Exposure to toxic chemicals from cured-in-place piping
What is the potential risk?
Cured-in-place piping (CIPP) is a method of repairing sanitary sewer and stormwater supply lines while the original piping remains in place. The process involves inserting a fabric liner, soaked with a liquid resin, into a damaged pipe. The liner is then inflated to cover the inside walls of the pipe. A hardening process called polymerization transforms the liquid resin into a polymer pipe inside the original, damaged pipe.
The polymerization reaction is usually initiated by heat from steam or hot water, but can also be initiated by ultraviolet (UV) light. The use of forced, heated air may release volatile chemicals into the environment around the release point. The air coming out from the CIPP is a multi-phase mixture (in other words, a mixture of solid, liquid, and gas) containing toxic contaminants. Any rips or ruptures in the fabric liner can cause these chemicals to leak and result in potential exposures.
Many of the chemicals used in CIPP can pose a risk of significant irritation and occupational disease, even at low exposure levels. For example, styrene — a chemical commonly used in this process — can cause upper respiratory tract irritation, central nervous system impairment, and hearing loss, and is a suspected human carcinogen. Exposure to the chemicals used or released by CIPP must be properly controlled.
Who is at risk?
CIPP is an emerging technology in B.C. In other countries, however, this technology is widely used for repairing existing infrastructure. Some examples of this technology in use include:
- Municipal sanitary sewer and stormwater lines
- Municipal potable water supply lines
- Industrial sewage systems
- Culverts and other stormwater run-off control systems under existing roads and other structures
Employers and workers who undertake this work may be at risk of significant exposure to various chemicals. This includes workers who may be on or around the worksite for other work tasks.
Furthermore, many of these projects occur near public spaces or other workplaces. An employer must direct contaminated air to a safe location where the objectionable odour will not expose workers at an adjacent workplace. The employer should consider posting contact information so that if controls in place are ineffective, workers or members of the public can have their concerns addressed.
How can I reduce the risk in my workplace?
If you’re an employer, the first step to reducing the risk is to understand and follow the manufacturer’s instructions for setting up the task. Also consider the project plan, physical layout of equipment, wind direction, controlling access to areas, and any necessary personal protective equipment (such as respirators). These instructions should form part of a written exposure control plan (ECP).
An ECP explains how you will control workers’ exposure to this chemical hazard and may be required, depending on the chemicals used. It may also need to include a ventilation plan for industrial ventilation systems, especially if work will be done in an enclosed or confined space.
It’s possible that volatile chemicals may leak from unexpected areas, so a thorough review of the pipe design layout is necessary. It’s also important to consider that “as designed” drawings of the piping may not match the actual installation. Therefore, you must carefully review the actual physical layout and connection to the damaged piping.
These projects often require many pieces of mobile equipment, high-pressure steam, air lines, and work being done in confined spaces. The complexity of these projects with the integration of several pieces of equipment is a significant hazard.
Where can I find more information?
- Occupational Health and Safety Regulation, Part 5, Chemical Agents and Biological Agents Sections of particular interest include:
- Working safely around confined spaces
- Worksite Chemical Air Emissions and Worker Exposure during Sanitary Sewer and Stormwater Pipe Rehabilitation Using Cured-in-Place-Pipe (American Chemical Society)
Learn more about managing risk in your workplace.