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An ambitious Washington County construction project intended to cut soaring energy costs and eliminate harmful wastewater runoff will begin in May in Stillwater Township.

The $19.7 million project will reconstruct the county's largest public works operation — known as the North Shop — to correct structural deficiencies that have caused fires, electrical hazards and mold.

Don Theisen, head of the public works division, said the new shop will address modern needs of a county that's nearing a quarter million residents. The current shop opened in 1962 and was modified in 1972. The new complex will open in late 2016. It will be paid for with proceeds from $17.5 million in bonds and $2.2 million in state aid funding.