The City of Tolleson, Arizona, awarded PCL the Construction Manager at Risk this Solids Improvements project, which focused primarily on the solids train of the Tolleson WWTP. The Phase 1 portion of the project included constructing a facility that houses rotary drum thickeners, a new biological odor-control scrubber system, and new chemical tanks and pumps. Also included in GMP1 was the procurement and installation of a new belt filter press, decant pumps, sludge cross collectors, and aluminum covers at the primary sedimentation basins. The electrical package of the project centered on bringing a new 12kV feed into the plant. Work under the Phase 2 package consisted of the rehabilitation of three existing digesters; installation of new concrete digester covers; construction of a new sludge storage tank with membrane cover; and installation of new gas collection equipment, boilers, and sludge heat exchangers.