The Boilers 3, 4, and 5 and MCC Replacement project at the Stickney Water Reclamation Plant involves replacing three aging steam boilers with 75,000 lb/hr co-fired digester gas and natural gas boilers and installing a new redundant 200,000 lb/hr deaerator with four feedwater pumps. Work also includes a new air compressor system, orifice plate type steam meters, updated MCCs, and modifications to DCS controls for both existing and new boilers. All construction is phased around active plant operations, requiring careful coordination to maintain continuous service.