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Calgary, Canada

Walker T.R.,Dillon Consulting Limited
Polish Polar Research

A total of 212 soil profiles were described and assessed for physical and chemical properties during July 2006 as part of an Ecological Land Classification study along the Churchill River in central Labrador. Two major soil types were found in the study area along the Churchill River: Podzols and Organic soils. Podzolic soils covered approximately 60% and Organic soils occurred in 24% of the study area. Approximately 15% of the study area was classified as rock and other unconsolidated material. Summary results and a sub-set of the following soil units (from 10 soil profiles) are presented here and were distinguished according to the Canadian System of Soil Classification (CSSC) (Soil Classification Working Group 1998): Orthic Humo-Ferric Podzol, Placic Ferro-Humic Podzol, Gleyed Humo-Ferric Podzol, Sombric Humo-Ferric Podzol, Gleyed Regosol and Orthic Luvic Gleysol. The basic properties of the soil units identified above included: (i) morphological descriptions of soil profiles with differentiated horizons; (ii) field-texture tests were used to determine classes and physical properties of sands, silts, loams and occurrence of mottles; and (iii) a range of soil chemical composition of different horizons (e.g., pH, total organic carbon [TOC] and select metal concentrations) which indicated no anthropogenic contamination above background concentrations in the area. Source

Agboma C.O.,Dillon Consulting Limited | Lye L.M.,Memorial University of Newfoundland
Journal of Hydrologic Engineering

Understanding the persistence in land surface processes, such as that in the deep subsurface moisture storage, has great implications for seasonal weather prediction over a drainage basin. The Canadian Prairies is a region of intense and recurrent drought outbreaks with myriad negative impacts on the regional ecosystem as well as on all sectors of the Prairies' economy due to high mitigation costs associated with these frequent outbreaks. Given that there are neither physical observations of soil moisture at depths of hydrological importance nor measurements of the total water storage over drought-prone Canadian Prairies subcatchments, this places constraints on studies that focus on the assessments of the interrelationship between the land surface and atmospheric processes. This study focuses on the estimation of the memory in the simulated deep soil moisture and total water storages over the 406,000 km2 Saskatchewan River Basin (SRB) in the Canadian Prairies using a physically based land surface model. The variable infiltration capacity (VIC) hydrological model was developed and deployed in simulating the deep soil moisture in conjunction with the total water storage over this large catchment. In developing a suitable hydrological model for the SRB, parameters estimated from the calibrated and validated hydrological model for the adjacent Upper Assiniboine River Basin (UARB) were transferred. Subsequently, the memory in the anomalies associated with the meteorological variables, simulated deep moisture and total water storage components in conjunction with the computed terrestrial storage deficit indices (TSDIs) estimated from the gravity recovery and climate experiment (GRACE) remote-sensing satellite system and the VIC model were assessed. Given the degree of agreement in the estimated memory associated with the hydrologic model-based terrestrial storage deficit indices with those estimated for the simulated deep moisture storage anomalies over this catchment, this study concludes that the latter could also be used in characterizing the severity of frequent Canadian Prairies droughts. © 2014 American Society of Civil Engineers. Source

This article reviews a comprehensive marine environmental effects monitoring program (MEEMP) comprised of components capable of detecting changes in the marine environment over short or extended temporal scales during remediation of one of Canada's most polluted sites at the Sydney Tar Ponds. The monitoring components included: water and sediment quality, amphipod toxicity testing, mussel tissue, crab hepatopancreas tissue, and benthic community assessments. The MEEMP was designed to verify the impact predictions for the remediation project (i.e., no immediate damage to the marine ecosystem through remediation activities). Some components were capable of providing conclusive data (e.g., sediment and water quality), while others only yielded data that were inconclusive or difficult to attribute to remediation activities (e.g., intertidal community assessments and amphipod toxicity testing). Components that provided only inconclusive results or were difficult to attribute to remediation activities were discontinued, resulting in substantial cost savings during the project, but without compromising the overall objectives of the program, which was to monitor for potential adverse environmental effects of remediation on the marine environment in Sydney Harbor and to verify environmental effects predictions made in the Environmental Impact Statement for the project. The rationale for discontinuing certain MEEMP components and discussion of conclusive results are incorporated into "lessons learned" for environmental remediation practitioners and regulators working on similar large-scale multiyear remediation projects. © 2014 Wiley Periodicals, Inc. Source

Maghrebi M.,State University of New York at Buffalo | Jankovic I.,State University of New York at Buffalo | Allen-King R.M.,State University of New York at Buffalo | Rabideau A.J.,State University of New York at Buffalo | And 2 more authors.
Advances in Water Resources

This work investigated the impacts of permeability and sorption heterogeneity on contaminant transport in groundwater using simulation experiments designed to elucidate the causes of tailing. The effects of advection, diffusion and sorption mechanisms and plume history were explored. A simple conceptual model consisting of a single inclusion (heterogeneity) of uniform hydraulic conductivity K and sorption distribution coefficient Kd was adopted. The 3D inclusion, shaped as a horizontal oblate ellipsoid of variable thickness, was placed in a homogeneous anisotropic background of different hydraulic conductivity and sorption distribution coefficient. The background represents average K and Kd of a heterogeneous porous formation. A closed-form analytic flow solution for uniform flow past the inclusion was coupled with a numerical transport solution to simulate contaminant migration for a wide range of transport parameters and two distinct source conditions. Over 2600 numerical simulations were performed in parallel. Transport results were presented in terms of travel time distributions at a control plane downstream of the inclusion and used to quantify tailing for a wide range of transport parameters, in order to separate advection-dominated from diffusion-dominated transport regime and to investigate effects of inclusion shape, diffusion, sorption and plume history on tailing. © 2014 Elsevier Ltd. Source

Hamilton M.M.,Dillon Consulting Limited
Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA

Strategies for evaluating the vapor intrusion pathway and related human health risk are very important for managing contaminated sites in a rigorous, yet cost-effective manner. Vapor intrusion risk assessment strategies were examined based on assessments conducted at different contaminated sites in western Canada. The only vapor migration model used was the Johnson and Ettinger model for vapor intrusion. The vapor intrusion pathway was assessed at each site through a step-wise process, which started with generic screening and moved towards more detailed evaluation using more site-specific data. With this step-wise process, the potential risk to human health due to vapor inhalation was estimated through a combination of soil, groundwater, NAPL, or vapor sampling and generic or site-specific vapor migration modeling. The vapor intrusion pathway through a step-wise process can include significantly reduced costs and time in future monitoring programs and site remediation. These strategies can be used to assess human health risks related to soil vapor intrusion on active sites as part of long-term risk management or for the preparation of site closure plans for inactive sites. This is an abstract of a paper presented at the 103rd AWMA Annual Conference and Exhibition (Alberta, Canada 6/22-25/2010). Source

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