Abstracts

in this basin. The HGS/OASIS model framework was used to evaluate the interactions
and dependencies between the engineered and natural hydrologic systems under historic
and projected future climatic conditions and potential structural water management alternatives
in this basin. Results emphasize the need to include groundwater, surface water and
their interactions in water management strategies and planning.
130 - Evaluating innovative techniques for in situ, real-time
remote monitoring of nitrate in groundwater
Graeme MacDonald & Jana Levison
School of Engineering - University of Guelph, Guelph, Ontario, Canada
Certain hydrogeological settings in southern Ontario are particularly vulnerable to nitrate
contamination of groundwater. Nitrate can leach into aquifers during recharge events,
where it is subject to complex fate and transport processes under spatially and temporally
variable flow conditions. Advancements in monitoring and data collection capabilities can
improve our understanding of these transport processes. Groundwater quality measurements
are traditionally obtained by purging wells and analyzing the collected samples ex
situ. This “snapshot” data can disrupt the natural subsurface flow system and is not always
detailed enough to determine critical water quality conditions. This research involved the
application of two innovative sensors, the YSI EXO and Satlantic SUNA V2, to develop
novel groundwater quality sampling techniques. Three unique methods were developed:
flow cell spot sampling, depth-discrete downhole geochemical profiling, and real
time remote groundwater quality monitoring (RTRM). While nitrate was the contaminant
of focus, field parameters including temperature, DO, ORP, EC, and turbidity were
also monitored. Research sites ranged from supply wells located in shallow overburden
aquifers to deep fractured bedrock boreholes. Flow cell spot sampling results were compared
to traditional laboratory sampling methods and were very strongly correlated (R 2 =
0.99), suggesting that the sensors can provide highly accurate field nitrate measurements.
Depth-discrete profiling techniques were used to identify groundwater quality zones corresponding
to different formations. Stratified nitrate concentrations were observed in an
open bedrock borehole (20 m depth) and an overburden well having a long (8 m) screened
interval. RTRM methods were conducted by installing sensor equipment directly downhole.
Groundwater quality parameters were obtained every 15 minutes for several months,
starting in November 2014, greatly improving the temporal resolution of measurements
compared to traditional sampling. Data was transmitted over the HSPA network and observed
in real time, allowing for remote monitoring and effectively reducing labour and
field visits compared to traditional techniques. The detailed datasets obtained will support
future nitrate transport modelling initiatives and complement field projects in which in
situ, detailed nitrate measurements are desired.
IAH-CNC 2015 WATERLOO CONFERENCE
135