Town of Strasburg Wastewater Treatment Plant

The need to achieve nutrient reduction requirements, accommodate higher flows, and meet EPA pollution reduction goals for the Chesapeake Bay watershed provided a sense of urgency to expanding and upgrading the Town of Strasburg’s wastewater treatment plant.

This project brought together a variety of engineering trades and disciplines in possibly one of the most unique applications the project team ever experienced. It entailed a combination of architecture, electrical/energy/mechanical/structural/process engineering, design-build, grant assistance, GIS and more. These disciplines came together cohesively. To add complication, the design included multiple new buildings, stairs, handrails, grating platforms/walkways, structural steel framing and access hatches.

A fast-tracked design from Preliminary Engineering Report to Certificate to Construct was completed in a mere eight months. The project came in under budget with $12M in net estimated savings compared to the original abandoned project, and achieved goals of increased capacity while meeting strict regulatory standards.

ORIGINAL or innovative application of new or existing techniques

A progressive design-build model provided transparent and inclusive planning process integrating all stakeholders. At project start, the team evaluated alternative treatment processes focusing on the nutrient removal process, a core treatment. The equipment and main process were modeled after several successful cold-weather nutrient removal Midwest facilities. Leveraging technology made this Virginia plant the first of its kind.

Future value to the engineering profession and perception by the public

This progressive design-build project approach represents the power of transparent partnership honoring both taxpayers and community need. Progressive design-build incorporated public engagement and owner involvement throughout the project.

Social, Economic and sustainable development considerations

The team’s proposal featured economic, energy and operational efficiencies as key elements to overall design. Energy consumption was reduced by 60% as compared to the original MBR process, thus reducing annual operating costs that rate payers would have shouldered.

Complexity

Originally operating a plant with a 0.975MGD design flow, Strasburg needed to expand and upgrade the facility to a 2.0MGD, state-of-the-art facility while meeting Department of Environmental Quality nutrient reduction requirements and accommodating higher flows for a 20-year design life.

The effluent nutrient targets are now quite stringent. Effluent total phosphorus is set at 0.3 mg/l, and effluent total nitrogen is set at 3.0 mg/l. High peak flows also complicated design. The maximum 30-day flow rate is 2.0MG. Peak 24 hour flow is 6.46MGD, and peak hourly flow is 9.66MGD. Production of a class A sludge was another design goal. The plant was designed with indexed reactor volumes in isolation to facilitate life cycling loading over the planned 20-year life.

Exceeding Client/owner needs

The $22M budget for new design provided an estimated $12M in savings from the original abandoned project. During design, the team worked closely with the owner to secure $5.6M in grant funding.

Strasburg’s goals were met and the team replaced an outdated Department of Public Works complex with a new $5M facility. Using an adjacent portion of the existing facility site in the plant expansion resulted in innovative design savings more than paying for the cost of the new facility.