Published reports have questioned the safety of emissions from the cured-in-place pipe (CIPP) process when using styrenated resin. In response, NASSCO has gone to great lengths to ensure our workers and communities stay healthy by understanding these claims through the funding of comprehensive, third-party, objective research. Safety is NASSCO’s number one priority and should be the top concern of all contractors within our industry.


RELATED: University of Texas at Arlington Research Team Completes CIPP Study Review


NASSCO’s funded research has been based on a progressive, three-phased approach:


Phase 1:


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 result? CUIRE found previously published reports to be non-conclusive (findings available at nassco.org/cipp-safety).


Phase 2:


Given the non-conclusive nature of previously published reports, as reported by CUIRE, 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.


RELATED: TTC Completes Environmental Impact Study of Steam-Cured CIPP


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 ft 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 ft 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


Please view the full TTC report and findings by visiting nassco.org/news/CIPP-study.


Phase 3:


Per TTC’s Phase 2 recommendation, an additional study is being launched 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 in parallel with the NASSCO Phase 3 study. The resulting data generated from these concurrent studies will be used to determine if NASSCO should conduct further testing beyond the items described above.


NASSCO intends to identify any specific health and safety precautions that workers may need in order to maintain a safe environment while working in or around the CIPP storage units that are typically found on a CIPP work site.


As NASSCO continues its mission to set standards for the assessment, maintenance and rehabilitation of underground infrastructure, safety will remain its number one value and we will do everything within our means to ensure we have left no stone unturned.


For full research reports, the latest on CIPP emission studies, styrene safety and more, please visit nassco.org.



Randy Belanger is a NASSCO Board member and sales manager at Visu-Sewer Inc. 



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