The town of Clearford, Alabama, is seeking proposals for a new wastewater treatment plant (WWTP) to meet increasingly stringent water quality limits that are anticipated when the next Alabama Department Environmental Management permits is received in three years. The wastewater flow from Clearford, population 180,000, is primarily domestic and commercial with limited industrial contributors. The current daily average wastewater flow rate is 100 gpcd. There is also a recently rehabilitated separate sanity sewer collection system that has little or no flow. Proposals are hereby requested from area engineers to meet the following anticipated new permit requirements and serve the town of Clearford for the next 20 years. 2021-2022 Permit Requirements Anticipated for Clearford WWTP Parameter 5-day BOD (mg/L) Total Suspended Solids (mg/L) % Volatile Suspended Solids (mg/L) Phosphorus, Total (mg/L) Ammonia (mg/L) Dissolved Oxygen (mg/L) pH Alkalinity (mg/L as CaCO3) Coliform (#/100 mL Geom. Mean) Temperature (deg. C) Current Influent Characteristics 230 200 80 9 23 n/a 7.2 100 n/a 25 summer: 17 winter Effluent Limits (average monthly) 10 30 n/a 2 2 6.0 6.0-9.0 n/a 200 n/a II. Conceptual Design You are required to prepare a conceptual design to meet the needs of Clearford. A conceptual design should include an estimate of the flow to be treated, the water quality of the wastewater, specification of the unit processes to be included in the treatment system, the size of the treatment units (i.e., dimensions, flow capacities, etc.), chemical dose, sludge production, and an estimate of the water quality that would result from the system. III. Treatment Processes You shall use standard published loading rates and design parameters in determining your treatment scheme. The conceptual design should use the process highlighted below: a. Preliminary/primary processes Sedimentation b. Secondary processes Activated sludge treatment Secondary settling c. Tertiary processes Tertiary treatments to meet the permit requirements, if required, are left to your discretion for selection and incorporation.