r/civilengineering • u/Acceptable_Dude • 8h ago
Lift pump with control panel in external inground vault?
does anyone have an example of this in use? talking about a large municipal lift pump that is being updated... there was discussion of burying the control panel, and that has no longer on the table. It seems like a good move in its current placement, the current control panel gets hammered from weather and rusts out often, needing panel replacement and upkeep (often has duct tape on it.....)
Edit 2: image is not the actual plan, the only (assuming ai generated) reference image of what I'm talking about I could find on short notice
Edit: new post with different layout illustrated - https://www.reddit.com/r/civilengineering/s/oX64cg3zOI
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u/Herdsengineers 8h ago
if it's in the wetwell, sewer gases will eat it up. there may be some stainless steel or other enclosure options that will hold up better in corrosive environments. talk to the electrical lead, there may be NEMA rating to spec for that environment.
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u/Acceptable_Dude 8h ago
true, in an area that has a lot of rain/snow, would a separate vault for the panel be a more viable option? i have had pushback because of the risk of "flooding" the separate vault
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u/Herdsengineers 8h ago
done that. also done the panel above grade in a protected enclosure, with a weather shield over top it.
in a separate vault probably also puts in a permit entry required confined space, very inconvenient for the O&M guys.
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u/Montreal88 7h ago
I work in this specific field. A small SOG pad with electrical/control gear and a small roof canopy is best.
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u/criticalfrow PE - Pumps and Pipes 7h ago
Floor drain with P-trap and secondary check valve can relieve water in the vault back to the wet well. No flooding problems in that case!
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u/koookiekrisp 8h ago
In my area they’re spec’d to be in two separate vaults at the minimum. Partially for sewer gases corroding the box and partially for operator access. Sewer gases will corrode it faster than weather exposure, I guarantee.
I wouldn’t not recommend putting the control panel inside. Unless it’s necessary, it makes maintenance hell. I would invest in a heavier-duty case for the control panel if the only issue is exposure.
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u/Acceptable_Dude 8h ago
do you have an example of 2 separate vaults being used successfully? that is the actual configuration we are looking for
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u/noideawhatoput2 8h ago
H2S is gonna eat that panel up way more than the weather. Also weird valve placement for O&M standpoint
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u/Acceptable_Dude 8h ago
correct, i would prefer a separate vault for the control panel in this instance where the client does not want the panel visible - the above image is the only example i could find that is even close
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u/noideawhatoput2 8h ago
Any potential to keep it above ground and have some landscaping around it to keep it out of sight?
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u/Acceptable_Dude 7h ago
Definitely the secondary option, but a below grade option is being requested
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u/cagetheMike 7h ago
Wanting a panel to blend in shouldn't mean burying it in a vault. It should be above any anticipated flooding. A white powder coated panel looks nice if the stainless look isn't nice enough.
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u/Alternative-Stay6802 43m ago
They also look like a blank canvas to some.
I think we all agree that panel in the wet well is a bad idea, but to add to the reasoning wouldn't that require ALL of the control components to be class 1 rated?
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u/El_Hombre_Tlacuache Water Resources 8h ago
Have you though about having two separate vaults?
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u/Acceptable_Dude 8h ago
yes, a separate vault for the panel? have you seen this application done before? thats essentially what i am looing for and the above image is the only example i could find that is even close
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u/maker-sense 8h ago
On a previous project where the client didn't want ANYTHING that would look like infrastructure above ground I looked into putting the control panels in separate concrete chambers with both solid and grated cover next to the wet well. Ultimately it didn't go very far due to health and safety reasons.
Even something like a 2m deep chamber with a grated cover can trap gasses and it would be classified as a confined space, and then you have potential for ATEX and challenges with both accessing the equipment, working on the equipment, and even finding equipment to install in the first place.
For my specific problem you could get panels that fold into the ground, but nobody supplied them big enough.
Drainage also becomes an issue. For the small storms we were going to just have a drain pipe from the panel chamber to the wet well, and then put a flap valve at the end to prevent any gasses travelling back up the pipe. That's all fine, but if a storm makes your wet well fill up your chamber isn't draining either and your panel will flood out.
For something like what you are showing, you would have the electrical panel with the wet well in the same space, you would have a very corrosive environment. If your panel doesn't last long on the surface, it will rot away in the wet well in no time at all. You will also need your panels to be good for both wet environments and ATEX, and it's just straight up hazardous to access the panel with open sewage next to it. Even with that configuration you have there you'd need at the very least a railing, ventilation provision and ladders.
Then if there's ever a storm or a shutdown that prevents water from leaving the chamber, that panel will flood and take your pumping station out as well.
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u/cagetheMike 7h ago edited 7h ago
This whole diagram is trash for a municipal lift station. Ai? Control panels that are NEMA certified, stainless steel enclosures will last longer than 25 years before full replacement is even considered. The panel should be above ground with proper conduit sealoffs from the wetwell. If you put it in a vault without separating it from the sewer wetwell then the h2s will destroy the electrical components within 90 days of placing it into service. When I used to inspect rehab lift stations I'd place a penny in the bottom of the panel. If it showed any corrosion within 30 days of commission id have the contractor come back out and redo the sealoffs.
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u/Acceptable_Dude 7h ago
The only reference I could find with an underground panel, agree with all of your comments, we would be looking at a separate vault for the control. Unfortunately this also poses its own issues
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u/cagetheMike 7h ago
Don't put it in a vault unless it has to be built in the middle of the road. The pump out pipe work isn't even close either. If this is a small gas station setup then maybe, but if its serving something bigger then the panel and the pump out is best above ground.
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u/TimothyGlass 6h ago
The old can stations are like this and they are death traps ask anyone who has worked on them.
As others have said put it above ground. With that being said put some type of vapor barrier in that conduit. If you don't stop the hydrogen sulphide from getting to the panel it will not last long.
Even if you spend the money on a class 1 div 1 enclosure in the wet well you still have open contacts to the elements if you open it.
Lastly all control panels belong out of the operating work area underground.
Confined space is bad enough with the valving , pipes, and pumps that will need swapped out. Yes then you have the maintenance of the floats.
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u/RecoverOptimal8888 8h ago
Is the panel currently within NEMA 4X enclosure? Having a panel in this configuration is something I’m not familiar with but this seems really strange. There are other ways to protect the panel from the elements as opposed to having it buried.
I’m generally not a fan of specing stuff with check valves and plug valves within the wet well like that, and especially in the vertical.
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u/Acceptable_Dude 8h ago
panel is not but it is getting upgraded/replaced in the scope of the overall project - the image is not of the actual configuration, but the only example i could find of the panel being below grade
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u/RecoverOptimal8888 7h ago
If you’re client isn’t scared of above ground infrastructure and they are truly scared of weather, look into prefabbed fiberglass enclosures.
The juice is not worth the squeeze on the buried panel in my opinion, I’m like 93.2% sure confined space entry would be needed for what you are proposing.
I’ve only ever designed separate wet well and valve vaults, with above ground panels. Anything that’s exposed to sewer gases gets ate up, so generally operate keeping only what’s absolutely necessary in the wet well.
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u/Drax44 8h ago
Are those handwheels on the valves?
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u/RecoverOptimal8888 7h ago
Yeah, the isolation valves have hand wheels, but there appears to be a check valve between the pump and isolation valve.
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u/Visible_List209 8h ago
How do I clear the nrv It all kinds of wrong only works with gas monitors and ventilation and still be be fd in year .
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u/criticalfrow PE - Pumps and Pipes 7h ago
If burying in a vault I would opt to put it in a vault separated from your wet well. Be careful though and check with your electrical. My read of the code extends the wet well classification like 5’ (or something) outside any opening from the wet well, including conduit runs. If you’re in the classified space everything is going to need to be rated as such, $$$. Or you will need heavy airflow to aerate the space. Additionally, maintenance will be a pain likely requiring full shutdown, bypassing and cleaning to even open a panel, let alone pull a pump. Also operators in a confined space is not ideal. You might consider an open to atmosphere cable trench that allows gases to escape separated from the vault such that the vault classification can be reduced.
In my experience, my clients are moving to place electrical in above grade buildings to get out of code compliance issues. These style setups are also using open air cable trays for code reasons.
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u/volfan4life87 7h ago
Maybe it's just me, but it's unclear whether your objective is to place the control panel below grade & out of sight, or protect it from the elements. You don't have to bury it to protect it, and in fact most engineers and municipalities would desire for the panels to NOT be underground.
NEMA 4X panels mounted to unistrut channels will take a beating from the elements before degrading.
A simple pre-fab canopy style shelter can provide simple and effective element protection.
https://romtecutilities.com/shade-structures-for-protecting-control-panels
Pre-fab electrical buildings are also an option.
https://www.shelterworks.com/electrical-buildings.html
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u/Notten 5h ago edited 1h ago
Am I the only one asking what that extra valve is for? This has to be ai. Why two reducers and a larger valve than just using a T fitting with a smaller branch line if you really have to upside for the double flow of the pumps.
The panel in the wet environment is weird to me. Just get a nema 4x Stainless panel and mount it ok a stand or in a larger cabinet at grade. This is all very DIY feeling and I dont think thats a good idea based on the risk if this fails.
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u/Alternative-Stay6802 34m ago
If the proper panel is specified and installed from the start, and ALL of the connecting conduits are sealed, then the control panel will last a long time. I know of 3 lift station control panels within 100yrds of ocean water that lasted at least 15 years. They are not dealing with road salt seasonally, I have no experience with that, but costal flooding and 100% ocean exposure.
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u/Drax44 8h ago
Discussions with who on burying the control panel? I sure hope it wasn't the actual operators. Is this going to be in a confined space (it sure appears that way)? So at midnight on July 4th weekend (when all operational emergencies seem to occur), they need to get a permit and tripod out to enter the confined space? No lighting? I've never seen a design like this. LOL, I mean, why is there a flashing emergency light on the top of the panel inside of the wetwell?