A portion of the Ridgefield Rail Trail is closed today through Friday.  Repair work is being done in the area of 140 Ivy Hill Road.  Trail users are asked to stay clear of the workers and their equipment and to plan their activities using alternate routes.  The 2.3 mile trail opened in 2000 and follows a portion of the abandoned railway that originally ran from Branchville to the center of Ridgefield. It was built by Eversource, formerly Connecticut Light & Power.  It stemmed from a state Department of Energy and Environment Protection mandated cleanup of arsenic used by the railroad to control weeds.