Challenge
The old Withlacoochee River Water Pollution Control Plant (WPCP) experienced extensive flooding, causing damage to the facility, permit violations, and spills into the Withlacoochee River. In response to a Georgia Environmental Protection Division consent order resulting from the flooding, the City of Valdosta sought a design-builder to fast-track a new greenfield plant to meet stringent effluent limits (4 mg/L biochemical oxygen demand, 5 mg/L total suspended solids, 0.5 mg/L ammonia, and 1 mg/L phosphorus) and produce Class B biosolids.
Approach
Using a one-step, performance-based fixed-price design-build procurement, the City of Valdosta selected Parsons and construction subcontractor Reynolds Construction to design and build the new 12 mgd Withlacoochee River Water Pollution Control Plant. The procurement documents specified a qualifications-based proposal together with a technical and a cost proposal, as well as phone interviews for any technical clarifications. The rigorous scoring system defined in the RFP placed significant value on the technical approach to be used to meet the regulatory-driven completion date, as well as ensuring that the City received the best value for its money for the $24 million project.
Parsons chose the sequencing batch reactor (SBR) biological nutrient-removal technology with rotating cloth filters and aerobic digestion to comply with stringent permit limits and Class B biosolids requirements.
Results
Parsons completed the project using the following project-specific design approaches:
• Worked closely with Aqua-Aerobic Systems to arrange for all process equipment to be delivered to the site within four months of the notice to proceed to eliminate potential equipment delays and accelerate start-up activities
• Used prestressed concrete tanks for the SBR and aerobic digester to significantly reduce tank construction time
• Employed a gravity-flow design approach to reduce structural requirements and eliminate capital and operating costs associated with pumping facilities
Parsons achieved more than $1 million in cost savings by reusing equipment from the existing WPCP, including:
• Influent fine screens and controls
• Positive-displacement blowers for the aerobic digester
• Two-meter belt filter press
• Dewatered cake screw conveyors
“Parsons has exceeded our expectations so far on the new Withlacoochee River WPCP design-build project. They are ahead of schedule and always looking for a way to save the City of Valdosta additional money on this project. They provide a unique perspective in their design, focusing on ease of operations and maintenance for the end user. As a utility director, it is extremely refreshing to see this approach used in the design and construction of a new facility as well as other capital improvements they have performed at our facilities.”
—Henry Hicks, Director of Utilities, City of Valdosta
