Lab Matters Spring 2019 - Page 17

FROM THE BENCH Rhode Island Leverages Agency Partnerships to Identify Contaminated Leachate By Louis Marchetti, PhD, CT coordinator, Rhode Island Department of Health State Health Laboratory To further the working relationship between the first responder community and state agencies, Rhode Island’s Chemical Threat (RI CT) laboratory has expanded its sample submission criteria to include requests for analysis of non-clinical samples. RI CT partners with CDC through its participation in the Laboratory Response Network for Chemical Threats (LRN-C). Chemical Threat laboratories, such as RI CT, may leverage this testing capacity to support emergency response stakeholders such as local law enforcement, hazmat teams, and other governmental partners that contact the laboratory for assistance. Utilizing the LRN-C infrastructure, requests for presumptive identification of unknown materials may be submitted directly to the CT laboratory by emergency response stakeholders. An Odoriferous Problem Recently, Rhode Island’s Department of Environmental Management (RIDEM) was contacted to investigate a complaint, made by several individuals, of a natural gas odor emanating from a Providence home. The homeowner had recently switched from oil to gas heating, which resulted in the installation of a new underground line from the street to the house. The local energy company was contacted to assist with air and soil probing to determine if a natural gas leak could be identified, but, despite the strong odor emanating from the property, results of all field screening analyses were negative. At this time, a liquid discharge pooling around the base of the piping of the regulator supplying the home with gas was observed. A sample of the water runoff from the piping was collected and submitted to the Rhode Island State Health Laboratory (RISHL), and the CT Coordinator was asked to assist in the investigation. With a few minor alterations to the LRN-C’s VOC method, the CT laboratory was able to presumptively identify, through library matching, the presence of PublicHealthLabs @APHL Chromatogram of tetrahydrothiophene with library match tetrahydrothiophene—a common odorant for natural gas—and pyridine within the sample. A Quick Response RIDEM was immediately notified of the results, and the energy provider was alerted of the possibility that contaminated leachate material was coming from the ground. As a result, a section of the yard of the home in question was excavated within the hour. It was determined that an old pipe connected to a gas main no longer in use was cut below the soil grade and capped with a rubber stopper that did not properly fit. Due to recent rain storms, groundwater was entering the main line that ran upgradient of the house. It was pushing the residual gas through the pipe and discharging into the property, thus contaminating the soil and resulting in the odor which triggered the investigation. The energy provider has since removed the pipe, and follow-up testing results came back negative for additional contamination. It was determined that because the old gas main was no longer under pressure, the gas company could not detect natural APHL.org Natural Gas Odorants Since natural gas is combustible and odorless, the government requires it be odorized as a safety measure. Odorants may smell like rotten eggs, kerosene, lighter fluid and skunk, and often vary regionally. While some compounds are used by themselves (such as tetrahydrothiophene), most odorants consist of a mixture of compounds including: • • • • • • • dimethyl sulfide sopropyl mercaptan methyl ethyl sulfide normal propyl mercaptan secondary butyl mercaptan tertiary butyl mercaptan tetrahydrothiophene. gas vapors under the ground near the release. The gas company had been out at the site on and off for over two weeks attempting to identify a gas release. Jim Ball of the Department of Environmental Management Office of Emergency Response indicated that, due to the coordinated efforts of the two agencies, the life safety hazard and toxic exposure to the public was eliminated in a much more expedient fashion. n Spring 2019 LAB MATTERS 15