Elevator pit pump 2

[MarauderX]

Anyone have experience with pumping ground water out of an elevator pit? The project is existing, and the elevator pit is below the nearby water table.

Thanks in advance -
~MX

 

[PEDARRIN2]

Usually, elevator pit pumps are only for when the sprinkler goes off.

How was the building built without a pump if the elevator pit was below the water table?

When you say it is below the water table, how far below is it?

If the bottom of the elevator pit is significantly below the top of the water table, then you could have some significant problems.

If it is, you are probably looking at a system where your pump could be working a substantial amount of time.

I would suggest getting some advice from a civil/geological engineer about groundwater flows in the area. There are probably some on this website who might give you guidance.

Size the pump to pump out at least equal the flow rate in. Duplex the pump system so if one is down, the other can operate or if the flow in peaks, at least you should be able to not flood the pit.

Good luck

 

[MarauderX]

The pit isn't that far below, and only a minor amount of water leaks in, usually during a rain when the nearby field has ponding. The operation time would most likely be periodic, and the pit is small. Some questions I have are:
1 - would the water pumped out of the pit have to be sent to a catch basin & oil separator?
2 - would the water need to be piped to the sanitary line, or could it be expelled to a street drain?
3 - could a typical well pump (such as a submersible) serve the purpose?
4 - would it be better to trench around the outside of the pit and provide a pump there after applying a water seal around the pit?

Thanks again -

 

[PEDARRIN2]

OK, your problem is not as severe as I thought.

1. As far as an oil separator, that would depend on your local code official. You would not have to send it to a catch basin. A floor sink (~10" deep) would suffice.

2. Most plumbing codes, at least the ones I am familiar with would require it to be sent to the sanitary system.

3. You would not need a well pump. A submersible dewatering pump would suffice. Zoeller or Weil would be a good one to use.

4. Are you installing the elevator and pit or is it existing? You could provide a trench with some perforated pipe that feeds into a sump basin which would be where you would place the pump. That is probably the best way to catch the water.

 

[Thomasjl]

Hi MarauderX,

What type of elevator do we talk about, electric or hydrauylic? Can there occur any spillage of oil or any other chemicals from the engine room or anywhere else into the elevator pit?

What I would do.
Take the smallest possible submergible pump that (over time) will do the job (depending on the required capacity), install this on the lowest point of the pit.

In case of an electric elevator:
Install a high and low level switch (this means there always remain a layer of water in the pit)and dump the water in the street sewer system.

In case the water can be contaminated there are a few options
It is to be pumped to a catch basin & oil separator. – If there is nothing like a catch basin & oil separator, install a handswitch. When the water is clean pump the water in the street sewer system. – If the water is not clean a special company that deals with contaminated water is to be called in. In this case you might need a bigger pump and a hose connection at the road side. Or perhaps no pump at all and this company will suck it out. Consult a local company for your possibilities.

Good luck,
Thomasjl.

 

[PEDARRIN2]

You probably would not need both a catch basin and a oil/water separator. The reason is that the catch basin would act as a separator due to the fact that water would be retained in it, thus promoting separation. While this is not necessarily a bad thing, why have two separators when you only need one. If you have oil, size the oil/wate separator for the proper retention time. You would have to determine how much oil is in it so that you could have it removed at the proper time.

As was said before, you would need to have controls on the pump to prevent water from rising too high and going too low.