Marine Manhole Rehabilitation Is Out Of Sight For The Heart Of The Valley Metropolitan Sewage District

The Heart of the Valley Metropolitan Sewerage District (HOVMSD) initiated a rehabilitation project for its eighteen (18) marine manholes located within the Fox River of NE Wisconsin. As work progressed on the first manhole, it became clear that each manhole was going to have to be re-evaluated individually. Contractors constructed a coffer dame around the manhole and dewatered the interior to the level of the river bottom. Upon doing so, sand bags and piles of concrete came into view. Upon closer view, the 24″ thick protective concrete collar surrounding the manhole barrel section had no visible means of structural support. In various locations around the base of the 24″ protective concrete collar, the exterior of the manhole barrel section was visible. An aggressive schedule to create a solution and implement corrective action was put into place to prevent collapse of the marine manholes