Chillers 1,2,3,4,5 & South Cooling Tower

  • Chillers 1,2,3,4,5 & South Cooling Tower
  • Chillers 1,2,3,4,5 & South Cooling Tower


Client:  Chicago Department of Aviation

Location: Chicago, IL


The Heating and Refrigeration (H&R) Building at O’Hare is responsible for heating and cooling all of the airport terminals and buildings. There were nine chillers in the previous H&R Building that had been in service since the 1960s. This project increased the energy efficiency of the cooling system by installing energy-efficient chillers with increased capacity, as well as installing new control panels and modulating valves to further improve chiller operation. The project also upgraded both the chilled water and condensed water circulation pumps, and it expanded the system’s cooling tower with more efficient equipment.

The electrical upgrades included replacing five of the legacy chillers with four new chillers designed to be driven by four new medium voltage variable frequency drives (MV-VFDs). An additional 10 new MV-VFDs were installed to control ten new chilled water pumps, replacing constant-speed starters on the existing pumps. Four new condenser water pumps with MV-VFDs were also installed to control pumping capacity. New low-voltage power sources were installed for the new chiller control panels, as were new control valves at all eight chillers in the upgraded system.

To accommodate the new chiller capacity, the South Cooling Tower needed to be expanded. This was accomplished by activating two unused bays with new fans with two new low voltage variable frequency drives, new tower controls, and well as increasing the size of the motors on four existing fans. Due to the critical nature of the cooling systems, design intentionally split the loads for similar systems onto different utility sources. Separating the electrical loads ensures that in the event of a failure of one source, there will still be operational chilling, condensing, pumping, and chilled water pumps as well as cooling towers.

Due to the space requirements to extend and reconfigure the necessary runways, the Chicago Department of Aviation needed to demolish the existing FedEx cargo and maintenance buildings and build new facilities on an empty field just outside of the airside fence. The O’Hare Modernization Program Construction Management team was placed in charge of the operation for full oversight of demolition, and the new facility construction from start to finish. There were four buildings in total including the Vehicle Maintenance Building, Airplane Maintenance Building, FedEx Administration Building, and The World Sort Center.

Services Provided

Our team provided a Contract Administrator and Resident Engineer for this project—providing managerial and clerical services to implement and enforce all applicable codes, standards, specifications, policies, and procedures. With a full understanding of the project scope, plans, and specifications, our team coordinated between the direct project assignment and other active Program assignments.

[Preparing for the bidding process and contract awards, verified quantities from the project teams were accepted and pay estimates were prepared. Pre-bid meetings were held prior to each subcontract package being solicited, and Requests for Information were received and answered.

As contracts were awarded, all required paperwork was collected and reviewed. Paperwork at the start of construction, as well as at monthly payment intervals, included pay estimate submittals, sworn statements, subcontractor payment certification, M/W/DBE status reports, certified payrolls, canvass reports, partial waivers of liens, etc. Contracts, maintained in the CDA


Computer Database (Prolog Converge), were set up by our team and administered throughout the project, including the Contract Document review for Method of Measurement and Basis of Payment sections.

During construction, the following reports and documentation were prepared and submitted for approval: Resident Engineers’ Field Orders, Proposed Contract Modifications (PCM), Request for Contract Modifications (RCM), Line Item Changes (LIC) Inspectors’ Daily Reports (IDR), Daily Construction Reports (DCR—including non-conformance reports (NCRs) or Quality Deficiency Reports (QDRs)), and Field Orders for Time & Material work. The approvals of all the listed reports, as applicable, were tracked and secured.

Based on updates received during weekly project meetings (including DOA Construction Working Operations Group meetings: CWOG, and Short Term Operations and Phasing: STOP), the resource-loaded, Primavera-based CPM Schedule would be updated and analyzed regularly, comparing contractors’ actual work completed against anticipated milestones and the program master schedule. Continued compliance with sustainable requirements, soil erosion and conservation requirements, safety protocols (including FAA Part 139), the CM Quality Assurance Plan, and other contractual obligations was assured by Construction Inspectors. The ongoing development of as-built documents throughout the project was monitored by our team, as well.

With regard to subcontractor/supplier coordination and invoice/monthly payment request processing, Contractors’ invoices were reviewed for alignment with quantity measurements of units of work completed and compliance with Contract Documents. Any outstanding Requests for Information (RFI), Submittals (processed in hard copy with the FAA and EOR), Requests for Inspection of Materials (RFIM), and mechanics liens were tracked and processed, as well. This information, as well as audit of M/W/DBE utilization/certified payrolls and certificates of insurance, was compiled into the monthly contract close-out as well as the final project close-out documentation. Updates from the Pay Estimates were integrated with the project budgets in order to ensure that actual expenditures tracked with anticipated spending.]