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:
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•
•
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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
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