The 2009 results include a $ 24.6 million or $ 0.64 per share non-cash mark-to-market gain for certain interest rate swaps ; a $ 16.9 million , or $ 0.44 per share , gain on the sale of a 23.5 percent ownership interest in the Wygen I power generation facility ; and a $ 27.8 million , or $ 0.72 per share , non-cash ceiling test impairment charge. be effective for South Dakota customers on April 1 , 2010. be effective for Wyoming customers in 2010. ownership interest in this generation facility was sold in April 2009. begin in third quarter 2010 with an in-service date of January 2012. filed in June 2009 , are expected to occur in December 2009 .