Horner & Shifrin assisted Pollution Management, Inc. in the design of a Sequencing Batch Reactor (SBR) wastewater treatment facility with a 1.27 MGD average flow and 6.2 MGD peak flow for the City of Blytheville. The project consolidated two of the City’s treatment facilities and converted them to equalization basins. The new SBR facility includes a influent flow meter and automated diversion valve vault, spiral screen, vortex grit chamber and classifier, sequencing batch reactor with jet aeration, UV disinfection, post-aeration, and flow monitoring. An operations and controls building will house all process and electrical controls in addition to daily laboratory testing capabilities. PMI designed 3 miles of 16” PVC forcemain to convey the wastewater from the converted West Plant Equalization Basin and associated pump stations. The West Plant EQ includes a new quadruplex aboveground suction lift pump station with two average flow duty pumps (550 gpm) and two peak flow pumps (2500 gpm). A new duplex above ground suction lift pump station (2500 gpm) to handle diverted peak flows will be installed at the converted South Plant EQ.
Project challenges consisted of the required ground improvements related to settlement and potential seismic activity in the area and peak flows received by the facility. All potential types of ground improvements were analyzed and preloading the site was determined to be the most cost effective solution. Preloading includes installation of wick drains, a drainage layer, and placing fill to a specified depth over the project site to develop bearing capacity and calculated settlement. Peak flows are handled with automated valves and mag meters in the influent flow vault. Converting the existing earthen extended air treatment basins to equalization basins allows for sufficient storage to buffer large rain events. Excess flow will be stored at the converted South Plant EQ until peak flows have decreased below peak design flow.