Project Overview
Hoyle Tanner is providing environmental engineering design and construction services for the Brighton Wastewater Treatment Facility (WWTF) upgrade. The Brighton WWTF operates a small lagoon system with screening, treatment lagoons, and disinfection. The facility was commissioned in 1976 and is permitted to discharge 150,000 gallons of treated effluent to the Pherrins River. A key component of the comprehensive plant upgrade is the removal of accumulated lagoon sludge that has built up over decades of operation. Sludge removal is critical to restoring lagoon treatment capacity and ensuring water quality permit compliance for discharges to the Pherrins River.
Technical Specifications
The plant has two aerated lagoons. Lagoon #1 is 1.3 acres in size and has a capacity of 3.0 million gallons (MG). Lagoon #2 is 0.9 acres in size and has a capacity of 2.2 MG. Both lagoons operate at a liquid depth of 10 feet. The depth of dense accumulated sludge in both lagoons varies from 1 to 4 feet, or approximately 1.5 MG of sludge. Reduced capacity from sludge accumulation can lead to challenges in maintaining consistent water quality, including higher levels of suspended solids, organic material, and bacteria.
The chosen method for sludge removal was by hydraulic dredging. The sludge removed from each lagoon was screened, pumped into a holding tank, treated with a polymer to aid thickening, and then dewatered using a centrifuge. Over several weeks, 940 tons of the dewatered sludge, or “cake” was trucked to a landfill for disposal.
Sludge Removal Challenges
Sludge removal activities often present significant logistical challenges due to constraints such as project budget, limited site laydown area, maintaining permit during removal, disposal options, and complex construction sequencing. Accurately estimating sludge quantities for bidding purposes can be particularly difficult and Hoyle Tanner successfully estimated the sludge quantities for bidding to within approximately 90% of the actual amount removed.
The Brighton WWTF site posed unique challenges due to its extremely limited space. Sludge removal operations required large laydown areas, directly overlapping with locations designated for other critical project components, necessitating careful coordination and sequencing throughout the construction process. Close coordination with treatment plant operators and the general contractor was instrumental in maintaining effluent quality compliance during the sludge removal process and ensuring that the project remained on schedule.
Serving Communities with Wastewater Challenges
We collaborate with you to arrive at the best possible solution given your project challenges and budget. We offer a full range of wastewater collection, conveyance, and treatment expertise to fortify your wastewater infrastructure for future generations. Contact me if there’s a WWTF in your community that needs attention!
