Cecil County, MD
In 1998, Cecil County was issued a new NPDES permit from the Maryland Department of Environment (MDE) for the Northeast River Advanced Wastewater Treatment Plant that required total nitrogen removal to 8 mg/l. In conjunction, a Biological Nutrient Removal (BNR) grant was offered by MDE to help facilitate the project. On the recommendation of George, Miles & Buhr, LLC (GMB), Cecil County and MDE agreed to modify the design to include Enhanced Nutrient Removal (ENR) treatment in anticipation of pending legislation. MDE provided additional grant funding to incorporate the ENR design. The total nitrogen loading to the Northeast River has been reduced by more than 30,000 pounds per year, providing a cost effective technique to improve the water quality in the Chesapeake Bay and its tributaries.
The upgrade includes a four-stage Bardenpho process which was constructed within the existing concrete aeration tanks. The oxidation ditch configuration includes two aeration zones for nitrification and two anoxic zones for denitrification. Internal recycle gates eliminate large recycle pumps which significantly reduce O&M costs. The new facility produces an effluent with a total nitrogen concentration of 3 mg/l or less. Other upgrades include: converting existing rectangular clarifiers to aerobic digestion; two new 75-foot diameter clarifiers and a new sludge pumping station; new sludge processing system (blowers, centrifuges, sludge conveyor, and polymer system); new headworks facility (screening and grit removal); filter renovations; UV disinfection to eliminate the use of chlorine gas; and cascade aeration.
George, Miles & Buhr, LLC (GMB) provided process, civil, architectural and structural design of the WWTP. Gipe Associates provided the electrical and mechanical design. Additional services provided by GMB included coordination of geotechnical investigations; storm water management and erosion & sediment control permitting; and construction phase services (inspection and contract administration).