City staff reports collapsed manhole, council approves manhole rehab and schedules system inspections

City of Imperial Public Services staff told the council that a sidewall in an existing manhole collapsed when crews attempted to connect to it during work on Aden Boulevard. The council approved a capital improvement project to rehabilitate multiple manholes and asked staff to proceed with broader inspections and planning.

Public Services Director David Dale said the collapsed structure was located at Shiloh and Ayton Boulevard and that a six-inch force main had been connected in an inappropriate manner, causing sewer flow to erode the manhole sidewall over time. Dale described manholes in parts of the city as being up to a century old, originally constructed of brick and mortar; repairs include trenchless lining techniques that use a form and cast-in-place concrete liner.

Dale said staff are preparing an RFP for a task-order contract to perform a camera inspection of all roughly 1,700 manholes in the collection system; the inspection would use a specialty camera and an AI program to score each structure on a 1-to-5 scale to prioritize repairs. He said staff plan to delay the full inspection work until cooler weather (October) and then follow with development of a wastewater collection system master plan.

Council members and staff discussed replacing severely damaged manholes when doing paving projects to avoid repeated openings and to limit future pavement failures. The council voted 5-0 to approve the manhole rehabilitation project and directed staff to bring inspection results and the master-plan timeline to a future council meeting.

Staff said the manhole issues were discovered while connecting to an existing structure and that addressing the repairs proactively should help prevent catastrophic failures that could affect service and public health.