Location: West Jefferson, NC Overview: This project involved the rehabilitation of a deteriorated corrugated metal storm drain following the development of a sinkhole. To restore system integrity and address subsurface instability, a new carrier pipe was installed, and the annular space was stabilized using a Low-Density Cellular Concrete. Challenge: The existing 60-inch corrugated metal pipe had experienced significant deterioration, resulting in a sinkhole and loss of surrounding soil support. The annular space between the new 42-inch carrier pipe and the host pipe required a material capable of flowing long distances, filling irregular voids, and stabilizing the surrounding soils without imposing excessive loads on the compromised infrastructure. Solution: RyanGeo placed 150 cubic yards of 33 pcf Low- Density Cellular Concrete (LDCC) into the annular space along 400 linear feet of stormwater pipe. The high flowability of LDCC allowed it to fully encapsulate the 42-inch carrier pipe, fill voids created by the sinkhole, and stabilize the failing host pipe while minimizing additional structural loading. Results: • Total Length Grouted: 400 linear feet • Pipe Configuration: 42-inch carrier pipe inside 60-inch CMP • Material Placed: 150 cubic yards of 33 pcf LDCC