Global Ampersand was fined more than $800,000 for excess ozone-related emissions and other violations from biomass power plants in Madera and Merced counties in California, federal authorities announced.

The fine is among the largest in the San Joaquin Valley and California over the past several years, officials at the U.S. Environmental Protection Agency were quoted as saying.

Ampersand, based in Boston, agreed to the fines for violations that began in 2008 at the Ampersand Chowchilla Biomass in Madera County and Merced Power near El Nido, the EPA said. The biomass plants burn woody waste from farms and cities to create electricity.

Ampersand agreed to reduce ozone-forming oxides of nitrogen and carbon monoxide. The company was fined $328,000 for its Chowchilla plant and $492,000 for the Merced County operation.

Ampersand bought and refurbished the two biomass plants in 2007 and 2008. Aside from nitrogen oxides and carbon monoxide, the plants violated limits for sulfur dioxide and also failed to perform timely testing to measure emissions. 

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