Tunneling Under Slab To Replace Pipes

When getting bids for sewer pipe repair, you may be presented with the option of “tunneling”. This is the process of digging a tunnel under a residential or commercial building and then having manpower crawl into the confined space under the building to remove the old pipes and hang new ones from the slab. The appeal in this process lies with the prospect of not having to cut through floors, saving costs in replacing flooring as well as other damaged finishes. However, Pipelining Technologies, Inc. strongly warns against the tunneling process due to serious safety concerns, structural repercussions and the liability involved.  A trenchless method, such as pipe lining, may be an eligible alternative for your property, eliminating these unnecessary risks.

What are the Safety Concerns of Tunneling to Replace Pipes?

Although due diligence may be performed for worksite safety according to OSHA guidelines, there is always room for human error. Of all workplace fatalities, 18.5% occur in the construction industry, with most occurring while performing considerably dangerous tasks such as tunneling. Two major safety concerns when tunneling include proper air quality/ventilation and the risk of loose soils collapsing.

First, proper ventilation must be ensured. OSHA requires that fresh air be supplied to all underground work areas in sufficient amounts to prevent accumulation of harmful gases, dusts, fumes, mists or vapors. If natural air flow does not provide the necessary air quality, the contractor must provide mechanical ventilation to ensure the employee has enough air.

Another safety concern would be loose soils. One of the “fatal four”, or the top four causes of death in the construction industry, includes “getting stuck in/between” somewhere or something.  If soil stability in the tunnel weakens after ground vibrations from heavy machinery or high tide, there is the possibility of a section of the tunnel wall caving in and trapping/engulfing a worker.

Not only would a serious injury or death on your property be tragic, but the property owner may be held liable for the damages and face serious financial consequences.

Is an OSHA Permit Required for Tunneling?

In most cases, an OSHA permit will be required to tunnel under a structure to replace pipes. According to the Occupational Safety & Health Administration (OSHA) a permit-required confined space is a confined space having safety hazards such as containing “a material with the potential to engulf someone who enters the space”. This is the case on tunnel projects where workers a space under the foundation by hand that is just big enough to crawl through. If a portion of the dirt walls were to cave in on or around the entrant, he/she may be engulfed and potentially asphyxiated. If a confined space has this or any other recognized serious safety or health hazard it will be considered a permit-required confined space.

When a tunneling project meets the permit-required confined space definition, an OSHA permit must be pulled to protect the life-safety and health of entrants. In many cases, however, contractors will not pull the required OSHA permit because of the extensive safety requirements involved as well as for fear of receiving fines from onsite OSHA personnel.

Some of the potential OSHA requirements for permit-required confined spaces include:

  • Employer must develop and implement an extensive written program for the space
  • Testing, monitoring, ventilating, communications and lighting equipment
  • Barriers and shields
  • Retrieval devices
  • Proper worker training
  • Provide an entry supervisor
  • Employer must provide and train rescue service personnel
  • Entrants must wear harnesses with retrieval lines

For more information about OSHA requirements for tunneling/permit-required confined spaces visit: https://www.osha.gov/Publications/osha3138.pdf

Is There Liability for the Property Owner/Association Liability?

If an OSHA permit is not pulled when required, the property owner/condominium association may be held liable for any injuries or deaths due to the negligence of not taking the necessary safety precautions by pulling an OSHA permit.

What are the Effects on the Home/Building After Tunneling?

If the home or building is not on piles, there is cause for concern about soil re-compaction. Standard soil compaction equipment is not able to fit in these tunnels making it impossible to restore the original soil density. This could result in an unsupported void under the slab throughout the length of the tunnel.

In order to determine whether the building’s structural integrity will be adversely affected during tunneling, a structural engineer must provide an assessment. A major concern comes from the soil strength around the perimeter of the building since the outer sides of a foundation typically carry much of the structures weight. If the soil is inadequate, undermining the perimeter of the foundation may result in settlement of the building.

Is There an Alternative to Tunneling Under Foundations to Replace Pipes?

As was mentioned at the outset of this article, tunneling is typically performed in lieu of cutting through floors, however, there is a substantial risk for serious injury/death, foundation settlement if not properly assessed as well as severe legal ramifications if an OSHA permit is not pulled.

The trenchless pipe repair method of pipe lining is capable of making permanent repairs to your underground plumbing infrastructure without the need for a tunnel or unnecessary risks. No cutting of floors or walls is required for pipe lining. Structural pipe lining is a solution for condominiums, commercial buildings as well as single family homes. Residents do not need to leave their home and businesses can operate with minimal interruption while pipe lining repairs are being made. In addition, the product has a 50+ year life-use expectancy and repairs can be performed in as little as a few days compared to weeks or months. Looking for an alternative to tunneling under your home or building to replace pipes?  Contact us today to see if pipe lining is right for you.