Sl Ross Environmental Research

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Marty J.,WSP Canada | Potter S.,Sl Ross Environmental Research
Proceedings of the 37th AMOP Technical Seminar on Environmental Contamination and Response | Year: 2014

A risk assessment was completed concerning marine oil spills in Canadian waters south of the 60th parallel. The study was commissioned by Transport Canada following the 2010 recommendations of the Commissioner of the Environment and Sustainable Development. The objective of the study was to provide an overall risk estimate to aid in a broader review of Canada's preparedness and response arrangements for ship-source spills. For this study, risk was defined as the product of the probability of a spill occurring and the potential consequences should a spill occur. These two elements were estimated for 77 geographical areas and the results used to provide a relative measure of risk across the country.


Buist I.,Sl Ross Environmental Research | Canevari G.,GP Canevari Associates | Nedwed T.,ExxonMobil
Proceedings of the 33rd AMOP Technical Seminar on Environmental Contamination and Response | Year: 2010

Buist et al. (2007) found that herding agents will allow thickening of oil slicks and in situ burning in drift ice and close a gap for this response option in ice. The herding agents studied were developed in the 1970's and used hydrocarbon-based surfactants as the active ingredient. The best herding agent found was a formula developed by the US Navy. There have been significant advances in surfactant technology since the 1970's with the development of two classes of "superwetter" surfactants - fluorosurfactants and silicone-based surfactants. This paper describes research that evaluated the use of these next-generation surfactants as the active ingredient in herding agents. In 2007 and 2008, tests were carried out comparing the efficacy of herding agents formulated with silicone-based surfactants, formulated with fluorosurfactants, and the US Navy herder. The fluorosurfactant-based herders did not perform significantly better than the US Navy herder. In static tests, a silicone-surfactant based herder initially produced significantly higher herded slick thicknesses but declined back to the thickness of the US Navy herder over the one-hour test period. In 2009, experiments were conducted with three new silicone-based surfactant herder formulations: first, in the SL Ross lab at small-scale (1-m2 pans); and second, at much larger scale using the US Army Corp of Engineers Cold Regions Research and Engineering Laboratory (CRREL). These tests and comparisons with prior work found that one of the new silicone surfactant formulations significantly outperformed the USN herder.


Buist I.,Sl Ross Environmental Research | Potter S.,Sl Ross Environmental Research | Nedwed T.,ExxonMobil | Mullin J.,U.S. Department of Interior
Cold Regions Science and Technology | Year: 2011

In situ burning is an oil spill response option particularly suited to remote, ice-covered waters. The key to effective in situ burning is thick oil slicks. If ice concentrations are high, the ice can limit oil spreading and keep slicks thick enough to burn. In drift ice conditions and open water, oil spills can rapidly spread to become too thin to ignite. Fire-resistant booms can collect and keep slicks thick in open water; however, even light ice conditions make using booms challenging. A multi-year research project was initiated to study oil-herding surfactants as an alternative to booms for thickening slicks in light ice conditions for in situ burning. Small-scale laboratory experiments were completed in 2003 and 2005 to examine the idea of using herding agents to thicken oil slicks among loose pack ice for the purpose of in situ burning. Encouraging results prompted further mid-scale testing in 2006 and 2007 at the US Army Cold Regions Research and Engineering Laboratory (CRREL) in Hanover, NH; at Ohmsett, the National Oil Spill Response Research & Renewable Energy Test Facility in Leonardo, NJ; and, at the Fire Training Grounds in Prudhoe Bay, AK. The non-proprietary hydrocarbon-based herder formulation used in these experiments proved effective in considerably contracting oil slicks in brash and slush ice concentrations of up to 70% coverage. Slicks in excess of 3. mm thick, the minimum required for ignition of weathered crude oil on water, were routinely achieved. Herded slicks were ignited, and burned equally well in both brash and slush ice conditions at air temperatures as low as -17 °C. The burn efficiencies measured for the herded slicks were only slightly less than the theoretical maximums achievable for equivalent-sized, physically contained slicks on open water. Successful meso-scale field trials of the technique were carried out in the Barents Sea off Svalbard in the spring of 2008 as one facet of a large joint industry project on oil spill response in ice co-ordinated by SINTEF. The larger field experiment involved the release of 630. L of fresh Heidrun crude onto water in a large lead. The free-drifting oil was allowed to spread for 15. min until it was far too thin to ignite (0.4. mm), and then the hydrocarbon-based herder was applied around the slick periphery. The slick contracted and thickened for approximately 10. min at which time the upwind end was ignited. A 9-minute long burn ensued that consumed an estimated 90% of the oil. From 2007 to 2009 experiments were carried out in the laboratory and at CRREL comparing the efficacy of herding agents formulated with silicone-based surfactants, herding agents formulated with second-generation fluorosurfactants, and the hydrocarbon-based herder. The results showed that the fluorosurfactant-based herders did not function better than the hydrocarbon-based herder; however, the new silicone surfactant formulations considerably outperformed the hydrocarbon-based herder. Most recently, experiments were conducted to determine if herding agents could: 1) improve skimming of spilled oil in drift ice; 2) clear oil from salt marshes; and, 3) improve the efficiency of dispersant application operations. © 2011 Elsevier B.V.


Trudel K.,Sl Ross Environmental Research | Belore R.C.,Sl Ross Environmental Research | Mullin J.V.,Engineering and Research Branch | Guarino A.,MAR Inc.
Marine Pollution Bulletin | Year: 2010

This study determined the limiting oil viscosity for chemical dispersion of oil spills under simulated sea conditions in the large outdoor wave tank at the US National Oil Spill Response Test Facility in New Jersey. Dispersant effectiveness tests were completed using crude oils with viscosities ranging from 67 to 40,100. cP at test temperature. Tests produced an effectiveness-viscosity curve with three phases when oil was treated with Corexit 9500 at a dispersant-to-oil ratio of 1:20. The oil viscosity that limited chemical dispersion under simulated at-sea conditions was in the range of 18,690. cP to 33,400. cP. Visual observations and measurements of oil concentrations and droplet size distributions in the water under treated and control slicks correlated well with direct measurements of effectiveness. The dispersant effectiveness versus oil viscosity relationship under simulated at sea conditions at Ohmsett was most similar to those from similar tests made using the Institut Francais du Pétrole and Exxon Dispersant Effectiveness (EXDET) test methods. © 2010 Elsevier Ltd.


Buist I.,Sl Ross Environmental Research | Meyer P.,MAR Inc.
Proceedings of the 35th AMOP Technical Seminar on Environmental Contamination and Response | Year: 2012

As a result of the experimental success to date thickening slicks for in situ burning in drift ice a research program has been undertaken to explore the use of herding agents for in situ burning in open water conditions as a rapid-response technique for oil spills offshore. The research involved two areas: 1. A series of comparative experiments was undertaken at the SL Ross lab with hydrocarbon-based and silicone-based herding agents in 1-m2 pans, a 10-m2 pan, small pans mounted on a rocking shaker and the SL Ross wind/wave tank to determine the best of several candidate herders for use on warmer water. Overhead digital photographs were taken and analyzed by computer to determine the herder effectiveness in the pan tests. The wind/wave tank tests were videotaped. 2. Surfactant film persistence (i.e., how long the monolayer generated by a specific herding agent will last as a function of sea state) and to what degree periodically replenishing the film can counteract this was investigated in an 8-day test program at Ohmsett from May 13 through 20, 2011. The experiments took advantage of the facility's newly upgraded wave making capabilities. Overhead digital video and photographs were taken to qualitatively compare and determine the persistence of three herding agents in calm conditions, a swell and breaking waves. A total of 11 experiments were completed with three herding agents (USN, Silsurf A108 and Silsurf A004-D) in the three wave conditions: 9 tests as per the test protocol plus an additional duplicate test and a control (no herder). Based on visual observations of the tests the following conclusions can be drawn: • The monolayer of each of the herders will survive for more than 45 minutes in a calm sea. • The presence of breaking or cresting waves rapidly disrupts the herder monolayer and the oil slick resulting in many small slicklets. • The monolayer survives for considerable periods of time in a swell condition, but the constant stretching and contracting of the herded slick results in elongating the oil slick and slowly breaking the slick into smaller segments. • The Silsurf A108 herder performed noticeably better than the other two herders in all test conditions.


Lewis A.,121 Laleham Road | Ken Trudel B.,Sl Ross Environmental Research | Belore R.C.,Sl Ross Environmental Research | Mullin J.V.,Engineering and Research Branch
Marine Pollution Bulletin | Year: 2010

The use of dispersants to treat oil spills in calm seas is discouraged because there is insufficient 'mixing energy' to cause immediate dispersion of the oil. However, dispersants might be applied while the seas are calm, in the expectation that they would work later when sea states increase. The present study examined the persistence of dispersants in treated oil slicks on calm water in a large outdoor wave tank. Test slicks, pre-mixed with dispersant, were allowed to stand on static and flowing water for up to six days, after which their dispersibility was tested by exposing them to breaking waves. Results showed that thicker slicks exposed to calm water for up to six days dispersed completely with the addition of breaking waves. Thinner slicks and slicks exposed to water movement became less dispersible within two days. The loss of dispersibility was caused by dispersant loss rather than by oil weathering. © 2009 Elsevier Ltd.


Belore R.,Sl Ross Environmental Research
Proceedings of the 38th AMOP Technical Seminar on Environmental Contamination and Response | Year: 2015

A study was conducted by SL Ross for the U.S. Bureau of Safety and Environmental Enforcement (BSEE) to provide information to support dispersant use decision-making with respect to oil spill chemical dispersant effectiveness under the environmental conditions likely to be encountered in the U.S. Beaufort and Chukchi Seas. This paper discusses the dispersant effectiveness testing conducted in the study. Interested readers can acquire the full research report from BSEE (SL Ross 2014). A suite of dispersant effectiveness tests using the SL Ross meso-scale wind-wave tank on four Alaskan crude oils with four water salinities were conducted to shed more light on the effectiveness of a marine dispersant over a range of water salinities under high energy breaking wave conditions. Alaska North Slope, Endicott, Northstar and Kuparuk crude oil were used in the testing. Tests were conducted on fresh, evaporated and evaporated plus emulsified crude oils. Tests were conducted in water with salinities of 5, 10, 20 and 30 ppt. All tests were conducted with a water temperature of 10 °C. Corexit 9500 was applied at a dispersant to oil ratio of 1:20 in all tests. The fresh oils were more effectively dispersed than the weathered oils that were more effectively dispersed than the weathered and emulsified oils. The most complete data sets collected (due to limitations of the LISST in measuring large oil drops) were for the fresh oil tests. The results for the fresh oils indicate that the final dispersant effectiveness values are highest for the 30 ppt water and in all cases drop linearly as the test water salinity decreased to 5 ppt.


Belore R.,Sl Ross Environmental Research
Proceedings of the 37th AMOP Technical Seminar on Environmental Contamination and Response | Year: 2014

The primary objective of this work was to determine if the presence of natnral gas or methane in a subsea oil and gas discharge would reduce the effectiveness of a dispersant injected into the gas-oil mixture. The underlying concern is that some of the dispersant might be attracted to the hydrocarbon gas bubble-water interface and not be available to attach to the oil-water interface and thus reduce the effectiveness of the applied dispersant. Tests were conducted with air (non-hydrocarbon) or methane (hydrocarbon) with all other parameters kept constant and the resulting oil drop size distributions compared. The significance of dispersant to oil ratio (DOR), gas to oil ratio (GOR). oil type and orifice diameter were also evaluated in the test program. The size of the oil drops generated in the subsea release, specifically the volume medium drop diameter (VMD) metric of the oil drop size distribution, was used as the criteria for comparison of dispersant effectiveness. Tests were conducted both at the SL Ross laboratory facilities in Ottawa and at the BSEE operated National Oil Spill Response Research & Renewable Energy Test Facility (Ohmsett) in Leonardo, New Jersey. The tests utilized a horizontal jet release to segregate the rising oil drops and gas bubbles to allow direct measurement of the oil drops using a laser in-situ particle size analyzer (LISST). Air pressurized supply tanks and precision needle valves for flow control were implemented for the oil and dispersant delivery systems. Gas flow was controlled using a rotameter flow meter. The effect of methane in the flow stream on dispersant effectiveness was not consistent throughout all tests. For two of the oils tested a slight reduction in dispersant effectiveness was identified, as measured by an increase in the oil drop size distribution VMD by about 20 to 30 microns, when methane as opposed to air was present in the flow stream. Terra Nova crude oil, in the small orifice tests conducted at SL Ross, and Endicott crude oil in the large orifice tests conducted at Ohmsett exhibited a slight reduction in effectiveness. For the Dorado oil tested at Ohmsett there was no apparent loss in effectiveness when methane was present in the discharge in either the small or large orifice tests conducted. The dispersant to oil ratio (DOR) had a significant effect on dispersant effectiveness in all of the tests conducted, as would be expected. DOR s of at least 1:100 were needed to achieve dispersions with oil drop VMDs of less than about 100 microns for the various conditions tested. The orifice size used in the testing appeared to have an effect on the dispersant effectiveness with better dispersant efficiency generally achieved in the larger orifice tests. The effect of gas to oil ratio (GOR) on the dispersant effectiveness was inconclusive. This study did not address the issue of deep water releases, gas properties under high pressure, complex natural gas mixtures, or hydrate formation under high pressure conditions and is applicable only to shallow well blowout situations.


Potter S.,Sl Ross Environmental Research | Buist I.,Sl Ross Environmental Research
Proceedings of the 33rd AMOP Technical Seminar on Environmental Contamination and Response | Year: 2010

A two-day test program was conducted in the Barents Sea in May 2009 to perform experiments related to in situ burning of oil in open drift ice. The tests were part of a broader program performed over a two-week period that included tests with skimmers, dispersants, and remote sensing systems, and studies of oil-in-ice behaviour. Preliminary tests were performed with the boom in 2008: these tests did not involve oil, but proved the feasibility of several operational aspects of fire-boom use in ice. In the 2009 test program, oil was collected in ice-affected waters and subsequently burned in situ with a high degree of effectiveness.


Buist I.,Sl Ross Environmental Research | Potter S.,Sl Ross Environmental Research | Sorstrom S.E.,Sintef
Proceedings of the 33rd AMOP Technical Seminar on Environmental Contamination and Response | Year: 2010

A 2-day field research program was conducted off Svalbard in late May 2008 to test the efficacy of a chemical herding agent in thickening oil slicks on water among very open drift ice for subsequent in situ burning. The objective of this study was to continue research on the use of chemical herding agents to thicken oil spills in broken ice to allow them to be effectively ignited and burned in situ. More specifically, the goal of the work was to conduct two meso-scale field burn experiments with crude oil slicks of approximately 0.1 and 0.7 m3 in open drift ice. Prior to carrying out the field experiments, two series of small laboratory tests were carried out with candidate crudes (Heidrun and Statfjord) for the field experiments to determine the ability of the USN herder to contract slicks of the oils. The first field experiment involved 102 L of fresh Heidrun crude released into a monolayer of USN herding agent that had just been placed on the water. This slick was unexpectedly carried by currents to a nearby ice edge where the oil was ignited and burned. Approximately 80% of the oil was consumed in the ensuing burns. The second experiment involving the release of 630 L of fresh Heidrun crude onto water in a large lead. The free-drifting oil was allowed to spread for 15 minutes until it was far too thin to ignite (0.4 mm), and then USN herder was applied around the slick periphery. The slick contracted and thickened for approximately 10 minutes at which time the upwind end was ignited using a gelled gas igniter. A 9-minute long burn ensued that consumed an estimated 90% of the oil.

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