The Stickney Water Reclamation Plant is the largest wastewater treatment plant in the world.  Part of the Metropolitan Water Reclamation District of Greater Chicago, Stickney was in need of an upgrade to the sludge thickening process to meet new EPA mandates.  Helm was the contractor for the installation of the new sludge process and odor control system.  Work was performed in 8 tunnels and 3 buildings in the existing plant under a complicated phasing system.