Utility-scale solar projects are pitched as being environmentally friendly because they are built on the ground itself, with little impermeable surfaces. (For example, see this article in the Farmville Herald about the 2,000-acre Riverstone Solar project, located 1/2 mile from the James River, in which the Apex Clean Energy public engagement manager asserts that “only 1% of the site will be converted to an impermeable surface.”)

Strictly speaking, this is true but only because it is using the most limited definition of “impermeable surface” relates to ground surfaces only. The definition of “impermeable” at LawInsider, for instance, is a “surface or pavement constructed and maintained to a standard sufficient to prevent the transmission of liquids beyond the pavement surface.”

However, a University of Delaware factsheet on permeable vs. impermeable surfaces defines “impermeable” as including all “solid surfaces that don’t allow water to penetrate, forcing it to run off.”

Because solar panels are solid surfaces, they are impermeable, even though they are elevated above the soil. Any large-scale solar project, then, poses several risks to the environment, as detailed by the U/Del factsheet:

  1. The pollution of surface water, because the runoff can pick up pollutants as it flows into creeks and streams.
  2. Flooding of surface water and erosion of stream banks, especially during periods of heavy rainfall which can cause flash flooding and erosion of stream banks.
  3. The formation of stagnate water, especially in large water retention ponds where mosquitoes can breed.

Every utility-scale solar project in Virginia has resulted in excess stormwater runoff that has flooded neighboring properties and eroded stream banks. (See this video for an example of solar-caused flooding.)

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