Wastewater Treatment Plant Outfall and Aeration System Upgrades
The City of Kingston, NY received a renewed State Pollutant Discharge Elimination System (SPDES) permit which included effluent ammonia limits requiring upgrades to the existing Wastewater Treatment Plant (WWTP) to treat wastewater to a higher level of quality. While the City had completed preliminary analysis and engineering reports which indicated extensive and energy-intensive WWTP upgrades were required, the City determined that additional evaluation was necessary and asked Tighe & Bond for a fresh perspective. Tighe & Bond worked with the City to provide an acceptable plan to the New York State Department of Environmental Conservation – Region 3 (NYSDEC) which outlined the proposed steps forward to achieve SPDES permit compliance.
Tighe & Bond collaborated closely with NYSDEC to determine how mixing and dilution impacted the WWTP effluent in the Rondout Creek (Rondout). Through detailed analysis and effective communication, the Tighe & Bond team was able to negotiate increased permit limits through improvements to the WWTP outfall and upgrades to the existing aeration system.
With the project approach accepted by NYSDEC, Tighe & Bond began the design of the modifications to the WWTP outfall and aeration system upgrades. The outfall modifications included extending and lowering the outfall piping into the Rondout to achieve a depth above the invert of 20 feet at mean low water (MLW), driven piles to support the outfall piping, a steel frame, and wood fender protection system for the outfall piping exposed to potential ice and impact at the water line, a marine mattress system to protect the outfall piping below the water line, a corrosion protection system, and installation of a steel bulkhead to reinforce the existing timber bulkhead at the shoreline.
Due to the location and potential environmental impacts, substantial coordination with permitting agencies was required for the outfall modifications. Tighe & Bond began early communication and collaboration with the US Army Corp of Engineers (Nationwide Permit 7), NYSDEC (Article 15.5 Water Quality Certification), NYSDOS (Coastal Zone Management Area Certification), and NYSOGS (Lands Underwater Easement for Utilities).
The upgrades to the WWTP aeration system included modifications to the existing aeration tanks for the Ludzack-Ettinger (LE) process for nitrification, diffuser replacement, blower replacement, new ventilation system for blowers, SCADA system expansion for improved automation and efficiencies, and safety and structural improvements at the aeration tanks. The modifications to the aeration tanks include the installation of a baffle wall and mixer to create a swing zone (anoxic or aerobic) to allow operational flexibility during the summer/winter nitrification seasons and the replacement of the influent gates to allow for step-feed operation during increased wet weather flows.
Tighe & Bond’s engineers provided design, permitting, and construction observation services for this project. The upgrades to the WWTP will result in lowered levels of ammonia in effluent, ensuring good quality of water in the area surrounding the outfall in Rondout Creek.