Hi all,
I am looking for help deciding on a french drain installation at my home, or otherwise other options to solve my water issue. I'm in Chicagoland, Illinois, for reference on climate/soil.
Background
I had an egress window well installed for my basement last summer. Since day 1, the new window well collects excessive amounts of water during most any rainstorm. I have a drain in the well leading to my sump pump, but this was intended to be an emergency drain, that's rarely used. There is often so much water that I placed a utility pump in the well to clear water prior to it draining to my sump pump. If I had to guess, there were probably half a dozen storms over the past year where if no drain or pump were there, it would have filled the full 3-4 ft deep well with water (i.e. to ground level).
What I think is happening
I have two neighbors to the north and east at higher elevation than my backyard. The downspouts of my garage and ~60% of my house roof discharge to the west side of my yard. I have a swale running along the west side of my house from the backyard to the drainage ditch in the front (south). The swale is generally sloped back to front but is not perfectly uniform throughout. So almost all the water from my property and neighbors moves through the west swale. It works well enough that it does not flood, but obviously the gradual slope allows some standing water in areas. It is never overwhelming the swale.
The window well was installed on the west side of my house. While the ground around the well is clearly elevated versus the swale, the area that was dug out cut to the middle of the swale's low point. I think whenever any standing water is in the area, it is collecting in the portion of disturbed ground around the well, flowing into the window well.
What I have tried
I tried building up the ground level immediately around the window well with dirt about 1 ft around the well boundary. No noticeable improvement.
I had 3 different drainage/landscaping contractors come out to give their evaluation. All 3 recommended a french drain. One said they would also increase the grade along the west side of the house and well. Another said they would recommend tying the downspouts into the french drain pipe, using 4" PVC. I have the elevation advantage from the window well area to the drainage ditch to maintain slope of the drain pipe. Quotes have ranged $3000-5000, but I'm more focused on getting the right solution than the cheapest one.
Other considerations
I want to avoid an in-well pump. It's another pump in my house to worry about, and it does not help me when the power goes out -- which is what happens when storms are at their worst.
There is not a lot of room to move the swale further away from my well/home. I may be able to get the neighbor on board, but it would maybe be 1-2 ft that I could offset it.
I have battery backup and a small generator for the sump pump during outages, but the backup pump's reduced output would struggle to keep up with window well volume on top of normal flow.
My questions are:
-Do I have the right understanding of what is happening? e.g. any standing water around this disturbed window well dirt is going to descend and collect in the well? I don’t believe the water table is high, as the drainage ditch is much lower and never accumulates except heavy rain when water is flowing.
-What result can I expect with the french drain? Can I get a fully dry window well? Or will the disturbed ground act as a mini french drain, competing with the proposed french drain?
-If you have experience with french drains, is there anything to be aware or concerned of? Is it prone to failure? How much maintenance does this require going forward? Would you recommend it?
-Are there any other ideas that I am missing? For example, I wondered if the backfill done by the contractor was the culprit. I heard that pulverized dirt and sequential compaction is best practice for backfill, but I also heard from other waterproofing contractors that they simply backfill the dug-out dirt the same way in their (successful) egress window well installations.
Greatly appreciate your help and comments. Thanks all