Illinois 90-Inch Hot Tap along I-90

TDW Services retained GRAEF to provide Resident Engineer and quality control services for the hot tapping of a 30-year-old 90-inch water main owned and operated by the Northwest Suburban Municipal Joint Action Water Agency on behalf of the Illinois Tollway. This project will allow for the widening of I-90 through the western suburbs.

“Hot tapping” involves cutting a coupon from the water main, installing a line plug and diverting the flow to a temporary bypass line under the operating pressure of the line (165 PSI). The final connections to the rerouted section of the water main are then completed without interruption in water service. A massive thrust restraint system consisting of deep foundations (4-foot drilled caissons, 80 feet in length) and a 600-cubic-yard connecting concrete block within a 22-foot deep earth retention system is required to be in place before the hot tapping is initiated.

GRAEF was involved in site safety, construction observation, scheduling, layout verification, coordination with adjacent contracts, and the CCM for the I-90 widening. Duties include daily reports, liaison with the structural design engineer and TDW representatives, coordination with project sub-contractors and addressing the documentation requirements of the Illinois Tollway, including e-builder submittals, processes and CAPTURE documentation.