United States
United States

Time filter

Source Type

Daniels S.R.,Stellenbosch University | McLeod C.,Golder Assoc. Ltd. | Carveth C.,Beacon Environmental | Mexim K.K.,Nangui Abrogoua University | Cumberlidge N.,Northern Michigan University
Journal of Crustacean Biology | Year: 2016

Evolutionary relationships amongst three species of freshwater crabs, Liberonautes latidactylus (De Man, 1903), L. nimba Cumberlidge, 1999, and L. rubigimanus Cumberlidge and Sachs, 1989, were examined using DNA sequence data of the mitochondrial cytochrome oxidase subunit I (COI) locus. The latter three species are listed in the IUCN Red List for 2008 as least concerned, vulnerable, and endangered, respectively. Specimens of the three species were collected in Liberia and neighbouring Guinea, West Africa. Phylogenetic results derived from maximum parsimony, maximum likelihood, and Bayesian inference revealed the monophyly of all three species. Moderate genetic variation was observed within L. latidactylus. Within the narrow endemic, montane species, L. nimba shallow divergence was observed, whereas marked genetic divergence was observed within L. rubigimanus. Three statistically well-supported clades were observed within the latter taxon, two of these clades were sympatric at Simandou, Liberia (clades A and B), and characterised by a 10% uncorrected sequence divergence for the COI locus, whereas the divergence between the latter two clades and the larger L. rubigimanus clade was 8%. Haplotype networks corroborate the absence of maternal gene flow amongst the three L. rubigimanus clades suggesting possible reproductive isolation and the presence of two novel species. Our results suggest that Liberonautes harbours undescribed, narrowly distributed species. The results are discussed in a conservation framework for the three Liberonautes species. © 2016 Copyright 2016 by The Crustacean Society. Published by Brill NV, Leiden.

Bleho B.I.,Golder Assoc. Ltd. | Koper N.,University of Manitoba | Borkowsky C.L.,Critical Wildlife Habitat Program | Hamel C.D.,Nature Conservancy of Canada
American Midland Naturalist | Year: 2015

The western prairie fringed-orchid is a rare North American orchid restricted to a few remnants of wet to mesic tallgrass prairie. It is federally listed in both Canada and the United States and both countries have developed a recovery plan for the species. Two key management objectives are to monitor population trends and identify beneficial management practices. We used 21 y of data from the Manitoba metapopulation to assess effects of weather and land management on this species. Our results suggest the metapopulation in Manitoba is relatively stable. Western prairie fringed-orchids appear to benefit most from a combination of warm temperatures in the previous growing season followed by cool snowy but short winters and wet springs. Periodic burning (e.g., every 2-3 y) may benefit fringed-orchids, whereas grazing may be detrimental. This was not a controlled experiment, however, and gaps in the data may have influenced our results. Prescribed burning is a viable management tool for curtailing woody invasion and both burning and grazing reduce litter and grass cover, but careful consideration of timing, frequency, and intensity of application is required so management does not hinder fringed-orchid reproduction or reduce survival, while also recognizing management requirements may vary among years depending on weather. Long-term studies are particularly valuable for the western prairie fringed-orchid due to its erratic life cycle and fluctuating populations, which complicate studies of environmental and management effects on this species. © 2015 American Midland Naturalist.

Baker J.A.,Nautilus Environmental | Elphick J.R.,Nautilus Environmental | McPherson C.A.,Golder Assoc. Ltd | Chapman P.M.,Golder Assoc. Ltd
Bulletin of Environmental Contamination and Toxicology | Year: 2015

Some studies have shown that the early life stages of salmonids are particularly sensitive to elevated concentrations of total dissolved solids (TDS). We evaluated the effect of TDS released in treated effluent into Snap Lake (Northwest Territories, Canada) by the Snap Lake Diamond Mine on two salmonids native to Snap Lake: Salvenius namaycush (lake trout) and Thymallus arcticus (Arctic grayling). Exposures encompassed the embryo-alevin-fry early life stages and extended to 142 days for lake trout and 69 days for Arctic grayling. Such extended testing is uncommon with these two species. Two exposures were conducted with each species, one initiated prior to fertilization, and the other subsequent to fertilization. Fertilization, survival, and growth were not adversely affected for either species by TDS at concentrations >1400 mg/L, with the exception of survival of lake trout, which produced an LC20 of 991 mg/L in one test, and >1484 mg/L in the second test. For the specific TDS composition tested, which was dominated by chloride (45 %-47 %) and calcium (20 %-21 %), the early life stages of these two fish species were relatively insensitive. Although some authors have suggested lower TDS regulatory limits for salmonid early life stages, our study indicates that this is not necessary, at least for these two fish species and for the specific ionic composition tested. © 2015 Springer Science+Business Media New York.

Haviland D.,Golder Assoc. Ltd. | Marshall J.,Queen's University
International Journal of Mining Science and Technology | Year: 2015

Ramps (or declines) are often used in underground mines to transport ore, waste, materials, and personnel. This paper studies mine ramp productivity and presents results from a set of computer simulations designed to model the fundamental behaviours of ramp haulage systems. Simulations show that, under fundamental assumptions without random disturbances, the haulage system always converges to a periodic behaviour in the steady state, but that productivities vary between equilibria. Simulations also demonstrate how productivity per vehicle does not necessarily decrease as more vehicles are added and, for example, in the five-vehicle case, how a 3.1% improvement can be achieved over the use of four vehicles. The result reveals the inefficiency of commonly-used lockout-style vehicle coordination strategies, and suggests a possible avenue for improving the productivity of haulage ramps by controlling the system to achieve more productive behaviours. © 2015 Published by Elsevier B.V. on behalf of China University of Mining and Technology.

Holder L.K.,Golder Assoc. Inc. | Shuri F.,Golder Assoc. Inc. | Nielsen B.,Freeport McMoRan Copper and Gold | Jones R.,Barrick Gold Corporation
2014 SME Annual Meeting and Exhibit, SME 2014: Leadership in Uncertain Times | Year: 2014

The White King / Lucky Lass Superfund site consists of two former uranium mines in south-central Oregon. The remedy included consolidating two large mining overburden stockpiles that contained low levels of radioactivity and heavy metals by moving over 700,000 cubic yards of material and then capping the combined stockpile. An innovative armored cap design was used to minimize the stockpile footprint and thereby prevent disturbing existing wetlands. In addition, the stockpile was designed to merge into the surrounding topography. The remedy also included stream restoration and development of new wetlands. The stream was returned to its pre-mining channel, with the addition of hydraulic features to create new wetlands. The wetlands have greatly enhanced the ecological value of the remedy and the site.

Dayyani S.,Golder Assoc. Ltd. | Daly G.,Golder Assoc. Ltd. | Vandenberg J.,590 McKay Avenue
Water Environment Research | Year: 2016

Snow cover forms a porous medium that acts as a receptor for aerially deposited polycyclic aromatic hydrocarbons (PAHs) and metals. The snowpack, acting as a temporary storage reservoir, releases contaminants accumulating over the winter during a relatively short melt period. This process could result in elevated concentrations of contaminants in melt water. Recent studies in the Alberta oil sands region have documented increases in snowpack and lake sediment concentrations; however, no studies have addressed the fate and transport of contaminants during the snowmelt period. This study describes modelling approaches that were developed to assess potential effects of aerially deposited PAHs and metals to snowpack and snowmelt water concentrations. The contribution of snowmelt to freshwater PAH concentrations is assessed using a dynamic, multi-compartmental fate model, and the contribution to metal concentrations is estimated using a mass-balance approach. The modelling approaches described herein were applied to two watersheds in the Alberta oil sands region for two planned oil sands developments. Accumulation of PAHs in a lake within the deposition zone was also modelled for comparison to observed concentrations.

McNally P.,Golder Assoc. Inc. | Minyard E.,Response Force 1 Corporation
Society of Petroleum Engineers - SPE E and P Health, Safety, Security and Environmental Conference - Americas 2015 | Year: 2015

Effective emergency preparedness and response benefits from the implementation of the Incident Command System (ICS) to improve the efficiency and effectiveness of emergency responses associated with Oil and Gas exploration and production (E&P) and preserve corporate integrity and reputation. Succesful Implementation of the ICS on fires, natural disasters, and acts of terrorism highlight the need to incorporate ICS in all Oil and Gas Incidents such as well blowouts, fires, personnel injuries, pipeline ruptures, spills and uncontrolled releases particularly those associated with the recent onshore shale oil and gas boom, which bring E&P operations close to residential areas. The ICS, developed by the US Forest Services in the 1970s and now used by most first responders, is a standardized emergency management system with proven key concepts that reduce costs, establishes objectives, mitigates environmental and human impacts, reduces recovery time, and preserves corporate image and intergrity. This paper describes the benefits of ICS, and provides recommendations for incorporating ICS into Emergency Response Plans (ERPs), training, practice drills, and actual incidents. It will show how ICS key concepts, such as management by objectives, communications, chain of command, span of control, and unity of command, should be incorporated into ERPs. Copyright 2015, Society of Petroleum Engineers.

Birdsell M.,Golder Assoc. Inc.
2016 SME Annual Conference and Expo: The Future for Mining in a Data-Driven World | Year: 2016

Sustainable long-term restoration requires adequate planning and preparation, implementation, and measurement goals to monitor success associated with restoring sites to pre-disturbance levels of ecological health. The Buckhom Mountain Mine riparian habitat restoration project has been a multi-year endeavor with a variety of restoration techniques implemented by Kinross Gold/Crown Resources Corporation. Copyright © 2016 by SME.

Holder L.K.,Golder Assoc. Inc.
2015 SME Annual Conference and Expo and CMA 117th National Western Mining Conference - Mining: Navigating the Global Waters | Year: 2015

The Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), commonly known as Superfund, mandates evaluation of remediation alternative using nine criteria: (1) overall protection of human health and the environment, (2) compliance with ARARs (applicable or relevant and appropriate standards), (3) long-term effectiveness and permanence, (4) reduction of toxicity, mobility or volume, (5) short-term effectiveness, (6) implementability, (7) cost, (8) state acceptance, and (9) community acceptance. Many states have adopted these or similar criteria for remedy selection under state laws. Although not explicitly addressed in the CERCLA criteria, consideration of sustainability can be incorporated into these criteria. This paper explores how sustainability can be evaluated for remedy selection using the CERCLA criteria. Copyright © 2015 by SME.

Vecsei P.,Golder Assoc. Ltd. | Panayi D.,Golder Assoc. Ltd.
Canadian Field-Naturalist | Year: 2015

We document the first occurrence of Pygmy Whitefish (Prosopium coulterii) in the Northwest Territories outside of Great Bear Lake. Six specimens were captured in Bluefish Lake in September 2012. Bluefish Lake is on the Yellowknife River, approximately 25 km upstream from Great Slave Lake.

Loading Golder Assoc. Inc. collaborators
Loading Golder Assoc. Inc. collaborators