NPL Completes Construction in Support of Airport Expansion
After several months of planning, preparation, and unanticipated delays, NPL Great Lakes began construction of a new sewer line designed to support expansion of the Gary/Chicago International Airport in Gary, Indiana. The sewer expansion project is the first phase of a $24 million infrastructure investment to expand the airport’s cargo logistics sector. Although most of the pipe installed on this project lies below ground, the impact on the future growth potential of the airport runs far deeper.
The NPL Great Lakes crew was responsible for ensuring the pipe was installed safely and within specifications. This project was also a unique public-private partnership, as it was designed and managed by the U.S. Army Corps of Engineers, marking the first time NPL was part of such a project. With the support of General Superintendent Adam Wilinski the crew successfully installed nearly 2,000’ of sewer pipe at depths of up to 20’. The installation of the sewer system began in October and was completed in March.
The complexity of this project goes far beyond the installation of the sewer pipe. Due to high groundwater levels, excavation depths beyond 3’ required utilization of a dewatering system; at times, over 1,000’ of ditch had to be continuously dewatered. This 24-hour-a-day dewatering system required nearly 900 wellpoints throughout the duration of the project, which had to be installed at depths near 25’ to ensure that no water was present in the trench. Over 8,000 tons of sandy spoil was excavated, hauled off, and replaced with compactible stone throughout the trenching and backfilling process.
After approximately every 300’ of pipe install, the project required 12 concrete sewer structures be put in place, some at depths of over 20’ deep. All the pipe and structures are responsible for carrying the flow to the 22’ tall grinder pump station. Final piping and electrical connections were field-installed to ensure proper alignment and operation of the system.
The scope of excavation on this project required some of NPL’s largest equipment; the large class excavators were necessary to safely install the large trench boxes to ensure the protection of the crew. At times, a total of 10 large trench boxes were required on the job. Prior to the removal of the trench boxes, each stone backfill layer was required to be compacted and tested in 6” lifts.
Despite these challenge, the team delivered another monumental project safely and reliably literally paving the way for growth and expansion.
