[mae-ling]

I have a home built in 1973, basic bungalow.
I am about to start renovating the basement, Was going to put in interior weeping tile as we did have a little water come in 2 years ago, it was a year of record rains and flooding. The water came up from the floor not through the walls.

In looking at things I found a plywood plate in the floor. Pulled it up and found what I thought may be a clean-out or back water valve. Took the cap off and noticed the flap down about 8" only thing is it is sitting flat (horizontal not vertical) with a 1.5" outlet and the inlet is full of mud. This sits at 90 degree to the sewer line which guessing from the stack location probably runs right near it.

Could this be a check valve for weeping tile? the water would push up on the valve and then allow it to flow to the sewer line, if the sewer backed up it would close off this valve.

In all my reno work I have always seen sump pumps used and the weeping tile is pumped into the sewer line (or outside and into the storm sewer.).

 

[mae-ling]

I did run water down the sewer line and it did not go through this.
I did run water in where I took off the cap and it did go out.

 

[mae-ling]

Talked to a local retired carpenter today. He built many houses in the area. (but not mine)
They ran weeping tile around the outside of the house. Then a pipe under the footing, through these back water flapper valves, then into the main sewer line inside the house.

Mine is probably full of silt and not really working, could dig down in summer and run a house into the weeping tile and check.

 

[Marqed97]

I would say you're right. Our municipality has been on a 'search and destroy' for 'I&I' (inflow and infiltration) such as that for years. My house (and my mom's) had a similar setup for the old original weeping tile systems and downspouts (minus the check valve) and the city came in and disconnected it from the sanitary system.

In her case the weeping tile was long since silted full, but they filled the old downspout drains with concrete. They had no easy way to disconnect at my house, so they left it. I've checked the manhole during heavy rain and never seen more than a trickle, so I'm sure mine are full of silt too.

The backflow preventer is a touch I haven't seen on these systems, though. Interesting.

 

[concretemasonry]

mae-ling

The "weeping tiles" were obviously not installed correctly. The drain tile installer probably use a clear rock around the tile instead of a proper mixture of sand cleean sand and coarse aggregate. The rock allows too high velocity that flushes the silt out of the soil and gets deposited later downstream rather than have a slower flow that allows filtering. Weeping tile does not act like a gutter/downspout off a roof and is much slower because the moisyure in the soil flows very slowly until it can speed up and scour fines through something like "clean aggregate", cause stoppages somewhere else.

Your leak from the floor is because the drain tile was probably not working (silted up), so the water increased around the foundation and under the slab and probably came up from hydrostatic pressure through any cracks or joints between the slab and walls.

The existing weeping tile is "toast". A proper interior drain tile below the footing base with proper aggregate is an alternate solution depending on the amount on the exterior obstructions (landscaping, patios, sidewalks, etc.) compared to the interior obstructions (steps or walls you cannot slip under). It also drains water from the exterior of the foundation 24/7 to reduce the hydrostatic pressure on the walls. One advantage of an interior system with a sump pump is that it often can be built in a loop with one or two openings to easily allow flushing into the sump for pumping out to discharge legally instead of illegally into a sewer. This is very beneficial initially until the soil/moisture situation moderates.

Because drain tile are really not subjected to rapid amount of drainage from a roof they are usually required to be separate from roof drainage since roof drains can back up leaves, needles, granules into a drain tile and plug it.

Without any details, this is just an example of common situations.

Dick

 

[mae-ling]

Here pumping into the sewer is legal. Yep the way they do it here as there are no storm sewers.
Not allowed to connect down spouts to it though. (as per my discussion with the carpenter who has been here for years and just retired.)

Going to go with interior weeping tile, 4" perforated plastic is what is available here with a 'sock' over it, cover with stones, then pour concrete.
To a sump pit and sump pump pumped into sewer line. That's code for here. Realize would not be allowed other places.

 

[concretemasonry]

mae-ling

A sock around a slotted, flexible pipe is really a bad and cheap way of using drain tile since the high velocity at the slots or openings in the tile/pipe since the high water velocity pulls in silt and plugs the sock quite quickly, depending on your soil that holds the water. Fabric between the natural soil and good aggregates around the pipe is much better. The sock wrapped around a slotted plastic pipe (collects the finer silt in the interior ridges) looks good and is easy for retailer to inventory and sell. You do not have to drain a real french drain quickly as people have learned for decades or centuries. - It is cheap and easy to finish the job after you have done the real work for the long term.

Dick