The fourth defendant who was charged with violating the Clean Water Act for dumping oilfield waste into a storm drain that emptied into a river in Youngstown, OH, last year (see Shale Daily, March 28), has pleaded guilty in U.S. District Court in Cleveland. Mark A. Goff, 46, will be sentenced on July 7. Hardrock Excavating LLC owner Ben W. Lupo previously pleaded guilty for directing Goff and Michael P. Guesman to dump the waste. Guesman pleaded guilty and was sentenced to probation and community service.