Theme: 09. Vapor Intrusion

Topic Area: 9c. Vapor Intrusion Preferential Pathways

Formatted Title:

Investigation of Plumbing Leakage: PVC Pipe Prototype Testing

Background/Objectives:

Volatile organic compounds (VOCs) are present in the subsurface at many hazardous waste sites. VOC vapors can migrate from subsurface sources through piping conduits and be transported into indoor spaces. A growing body of evidence has confirmed that sewer conduits/pipelines can act as an intrusion pathway. Thus, there is a need to better understand how VOC vapors enter indoor air spaces. Indoor plumbing pipe fixtures are suspected to create pathways for vapors to migrate into buildings, although there is a need for improved understanding about how vapors enter indoor spaces. This research specifically investigates common plumbing fixtures and the potential for vapor leakage from indoor plumbing joints.

Approach/Activities:

This study systematically investigates vapor leakage through common indoor plumbing systems. Depressurization and chemical tests are performed on multiple prototypes of different polyvinyl chloride (PVC) pipe fittings and joints to measure and quantify vapor leakage. All plumbing joints and fittings in this study conform to the Uniform Plumbing Code (UPC) and International Plumbing Code (IPC). Three joints are included in testing: 1) clamp-on flexible coupling (UPC 705.1), 2) threaded joint (UPC 705.6.3), and 3) cleanout threaded plug and tee (UPC 707.2). Depressurization tests include the prototypes being pressurized to approximately 1.5 psi and pressure reading being recorded at designated intervals until atmospheric pressure is reached. To test chemical leakage, 10 ppb concentration of a commercial standard VOC vapor mixture is flushed into the joint prototype. The joint protype, with the VOC vapors, is enclosed in a sealed container. Daily samples will be extracted from the sealed container to measure VOC vapors leaking from the joint prototypes.

Results/Lessons Learned:

Depressurization tests for the joints experienced different pressure drop trends. The clamp-on flexible coupling (UPC 705.1) had a linear decrease in pressure. In contrast, threaded joint (UPC 705.6.3) and the cleanout threaded plug and tee (UPC 707.2) had rapid exponential decreases in pressure, with both joints reaching atmospheric pressure in less than 3 hours. The flexible coupling did not reach atmospheric pressure until 2 days. Chemical leakage tests are ongoing. To date, the flexible coupling has been tested and the results substantial VOC vapor leakage. Additional tests will be conducted.

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Kelly G. Pennell