Easterly Aeration Tanks
Northeast Ohio Regional Sewer District | Cleveland , Ohio
Structural services involved performing a visual on-site condition assessment of the Aeration Tanks and the East and West Piping Gallery, as well as limited areas of the Pump Building and Blower Building. The condition survey included observation of concrete columns, beams, slabs, and walls. The deteriorated areas were quantified, and a Basis of Design Report was prepared that included descriptions of the deteriorated areas, as well as repair recommendations and representative photos. A detailed construction documents package was also prepared that showed where the deteriorated structural members occurred, the quantities associated with each repair type. Specific repairs were detailed by tying back to the plans utilizing specially proven repair products valid for wastewater use. Typical repairs included patching concrete delaminations, injecting cracks in concrete, and removing damaged expansion joints.
NEORSD has experienced overheating of the cooling loop that serves the Easterly Aeration Blower motor air cooler and lube oil cooler. The cooling supply water loop consists of a cooling tower to reject the heat in to the atmosphere and to provide 85 degree water to the 2 coils. Easterly personnel have stated that they only operate 1 of the 5 aeration blowers at a time. It appears the cooling system was designed for a single larger horsepower aeration blower in operation.
Drawings obtained from the District Wide HVAC Improvements GES Task Order 25 dated November 2011 with an as-built of June 17, 2013 indicate the removal of the Cooling Tower from the loop and the installation of an air cooled chiller into the system. The loop was converted from an open system to a closed loop system. The system serves two different coils, a coil that cools the lube oil on the blower and a coil that cools the blower air. Each one of the 5 Blower motors has the same coils and control sequence.
The sequence of operation calls for the operation of the cooling loop pumps when an Aeration Blower is activated. When the temperature of the loop increased to an adjustable set point the chiller will activate to reduce the loop temperature.