Offshore Wind Power Projects in the Great Lakes - Ministry of ...

More documents

Recommendations

Info

Offshore wind power projects in the Great Lakes: Background and science considerations for fish and fish habitat projects should be further investigated, as they could have the added benefit of reducing noise levels or acting as fish deterrents. Mitigation options to address the alteration of sediment transport The increase in current velocity and change in water flow that occurs around below-water turbine components alters local sediment transport dynamics, resulting in scour and substrate loss around the foundation and subsequent redistribution of fine sediments further away. Scour protection materials placed around the turbine base are used to prevent the formation of scour pits and stabilize the structure, although changes in sediment erosion and deposition patterns through what is known as secondary scour is still possible even with these materials in place (Rees et al. 2006). The effects of altered sediment transport might be reduced by streamlining component shapes, or by reducing their size and surface area (U.S. Department of Energy 2009). Cumulative impacts on sediment transport and potential far-field effects from multiple turbines can be minimized by increasing the spacing between turbine units or altering their orientation (Meißner & Sordyl 2006). Exercising precaution in site selection so as to avoid placing turbines in or near shoreline areas with particular sensitivity to altered coastal or sediment dynamics such as sandy shoals or beaches is also recommended to reduce detrimental impacts to benthic habitats from wind turbine-related changes in sediment transport. 2.6 Minimizing habitat loss Another potential impact of offshore wind power projects is habitat loss or destruction. The immediate area of benthic habitat to be covered by the turbine foundations and scour protecting materials will necessarily be destroyed. However, the physical area occupied by the turbine structures themselves is generally less than 1% of the total area of a wind power project, so the loss of habitat due to foundation placement is not that significant. Aside from opting for smaller footprint foundation types like monopiles as opposed to the larger gravity base foundations, there is very little that can be done to avoid this rather minimal loss of benthic habitat. If project sites are selected so as to avoid sensitive or critical habitat areas (e.g. spawning shoals), the loss of benthic habitat resulting from foundation installation should have minimal impact on local fish species. Habitat loss or destruction could also occur during the sediment dredging activities which are required to level the substrate for gravity base foundation installation and for cable laying. As Aquatic Research and Development Section 38
Offshore wind power projects in the Great Lakes: Background and science considerations for fish and fish habitat discussed above, the use of horizontal directional drilling to minimize impacts to shallow-water and shoreline habitats from cable crossings, and the use of jet ploughing technology to lay and bury the cables are recommended to reduce the extent of damage to benthic habitats. 2.7 Reducing the potential for water quality degradation There are several ways in which the construction and operation of offshore wind power projects could negatively impact local water quality (Nienhuis & Dunlop 2011). Of primary concern is the potential release of sediment-bound contaminants during dredging and drilling activities. While silt curtains or other types of turbidity barriers could help to reduce the spread of disturbed and potentially contaminated sediments (Palermo et al. 2008), the most effective way to reduce the risk of remobilizing harmful contaminants during construction activities is to simply avoid installing turbines or cables in areas with unacceptable levels of persistent organic pollutants or heavy metals. Through the Great Lakes Water Quality Agreement, the US and Canadian governments have identified Areas of Concern where sediment contamination is so great as to require dredging restrictions for the protection of aquatic organisms and human health (Krantzberg & Montgomery 2007). Furthermore, outside of these designated areas there are additional sites within the Great Lakes where sediment contaminant levels exceed provincial standards or guidelines. Areas such as these with high sediment contaminant levels should be considered as areas to avoid turbine installation. Sediment sampling surveys and associated chemical analyses, bioassessments and toxicity testing procedures are relatively straightforward to conduct (Palermo et al. 2008), and an option is to include them as part of the site selection process. In addition to contaminant release from dredged sediment, water quality issues associated with the evolution and discharge of drill cuttings and other associated waste products could arise during horizontal direction drilling activities or if monopile installation requires partial drilling. To reduce potential adverse effects of drill cuttings, it is recommended that construction crews use water-based drilling fluids as opposed to synthetic- or oil-based muds to lubricate the drill bit, as the latter have been identified as potential sources of hydrocarbon and other contaminant release and toxicity (OSPAR Commission 2009). Aquatic Research and Development Section 39
Page 1 and 2: Aquatic Research and Development Se
Page 3: Abstract Owing to their large open
Page 6 and 7: Offshore wind power projects in the
Page 90 and 91:
Offshore wind power projects in the
Page 92 and 93:
Page 94 and 95:
Page 96 and 97:
Page 98 and 99:
Page 100 and 101:
Page 102 and 103:
Page 104 and 105:
Page 106 and 107:
Page 108 and 109:
Page 110 and 111:
Page 112 and 113:
Page 114 and 115:
Page 116 and 117:
Page 118 and 119:
Page 120 and 121:
Page 122 and 123:
Page 124 and 125:
show all

Offshore Wind Power Projects in the Great Lakes - Ministry of ...

Create successful ePaper yourself

Delete template?

Save as template?