Utility-Scale Solar Stormwater Run-off, Erosion and Flooding Issues

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Landowners are concerned with increased runoff from utility scale solar facilities both during construction and during ongoing operations. During construction the land will be scraped of vegetation and bare ground exposed to rain and wind. This exposure will only be made worse by months of grading, road construction, trenching, and heavy equipment traversing the landscape. Most soils in the area are classified as highly erodible or erodible Sibleyville soils. Increased runoff will result in costly erosion on adjacent properties and harm adjacent landowners.

1) Comments from Darren Coffey, Berkley Consulting, Before the Johnson County Planning Commission, September 14, 2021

“One of the things that we’ve done in more of the administrative sections of these regulations is talked about the importance of erosion and sediment control and stormwater design, third party design review, before it ever goes to the regulatory authority for their review. What that does is ensures that the industry has designed it appropriately and that once it’s built and implemented appropriately, if it’s approved, that there will be minimal if any stormwater erosion and sediment issues. When these things are done correctly, there tend to be very few issues. If they’re not done correctly, they can have very, very detrimental impacts, particularly on adjacent property owners.”

2)  Discussion on General Land Maintenance in the article at North Carolina State University
Cooperative Extension (ncsu.edu)

Excerpt from section on General Land Maintenance:

Farmland maintenance will especially be critical shortly after development or for land that has a permanent stream in order to protect against erosion or flooding concerns. Removal from agricultural land use does not exempt the landowner from soil or stream maintenance that might otherwise impact water flow or degrade soil or water quality.

Many soils within Craven County, NC are either very coarse sand or soils that drain poorly. Both of these situations may result in topsoil either shifting, sinking or eroding near the base of equipment. Slight shifts in solar panels will alter the degree of tilt required for the unit to function properly or even may cause a fire hazard (See Fire Safety). Thus, replacement of eroded topsoil should be a priority, especially between the time after completion of the construction and establishment of a permanent ground cover.

Flooding is another issue that should be examined. Storm events within this area historically cause flooding for some areas. Maps showing the flood plains are available for review at NC Floodmaps. However, also consider that continued development and increased impervious surface modifies this map data. Thus, some variance is likely due to a changing environment, increased development and water management (or lack thereof).

One should also consider that Eastern NC is at risk for frequent tropical storm systems. Trees and debris will fall into the area. As farmland, the farmer tending the land normally assumes the
responsibilities and cost of cleanup. In some cases, the farmer may qualify for financial assistance for cleaning up the debris. Commercial property may or may not qualify for such and it will be the responsibility of the landowner to clean up debris.

3) Altenergymag.com article on erosion due to solar panels

Erosion is one risk that workers must mitigate or fix when working with solar panels. These farms can span several acres, with the structures covering most of that land. Underneath it all, the soil and dirt must stay in place. Otherwise, the structures could shift and become less efficient — or become damaged beyond function.

All forms of solar panel installation and management must include plans for erosion control. Water and wind are two of the biggest culprits of erosion. During high winds or strong storms, topsoil erodes and changes the landscape of the farm.

If erosion exposes the electrical wirings, power failures can occur. If storms bring enough rain, mudslides can happen on a significant slope. Workers must be cautious of flat land, too, since it can cause flooding.

With these potential risks and outcomes, mitigation is necessary. However, that, too, can be tricky due to the environment.

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