Can there be too much water for a drain system to move?

Question

My neighbour built a new home and laneway home, completed in 2015. He excavated much much much lower than previous home. Original house had a 3/4 basement in ground,with steps up to front door. Now level entry to front door, and full basement with 10 ft ceilings below ground. You have to take 3 steps down from front sidewalk/street to his lot which is now totally flat through to laneway house. I would say my back yard height is 8 feet higher than his now.

I have an existing retaining wall, as I am uphill from him, complete with rebar holdbacks,to 3 concrete footings. There is approx 16" of my property after my wall,filled with 3/4" gravel to the property line. Where he poured a non permitted concrete landscape wall,the entire length of property, that is below ground 3 ft, with 6"-12" showing above ground, that his fence is attached too. Frost levels are 12" here.

So my concrete wall, 16 inches gravel, and just above the footing of my wall his wall starts. Approx 24" of his concrete is lower than my footing.

He has 2 sumps in the front yard, below street level and a least 1 sump in back. There is some purposely hidden spots, that are actively being worked on. I think another sump or pit.

I have never heard a pump operating from front sump to street. Ive never heard a pump period. In 4 years. There is a permit for a pump, and a permit for secondary pump.

We have discovered in the last year, an overflow system from his front sump to my property. Discharging water under my detached garage. And also realized his wall is a blockage or dam. (cut off wall) The pipes for this overflow were laid between the walls. On my property. ( I should clarify, I did not live here during the construction to notice.)

Us exposing the area between the walls, has forced some changes (non permitted) to be happening on his property, and for the first time, I heard what I can only guess is a pump from below (?) his house, going up to a secondary system ? I heard it all the way around the exterior of the house, travelling thru copper pipes that appear to be his down spouts from a hidden gutter system on the 2 storeys above ground. It was loud enough to hear across my property, and the opposite neighbour heard it as well. Sounded like an empty tub, being filled with full blasting water in a big tile bathroom. Or like how a rec center pool echoes.

And honestly, it sounded like the gutters were being drained down, to a concrete pit below ground. If I had to pick what I heard, this is it. But that seems so unlikely. It lasted over 5 mins and it was an echoey hollow sound. AND IT WAS RUSHING.

BECAUSE he cant overflow to me any longer, is he now storing water to dump??? WHEN ITS SUNNY, AND BEFORE PREDICTED RAINFALL, like the case on Monday when I recorded the sound. Could he be using the hidden gutters, inside the gigantic mouldings surrounding his flat roofed, 3 storey house?

Is it possible, he cant properly get rid of his water thru the line, that is a combination of sewer and drain water to street? There is only 1 combination pipeline connected to street. For both houses.

It should also be noted it was an owner build, before the change, and he is not in construction at all. Skimped everywhere he could for signoffs, no geotech, basic engineering sign offs, foundation, dig, and had 1 single contractor with a drinking problem and a couple labourers do the entire job. No crews. Just inspections.

Is it possible to have an illegal drain system operating while also having drain tile systems for both houses? Ive seen the permits for drain tile on both houses. Perhaps a dry well, or french drain? A rock pit???

Im looking for someone to help me solve a strange puzzle, what the heck is happening there?

My concern is, I was flooding. Actually, I had a lake under my garage. My water table was 6" below the top of his wall. Right under the slab in my garage. Water was pooling, as it was blocked, and even though it sounds unlikely, he had a 2" white pex pipe, from his front sump, that is higher than the other end of it, under my garage foundation. We put a hose in the pipe, and it filled his sump, and then either a pop up emitter, or just an open end pipe, close to the sump, started to let water out slowly.This pipe was T'd, and the other end capped. Exposed and placed at the very end of property line, passed my garage. I think it started as temporary drainage for the laneway house. theres a note on permit that Inspector wanted to see it removed or capped off. So basically, a decoy? we are on clay. so the saturation is amplified. These pipes were not part of his building plan, the inspector told me. There was also a incorrectly installed, crude black 4" drainage pipe in my garage are, seemingly to collect water. However, when we put a hose in it, his sump didnt fill, water surfaced through the cracks in asphalt alley,in front of laneway house. I think it was capped on his end. Its all really bizarre I realize. He has the same (not sure of depths) wall on other side of his property. So if there was uncontrollable water amounts, he will have dammed himself in on that end. The neighbour is higher, not as much as me, but higher. We are close to the bottom of a gulley, that historically was swampy, now a ball field.

Answer 1

If your perimeter drain (drain tile for houses built with vitrified clay) is lower than the sewer or storm drain service line from the city you need a sump to collect the water and you'd need to pump it or gravity drain to somewhere lower than your property. The pumped water is typically directed to a gravity sump well that allows any sediment to settle before the water gravity feeds to the city storm/sewer. Secondary pump is probably a sewer pump if they have washrooms/kitchen/laundry etc in the basement.

Illegal isn't a word I'd use in construction. Non code compliant, non bylaw compliant, non-zoning compliant would likely be more accurate. Even non compliant construction can still be accepted with inspector supervisor sign offs, grandfathering or board of variance approvals.

A lot of jurisdictions do not require engineers forget geotechs to sign off on anything. Geotechs in residential construction I'd expect to be quite rare and reserved for only the most challenging soils / geology (cliff faces, peat bogs, underwater, rivers, swamps). A lot of jurisdictions don't care about retaining walls that are not related to the house - these are considered landscaping features, much the same way many decks, fences and sheds do not require permits. Certainly a 3'-4' retaining wall seems pretty reasonable to not expect a permit.

Ideally you do store water before pumping. You want to minimize the cycles on the pump. The easiest way to avoid cycling is to have a massive reservoir and only activate the pump when the reservoir is full. Since the water from the powered sump dumps into the same gravity sump that the rain water would enter it makes sense that you hear the sump pump noises from the down spouts.

It is almost unimaginable that he wouldn't be able to get rid of his water through the city service line but there was that mud volcano in Indonesia that was putting out the equivalent of a football field of mud at 8' high everyday. I suppose if you hit something like that you'd have a hard time draining it out to the city.

Overflow from a gravity sump sounds odd as it would never be used unless the line to the city was plugged which you hope would be rare as the sewer system would also start backing up into the house and in a combined sewer/storm the storm water would sooner backup in a basement than up to an overflow unless there was a huge surge that made it both backup into a basement as well as out the overflow (but that should be almost unimaginable as well ).

If I had to guess it would be the reverse - your garage and/or retaining wall is taking advantage of this sump and draining to it. It would make sense to put drainage at the bottom of your retaining wall that goes into a gravity well instead of paying to pump the water up from a sump that is lower than the sewer line and it would also make sense that your neighbor would allow your garage to drain in the same way if your garage didn't have proper rain drains that were connected to the storm. Sometimes garages drain to rock pits which if your property is at a higher elevation would really just end up in your neighbors powered sump. Your drainage system is possibly non-conforming to current bylaws.

2" pex? are you sure it isn't 2" pvc. Often perimeter drain is installed poorly with little to no slope or bellies. Often even if initially installed correctly uncompacted soil that the pipe is resting on can settle and make a previously properly slopped pipe slope the wrong way. How much higher is the sump end of the pipe? Do you think water is coming from his sump and flooding your garage subsoil? Did his builder build your garage as well, how did a pipe from this build get under your garage slab?

I suppose if his property were at the lowest elevation of a gully and properties on either side are higher and each property as you move away is higher still then you could have a tendency for surface water to naturally flow to his property. In that scenario possibly building a concrete wall would mitigate/slow water moving onto his property. Coding and zoning wise though he doesn't have to allow water from your property to flow onto his. Whether the wall is built on the property line or a foot in would probably have the same effect, water that flowed onto your property possibly from the uphill neighbor would be prevented or at least slowed from draining out to his lot. So the construction of the wall might prevent or delay your water from coming onto his property. You might have a spring that would have naturally drained to his property - there is no rule that your neighbor has to manage water from your property. Your lot might have been benefiting from his naturally lower lot previously but that doesn't mean you were entitled to benefit from it. You might just need to add some drainage now - maybe all you need is to lower the pipe near your garage so it properly drains into his sump.

The other purpose for the wall might be to prevent your retaining wall from being undermined. If water is naturally flowing from your property to his and it flows from under your retaining wall then soil can migrate with it and your wall could then end up collapsing. Does your retaining wall have holes for water to drain out or is it solid on his side? Building another retaining wall on his side such that the top of his retaining wall is higher than the footing of yours would prevent that. I'd guess that would be the purpose of his wall - not to manage water but to prevent undermining of your retaining wall.

Answer 2

Honestly, I'm having a hard time completely following your story and envisioning what's going on. It is quite evident, though, that you've got such a mess going on that some folks on the internet aren't going to be able to help you very much.

I'd suggest you're going to have to spend some money to get your site surveyed to compare the current situation to the known situation when the house was built and maybe have a civil engineer do a survey of the land to determine what the expected sink/settling rate should be for your area. Once you have determined (with some "official" documentation) that the actual has significantly exceeded the expected, one or the other (or both) of these professionals will probably recommend some excavation or monitoring systems to determine what's causing the problems.

Once/if they can determine that it's being caused by the neighbor's construction work, you will have to have someone dig into his permits and inspections to ensure that it was done properly and legally. Once you have some well documented proof that it's the neighbors system that's causing you problems, you can address it with the neighbor, either somewhat informally with a knock at the door and a discussion over a cup of coffee, or (worst case scenario) with dueling lawyers.

I'm pretty sure this isn't what you want to hear, but if your neighbor is doing something that's damaging not just your property, but the building on it, this will, unfortunately, probably end up in court before it's totally settled.