Excavation and trenching - Iowa

Iowa operates an OSHA-approved State Plan covering most private sector workers and all state and local government workers. Iowa OSHA is part of the Iowa Division of Labor Services in the Department of Workforce Development. Iowa OSHA has adopted federal OSHA's standards.

Underground facilities

Additional state standards govern excavations that occur in the area of underground facilities such as public utilities. Iowa has established a statewide notification center that notifies operators of underground facilities whenever excavators notify the center of a proposed excavation. After notification by the center, operators must locate and mark their underground facilities to prevent damage, interruption of service, and injury to excavation workers. No person may engage in any excavation unless these state standards have been met. The standards are located at Iowa Code §§ 480.1 -- 480.11.

Septic tanks 567 IAC 69.8 (455B)

The general excavation requirements for septic tanks are as follows:

• Fill soil. Any septic tank placed in fill soil must be placed upon a level, stable base that will not settle (69.8 (3) a.).
• Pipe in unstable ground. Schedule 40 plastic pipe must be used extending across excavations or unstable ground to at least 2 feet beyond the point where the original ground has not been disturbed in septic tank installations. If the excavation span is more than 2 feet wide, it must be filled with sand or compacted fill to provide a firm bed for the pipe. The first 12 inches of backfill over the pipe must be applied in thin layers, using material free from stones, boulders, large frozen chunks of earth or any similar material that would damage or break the pipe (69.8 (11) d.).

Mound septic systems 567-69.10 (455B)

A mound septic system is an alternative wastewater treatment system used in areas where the soil conditions are not suitable for a traditional septic system. It consists of a septic tank, a pump chamber, a distribution system, and an elevated mound of sand or gravel.

At-grade sewage system 567-69.11 (455B)

At-grade sewage system is an onsite sewage disposal system that utilizes a raised bed of gravel or stone over the natural soil surface. It is designed for sites with restrictive soil conditions and serves as an alternative to placing an elevated sand mound on some sites.