I-70 Hamilton Gulch Culvert Work

The work consisted of slip-lining a culvert under I-70 that conveyed water from Hamilton Gulch from north to south. The culvert consisted of two different sized pipes connected at a joint 50’ below I-70. The first was 155 LF of 48” CMP placed at 27%. The second pipe was a 60” CMP placed at 2%. At the joint, two 12” underdrains intercepted the 48” culvert. Due to the unknown locations of the underdrains, the condition of the joint and the condition of the pipe, it was unknown how the pipe would be lined.

Prior to being able to enter the pipe, the flows from Hamilton Gulch needed to be diverted. The contract stated that flows ranged from 40-70 CFS. A bypass was installed using two 18” HDPE pipes. The pipes ran approximately 2,500 LF to a drainage inlet west of the project. Additional nuisance water was controlled using submersible pumps.

Once the water was diverted, the crews entered the pipe, cleaned the pipe, and took measurements in order to determine what size pipe could be used. The decision was made to use a 33.65” ID HDPE pipe. The plans and specs also called for the installation of a 12” PVC pipe to convey the flows from the underdrains to the outlet of the pipe. We eliminated the 12” pipe and connected the underdrains to the main liner.

The pipe was lined, the underdrains were connected and the work was completed on time.