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Calgary, Canada

Derksen B.G.,Waterline Resources Inc.
Proceedings, Annual Conference - Canadian Society for Civil Engineering | Year: 2012

An area that continues to present challenges with in-situ remediation technology is the system of delivery for the treatment. Conventional treatment delivery systems include direct push, pneumatic and hydraulic fracturing. There are limited studies that have investigated multiple treatment systems under the same conditions (same test site). This study is unique in observing the affects of combining methods of two delivery systems under the same conditions. The objective of this study is to observe the effects of direct push fluid injection compared to a combination of air and fluid injection delivered into the subsurface through a pulsing system. It is generally accepted that water will travel the path of least resistance. It is expected that the air pulse will move out into the finer pore spaces creating a conduit for the water to follow. The goal is to determine the optimal design to maximize the use of a pre-existing groundwater well network. Two methods of enhanced delivery for in situ remediation amendments were tested in both a laboratory setting: direct push injection of fluid and pulsed injection of air followed by fluid. The testing in the laboratory was carried out within a sand filled Plexiglass container. The test show that injected fluids travel farther through the matrix in the x-direction during the pulsing system method than they do under the direct injection method. The spatial distribution of the pulsed fluids at the end of the injection is uniquely different form that of the direct push. Source

Bishop J.M.,Waterline Resources Inc. | Callaghan M.V.,University of Calgary | Cey E.E.,University of Calgary | Bentley L.R.,University of Calgary
Water Resources Research | Year: 2015

Multiyear monitoring and simulation of a conservative tracer was used in this study to investigate preferential flow and macropore-matrix interactions in low permeability, macroporous soil. 2,6-Difluorobenzoic acid (DFBA) tracer was applied to a 20 × 20 m drip irrigated test plot situated over two tile drains. Tracer movement over the 2009 and 2010 field seasons was monitored using tile drain effluent, suction lysimeters, monitoring wells, and soil cores. Despite similar volumes of water application to the plot in each season, 10 times more water and 14 times more DFBA were captured by the drains in 2010 due to wetter regional hydrologic conditions. The importance of preferential flow along macropores was shown by rapid DFBA breakthrough to the tile (<47 h), and DFBA detections in sand units below the tile drains. Preferential flow resulted in less than 8% of the DFBA mass being captured by the tiles over both years. With much of the DFBA mass (75%) retained in the upper 0.25 m of the soil at the end of 2009, numerical simulations were used to quantify the migration of this in situ tracer during the subsequent 2010 field season. Dual permeability and dual porosity models produced similar matches to measured tile drain flows and concentrations, but solute leaching was captured more effectively by the dual permeability formulation. The simulations highlighted limitations in current descriptions for small-scale mass transfer between matrix and macropore domains, which do not consider time-dependent transfer coefficients or nonuniform distributions of solute mass within soil matrix blocks. Key Points: Macropore-matrix mass exchange controls solute transport in low K soil Antecedent moisture conditions influence flow and solute transport between years Model mass exchange coefficients may vary with time or solute distribution © 2015. American Geophysical Union. All Rights Reserved. Source

Doyle J.M.,University of British Columbia | Doyle J.M.,Waterline Resources Inc. | Gleeson T.,McGill University | Gleeson T.,University of Victoria | And 2 more authors.
Water Resources Research | Year: 2015

Environmental tracers provide information on groundwater age, recharge conditions, and flow processes which can be helpful for evaluating groundwater sustainability and vulnerability. Dissolved noble gas data have proven particularly useful in mountainous terrain because they can be used to determine recharge elevation. However, tracer-derived recharge elevations have not been utilized as calibration targets for numerical groundwater flow models. Herein, we constrain and calibrate a regional groundwater flow model with noble-gas-derived recharge elevations for the first time. Tritium and noble gas tracer results improved the site conceptual model by identifying a previously uncertain contribution of mountain block recharge from the Coast Mountains to an alluvial coastal aquifer in humid southwestern British Columbia. The revised conceptual model was integrated into a three-dimensional numerical groundwater flow model and calibrated to hydraulic head data in addition to recharge elevations estimated from noble gas recharge temperatures. Recharge elevations proved to be imperative for constraining hydraulic conductivity, recharge location, and bedrock geometry, and thus minimizing model nonuniqueness. Results indicate that 45% of recharge to the aquifer is mountain block recharge. A similar match between measured and modeled heads was achieved in a second numerical model that excludes the mountain block (no mountain block recharge), demonstrating that hydraulic head data alone are incapable of quantifying mountain block recharge. This result has significant implications for understanding and managing source water protection in recharge areas, potential effects of climate change, the overall water budget, and ultimately ensuring groundwater sustainability. © 2015. American Geophysical Union. All Rights Reserved. Source

Mellor A.F.P.,Waterline Resources Inc. | Cey E.E.,University of Calgary
Journal of Contaminant Hydrology | Year: 2015

The Abbotsford-Sumas aquifer (ASA) has a history of nitrate contamination from agricultural land use and manure application to soils, yet little is known about its microbial groundwater quality. The goal of this study was to investigate the spatiotemporal distribution of pathogen indicators (Escherichia coli [E. coli] and total coliform [TC]) and nitrate in groundwater, and their potential relation to hydrologic drivers. Sampling of 46 wells over an 11-month period confirmed elevated nitrate concentrations, with more than 50% of samples exceeding 10 mg-N/L. E. coli detections in groundwater were infrequent (4 of 385 total samples) and attributed mainly to surface water-groundwater connections along Fishtrap Creek, which tested positive for E. coli in every sampling event. TC was detected frequently in groundwater (70% of samples) across the ASA. Generalized additive mixed models (GAMMs) yielded valuable insights into relationships between TC or nitrate and a range of spatial, temporal, and hydrologic explanatory variables. Increased TC values over the wetter fall and winter period were most strongly related to groundwater temperatures and levels, while precipitation and well location were weaker (but still significant) predictors. In contrast, the moderate temporal variability in nitrate concentrations was not significantly related to hydrologic forcings. TC was relatively widespread across the ASA and spatial patterns could not be attributed solely to surface water connectivity. Varying nitrate concentrations across the ASA were significantly related to both well location and depth, likely due to spatially variable nitrogen loading and localized geochemical attenuation (i.e., denitrification). Vulnerability of the ASA to bacteria was clearly linked to hydrologic conditions, and was distinct from nitrate, such that a groundwater management strategy specifically for bacterial contaminants is warranted. © 2015 Elsevier B.V. All rights reserved. Source

Groundwater recharge sets a constraint on aquifer water balance in the context of water management. Historical data on groundwater and other relevant hydrological processes can be used to understand the effects of climatic variability on recharge, but such data sets are rare. The climate of the Canadian prairies is characterized by large inter-annual and inter-decadal variability in precipitation, which provides opportunities to examine the response of groundwater recharge to changes in meteorological conditions. A decadal study was conducted in a small (250 km2) prairie watershed in Alberta, Canada. Relative magnitude of annual recharge, indicated by water-level rise, was significantly correlated with a combination of growing-season precipitation and snowmelt runoff, which drives depression-focussed infiltration of meltwater. Annual precipitation was greater than vapour flux at an experimental site in some years and smaller in other years. On average precipitation minus vapour flux was 10 mm y−1, which was comparable to the magnitude of watershed-scale groundwater recharge estimated from creek baseflow. Average baseflow showed a distinct shift from a low value (4 mm y−1) in 1982–1995 to a high value (15 mm y−1) in 2003–2013, indicating the sensitivity of groundwater recharge to a decadal-scale variability of meteorological conditions. © 2014, Springer-Verlag Berlin Heidelberg. Source

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