In an agreement with federal and state agencies, contractor Swinerton Builders will pay $2.3 million to resolve allegations that it violated the Clean Water Act in constructing solar energy projects in Alabama, Idaho and Illinois that totaled about 500 MW..

The U.S. Justice Dept. and Environmental Protection Agency said on Jan. 17 that Swinerton also will contribute $600,000 for environmental mitigation in Idaho and buy about 14,000 stream credits from a mitigation bank to make improvements to a watershed in Lafayette, Ala.

Agencies in Alabama and Illinois also signed the consent decree that details the background and terms of the agreement. The government alleges that Swinerton violated limits set by National Pollutant Discharge Elimination System permits for the projects, claiming work was done “without adequate safeguards designed to prevent discharges of excess sediment in stormwater to nearby waterways.”

Swinerton had been the largest U.S. builder of utility-scale solar energy projects but no longer builds in the sector after selling its Swinerton Renewables business unit to a private equity firm in December 2021 that now is called SOLV Energy LLC. The change was noted in the settlement document.

The agencies also stated that Swinerton did not admit any liability to the U.S. or to states involved in the case. 

Of Swinerton's total payment, the U.S. government will receive about $1.6 million. The Alabama Dept. of Environmental Management will receive about $540,000 and the Illinois EPA about $145,000. Idaho will not receive a cash payment but Swinerton will provide $600,000 for environmental mitigation work at the Portneuf River in Pocatello to include capturing sediment, reconnecting riparian and wetland habitat and providing environmental and recreational benefits, agencies said.

They noted that clearing and grading tracts of land for solar projects can result in significant erosion and sediment runoff, if controls on stormwater are not adequate. 

The government also reached settlements with owners of the projects in 2022 that included $1.3 million in civil penalties.

David M. Uhlmann, EPA assistant administrator for enforcement and compliance assurance, said in a statement, "Solar farms are vital to slowing the effects of climate change but companies building solar farms must comply with environmental protection requirements just as companies must do for any other construction project."

The consent decree, filed in the U.S. District Court for the Northern District of California, is subject to final court approval that will include a public comment period.

Swinerton did not immediately reply to ENR's request for comment.