Kilgour and Associates Ltd

Ottawa, Canada

Kilgour and Associates Ltd

Ottawa, Canada

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Whiteway S.A.,Whiteway | Paine M.D.,Paine | Wells T.A.,Suncor Energy | DeBlois E.M.,Elisabeth DeBlois Inc. | And 5 more authors.
Deep-Sea Research Part II: Topical Studies in Oceanography | Year: 2014

This paper discusses toxicity test results on sediments from the Terra Nova offshore oil development. The Terra Nova Field is located on the Grand Banks approximately 350km southeast of Newfoundland (Canada). The amphipod (Rhepoxynius abronius) survival and solid phase luminescent bacteria (Vibrio fischeri, or Microtox) assays were conducted on sediment samples collected from approximately 50 stations per program year around Terra Nova during baseline (1997), prior to drilling, and in 2000, 2001, 2002, 2004, 2006, 2008 and 2010 after drilling began. The frequency of toxic responses in the amphipod toxicity test was low. Of the ten stations that were toxic in environmental effects monitoring (EEM) years, only one (station 30(FE)) was toxic in more than one year and could be directly attributed to Terra Nova project activities. In contrast, 65 (18%) of 364 EEM samples were toxic to Microtox. Microtox toxicity in EEM years was not related to distance from Terra Nova drill centres or concentrations of >C10-C21 hydrocarbons or barium, the primary constituents of the synthetic-based drill muds used at Terra Nova. Of the variables tested, fines and strontium levels showed the strongest (positive) correlations with toxicity. Neither fines nor strontium levels were affected by drill cuttings discharge at Terra Nova, except at station 30(FE) (and that station was not toxic to Microtox). Benthic macro-invertebrate abundance, richness and diversity were greater in toxic than in non-toxic sediments. Therefore, Microtox responses indicating toxicity were associated with positive biological responses in the field. This result may have been an indirect function of the increased abundance of most invertebrate taxa in less sandy sediments with higher gravel content, where fines and strontium levels and, consequently, toxicity to Microtox were high; or chemical substances released by biodegradation of organic matter, where invertebrates are abundant, may be toxic to Microtox. Given the lack of association between Microtox results and discharge from Terra Nova, coupled with the confounding effects of other variables, the usefulness of Microtox toxicity tests within the context of environmental monitoring for the Terra Nova and, potentially, other offshore oil operations needs to be questioned. The amphipod toxicity tests showed that sediments in the vicinity of discharges of synthetic-based drilling mud cuttings are rarely toxic. © 2014 Elsevier Ltd.


DeBlois E.M.,Elisabeth DeBlois Inc. | Paine M.D.,Paine | Kilgour B.W.,Kilgour and Associates Ltd | Tracy E.,Stantec Consulting Ltd. | And 3 more authors.
Deep-Sea Research Part II: Topical Studies in Oceanography | Year: 2014

This paper describes sediment composition at the Terra Nova offshore oil development. The Terra Nova Field is located on the Grand Banks approximately 350km southeast of Newfoundland, Canada, at an approximate water depth of 100m. Surface sediment samples (upper 3cm) were collected for chemical and particle size analyses at the site pre-development (1997) and in 2000-2002, 2004, 2006, 2008 and 2010. Approximately 50 stations have been sampled in each program year, with stations extending from less than 1km to a maximum of 20km from source (drill centres) along five gradients, extending to the southeast, southwest, northeast, northwest and east of Terra Nova. Results show that Terra Nova sediments were contaminated with >C10-C21 hydrocarbons and barium-the two main constituents of synthetic-based drilling muds used at the site. Highest levels of contamination occurred within 1 to 2km from source, consistent with predictions from drill cuttings dispersion modelling. The strength of distance gradients for >C10-C21 hydrocarbons and barium, and overall levels, generally increased as drilling progressed but decreased from 2006 to 2010, coincident with a reduction in drilling. As seen at other offshore oil development sites, metals other than barium, sulphur and sulphide levels were elevated and sediment fines content was higher in the immediate vicinity (less than 0.5km) of drill centres in some sampling years; but there was no strong evidence of project-related alterations of these variables. Overall, sediment contamination at Terra Nova was spatially limited and only the two major constituents of synthetic-based drilling muds used at the site, >C10-C21 hydrocarbons and barium, showed clear evidence of project-related alternations. © 2014 Elsevier Ltd.


Stanfield L.W.,Ontario Ministry of Natural Resources | Kilgour B.W.,Kilgour and Associates Ltd
River Research and Applications | Year: 2013

This study quantified the unique variation in stream fish and habitat and a land use disturbance index (LDI) at a variety of spatial scales: catchment, eight riparian polygons that varied in width and length (e.g. 50 m to all upstream reaches), upstream polygons of 1.6 and 3.2 km and the residual upland area of each site watershed not accounted for by each polygon. The analyses confirmed a hockey stick-shaped relationship between the fish community and the LDI, with sensitive species only present below an LDI of 11. The largest variation for most metrics was explained by the largest polygons, suggesting that local riparian conditions were not as important predictors of stream condition. LDI in upland areas, where zero-order streams occur, was also an important predictor of fish biomass and taxa richness. Contrary to expected, additive models with both catchment and riparian corridors provided minimal increases in predictive power, and no improvement in model performance occurred when data sets were stratified into sites below the LDI threshold. Finally, there was considerable covariation in the template and stressor predictor variables that made it difficult to quantify the unique variation in biological and physical responses accounted for by land use. That the 1600-m proximal polygon provided the best predictor of the fish community and temperature is supportive of there being some proximal effects of land use. Overall, our findings suggest that stream management must consider processes that occur in the entire upstream catchment and the entire riparian corridor, including the headwaters for success. © 2012 John Wiley & Sons, Ltd.


Kilgour B.W.,Kilgour and Associates Ltd | Gharabaghi B.,University of Guelph | Perera N.,University of Guelph
Water Quality Research Journal of Canada | Year: 2013

Despite an overall increase in total road salt used over the past 14 years (the data record in this manuscript), there has been a 26% reduction in the rate (normalized as tonnes of salt per cm of snow per km of road) of road salt application by the City of Toronto since that city implemented mitigations from the Road Salt Code of Practice. The ecological benefit of the reduced use of road salt was approximated by comparing the estimated 26% salt reduction to the distribution of chloride tolerances that has been recently published by the Canadian Council of Ministers of the Environment (i.e., CCME). Species sensitivity distributions predict that between 1 and 14% of taxa would benefit from a 26% reduction in chloride concentrations in surface waters. Assuming that a typical 'healthy' Canadian watercourse might support between 100 and 200 species of fish, invertebrates and plants, the Code of Practice might provide benefit to between 14 and 28 species. However, the net ecological benefit of implementing the Code may be undermined in rapidly urbanizing watersheds where road networks continue to expand at a rate of 3-5% per year and chloride loads to urban streams are steadily increasing. © IWA Publishing 2014.


Kilgour B.W.,Kilgour and Associates Ltd | Francis A.P.,Kilgour and Associates Ltd | Mercier V.,University of Moncton
Water Quality Research Journal of Canada | Year: 2013

We demonstrated a general relationship between water quality index (WQI) values and indices of benthic community composition for a set of 32 streams from British Columbia and Ontario. Streams that produced lower WQI values tended to have benthic communities characteristic of degraded water quality. Streams, in contrast, that produced higher WQI scores tended to have a fauna characteristic of high water quality. Trimming the water quality data for high-total suspended solids (TSS) events increased the WQI values by as much as 30 points. There were modest but apparent increases in the strength of the association between the WQI and indices of benthic community composition when the water quality data records were trimmed of values that occurred during periods of high (extreme) turbidity. Trimming data that contained turbidity (or TSS) values beyond the mirrored 5th, 90th, or 95th percentile were about equal in their effect on the WQI. The removal of high TSS samples on the basis of the 'mirror' method can be recommended on the basis that it will likely correctly remove data that have a long right-hand tail, and will also correctly not remove data when the data are more normally distributed. © IWA Publishing 2013.

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