Solvent, LNAPL/DNAPL Mobility and Natural Attenuation Studies

NAPL and Dissolved Phase Stability and Natural Attenuation Study, Northern British Columbia. GeoCentric was responsible for evaluating and completing a NAPL and dissolved Phase Plume Stability and Natural Attenuation approach for the impacts related to groundwater and remaining source area. The study protocol was designed to determine the technical criteria for site closure and included the development of the NAPL architecture; 3-D conceptual model of the site using the existing data set- to create a geological and hydrogeological framework; completing detailed statistical analysis including Mann-Kandell, NAPL pore entry calculations, BC Protocol 16 evaluation, NAPL Transmissivity analysis, NAPL saturation indicators and completing a Natural Attenuation. A Natural Attenuation & Risk Based Groundwater Monitoring Strategy (NARB-GWS) was developed to describe an approach that can be employed for sites currently considered under or entering a Long Term Monitoring (LTM) program. The end goal was to terminate/reduce LTM programs while documenting, controlling and/or preventing impacts.

Plume Stability and Natural Attenuation Study, Eastern Manitoba. Developed a Strategic Evaluation and Natural Attenuation approach for the impacts related to groundwater and remaining source area. The study protocol included the develop of a 3-D conceptual model of the site to create a geological and hydrogeological framework. The work included completing a Natural Attenuation, Plume Stability study focusing on the PAH and petroleum hydrocarbon source and groundwater geochemical ratios, patterns and fingerprinting, statistical analysis of the data (concentration trends, water levels over time) and attenuation and transport processes. Detailed analysis was completed on the data set including Mann-Kandell and the Ricker Method. As an outcome of the study, a MNA/Plume Stability protocol was developed and recommendations to meet short- and intermediate-term goals, which will form the framework of a longer-term management strategy.

DNAPL Stability Assessment and Site Development Support, Eastern Alberta. GeoCentric was responsible for an area wide investigation in the sources and contaminate fate and transport of creosote DNAPL in a shallow and deeper groundwater flow systems. Detailed 3-D geological modelling, mobility assessments and chemical fingerprinting/ratios were used to understand the residual DNAPL potential sources, impacts and mobility. An exposure assessment to evaluate potential risk to off-site receptors was completed. Prepared a comprehensive final report with results and recommendations for remedial options as part of an ongoing litigation support and property development.

CVOC Investigation, Remedial Options Analysis, Site Closure Strategies and Litigation Support, Eastern Ontario. The site was crown owned property that was leased to an aircraft manufacturer. A chlorinated plume was detected in the shallow overburden and deep fractured rock. Litigation is ongoing between the manufacturer and the crown. A plume source investigation was completed to evaluate possible source areas using a weight of evidence approach including historical research and NAPL indicators, site hydrogeology, chemical signatures and ratios, and Advanced Isotopic Analysis. Team developed cost allocations, risk management plans and site closure strategies.

Dual Porosity LNAPL Assessment, Eastern Ontario. Behaviour of the LNAPL and associated PHC groundwater plume was evaluated based on a revised conceptual understanding of the LNAPL behaviour and stability using a Dual Porosity (DP) model (porous media and fractured rock setting) to help explain the LNAPL presence and variability, fluctuating local scale PHC concentrations over time and overall poor LNAPL recovery. Study presented a new technical evaluation of LNAPL and dissolved phase plume stability using a DP model to help focus the remedial efforts and guide the overall site LNAPL and PHC dissolved phase management framework.