The first stop raw wastewater makes at the plant is the Raw Station. This station is comprised of a thirty-six foot deep wet well, three ABS and one Myers 15 HP submersible pumps, and the pump control station. Seen in the pictures here is the discharge piping from the submersible pumps and the manifold which carries the pumped wastewater to its next destination. In the picture to the right, the pump control station can be seen in the back.
From the raw station, the wastewater moves to the first step in the treatment process. Here in the headworks, the raw water is first screened to remove large items such as rags, sticks, and other bigger pieces. Shown in the first shot below is the screen mounted in front of the main bar screen bypass. We installed this due to the limitations of the mechanical bar screen that was installed when the plant was built. The mechanical screen is shown in the two pictures below the bypass screen shot. It does an excellent job except when flows are high. The mechanism travels too slowly to keep its screen clear under high flows, and spills at the headworks were becoming more common. Hence, the bypass, which we installed in 2002.
Seen below is a shot of the headworks from the far right of the installation. You can see it is a two-channel design, with the channel on the left being continually aerated. This installation does three things for the plant -- first, the flows in here are slow enough to allow sand and other grit to settle to the bottom, second, the aeration adds dissolved oxygen to the wastewater, which helps the activated sludge process do its job, and third, the design of this installation forces congealed grease and other floating scum up and to the right, where it collects for later removal and disposal. The mechanical bar screen can be seen in the rear left of this shot.
Below is the traveling bridge. This is designed to move back and forth along the channels shown above and serves a dual purpose. On the right, you can see a vertical boom, which carries a submersible pump along the floor of the headworks. This pump removes settled sand and grit, moving it to a degritter. On the left is a sweeper arm, which is carried along the right-hand channel and moves floating grease and scum to a collection pit (seen in the upper right of the picture above).
The left-hand picture below is the plant's degritter. Its job is to take the water pumped from the traveling bridge and remove the grit from it. Grit settles to the bottom of the hopper and is removed up and to the left by a screw, where it is discharged into a dumpster for later landfill disposal. On the right you can see the plant's grease screen. The collection pit is pumped out on a regular basis by a float-controlled pump to this screen. This is not a good shot of the installation, but the surface of the screen is covered with a myriad of thin slots which allow water to pass through but not grease particles. The grease particles fall off the screen into a large bag underneath, and are taken to a landfill once the bag is full enough.
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