Discussion: View Thread

Does anyone have suggestions for a forebay design in front of a sand filter box that is filtering TSS within a tight footprint? Our original design/ install did not have a forebay and now the filter box is filling up with sediment too quickly. We need a forebay box. Are there any proven prefab boxes available with cyclone or baffles?  Design is for 400 gpm.  Location is WA.

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Margarete Vest P.E., M.ASCE
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I like the Hydro Dryscreen by Hydro-International.

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Richard Evans P.E., M.ASCE
Project Engineer
Bradford VT
(802)4393559
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Original Message:
Sent: 12-20-2018 08:35
From: Margarete Vest
Subject: Sand Filter Box Forebay Design

Does anyone have suggestions for a forebay design in front of a sand filter box that is filtering TSS within a tight footprint? Our original design/ install did not have a forebay and now the filter box is filling up with sediment too quickly. We need a forebay box. Are there any proven prefab boxes available with cyclone or baffles?  Design is for 400 gpm.  Location is WA.

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Margarete Vest P.E., M.ASCE
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Have you looked at the sediment characteristics for design purposes? Given the location, is there room for open forebay or are you restricted to underground tank given the tight footprint and surrounding land uses? Although I'm not a fan, various mechanical swirl type concentrators work well for larger particles based on your flow range. Effectively look to wastewater treatment design parameters, such that you check how low you can get your velocities for your drop out range within the footprint you have and the size of particle you are targeting. If it just can't fit, you might look upstream in the system and see what you can work with within the foot print of the collection alignment...longer/narrow tank to get your drop out zone... I've gone as far as using upstream manholes that have direct maintenance (vactor truck) access and placed weirs for larger grit chambers. Care should be taken that you have scouring in the upstream pipes or increased pipe cleaning maintenance activities if such actions are pursued. Just thinking out loud, good luck!

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Brian Neilson P.E., M.ASCE
HWC Engineering, Inc.
Indianapolis IN
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Original Message:
Sent: 12-20-2018 08:35
From: Margarete Vest
Subject: Sand Filter Box Forebay Design

Does anyone have suggestions for a forebay design in front of a sand filter box that is filtering TSS within a tight footprint? Our original design/ install did not have a forebay and now the filter box is filling up with sediment too quickly. We need a forebay box. Are there any proven prefab boxes available with cyclone or baffles?  Design is for 400 gpm.  Location is WA.

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Margarete Vest P.E., M.ASCE
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Thank you all for your responses! Yes, the forebay will probably have to be below grade due to truck traffic and space. I like the idea of weirs in the upstream inlets as well as the cyclonic Vortechnics option, which i have seen in use at similar locations.  We will probably use a combination of these ideas. Thank you!

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Margarete Vest P.E., M.ASCE
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Original Message:
Sent: 12-21-2018 08:44
From: Brian Neilson
Subject: Sand Filter Box Forebay Design

Have you looked at the sediment characteristics for design purposes? Given the location, is there room for open forebay or are you restricted to underground tank given the tight footprint and surrounding land uses? Although I'm not a fan, various mechanical swirl type concentrators work well for larger particles based on your flow range. Effectively look to wastewater treatment design parameters, such that you check how low you can get your velocities for your drop out range within the footprint you have and the size of particle you are targeting. If it just can't fit, you might look upstream in the system and see what you can work with within the foot print of the collection alignment...longer/narrow tank to get your drop out zone... I've gone as far as using upstream manholes that have direct maintenance (vactor truck) access and placed weirs for larger grit chambers. Care should be taken that you have scouring in the upstream pipes or increased pipe cleaning maintenance activities if such actions are pursued. Just thinking out loud, good luck!

------------------------------
Brian Neilson P.E., M.ASCE
HWC Engineering, Inc.
Indianapolis IN

Original Message:
Sent: 12-20-2018 08:35
From: Margarete Vest
Subject: Sand Filter Box Forebay Design

Does anyone have suggestions for a forebay design in front of a sand filter box that is filtering TSS within a tight footprint? Our original design/ install did not have a forebay and now the filter box is filling up with sediment too quickly. We need a forebay box. Are there any proven prefab boxes available with cyclone or baffles?  Design is for 400 gpm.  Location is WA.

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Margarete Vest P.E., M.ASCE
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There is lots of bad press for systems like Stormceptor, Storm Troopers, or Vortechnic's system, but one of the things that they do well is pretreatment involving removing settleable materials and sediment.   Vortechnics systems have a cyclone.

These things require regular inspection (monthly at minimum) and regular clean out or they just become part of the problem.  


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Dwayne Culp, Ph.D., P.E., P.Eng, M.ASCE
Culp Engineering, LLC
Rosenberg TX
(713)898-1977
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Original Message:
Sent: 12-20-2018 08:35
From: Margarete Vest
Subject: Sand Filter Box Forebay Design

Does anyone have suggestions for a forebay design in front of a sand filter box that is filtering TSS within a tight footprint? Our original design/ install did not have a forebay and now the filter box is filling up with sediment too quickly. We need a forebay box. Are there any proven prefab boxes available with cyclone or baffles?  Design is for 400 gpm.  Location is WA.

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Margarete Vest P.E., M.ASCE
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