Engineering Evaluation at Back River and Patapsco Wastewater Treatment Plants

The City of Baltimore (City) retained Greeley and Hansen to perform an independent review of the current wastewater treatment operations, review the ongoing engineering evaluations, and review the current/future capital improvement projects. The City operates the Back River Wastewater Treatment Plan with an average daily flow of 180 MGD and Patapsco Wastewater Treatment Plan with an average daily flow of 73 MGD. The purpose of this evaluation was to provide Third-Party Certified Engineering Evaluation and Report to Maryland Department of the Environment (MDE) on how the City will achieve and maintain National Pollutant Discharge Elimination System National Pollutant Discharge Elimination System (NPDES) permit compliance in the near and long-term. 

The project team performed a review of the wastewater treatment plants’ operations and facilities, engineering evaluations by other consultants, and the current capital improvement plan. The project included facilities evaluation of the units process for Headworks, Primary Clarifiers, Activated Sludge Tanks, Secondary Clarifiers, Gravity Sludge Thickeners (GSTs), Dissolved Air Floatation Thickener, Gravity Belt Thickeners, Acid Phase and Mesophilic Anaerobic Digestion, and Centrifuge Dewatering. This evaluation identified key challenges with equipment operation, maintenance, and reliability as well as organizational staffing vacancies. Greeley and Hansen developed recommendations to improve operations and process performance to reliably meet effluent permit requirements. Organizational changes for staffing and management were also recommended to reduce issues with staff retention, vacancies, and maintenance of institutional knowledge. These recommendations were prioritized based on the ability to achieve and maintain permit compliance, and the projects were categorized based upon realistic completion timeframes. 

Project Highlights 

• Performed engineering analysis of both Back River and Patapsco WWTP unit processes. 
• Utilized a purpose-drive approach to achieve permit compliance. 
• Provided stakeholder management of consulting engineers, operations staff, regulatory staff, and City staff. 
• Understanding of facility-wide planning needs and prioritization of the CIP improvements required. 
• Identified alternative approaches for biosolids processing.