Sump pump for basement sink and groundwater drain - is this a good plan?

My basement is unfinished. There is 4ft of field stone wall below ground and the rest above ground. I am renovating and the basement will eventually be ‘finished’. I am installing a 4inch drainage pipe in a trench around the whole perimeter. This will carry any moisture that comes through the wall. There will be a moisture barrier between the field stone wall and the finished wall. Here is the corner where I’ll install the sump pump. I have dug a small inspection / feasibility pit.



Here is a section where I’ve already dug a trench for gravel and drainage pipe.



Here is my rough solution, top half is plan, bottom half is elevation.



The 4inch drainage pipe runs in a loop around the whole basement and then into a T section. This branches to a sand / silt trap, something like this:



It will give me access for regular maintenance and also be used as a drain on the finished floor.

The next part is a Charlotte Section - a T section going from 4 inch to 2 inch with the 2 inch section pointing down:



Water then flows to a T section and into the sump pump ‘bucket’ to be pumped up to the 4 inch sewer pipe you can see on the left in the first picture. I may install a diverter to pump the water outside and use in the garden, but that’s a year or more away and currently out of scope.

I’ll install a P trap inside the bucket and include a vent pipe.

The other arm of the T section leads to a utility / basement sink which I will install.

That’s the theory. I’m trying to figure out if it’s the correct one and is code compliant. I can’t find any examples of a sump pump being used for grey water and ground water. I like the idea of both, less stuff, less cost, less work. More importantly, it’s possible there won’t be much ground water and it could take months before there’s enough to activate the pump. Attaching a sink means it will get regular use.

Seems like a solid plan to me! The hardest part will be sloping the trench around the wall in a way that ensures it all drains into your sump pit, rather than sitting and stagnating in low spots.
I quite like the double duty of using the pit to do the sink too. Great way to regularly test the system through just using it. The chances of this being code compliant is pretty slim though. But that would not be an issue until some day if you were selling the house and an inspector called it out.  

Will you have a 'sock' on the trench pipe to prevent soil getting in?

I'm trying  to understand your drawing.  From the trap in the drain tile you are necking it down to 2" and then connecting it to the sump pit bucket?  Why not just run the 4" right into the sump?  I think that's much more standard.

I don't see a problem with the sink going into the sump unless the department of making you sad visits and has a problem with it.  I'd just run that to the sump independently of the drain tile piping.  

You might also want to think about radon as you plot and scheme.  A sump and drain tile piping system under a solid floor can act as a good suction/vacuum apparatus for a radon removal system.  But the sump pit may need to be designed for it up front to work optimally (I don't know).

Thanks chaps.

My main priority is to insulate the north facing basement wall before winter. The north wall is the big problem, there is lots of evidence of water and water damage to wooden walls and floor. The main reason is the previous owner didn’t maintain his gutters. When we first moved in there was water pouring down a section of wall after a big storm. Outside the drainpipe wasn’t connected to the gutter. Bizarrely, the previous owner had done lots of repairs to the water damaged woodwork but hadn’t fixed the guttering! I don’t have the time or money to insulate the other walls, however, the east wall has a massive fireplace and brick bread-oven, the west wall is under a ten foot deep porch that runs the full width of the house and the south wall is complicated - two chimney breasts and all the services - boiler etc.

I’m now having a rethink and going to locate the pump midway along the north wall so I have two sloping drains from basement corner to basement corner. I won’t have to dig so deep. I was going to run 4 inch into 2 inch so I could install the P trap inside the bucket.

As for a sock, that’s what the trap is for, to collect any silt / sand from the drain.

Good question about radon - I’ll investigate.

Pipes going in:



Now for the back fill . . . Started a new thread:

Ok to use my own dirt . . .