Ron Yankey and Walter Eickelman died March 10th when the soft dirt collapsed into the Millstadt trench they working in as part of a construction projection for a new sewage treatment plant.
The lawsuit accuses Followell Construction of negligence.
Messages have been left with Followell, seeking comment.
Federal workplace safety officials are investigating the collapse, but no report has yet been issued.
Information from: St. Louis Post-Dispatch, http://www.stltoday.com