2012-04-13 12:00:00 DLZ Designed $350 Million Columbus Sewer Project Bores Ahead The DLZ designed Olentangy Scioto Interceptor Sewer project (OSIS) for the City of Columbus continues to progress. OSIS is the largest public works project in the City’s history. The project’s tunneling machine is currently being constructed 180 feet below ground near the Jackson Pike Sewage Treatment Plant. The tunnel is expected to be completed by the end of 2014. Read more here: http://www.dispatch.com/content/stories/local/2012/04/13/540-foot-long-machine-to-bore-412-mile-sewer-line.html