Tri-Lakes Wastewater Treatment Facility
Monument Sanitation District, Palmer Lake Sanitation District, and Woodmoor Water & Sanitation District No. 1, jointly known as the Tri-Lakes Joint-Use Authority, own and operate the wastewater treatment plant.
The expansion of the original plant built in 1977, an aerated-lagoon system of three basins in series, increased basin capacities from 0.8 mgd to 1.5 mgd, for a total plant capacity of 4.6 million gallons per day. The chosen process technology involved an innovative variation of the activated sludge process-single-basin biological nitrogen removal.
The new facility reused existing facilities to the greatest extent possible which encompassed regrading and converting one existing lagoon to two earthen aeration basins. The existing aeration system was replaced with new blowers and flexible tube diffusers, allowing for additional BOD removal and ammonia control. Automated valves allowed for control of DO concentrations at various locations in the basins to provide anoxic zones for denitrification. A second lagoon was retrofitted for biosolids digestion, storage, and decant. The third lagoon was cleaned and abandoned. The chlorination and dechlorination facilities were converted to UV disinfection. New facilities added to the plant included two secondary clarifiers, RAS/WAS pumping, mechanical bar screening and grit removal facilities, an operations building, and a PLC-based control system.