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| | | Forum Newbie
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Last Login: 5/14/2007 8:21:22 AM
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| | We are looking to construct a 6 to 10 mgd flow equalization basin in order to handle wet weather flows at our plant. We are wanting any information on performance, pros & cons of a flow equalization, issues such as odor, aeration, concrete lined or earthen, etc. |
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| | | Supreme Being
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Last Login: 6/22/2008 3:46:07 PM
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| | Equalization basins do what they claim, however they could produce odors, and increase the strength of your sewage depending on detention time. It really depends on your flows vs strength (BOD) to what kind of problems you'll have. For example, aeration can be a good thing at some eq basins, but release odors at others. If you have a real low flow the sewage in the eq basin can get septic, depending on how it was designed. It boils down to knowing your existing and future flows and strength, and design based on this information. |
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| | | Supreme Being
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Last Login: 6/26/2008 9:18:16 PM
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| EQ basins do indeed have the potential for odor generation. If you construct one, you should probably include a domed cover with a scrubber. It is also presumed that at low flows, you will empty the EQ tank so unlikely odor generation at that time.
David |
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| | | Forum Newbie
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Last Login: 7/11/2007 11:57:37 AM
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| | We too heard "rumors" that they were thinking about building a equalization basin here at our plant also. My questions are,1)Wouldn't it be better to fix a "long neglected" collection system's I & I problems, this includes many of the residents have their roof leaders etc. entering the collection system, most of the manholes need repaired and after video taping the collection system piping it just proves how deteriorated it really is. 2) Would a state agency even entertain this idea with them knowing how poorly the collection system condition is in? Being an operator here, the biggest eq. basin they could prob. construct due to land availability is in the range of 1.5 m/g. The collection system is in that poor of shape that when we get a "substantial" rain event we receive more than 4.5 mgd and sometimes even more, so would an eq. basin even really help? |
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| | | Supreme Being
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| shwasteact (7/11/2007)
We too heard "rumors" that they were thinking about building a equalization basin here at our plant also. My questions are,1)Wouldn't it be better to fix a "long neglected" collection system's I & I problems, this includes many of the residents have their roof leaders etc. entering the collection system, most of the manholes need repaired and after video taping the collection system piping it just proves how deteriorated it really is. 2) Would a state agency even entertain this idea with them knowing how poorly the collection system condition is in? Being an operator here, the biggest eq. basin they could prob. construct due to land availability is in the range of 1.5 m/g. The collection system is in that poor of shape that when we get a "substantial" rain event we receive more than 4.5 mgd and sometimes even more, so would an eq. basin even really help?In answer to your questions. 1) Yes to fix the system would be an excellent start. 2) Maybe but probably not. An equalisation basin would help , but you are right it might not be big enoughalthough equalisation basins are rarely big enough to handle major wet weather flows. They tend to be sized to level out the normal diurnal variation to allow a plant to spread its load over the whole day instead of having to be sized for the morning and evening peaks. Regards TerryF |
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| | | Forum Member
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Last Login: 6/16/2008 8:44:25 AM
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| | The answer to whether a state agency would allow/require an EQ basin when the collection system is so poor is YES! The EQ baisn, if sized properly, will prevent uncontrolled overflows. My city went through this process over the past several years. After pump station upgrades and an ongoing I&I abatement program we do not experience overflows at the plant and do not always see overflows at our major pump stations. I suppose the key here is properly sizing the basin to handle past peak flows with the idea in mind that as the collection system is improved this level of flow will diminish over time. During dry weather we pump a steady 1.0 MGD rate and allow our basin to fill during the day and empty out overnight. During rainstorms(like yesterday's 1.7" in 30 minutes) the flowrate to the headworks can rise to 6.8mgd rate and then we increase our pumping rate out of basin to a maximum of 3.5 mgd rate. It works quite well. ~Egadz |
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| | | Supreme Being
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Last Login: 6/26/2008 4:01:08 PM
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| | I would expect regulatory agencies to accept a properly sized Eq. tank, as noted by the others, though this could vary from state to state. Of course, fixing up the collection system is preferable, though often very expensive. I know of a couple of plants where they used stormwater retention basins instead, which is a little different. Surplus flows are diverted to a separate basin during wet weather events, and then later fed gradually back into the process. Results have been mixed. In one case, it seems to work out OK; in another, flows were still way too high, overloading the storage capacity, and they ended up having to do a lot of sewer replacement anyway. Need to have your consultants do an analysis, figure out how much extra flow is involved, and what the costs of different options would be. |
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| | | Forum Newbie
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Last Login: 4/10/2008 10:42:46 AM
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| | Thanks to all who answered, good points were made such as odor problems,but since this will be a temporary containment area for wet weather flows the majority of this flow i'm going to presume will be just that "rain water".My plan is to use our plant effluent to basically wash everything down the drain so to speak. I believe some type of screen mechanism and sump hole that could be vactored out would also help in odor control,since it is going to be at the existing treatment plant I don't think there will be any more obnoxious odors added that are not already common in the area. Although there is numerous repair measures that can be taken to rehab the collection system, after a SSES was conducted no smoking gun was found its just a little bit here there and everywhere,I/I that is. So with the plan to proceed with a EQ, can somebody give me some insight on how to proceed with the structure ie. a liner concrete or some other new technology? Its looking like about 6to8 MG size ,we do have plenty of area to work with. The ability to keep it "fresh" is a concern also-any ideas on how ie. diffused air from PD blowers? floating aerators like on a lagoon ? air induction pumps? Does any one out there actually have one that they are so proud of they would be willing to show it off ? Thanks for your help! |
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