Abstracts

aquifers and (ii) the uncertain integrity of domestic and farm wells, there is clearly a burden
of proof on those sampling such wells to demonstrate that the ‘pre-drill’ data collected are
robust and provide reliable information for use in dispute resolution and resource management.
If the only purpose of such ‘baseline’ sampling is the collection of natural gas samples,
then (i) the transient nature of natural gas emissions from oil and gas wells needs to be
considered in terms of monitoring and (ii) sample collection must be optimized to reduce
degassing at the well. Neither constraint is easily overcome with domestic wells.
An exemplary protocol for testing of domestic and farm wells is that developed by Alberta
Environment (Standard for Baseline Water Well Testing for Coalbed Methane/Natural
Gas in Coal Operations, April 2006) that encourages (but does not require) the removal
of the sanitary seal of a landowner’s well in order to conduct both a water-supply ‘yield
test’ and GWQ sampling downhole. The additional expense (~$3,000 per well) of such a
precaution may be considered as part of the cost of acquiring better scientific data from a
water well not designed to yield scientifically reliable GWQ data.
145 - Case Study Source Discrimination of a Benzene Release
Using a Two-Dimensional (2D) Compound Specific Isotopic
Analysis (CSIA) Approach
Natalie Szponar, Brad J. MacLean, Tom H. Grimminck, Heather Stuart, & Rob F. Kell
Dillon Consulting Limited, Oakville, Ontario, Canada
In recent years, Compound Specific Isotope Analysis (CSIA) has emerged as an important
tool in environmental forensics in assessing source(s) at contaminated sites, understanding
comingled plumes and evaluating contaminant attenuation. This case study presents
a Two-Dimensional (2D) CSIA approach that was used to gain a better understanding
of the potential source(s) and age of benzene impacts to groundwater where no definitive
source or release date had been identified.
Extensive groundwater and soil characterization at the site of the case study identified benzene
impacts in soil from 1 to greater than 4 meter below ground surface, with a maximum
identified benzene concentration of 1,500 ug/g in soil; and 939,000 ug/L in groundwater.
Although the characterization has provided a good understanding of the distribution of
the benzene impacts, the source of the identified impacts and the time of release(s) were
unknown. These unknowns were further complicated by the presence of numerous potential
sources and a complex array of underground services and pipelines.
Stable isotope techniques provide a powerful tool for source discrimination. In particular, stable
carbon (δ 13 C) and hydrogen (δ 2 H) isotopes when plotted against each other for a specific
compound (i.e., benzene) [referred to 2D-CSIA] can provide a “fingerprint” plot. This plot
can be used to distinguish between different physical and biological processes affecting the
compound, and may also provide further differentiation between different sources of refined/
manufactured benzene product (based on source material and manufacturing process).
IAH-CNC 2015 WATERLOO CONFERENCE
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