Portland weighs new biosolids dewatering building to avoid $7M temporary bypass costs

Portland weighs new biosolids dewatering building to avoid $7M temporary bypass costsThe Portland Water District is re-evaluating the installation phase of a major wastewater treatment upgrade, directing its design-builder to compile estimates for a new dewatering facility to avoid the exorbitant costs and risks of temporary biosolids management.

Contractors quoted $7 million to temporarily process the facility's biosolids for 12 months during construction.

The plant produces approximately one-third of Maine's biosolids, making temporary single-unit bypass systems highly risky.

The board has already approved $22 million for early project phases, including equipment procurement, but has delayed installation to evaluate the new building option.

Any new structure will be designed for compatibility with a forthcoming regional biosolids facility.

The Portland Water District (PWD) is exploring the construction of a new biosolids dewatering building as part of its ongoing wastewater project, pivoting from original plans to install new equipment within an existing facility. The shift in strategy was prompted by the extreme costs and operational complexities of maintaining plant operations (MOPO) during the upgrade. According to the district's General Manager, initial quotes from contractors to handle temporary biosolids processing over a 12-month construction period came in at $7 million. Beyond the financial toll, district staff highlighted severe risk factors. The facility currently produces roughly one-third of the state's biosolids. Temporary dewatering alternatives typically rely on a single processing unit; if that unit were to fail, the district would face an unmanageable volume of sludge. To mitigate this, the project's design-builder is compiling a budgetary cost estimate for a new, dedicated dewatering structure. The proposed building would likely be located near the primary settling tanks, north of the process control building. Constructing a new facility would allow the district to install and commission the new dewatering equipment before decommissioning the old system, entirely avoiding the need for a temporary bypass. While new process buildings carry high capital costs and potential permitting challenges due to tight site constraints, district leadership noted that the $7 million saved on temporary bypasses would offset a significant portion of the construction expense. A new building would also resolve long-standing deferred maintenance issues and provide much-needed spatial clearances for future equipment maintenance. The district has already approved $22 million for the current phase of the wastewater project, which covers a return activated sludge (RAS) splitter box, HVAC upgrades, headworks improvements, and the procurement of the new dewatering equipment itself. However, the actual installation contract has been intentionally delayed while the district finalizes the new building evaluation. Regardless of the final footprint, the General Manager confirmed that the upgraded dewatering process is being designed to be fully compatible with a planned regional biosolids facility, ensuring long-term processing efficiency at the site.