Big Hollow Manhole Seepage RFP Closed Nov 2026

Des Moines County Conservation Issues Bid Request for Big Hollow Manhole Repairs

Des Moines County Conservation (DMCC) has officially closed its solicitation period for a critical infrastructure project aimed at addressing ongoing water seepage issues at the Big Hollow Recreation Area. The agency set a firm deadline of 3:00 p.m. on November 3, 2026, for contractors to submit proposals for the remediation of specific manholes that have been compromised by groundwater infiltration.

The project, which requires specialized technical intervention, targets the integrity of the manhole structures currently serving the recreation area. According to the project scope, the successful bidder will be tasked with sealing the annular space between the concrete manhole walls and the PVC risers.

Install Reinforced Concrete Collars to Counteract Buoyant Forces

The technical demands of this project extend beyond basic sealing. DMCC requires the installation of reinforced concrete collars on the exterior of the affected manholes. These collars are engineered to counteract buoyant forces—the physical tendency of a structure to “float” or shift when surrounded by saturated soil—which can lead to misalignment and further structural failure if left unaddressed. Detailed engineering schematics were provided to interested contractors via Attachment A.

Because this work involves entry into a sewer environment, the project carries inherent occupational hazards. Contractors are strictly required to adhere to all confined-space entry protocols, including the acquisition of necessary permits and the implementation of rigorous safety measures. The project scope also mandates that, following the completion of the structural repairs, the site must be excavated, backfilled, and restored to its original condition.

Complete Project Within the 2026 Construction Season

DMCC has expressed a preference for the project to be completed within the 2026 construction season, provided that Iowa’s notoriously variable late-autumn weather remains cooperative. However, the agency has established a final completion deadline of April 1, 2027, for the project to be fully realized.

DMCC retains the right to reject all bids if the submitted proposals fail to meet the agency’s budgetary expectations or technical requirements. For now, the county moves into the evaluation phase, with the physical restoration of the Big Hollow infrastructure resting on the ability of the chosen contractor to meet these stringent engineering standards before the April deadline.

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