Building lot with high sewer line - don't want backups to flood basement...

[JimLS]

Looking at building a home in an older neighborhood on a lot that slopes away from the street. Sewer line is 8' below street. The existing houses main floors are several feet above ground level and the street and have basements. Looks like we can do a walk out but have some concerns about sewer backups. There is an existing pipe from the main to the property - previous house burned and was removed about 15 years ago. Don't know the depth of the line where it comes on the property.

If the depth is such that we can drain the basement bathroom without a pump the drains will be only a little above the main and any minor backup could flood the basement. A check valve at minimum seems like a good idea.

If we go with a pump the main level could go into the sewer through the basement side wall and only use the pump for the lower level.

One suggestion is to put the pump pit outside. That puts any overflows outside which is a HUGE plus.

Have asked around a bit and haven't heard of any issues with sewer here but have had issues at a previous house with a failed pump and never want that again.

Thinking of locating the end of the connection before we start digging for foundation so we know exactly what we are dealing with. Other choice is to do that as part of the foundation dig but then we may have to change course quickly.

Suggestions and advice?

 

[Reach4]

There is an existing pipe from the main to the property - previous house burned and was removed about 15 years ago. Don't know the depth of the line where it comes on the property.

If that existing line is tile, replace as much of that with PVC through the yard as you can.

Your new house should probably have overhead sewers. With overhead sewers, there is a sealed pit with a grinder pump serving the basement. That sealed pit gets a 2 inch roof vent. This is in addition to the sump pit for ground water. I think you are saying that the street is significantly higher than your yard. Will the floor joists for the first floor be higher than the street?

Are you allowed to dump the sump pump into the sewer? Some places have a storm sewer that you can connect to. I think most places you are supposed to have the sump pump dumping into the yard.

 

[Sponsor]

 

[JimLS]

Yes, first floor (main floor) will be at least 2' above the street so well above with no chance of overflow - it will run out the manhole cover first. I had not heard the term "overhead sewer" before but I see lots of info on line about it - thanks for that!

The lot has about 10' of elevation change from the front to back of lot so ground water is not an issue. New construction requires a foundation drain sump and if a pump is needed it discharges onto the ground.

This area has storm sewers separate from the sanitary sewer but I think the storm sewers may have been added after many of the houses were built so some storm water probably still goes into the sanitary sewer.

Even if we can place the house elevation such that the basement fixtures would drain into the sewer without a pump the fact that they are below the street is a concern for backups. If we go with a pump that will eliminate any potential backup except from pump failure and alarms can warn for that. Even with pump failure we can stop using the lower level until repaired and not have flooding.

We plan to have a detached garage with fixtures about the same level as the basement. Could put the pump in the detached garage but that would mean two pipes between buildings (one for basement to pump in detached garage and output of the pump back to house). Seems best to put pump in basement.

What sort of additional cost am I looking at to add a pump for new construction? It will need to handle a full bath in the basement and a half bath in the detached garage.

 

[Reach4]

What sort of additional cost am I looking at to add a pump for new construction? It will need to handle a full bath in the basement and a half bath in the detached garage.

I am not a plumber or contractor. Note when a contractor selects the parts as part of a fixed-price contract, you get "contractor grade". That is the lowest grade. So for grinder pump and even pit selection, you might want to get involved in that. In pits, bigger is better to a point. In pumps, that is not the case. Big enough is the right size, but better construction is worth extra. I will message you with what I might consider initially.

 

[Sylvan]

POI

Knowing your in ILL it gets pretty cold there so a 2" VTR is not an option you will need 4" to prevent hoarfrost

A check valve (back water valve) on the main sewer is not the best idea as it does cause restriction for gravity waste and over time the check inside the valve will have debris restricting the valve to close when an emergency arises

You can install a sewer ejector system inside the house as outside it may freeze if not installed below the frost line

The pump discharge has to be after the bldg house trap so it does not blow out the trap seal

Personally I would contact some local master plumbers and get several ideas as what they would suggest as there maybe some filing required by the building department or DEP

 

[Reach4]

What did you end up doing?

If we go with a pump the main level could go into the sewer through the basement side wall and only use the pump for the lower level.

You were describing "overhead sewers". Use that as a search term. Retrofitting an existing house that gravity sewers for a basement would probably be 14 to 20 k. Adding a septic pit and pump for the basement in a house with overhead sewers already, would be a lot less.

For starting with the foundation, putting in overhead sewers during the rebuild is a good idea. Yes, you would have needed a pit with a 2 inch roof vent and grinder pump. If that were outdoors, you would need a concrete vault that goes pretty deep.