[en] At the conclusion of two major phases of a study on subsurface treatment technologies for Alberta sour gas plants, a candidate site was selected for a remediation technologies demonstration project. The plant has an extensive groundwater monitoring network in place, monitoring records for a period exceeding 10 years, ten recovery wells with aquifer test data and four reinjection wells. Hydrogeological exploration determined the presence and delineated a plume of free phase natural gas condensate. Aquifer remediation efforts at the site began in 1990 with the installation of recovery wells. Recovered groundwater was treated using a pilot scale air stripping system with pretreatment for iron, manganese and hardness. Dual pump system, water depression and free product skimmers were installed in the wells and tested. The nature and extent of contamination, study methodology, technology-dependent criteria, assessment of technology, and conceptual design are discussed for the three demonstration projects selected, which are enhanced soil vapour extraction with off-gas treatment, pump-and-treat with soil vapour extraction, biological treatment and air sparging, and treatment of dissolved process chemicals by advanced oxidation. 5 refs., 1 fig., 1 tab

[en] Field evaluation of various contamination attenuation mechanisms were conducted at four contaminated natural wetlands in Alberta. Contaminant impact on vegetation was also assessed. Results indicate that in wetlands contaminant attenuation is influenced by several parameters: flow rates, depth of impact, the nature of the contaminant, presence of peat, and seasonal effects. Nevertheless, natural processes appear to be capable of completely attenuating hydrocarbon contamination, although at two of the sites minor concentrations of contaminants reached down-gradient receptors. Impact on shallow vegetation was negligible, but there was significant evidence of black spruce die-off at three of the four sites. Peat wetlands appeared to possess the best capabilities for the attenuation of hydrocarbon contaminants.11 refs., 1 tab., 5 figs

[en] The concentration of BTEX was determined for 60 groundwater samples collected from 6 gas plants in Western Canada, using conventional purge-and-trap GC/MS procedures. The gas plants were selected to cover different types of operations with different amine process chemicals employed for the sweetening of the raw sour-gas condensates. Aliquots of the ground water samples were subjected to toxicity screening tests, specifically, (a) bacterial luminescence (microtox); (b) daphnia mortality and (c) fathead minnow mortality. For the toxicity tests, sample handling procedures were developed to minimize the loss of volatile organics during the experiments. To account for possible losses, the levels of BTEX were monitored at the start and upon completion of these tests. The results indicated that the toxicity of the groundwater was in general, well correlated to the concentration of BTEX (primarily xylene). Approximately 5% of the samples, however, were observed to be toxic although the concentration of BTEX were below the method detection limit (1 microg/1). Thiophenic volatile organics were implicated for the latter. Based on the laboratory results, the remediation of BTEX is expected to correlate with the removal of the toxicity of the groundwater. These findings are of direct relevance to present technologies employed for remediation of ground water at the Sourgas plants