JANESVILLE The mammoth former General Motors plant site in Janesville is still idleââbuttoned upâ for a long winter, as one local real estate broker put it. And sources say that likely will remain so for months as the owner of the former GM site awaits a state Department of Natural Resources environmental review that city officials said is now several months overdue, apparently delayed because of the COVID-19 pandemicâs impact on state agencies. That ties up about half of the 250-acre industrial brownfield propertyâby far the largest bloc of such land in Janesville held by any single private or public owner.