Excavation and trenching - New Hampshire

New Hampshire 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 facilities

The New Hampshire Underground Facility Damage Prevention System law (RSA 374:48 – 374.56) requires excavators to give notice to the system prior to excavation so that the system can transmit notice to operators of underground facilities to locate and mark their facilities to prevent damage, service interruption, or injury to excavation workers.

Minimum and express operational standards

No person or owner may excavate when an excavation is subject to a permit without complying with the following minimum standards or when such excavation is not subject to a permit without complying with the following express standards:

• No excavation may be permitted below road level within 50 feet of the right of way of any public highway unless such excavation is for the purpose of said highway.
• No excavation may be permitted within 50 feet of the boundary of a disapproving abutter, within 150 feet of any dwelling which either existed or for which a building permit has been issued at the time the excavation commenced.
• No excavation may be permitted within 75 feet of any great pond, navigable river, or any other standing body of water 10 acres or more in area or within 25 feet of any other stream, river or brook which normally flows throughout the year, or any naturally occurring standing body of water less than 10 acres, prime wetland, or any other wetland greater than five acres in area as defined by the department of environmental services.
• Vegetation must be maintained or provided within peripheral areas.
• Drainage must be maintained so as to prevent the accumulation of free-standing water for prolonged periods.
• No fuels, lubricants, or other toxic or polluting materials may be stored on-site unless in compliance with state laws or rules pertaining to such materials.
• Where temporary slopes will exceed a grade of 1:1, a fence or other suitable barricade must be erected to warn of danger or limit access to the site.
• Prior to the removal of topsoil or other overburden material from any land area that has not yet been excavated, the excavator must file a reclamation bond or other security as prescribed by the regulator, sufficient to secure the reclamation of the land area to be excavated.

Employer excavation and trenching rules

The employer must ensure compliance with the following requirements:

• Before excavation, underground utilities must be identified and marked, and utility companies contacted to determine if there are underground utility installations in the area.
• A competent person as defined in N.H. Admin. Rules, Lab 1402.01 must inspect and evaluate the condition of all trenches and excavations prior to permitting an employee to enter.
• The inspection must be performed at the beginning of each day and at least four times during the workday thereafter, and include the following:
  • Attention must be given when adverse weather conditions might affect the condition of the excavation or trench; and
  • If evidence of possible cave-ins or slides is apparent, all work in the excavation shall cease until the requirements below have been met.
• The walls and faces of trenches five feet or more deep, and all excavations, in which employees are exposed to danger from moving ground or cave-in, must be guarded by a trench protective system or sloping of the ground.
• In excavations which employees might be required to enter, excavated or other material must be stored and retained at least two feet or more from the edge of the excavation.
• Trenches four feet deep or more must have an adequate means of exit such as ladders or steps in the protected area of the trench. The exit must be located to require no more than 25 feet of lateral travel.
• Excavations near retaining walls, utility poles and other objects that are supported by compacted soil must always be supported to prevent their collapse or undermining.