1 5.12 VISUAL RESOURCES

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• The list of direct and indirect actions or activities associated with utility-scale

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solar energy development that can produce visual changes in Section 5.12 of

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the Draft Solar PEIS is being updated with the addition of the following items.

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The presence of litter or debris could produce visual changes.

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Lighting at some facilities could also potentially cause substantial impacts

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on night skies in non-industrialized landscapes.

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During site characterization (discussed in Section 5.12.1.1 of the Draft

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Solar PEIS), fencing around meteorological stations could be a source of

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visual contrasts.

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During construction (discussed in Section 5.12.1.2 of the Draft Solar

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PEIS), fencing around construction areas could be a source of visual

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contrasts.

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The discussion of lighting impacts in Section 5.12.1.3.4 of the Draft Solar

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PEIS is being updated with information published after the Draft Solar

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PEIS was published, as follows. The discussion of the impacts of aircraft

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warning lights should note that such lights mounted on wind turbines are

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easily visible at a distance of 36 mi (58 km) (Sullivan et al. 2012a).

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Construction of transmission lines and roads (discussed in Section 5.12.1.5

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of the Draft Solar PEIS) could result in litter, an additional source of

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visual contrasts.

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• With respect to the impacts of glare from parabolic trough collector arrays

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discussed in Section 5.12.2.1.1 of the Draft Solar PEIS, Sullivan et al. (2012b)

Final Solar PEIS

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July 2012

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routinely observed strong glare from two solar trough facilities during three

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site visits between April 2010 and January 2012. Glare was observed from the

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front, sides, and tops of parabolic trough arrays from mid-morning through

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late-afternoon, at distances ranging from 0.1 to approximately 3.6 mi (0.16 to

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5.8 km) from the facilities. The occurrence of glare was highly variable, with

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it appearing and disappearing suddenly in some instances, while in others, it

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varied greatly in intensity over a short period of time. Glare was observed on

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both the east and west sides of the facilities, and from viewpoints to the

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northwest and northeast of the facilities, but not south of the facilities.

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• Figure 5.12-9 in Section 5.12.2.2 of the Draft Solar PEIS depicts a close-up of

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a portion of a commercial compact linear Fresnel reflector (CLFR) solar array.

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In response to comments, it is being clarified that the height of the top of the

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CLFR array is 60 ft (18 m).

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• With respect to the discussion of visibility of power tower receivers in

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Section 5.12.2.3 of the Draft Solar PEIS, the Torresol Gemasolar 19.9 MW

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(tower height of 140 m [459 ft]) was observed in September 2011 and

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found to be visible as a bright white light on the horizon at a distance of

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approximately 20 mi (32 km) (Sullivan 2012b). The author suggested it would

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have been visible at longer distances if topography had allowed unobstructed

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views at greater distances.

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• The discussion of PV facility impacts in Section 5.12.2.5 of the Draft Solar

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PEIS is being augmented as follows. Sullivan (2012b) repeatedly observed

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that at two thin-film facilities in Nevada, apparent panel color varied from

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black through a range of dark to light blue to nearly white as the observer

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passed from north to south (and vice versa) on either the west or east side of

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the facilities on sunny days. Both facilities had nontracking south-facing

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panels. The effect was visually striking, particularly when viewed from an

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automobile at highway speeds. In the space of approximately one minute, the

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entire collector field transitioned from black to deep blue to white, and as the

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viewer passed the north–south midpoint of the facility, the color sequence

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reversed, so that the white collectors appeared to be light blue, then dark blue,

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and eventually appeared black again. The phenomenon was observed at

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distances up to approximately 2 mi (3 km); the maximum distance from which

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this phenomenon might be visible is unknown.

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• Section 5.12.3 of the Draft Solar PEIS presented a list of BLM and DOI

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publications pertinent to mitigation for impacts on visual resources.

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BLM IM 98-164 contains policy requirements and clarifications (BLM 1998).

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The following IM issued after publication of the Draft Solar PEIS are also

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relevant: IM 2008-204, IM 2009-167, and IM 2011-061 (BLM 2008,

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2009, 2011c).

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Final Solar PEIS

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