Studying CIPP Emission Safety

Commitment to research and recommendations continues with third phase of CIPP study.

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NASSCO continues to fund important third-party research on the safety of emissions from the cured-in-place pipe process when using styrenated resin. To date, there have been three phases of NASSCO-funded research, with each phase providing findings, valuable information, recommended safety protocols and direction for additional research and next steps.

Phase 1

Previously published reports questioned the safety of emissions from the CIPP process when using styrenated resin. In response, NASSCO made the decision to fund research to validate these claims. After submittal of an RFP and exhaustive screening of potential research labs and universities, NASSCO selected the Center for Underground Infrastructure Research and Education (CUIRE) to fully evaluate all previously published reports questioning the safety of CIPP emissions. The CUIRE report found previously published reports to be nonconclusive.

Phase 2

Given CUIRE’s findings and the nonconclusive nature of previously published reports, NASSCO wanted to dig deeper with an independent study. Once again, the process of RFP solicitation and submittal began and this time the Trenchless Technology Center at Louisiana Tech University (TTC) was selected. The nearly two-year research project, including field studies in a variety of geographic locations (testing different CIPP dimensions, conditions and worker exposure), resulted in specific recommendations for refrigeration/storage units and steam cure emission stacks.

CIPP storage units:

 For those immediately entering the liner transport truck or storage unit, active air monitoring should be utilized at the initial opening of the truck or storage unit door to ensure a safe work environment.

 At the initial opening of the CIPP refrigerated truck or storage unit, suitable PPE should be worn by those immediately entering the truck or storage unit.

Emission stacks:

 A perimeter of 15 feet should be implemented around exhaust manholes and emission stacks during curing. This perimeter could be entered for short amounts of time not exceeding five minutes. If this area must be entered for longer than five minutes, suitable PPE should be used.

 Emission stacks should be a minimum of 6 feet in height to enhance the dispersion of emissions and lessen the likelihood of workers entering the perimeter from having to cross into the plume even when wearing PPE.

Phase 3

Per TTC’s Phase 2 recommendation, an additional study is currently in progress to focus on task-oriented worker exposure to emissions relative to the CIPP storage unit. Phase 3 will include testing in two steps:

1. The styrene emissions generated inside and around a “test” CIPP storage unit to develop a baseline for monitoring in actual CIPP storage units.

2. The styrene emissions generated inside and around actual CIPP storage units based upon the findings of step one, while considering CIPP liner sizes, resin weight, liner stacking and liner coatings.

The results of this research will be evaluated and compared to other studies running parallel with the NASSCO Phase 3 study. The data generated from these studies will be used to determine if NASSCO should conduct further testing (e.g. Phase 4) beyond the items described above. 

As NASSCO continues its mission to set standards for the assessment, maintenance and rehabilitation of underground infrastructure, safety will remain its No. 1 value. As NASSCO’s top priority, safety should also be of critical concern to all contractors within our industry.

As a 501(c)(6) trade association whose responsibility is to represent and protect the entire industry, NASSCO will do everything within its means to ensure no stone is left unturned. For full research reports, the latest on CIPP emission studies, styrene safety and more, visit 


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