Hopedale, Massachusetts – Wastewater Treatment
Tata & Howard assisted the Town of Hopedale with the design of upgrades to the existing wastewater treatment facility. The upgrades allowed for compliance with the National Pollutant Discharge Elimination Systems Permit (NPDES).
In September of 2005, the Town of Hopedale received an administrative consent order (ACO) for a violation of the NPDES permit. The permit violation was caused by high levels of ammonia nitrogen, and copper in the Hopedale Wastewater Treatment Facility’s effluent. Tata & Howard prepared an Ammonia-Nitrogen Optimization Report in January of 2006 and a Copper Optimization Report in December of 2006. These reports presented recommendations for upgrades to the facility based on its findings.
The recommended upgrades to the facility were designed and constructed over the course of three projects. The first project took place in December of 2007 and included the construction of a fully automated soda ash dry feed system.
The second project consisted of upgrades to the existing grit collection system and aeration system. A new grit washer was installed allowing a greater percentage of fine organics to remain within the system while dewatering the grit removed from the headworks process. The resulting grit has less water resulting in a more manageable end product and a reduction in waste costs. The upgrades to the aeration system included installing a fixed media IFAS (Integrated Fixed-Film Activated Sludge) system within the existing aeration basins. The IFAS system allows for greater ammonia-nitrogen removal by increasing the surface area for microbiological growth without the need to install additional basins. The facility was able to maintain this growth for the duration of the winter, a feat not previously achieved at the plant. In addition to the installation of the IFAS system, the existing aeration system was replaced providing new high-effeciency blowers with full automation. The blower speed is now automatically increased or decreased based on D.O. reading from the aeration basin allowing for more efficient operation and energy use.
The third project consisted of installing a new chemical feed system and tertiary filter. The new chemical feed system doses Polyaluminum Chloride (PACL) based on the influent flow into the plant. The PACL acts as a coagulant improving the settlability in the secondary clarifiers, increasing the copper removal while also aiding in phosphorus removal. The stainless steel disk filters remove the coagulated copper resulting is a high quality effluent.
In addition to upgrades at the WWTF, Tata & Howard has worked with the Town of Hopedale to remove sources of Infiltration and Inflow (I/I). By reducing I/I from the sewer collection system, the strain on the WWTF is significantly reduced during rain events.