During a routine bridge inspection, it was discovered that the 6-span, 5
Howard Concrete Pumping was contracted to perform the first phase in mine stabilization by drilling and grouting beneath pier 3 under an emergency contract let by the Illinois Department of Natural Resources (IDNR). We drilled 60 grout injection boreholes beneath and adjacent to pier 3, and 2,839 cubic yards of grout were injected through the boreholes into the mine below. Survey of the structure indicated that movement of pier 3 had ceased upon placement of the grout.
Soon after completion of Phase I, we were again contracted for Phase II, which involved stabilization of the abandoned mine below piers 4 and 5. We drilled 48 grout injection boreholes, and 4,463 cubic yards of grout were injected through the boreholes into the mine below. As with pier 3, movement of piers 4 and 5 ceased upon placement of the grout.
We overcame numerous challenges during the project to save the bridge,