Physical Impacts
How will Cape Wind impact the geology of Nantucket Sound?
Building Cape Wind would involve driving piles approximately 85 feet into the seabed to support turbines, as well as embedding transmission cables to interlink the turbine towers and carry their power to the mainland at Yarmouth. The Army Corps of Engineers concluded that these activities would have temporary and localized effects on the seabed. No drilling or blasting is expected because the piles will not be driven into bedrock. The piles are open-ended, so they will suspend a minimal volume of subsurface sediments that is expected to resettle within one to two tidal cycles.
Project decommissioning is the reverse of installation, without pile driving (piles will be cut off about 6.5 feet below the surface), so it will have fewer impacts than installation. Similarly, the Corps concluded impacts from installing and operating transmission cables would be short-term and localized. No adverse impacts were anticipated in either federal or state waters or on land from installing and operating the cables. Click here to read the Corps assessment (Section 5.1.4, pp. 5-12 to 5-20).1
How will the transmission system linking Cape Wind to the power grid affect areas that it crosses under water and on land?
To connect to the regional power grid, Cape Wind proposes to install two 18-mile transmission lines running underwater from the wind farm to Yarmouth, then underground from this landfall point to the Barnstable switching station. The Energy Facility Siting Board found that Cape Wind had examined a reasonable range of alternative routes, and that subject to several specific conditions, the marine and land impacts of constructing and operating the transmission system would be minimized.
The board directed Cape Wind to consult with appropriate agencies on protecting coastal shorebirds during construction; to work with the towns of Barnstable and Yarmouth (as well as the Coast Guard and private transit companies) to prevent construction from impeding navigation; and to file a traffic management plan with the town of Yarmouth at least six months before starting work on the land transmission line. Click here2 to read the board’s opinion on impacts associated with building and operating the transmission line (Section III C., pp. 51-124).
How visible will the wind turbine towers be from Cape Cod, Martha’s Vineyard and Nantucket?
Cape Wind’s turbine towers would be visible from locations on Cape Cod, Martha’s Vineyard, and Nantucket. The closest points of land to Cape Wind’s proposed location on Horseshoe Shoal are Point Gammon, near the entrance to Lewis Bay and Hyannis Harbor on the mainland (4.7 miles from the nearest turbines); Great Point on Nantucket Island (11 miles); and Cape Poge on Martha’s Vineyard (5.5 miles). The towers would be painted to blend in with the horizon, and some would be equipped with safety lights to warn away airplanes.
Cape Wind and the Alliance to Protect Nantucket Sound, an organization that opposes construction of the wind farm, each commissioned simulations of how the towers could look from various shore points. There is relatively little difference between these simulations. Click here3 for a presentation on Cape Wind's visual simulation of the wind farm, and here4 for a presentation on the Alliance’s visual simulation from a 2002 MTC stakeholder meeting. For a simulation of the Denmark’s Horns Rev offshore wind farm from about 3.8 nautical miles and an actual photo of Horns Rev from 9.1 nautical miles, click here (p. 5-126)5.
Assessing the visual impacts of the Cape Wind project involves aesthetic judgments. Depending upon an individual’s feelings about the physical appearance of wind turbines, the impact of a significant number of turbines in Nantucket Sound would be either welcomed, acceptable, or unacceptable. The Minerals Management Service noted that many people who commented on Cape Wind raised the issue of visual impact, with some arguing that the wind farm would be unsightly and others contending that it would be attractive. MMS concluded that the public was unlikely to stop using recreational areas around Nantucket Sound because Cape Wind towers would be visible from points on shore. Section 5.3.3.4.2 of the MMS Draft Environmental Impact Statement (pages 5-197 to 5-202)6 contains the MMS assessment of visual impacts from Cape Wind, and Figure 5.3.3-8 contains simulations of how the park could look from shore.
1http://www.nae.usace.army.mil/projects/ma/ccwf/section5.pdf, Section 5.1.4, pp. 5-12 to 5-20
2http://www.mass.gov/Eoca/docs/dte/siting/efsb02-2/72cwind.pdf, Section III C., pp. 51-124
3http://www.masstech.org/offshore/Meeting4/EDR_final.pdf
4http://www.masstech.org/offshore/Meeting4/MTCforum1211alliance.pdf
5http://www.ocsenergy.anl.gov/documents/fpeis/Alt_Energy_FPEIS_Chapter5.pdf, p. 5-126
6http://www.masstech.org/offshore/docs/CapeWindDEIS.pdf, Section 5.3.3.4.2, pages 5-197 to 5-202