total cost.

Parallel cables. In addition to the above requirements, the following requirements apply to cables installed parallel to the highway:

• Installations must occupy available space within the back 10 feet of the right-of-way (located on the side most distant from the traveled roadway), except where, upon showing of actual necessity, a permit is issued for another location.
• Installations must have a minimum earth cover of 36 inches.
• Installations must have a minimum clearance of 24 inches below existing or proposed drainage structures, unless otherwise approved by the department.
• There must be no installation of cable within the median.

Cables crossing the highway. Crossings must have at least five feet of cover below the roadway and 24 inches of cover below ditches or drainage structures. Crossings must be made at as nearly right angles to the highway as possible. No existing drainage structure under the highway may be used for this purpose. Construction methods include:

• Cutting and tunneling is prohibited. Cutting the surface or tunneling under it is specifically prohibited.
• Boring or jacking. Installation must be made either by boring or jacking under the highway from ditch bottom to ditch bottom.
  • In the absence of ditches, or along sections of highway with curb or gutter, boring or jacking must extend beyond the outside edge of the traveled way to a point at least equal to three times the vertical difference between the elevation of the roadway surfacing and the elevation of the top of the cable.
  • Where width of right-of-way is insufficient to enable compliance with this requirement or where it is necessary to make a connection to an existing parallel facility which precludes compliance, the distance must be computed to the right-of-way line or to the parallel facility.
  • Any voids or overbreaks resulting from this task must be backfilled with grout consisting of a cement mortar or a slurry of fine sand or clay, as conditions require.
  • Excavating an open ditch to the edge of the pavement and boring and jacking the remainder of the distance is prohibited.