OK, I think I have figured this out. The plate I saw was being used to prevent a vortex from forming at the water surface near the pump inteake. It was thin sheet steel with holes installed at an angle and attached to the side divider walls.
You could use that, or just toss some pallets in the well (and hope they float/stay in one piece!)
One of the pump mechanics I've worked with told me a story about that. The well was poorly designed so that when draining the brine pits, they could not be completely drained (only 14" submergence at zero pit level!) So the operators took wooden shipping pallets and tossed them in the pit to act as baffles.
I suppose it worked but pump reliability wasn't exactly a concern in those days!
I'm not "using" anything. I inspected a large pump station last week and was just curious as to the exact function of these plates. See attached section of the wet well. The plans actually call it a "wall" but it is really just 1/2" steel plate with stiffeners and drain holes.
OK, here's my best bluff. You must know that these installations arn't my speciality and this is an inside straight that I'm drawing for here...
Since its behind a trash rack, it looks like ... while allowing some water to flow though to the region above the pump intake, the bulk of the water is forced to enter the intake region from below the plate. The head differential across the plate would tend to maintain a surface "turnover" replenishing flow behind the plate, rather than allow water to "stagnate" against the riser. Why is that important? Well... that might keep surface water turnover going fast enough to thereby not allow large quantities of surface junk to collect near the riser before finally being sucked down into the inlet in one big pump-clogging-shutdown quantity. You know... it's like a lot of little pills taken at a well regulated pace go down easier then one big horse-choker pill.
"The top of the organisation doesn't listen sufficiently to what the bottom is saying." Tony Hayward X-CEO BP
"Being GREEN isn't easy." Kermit
well, I'm not sure about the trash theory but that may be part of it. I'm thinking this pump can handle just about any amount of paper cups and plastic bottles you could throw at it, one at a time or all at once. The bigger trash won't make it through the bar screen. Trash is definitely a concern because this is a storm water pump.
It would prevent any vortexing from occuring above the pump inlet. The plan also shows significant other features designed to prevent vortexing or stagnation in the corners, along the bottom of the walls and below the pump intake.
You know, this whole thing looks like a poor well design for the presently installed equipment. Was it an attempt to make an old installation work for a larger pump than originally intended, or are we just looking at a bungleup from the start.
"The top of the organisation doesn't listen sufficiently to what the bottom is saying." Tony Hayward X-CEO BP
"Being GREEN isn't easy." Kermit
relatively new pump station and from all accounts it works well with one or two pumps running. Has never run with more than two. However difficult to really test because of lack of adequate supply of test water. Total pump rate is over 130,000 gpm
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