Chapter 5: Siting Guidelines


As with any large energy facility, community wind projects raise a wide variety of siting issues. Placing turbines to take advantage of the best wind resources must be balanced with minimizing their impact on existing land uses, neighbors, and the environment. The first part of this section of the Community Wind Energy Toolbox discusses the various issues (apart from wind resource) that should be taken into consideration in siting a community wind project, including:

  • Land use
  • Aesthetics
  • Property values
  • Sound
  • Public safety
  • Liability prevention
  • Environmental impacts
  • Construction impacts

Many of these issues are addressed as part of the permitting process, but permit requirements vary widely from one jurisdiction to another. (See the following section of the Toolbox for more on Permitting and Zoning.) Prudent and responsible wind developers start by familiarizing themselves with how wind energy projects are viewed and regulated in a given location, and are prepared to address any of the siting issues that are likely to arise.

The second part of this section touches on other aspects of site layout, design and planning that warrant consideration. Here are the main topics covered in this section:

Siting Issues

Land Use

Although wind turbines themselves have a relatively small footprint (roughly one quarter acre for a large turbine), they require large open spaces, both because the turbines must maintain access to the wind resource, and because even a project consisting of a single commercial-scale turbine can impact surrounding areas through such things as aesthetics, sound, and safety.

The need to maintain wind access means that turbines must be sited away from tall buildings, other wind turbines, and trees, as well as any topographic obstacles. Wind projects are best sited in areas where the winds are not turbulent (in other words, the winds are clean and undisturbed). Even if a site has high average wind speeds, turbulent wind is not good for creating lift onwind turbine blades which is responsible for causing the machine to spin, and creates much stress on the machine. For further information about wind resource and siting a wind project visit the section of the Toolbox on Wind Resource Assessment.

In considering the impact of the wind system on the surrounding area, developers must consider not only the footprint of the turbines themselves, but also the size and placement of construction areas, guy wires for meteorological towers, power line corridors, access roads, and electrical equipment foundations. Developers should also talk to local citizens to find out what their concerns are. For example, one community considering a wind development was concerned about guy wires on or near snow mobile trails. In this case, the developer placed the met towers carefully to avoid conflicts with the trails.

In natural areas, this could mean working with the State Department of Natural Resources or U.S. Fish and Wildlife Service to minimize impacts on wildlife and habitat. On farmland, this means placing wind energy facilities with the farmer’s needs in mind. For example, roads should be placed along fence lines or other natural barriers whenever possible to avoid carving up fields. The developers should include the landowners in the siting process to make sure turbines and roads will minimally interfere with farm operations or other activities on the land and to protect the wind resource available to the project. Acquiring a wind easement for a buffer zone aroundyour project also has the affect of protecting your wind resource from other wind projects that may be constructed inyour area. For more information about wind energy easements visit the Leases and Easements section of the Community Wind Toolbox.

Where setbacks are required by local zoning laws, the site must be large enough to accommodate setbacks from a neighbor's property or buildings. (See Addressing Siting Issues below, as well as the section on Permitting and Zoning for more about setbacks.)

Even where setbacks are not required, it is a good idea to place your turbine well away from property lines, in case your neighbors later build obstructions that affect the flow of wind or wish to place turbines on their own land.

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Aesthetics

People have varied reactions to seeing wind turbines on the landscape. Where some people see graceful symbols of economic development and environmental progress or sleek icons of modern technology, others might see industrial encroachment on natural or rural landscapes. Many factors influence these perceptions, but it has been found that observers are more likely to forgive any visual intrusion if the wind turbines are seen as serving a beneficial purpose.

Turbines that are stationary too often can give the impression that the technology is unreliable. If a turbine stops working for any reason, it should be fixed as soon as possible both for economic reasons and to convey a good image to the public.

In addition, a visual simulation to show what the project will look like after it is constructed can help if there is a significant concern about a site or particular view. Developers should take care to locate substations and other electrical infrastructure in a less visible areas if possible.

Signage. Billboards, like any other extraneous structure, add visual clutter to the landscape. Developers should avoid using wind turbines as a means for elevating advertising billboards. It may be helpful to install an appropriately-scaled sign or visitor kiosk at or near the project site that informs the public about the wind turbines and their place on the landscape.

Lighting. Large wind turbines are often well over 200 feet tall and cannot help but be visible. While project and turbine design may seek to minimize visual impact, aircraft obstruction marking, by intent, seeks to increase contrast with the landscape.

Federal Aviation Administration (FAA) recommendations should be strictly adhered to for legal and safety reasons. Man-made objects taller than 200 feet are required to file for an FAA permit. Permits typically require red and white lights to be installed on the nacelle. Nighttime security lights are nonessential and can be activated as needed by motion detectors.

On-site lights should be minimized to avoid bothering neighbors or attracting wildlife such as birds.

Shadow flicker. Shadow flicker occurs when the blades of the turbine rotor cast shadows that move rapidly across the ground and nearby structures. These moving shadows can be unpleasant if they fall across occupied buildings, especially when windows face a turbine. They often occur when the sun is at low angles in the winter sky, and typically happen only a few dozen minutes per year. This issue can be mitigated by properly siting projects so as to minimize or eliminate flicker all together.

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Property Values

According to a national study published in 2003 by the Renewable Energy Policy Project (REPP), commercial-scale wind turbines do not harm “viewshed” property values. The Effect of Wind Development on Local Property Values systematically analyzed property values data, including over 25,000 transactions of properties in view of wind projects over 10 MW in size from 1998 to 2001. REPP found no evidence that property values are harmed by wind installations. In fact, for the great majority of wind projects, property values in the viewshed actually rose faster than in the comparable community with the pace increasing after the turbines came online.

The full study is available front Renewable Energy Policy Project (REPP). REPP publsihed another study from New York analyzed home sales from 1996 to 2005 near a 30MW wind farm. It found no measurable effect of wind farm visibility on property values. 

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Sound

Next to aesthetics, sound emissions are a commonly-raised issue for wind projects. Whether rotating wind turbines are “noisy” is a subjective matter; people who perceive wind turbines as an intrusion on an otherwise rural setting are more likely to find them noisier than do people who perceive them as beneficial and useful. Sound emissions are, however, objectively measurable.


Table 1 shows how sound emissions about 1000 feet from operational wind turbines compare with other sounds in terms of decibel output. The sounds of wind turbines do not interfere with normal activities any more than the sounds common in any suburban or rural setting. Moreover, they are likely to be masked to some extent by the background sound of the wind itself.

You might need to perform a study for your project to comply with sound regulations. In Illinois, for example, consult Title 35: Environmental Protection Subtitle H: Noise Chapter I: Pollution Control Board, Part 901- Sound Emission Standards and Limitations for Property Line-Noise-Sources to learn more. 

The National Wind Coordinating Committee’s Permitting of Wind Energy Facilities Handbook also addresses noise issues and can help you determine if unwanted sound will be an issue at your site.

The Minnesota Pollution Control Agency (MNPCA) has created a guide to help the public understand how noise is measured and how to understand what those measurements mean entitled A Guide To Noise Control in Minnesota which can be found from the MN Pollution Control Agency

For a more detailed discussion of technical siting issues related to the impact of sound from wind turbines, see the Proceedings of the NWCC Siting Technical Meeting (Washington, DC. December 2005, proceedings published March 2006).

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Public Safety

Safety is important around tall towers, moving parts and high voltage electrical equipment. If an unauthorized person climbs a turbine or wind instrument tower, it may be viewed as an “attractive nuisance” for which the owner may be held liable. Other safety concerns arise from falling ice, guy wires, turbine breakage and accessibility to electrical equipment and interiors of tubular towers. Standard safeguards include locking the turbine tower doors, placing information kiosks a good distance away from the turbines, and cautioning people from being under the machine during icing events. Federal Aviation Administration lighting requirements for aircraft safety are site specific.

You will also need to contact local law enforcement to set up a 911 address for the project. This allows emergency personnel to plan best ways to approach the site should a medical or other type of emergency take place while the project is underconstruction or after it is commissioned. Local fire fighting and other emergency response officials will also want to know the layout of the projects as well set up procedures should they have to climb a turbine tower to rescue a technician who might be having a medical emergency while performing maintenance on the project.

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Liability Prevention

From the outset of project planning, and throughout decision-making and implementation with regard to project location, design, installation, operation, and decommissioning, liability prevention is essential. Depending on insurance as a substitute for solid planning is a poor practice and could be costly in a number of ways. The key is diligence throughout planning and implementation of your project.

As the project is under construction, you should prominently post “Danger: High Voltage” or “Danger: Authorized Personnel Only” warning signs at eye level.

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Environmental Impacts

As with any construction project or large structure, wind turbines can impact plants and animals, with the significance of those impacts depending on the sensitivity of the area. A windy site over a wetland is not likely to be “developable,” and projects on native prairie or other delicate ecosystems may raise special concerns. Among the concerns associated with wind energy development are wildlife fatalities from collisions and loss of wildlife habitat and natural vegetation.

Before applying for permits you should consult with the state Department of Natural Resources and the U.S. Fish and Wildlife Service to obtain an inventory of threatened and endangered species and habitat that may be affected by the project.Working with these agencies early in the process will allow you to take appropriate measures to minimize or eliminate the impacts on sensitive plants and animals in the area.

Collision fatalities. Avian fatalities due to collision with wind turbines have raised considerable concern, as have recent incidents of collision-related bat fatalities, particularly on forested ridges in the eastern United States. Almost all large structures (buildings, cellular towers, smoke stacks, lighthouses, transmission lines, monuments, and so on) kill some number of birds. Table 2 helps to put the risk to birds posed by wind turbines in perspective. Evidence from the growing body of research on bird/bat-wind turbine collisions suggests that the risk to birds and bats is greater at some sites than at others.

 

Full results from Avian Monitoring Studies at the Buffalo Ridge, Minnesota Wind Resource Area Results of a 4-Year Study, are available here.

Mitigating avian collision impact. A number of steps are commonly required of new wind projects to help mitigate impacts on birds. How intensively they are performed depends on the scale of the project and its location. Mitigation steps commonly include a preconstruction review of whether and what species use the site and immediate area. For larger projects or projects in sensitive avian areas, this may include an expensive year-long field study, or spring and fall migration studies. Many smaller projects simply need to review existing information with state wildlife officials. If a single turbine project is proposed to be located “in harm’s way,” a greater degree of concern and scrutiny would arise. State officials estimate the likely impact on birds and issue a ruling: proceed as planned; proceed with modifications to the plan; or do not build. Building permits may include ongoing impact monitoring requirements and periodic reviews of actual results.

For further discussion of wind energy’s impact on birds and bats, see the National Wind Coordinating Committee’s Avian/Wind publications 

The GAO report on the impacts of wind power on wildlife can be found by searching the GAO Reports and Comptroller General Decisions for “GAO-05-906”.

An “Avian Risk Assessment” was performed for the Crescent Ridge Wind Power Project in Bureau County, Illinois, in 2002 using information about known bird risks from North America and Europe and observations of the proposed wind farm’s site. It concluded that installing wind turbines at that location would have no significant adverse impact on bird populations.

The complete study is available from Crescent Ridge Wind Farm.

Wildlife and habitat loss. Wind project developers must also be sensitive to other kinds of wildlife and wildlife habitat when choosing sites for wind turbines. Although wind farms in agricultural areas are unlikely to have significant impacts on wildlife or habitat, it is still necessary to consider the issue.

Wind developers should also be mindful of endangered or threatened species in the proposed project area, both to be responsible stewards of the environment as well as to prevent being levied hefty fines by the state or federal government from impacts from your project.

Before applying for your permits you should contact the state Department of Natural Resources or Fish and Wildlife office to obtain an inventory of threatened and endangered species and habitat in the area of the project. Working with these agencies will help you to understand the impacts your project will have on local wildlife and what measures you can take to mitigate these.

The U.S. Fish and Wildlife released a set of voluntary guidelines in June 2003 for wind developers to follow for the purpose of minimizing impacts on wildlife. The guidelines address three key areas: proper evaluation and selection of potential sites for wind energy facilities, proper location and design of turbines and associated structures within the site areas, and research and monitoring to assess impacts of the project on wildlife.

The guidelines are available by contacting the USFWS at 1-800-344-WILD or online.

These guidelines will soon be revised through a Federal Advisory Committee process taking into account current research on wildlife impacts on wind turbines as well as current wind turbine technology and siting guidelines that have shown to significantly reduce wildlife impacts.

You can find out more information about many of the issues to be revised by reading the American Wind Energy Association’s comments on the guidelines online.

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Historical Sites

When undertaking any construction project there is the potential that you may unearth or disturb something from the distant past that has important cultural and/or historical significance to people that used to or currently inhabit the area. While investigating potential sites you should have conversations with the State Historical Preservation Office, the National Register of Historic Places to determine if there are any known sensitive artifacts in the area of the project, whether a more detailed study needs to be performed, and what is the proper protocol to follow should the construction team disturb cultural artifacts that were previously unknown. Agricultural land that has been in production for many years typically should pose little chance of this happening but it is always a good idea to check well before you dig to reassure yourself and members of the community that your project will have as minimal impact as possible. You may also be required to assess the impact of the turbines on the viewshed from historical buildings or sites.

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Construction Impacts

Wind turbine construction involves the transportation of large and heavy equipment, including cement mixing trucks and large cranes. These vehicles can compact soils and damage roadways not built to handle their weights. Unpaved public roads are likely to have weight restrictions during rainy seasons and spring thaws, but frozen roads are good for carrying high loads. Wind developers may need to improve roads before construction begins, or repair any damage to existing roads.

Turbine components need to be placed close enough to the tower for a crane to reach while the project is being built, when major rebuilding or large component replacements occur and when the turbine is being dismantled. This can cause a large temporarily disturbed area near the turbines. Soil excavated for foundations and construction waste must also be stored, recycled, or disposed of properly.

Erosion is another potential environmental problem that can stem from construction projects. Erosion impacts can include increased siltation of streambeds, alteration of stream courses, and increased flooding, leaving scars on the land. Wind developers can reduce the risk of serious erosion by minimizing the amount of earth disturbed during construction, principally by eliminating unnecessary roads, avoiding construction on steep slopes, allowing buffers of undisturbed soil near drainages and at the edge of plateaus, assuring re-vegetation of disturbed soils, and designing erosion-control structures adequate to the task.

The single most reliable technique for limiting erosion is to avoid grading roads in the first place. The Bureau of Land Management’s Ridgecrest, California office suggests that driving overland to install and service turbines, rather than grading roads, will significantly lessen erosion damage. Instead of using wide roads graded to bare earth, British, German, and Danish wind plant operators use farm tracks to service their wind turbines as a “tread lightly” practice to minimize erosion. However, compacted topsoil on farms makes it difficult for crops to grow. You should have a plan to separate and return topsoil from construction areas on farms.

Most state or local agencies will require that before building and other permits are issued that you attain an Industrial National Pollutant Discharge Elimination (NPDES) permit. The permit assures local and state agencies that you have a plan in place to minimize erosion from the site and potential harmful affects on water quality in local lakes and streams from run off or oil and other chemicals that might be spilled during the construction process.

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Dismantling and Restoration

Once a wind project reaches the end of its useful life, the turbines and ancillary structures and equipment must be dismantled and the project site restored to usable condition. This is an aesthetic as well as an environmental and safety issue. A common issue is determining how much of the foundation will be removed in the end. Developers often commit to removing foundations to several feet below the ground. Dismantling and restoration (sometimes called “decommissioning”) costs should be budgeted from the outset. Some jurisdictions require that an escrow account be set up that is accessible to the land owner should the project need to be removed from the property before the end of its useful lifetime. Agreements with the town and landowners should include decommissioning provisions.

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Site Layout, Design and Planning

Once a site is selected, there are a number of other issues to consider when planning the layout and design of the project within that site.

Setbacks

Maintaining distances from various features and environmentally sensitive areas can address several issues. Turbines can be located away from residences to reduce sound emissions and shadow flicker impacts, and away from public rights-of-way and locations frequented by people for safety reasons. Space is also required between turbines and other wind obstructions. Lastly, turbines may need to be located away from aesthetic vistas, landmarks and cultural or historic sites. Setbacks might be dictated in local zoning ordinances, so it is important to check whether your community has setback regulations in the early stages of designing your project.

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Turbine Layout

A common question about siting wind energy projects is “how much space is needed?” The answer depends on many factors, including not only setback requirements but also: how many turbines the wind farm will contain, the surrounding topography, as well as the prevailing wind direction.

Single turbine projects. For a single turbine project the amount of space needed will depend upon the local permitting agencies’ requirements for setbacks from easement and/or property lines, and setbacks from buildings or dwellings. This can vary a fair amount from community to community. Sometimes mandatory setbacks are defined in terms of the height of the tower. Other communities may require setbacks of a certain number of feet, either from property lines or from other structures, and some communities may not have any standards set for this at all.

The key is to start conversations with the local permitting authority early on in the process so that you can understand if the proposed site has enough space or if you need to attain control of more of the area or a larger site.

Multi-turbine projects. For multi-turbine projects, siting becomes a bit more complicated. The prevailing wind in relation to the point of interconnection is a strong factor in determining the final configuration of your project. Developers use different rules for laying out projects to achieve a balance between low installed cost and higher production. Some consulting firms begin laying out a project using the following rule-of-thumb: In the direction of the prevailing wind, the turbines should be spaced 8 rotor diameters apart. In the direction perpendicular to the prevailing wind, the machines should be 4 rotor diameters apart.

This means that a four-generator project that uses 82 meter diameter rotors may be expected to require a little over 200 acres of land. Taking into account the space requirements of the turbines as well as required setbacks from easement and property lines, a project this size will need more than a quartersection of land. This is a simplified example and should be used only as a place to begin understanding how to lay out your project. The final project layout including the total space required in terms of land lease and turbine spacing should be determined based on maximizing project economics described in more detail below.

Optimizing turbine layout. Turbines can be placed closer together, but will incur higher wake losses, which occur when the power of the wind is reduced as it flows around and through other turbines. Machines that are placed farther apart will produce more electricity but will cost more in terms of land lease, buried underground cable and construction costs. These costs and benefits should be weighed when determining the layout of a wind farm. For sites where the wind does not come from a single predominant direction, or that have complex topography, optimal placement of turbines becomes more complicated. There are computer software packages that turbine siting companies and consultants can use which help to perform these calculations to determine the optimum layout for a project.

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Project Design

Many aspects of turbine and project design are intended to minimize impact and improve safety:

  • Turbines are usually painted a neutral or subdued color and are free of advertising. New FAA recommendations recommend turbines be bright white or light off-white.

Read their new Advisory Circular online.

  • Projects typically have minimal signage but post appropriate warnings and emergency contacts.
  • Turbines can be selected for low sound emissions.
  • Tubular towers have become common due to aesthetics, easy winter maintenance access, and diminished opportunity for birds to perch.
  • Appropriate steps are taken to prevent fluids from being spilled on the ground. Fluids can be used in turbines and electrical equipment that will not be hazardous in case there is a spill.
  • Appropriate fencing, gates, locks, warning signs, equipment enclosures, anti-climb provisions, and guy wire markings are common features contributing to safety.
  • Use of proper erosion and drainage controls is common as well.
  • The project footprint can be minimized by using preexisting roadways and rights-of-way, putting turbine foundations next to roads, placing electric lines underground, and using existing rights-of-way for electrical wiring.

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Project Plans

Wind developers and permitting authorities use plans to organize activities and assure that they are done properly. While small (single-turbine) projects may require little more than informal discussions and coordination with the people/agencies involved, a commercial-scale, multi turbine wind energy project typically requires preparation of detailed planning documents that must be formally approved and monitored for compliance. Detailed plans cover a wide variety of activities, including:

  • Transportation routing
  • Roadway maintenance and repair
  • Temporary construction area definition
  • How and when to conduct avian impact surveys during operations
  • Erosion control
  • Routine maintenance procedures, including how to dispose of used lubricants and bad parts and protocols in case of fluid spills
  • Restoration of vegetation and prevention of noxious weeds
  • How to handle historical or archaeological artifacts which may be found
  • Project dismantling and site restoration procedures.

A detailed project plan essentially organizes all aspects of project development, operation, maintenance and decommissioning. Project planning is discussed in more detail in the Project Management and Planning section of the Toolbox.

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