Phosphorous Reduction & Cost-Effective Improvements
The Town of Plainville’s water pollution control facility (WPCF) needed to comply with the State of Connecticut’s new stringent phosphorous limits. Without this, the town would lose significant Clean Water Grant Funding, as well as be subject to fines.
In anticipation of these new limits, Tighe & Bond completed a Phosphorus Removal Plan for Plainville’s 2.6 MGD water pollution control facility. The plan recommended cost-effective improvements to the existing processes and new technologies that needed to be added to the plant to achieve low-level phosphorus limits.
Recommendations included multi-point chemical addition and process modifications to optimize the sequencing batch reactors (SBRs) for biological phosphorus removal and modifying the destination of the plant’s recycle flows to preserve the capacity of the existing SBRs. A key factor in the analysis was to avoid negatively impacting the plant’s nitrogen removal performance. Another key recommendation was to include a flow equalization (tank and pump station) after the SBRs to reduce peak flows through the proposed low-level phosphorus removal system and ultraviolet light disinfection system. This also allows the new process equipment, and the relocated UV system, to meet the new resiliency requirements being adopted by regulators.
For the installation of new low-level phosphorus technologies, we evaluated three technologies (disc filtration, ballasted flocculation, and deep bed sand filters) in terms of non-economic factors, and based on a life-cycle cost analysis, before recommending disc filtration.
Our team designed the recommended improvements. The project was eligible for Clean Water Funding under the Connecticut State Revolving Fund, and we prepared the funding application on behalf of the town. This project was successfully completed and started up four months ahead of schedule and significantly under budget.
Besides comprehensive planning and design, our services included cost analysis, permitting, funding application assistance, and construction services. The project team was honored with an Engineering Excellence Award in 2021 from ACEC/CT.