The chief engineer at one of the buildings at Rockefeller Center in New York City had a problem: they were spending upwards of $21,000 annually for pit cleaning, odor control and enzyme treatment to soften solids of a sewage pit in addition to the cost of maintenance calls and overtime.
Rockefeller Center had a sewage pit at One Rockefeller Plaza with extremely heavy solids built up and laying on top of the water and grease built up on the walls. They were using vertical shaft sewage pumps as a duplex system with actuator style ball floats for level control and no real logic for controls. The pumps constantly failed from clogging and required a lot of attention. The check valves had been replaced several times due to rags caught on the flapper and the gate valves had failed due to wear.
GA Fleet provided a Duplex Flygt Submersible Sewage Pump system using model NP 3127 10 HP submersible pumps, each with a Flygt mix flush valve for suspending solids in the wet well. We provided state-of-the art, while simple to operate, controls with a unique Fleet control methodology for removing surface solids and preventing grease ring build up. All the functionality of a sewage pump station are built into the controller i.e. on, off, lead, lag, high alarm, low alarm and alternation. The levels are completely field-adjustable and there is no longer a need to enter the wet well.
To facilitate installation Fleet provided a unique FPS SubRig pipe and valve assembly. The SubRig is a pre-engineered, modular submersible pump piping system. Fully integrated with the frames and covers, and the electrical connection system, the SubRig facilitates easy, correct installation and uses components of better quality than the industry normally installs for this application. Engineers throughout NYC are now specifying SubRigs on new installations and many experienced plumbing contractors request them as well.
With the retrofit of the wet well the building has achieved a more efficient and far less tasking system than before, as well as saving on the life-cost of the equipment with minimal maintenance.