Watering travelling along sewer gravel fill into basement 1

[Madpotter]

I have a theory that the water in my basement, a constant flow of very very clean water into my sump pit that I never had until a lot of contsruction of homes up (and higher) the street occured.

I have a basement with a 9" ceiling and plumbing with natural fall, albeit not a lot of fall, to the sewer.

When it rains, I get a heavy flow of water into my sump pit, more than what I beleive downspouts would do (and yes my downspouts are all aimed away from my foundation many many feet). Sump cycles once every 30 seconds (check valve is good). But in the dead of summer, when we are in drought mode in Northern Indiana, I still get a nice flow of water into my pit.

So, since I have very little fall on my sewer line, and it is bedded in a layer of gravel, and the sewer line is bedded in gravel too, is it possible that the main sewer line gravel bed is acting like a french drain to my footer drain around my basement? My house is low on the street and it seems to me that the load on the external side of the sewer pipe would be increasing with every house going in.

So if this makes sense, and I excavate down to my sewer line in my front yard, remove the gravel fill, and replace it with concrete to make a block for the water from the main sewer "french drain effect", will I solve my problem?

Also, this water in my sump seems to be very hard as it is leaving a hard white scale in the sump pit and on the pumps. Never noticed this until all the new construction, but then again, my pump was never being fed with water continuously.

Had the water shut off the house for a day and no change to my problem?

Any thoughts from the pros out there would be appreciated because Monday we are digging my front yard to the sewer line!

 

[semo]

It is highly possible that the bedding in the trench will channel water to the house. If the bedding is limestone, it can also pick up the calcium that is depositing in the sump causing the white scale. Clay can also be used instead of concrete; but, might not be any cheaper.

I would have thought the problem would have developed at the beginning; but, the nearby construction could have changed the conditions and opened a place for water to enter the pipe bedding.

 

[ctmtwilliams]

Even based upon what you have said, I find it difficult to believe that the trench for your sewer line would saturate/fill to the point of overcoming the drop away from your home. Sufficient “new” housing upslope from you could be adding additional water from landscaping alone. Its not an uncommon problem.

 

[ctmtwilliams]

I responded to this thread prior to seeing the author’s “semi-duplicate” thread on the same subject. Please refer to my response in the thread titled :“Sudden Contstant Flow of Water in Sump Pit”

 

[Madpotter]

Wow, Thanks for all the responses everyone. Here is some more information. I foudn out from my builder that I have very little fall on my sewer line, probably only 1/8" per 10ft. I am amazed with this little fall my sewer works for well. So I think the backflow along the sewer trench makes even more sense.

We had sanitary sewer backups down my street one year ago. Have a HUGE rain event. So, I am many of my neighbors puts backflow valves on our sewerlines. I do recall that when they dug down to mine, they had to put a sump pump in the pit as their was water in the trench. And since i jsut found out I am very horizontal, this may be even more plausible? Thoughts? Monday is demolition day.

Any thoughts from the Civil Engineers out their as to how to dam this? My builder, and his excavator, are talking about digging a trench perpendicular to my sewer line, making it overly long, then over-digging the gravel out, and then backfilling with concrete. We are in hard indiana clay so will this work? How wide should me concrete dam be?

I guess when we stick a trash pump in the ditch after excavating, and water stops dlowing into my sump pit, we can assume we found the source?

 

[ctmtwilliams]

In my opinion, listening to the builder and excavator is a major mistake, after all didn't a builder and an excavator dig your near horizontal sewer line? As I stated in my previous responce "Before you run out and start digging up your yard, I strongly suggest that you hire a local Geotechnical firm to give you a professional assessment of the situation."

All of what you have said are just band-aids on presumed/assumed guessed at causes. You need to find the root of the problem and design the proper mitigation. You can not dam the water, you must re-route it to give it somewhere to go.

 

[KRSServices]

I my humble opinion, from the information you provided, I think you are wasting your money in hiring a contractor to excavate to determine whether the sewer line is leaking and the effluent is migrating to your sump.

Your thread is silent on whether the municipality was contacted, and what their response was. Secondly, your thread did not mention as to whether your system has both a sanitary and storm sewer system. I presume your sump discharges to gradeand the sewer you speak about is a sanitary sewer. If so, some critical points:

1) Regarding your sump....you did not write about an unmistakable no odour. If your system is constantly pumping raw effluent flowing from a mainline break, the deposits lining on the sump wall will stink.

2) Sanitary or runoff water from the storm system, particularly if now construction is occouring in your area or landscaping, will never be clean.

3) Over time, the surrounding soils will aggregate with the tranch backfill material (gravel or other accepted backfill) , particularly in very wet condidtions such as a break of long term leak. Leaks from sewer mains rarely migrate easily to another location because the actual conduit, being the pipe, is the path of least resistance, assuming it's new and unblocked.

4) Water leaking from a pressure system will always find the path of least resistance. I can tell you from years of experience that a leaking service line or mainline can migrate and surface (in this case, your sump), many metres from the origin.

5) You also indicated heavy rains. While I do not know the specific topography of your location, I get the feeling that your residence is lower or situated lower than others. You may have a fluctuating groundwater issue.

Based on the information you provided, I would firstly suggest that your water service may be leaking and finding it's way back to your sump. If your municipality chlorinates and/or add florides to the water, this can be easily determined by taking a sample to the municipality or local lab for testing. Failing this, you may want to investigate further the aspect of groundwater issues.

Even though I am many miles from you, I am confident that you can qickly rule out a sanitary issue.



KRS Services

http://www.krs-services.com

 

[Madpotter]

This response is for ctmtwilliams. In your first response, you mention that sufficient new housing upslope could be adding additional new water from the landscape alone.

Do you mean that this water is filling my sewer line trench, or that it is merely adding more water to the earth in general.

Thanks for the dialogue.

 

[bimr]

Not really possible to provide a concrete answer without looking at a soil profile.

I have a similiar problem myself. The problem seems to be due to the loose backfill material around the foundation wall that allows water to percolate through. Prior to construction, the clay soil prevented water from percolating downward.

The problem may be made worse my layers of clay which will channel the water horizontally.

The new development in your area may be partly to blame. The reason being, is that the runoff from roofs and impervious driveways should have increased. However, I don't think that you can blame the neighbors for this one. The neigbors should be having the same problem.

If in fact your sewer line is embeded in gravel, the water will travel down the sewer line. The loose fill in the sewer line will also allow water to percolate down to the sewer line.

I don't think there is much you can do to stop the water unless you have buckets of money. The sure way to stop it is to excavate around your house and install a bentonite slurry wall.

 

[kumar1921]

Hi,
I have a similar problem. I have a 9ft foundation walls in my basement. All the surrounding houses are the standard 8 ft. I have an overactive sump pump. I have been in this house right from its new construction, for three years now. There is another 9ft basement in my block 3 or houses down the line that has the same problem. Most of the other houses had their sump pumps running soon after construction for a period of time. Then it went into the normal routine of running only during rains.

I am trying to figure out whether it is a shallow water table issue or some other issue. You post about the sanitary drain has given me something else to look into. Thanks.

I am very interested in seeing how your problem resolves. Thanks for the post.

 

[KRSServices]

Happy New Year folks,

Just one more thought regarding this issue, particularly the last posting (Kumar). In our Province, at the conceptual/predesign stage of a new subdivision a geotechnical investigation is undertaken. This investigation provides recommendations for road structurefoundations, underground utility installation (relating to geotechnical issues) and general footing/foundations. This work includes the drilling of test holes throughout the site. The logs typically show where the groundwater elevation was at that time.

You may wish to contact the local authority whom approved the subdivision. I would wager that if a geotechnical investigation was undertaken, the authority would have the information on file.

That would be a good start. While it is possible the a watermain could be leaking as well, I think it is unlikely since another deeper (similar to yours) foundation has a sump pump cycling frequently as well. I think your foundation is sitting on or just below the groundwater table at this time. Since the table may flucuate with the seasons, it may be interesting to observe the pump a little more closely, in addition to looking at the file.



KRS Services

http://www.krs-services.com

 

[kumar1921]

Some more symptoms I saw that relates to Madpotter's post.

1. I seem to have white calcium like deposits

2. When they dug my heighbours foundation, they hit water at 7 or 8 ft. They used a sump to clear it.

I think these are similar problems. I live in Will County Illinois. I don't know the soil type here.

If it is a shallow water table issue would my basement not have atleast 2 feet of water before installing a sump pump. Consideing that my basement is 9 ft and the neighbour hit water at 7 ft. Before installing the sump pump there was about 2 inches of water. It looks like the soil is acting as a barrier. The water is migrating some other means.

The builder said that it was possible a farmer's or other buried drain tile that is causing water to be added to the system. This was farmland before. I have no way of verifying.

Another intersting fact is that, one of the solutions proposed to me is to use the deep sanitary trench to re route the water elsewhere. They volunteered that they had little success before with this approach.

Sorry, I didnt mean to take over Madpotter's thread with my issue. I will stay quiet and listen to what people have to say.

 

[Madpotter]

It's Madpotter again. Haven't been on the forum for a while but am very interested in the recent postings, especially from kumar1921 and others.

I have pretty much given up on trying to figure out where the water is entering my footer drain. I have read about bentonite slurry walls etc, and that seems logical, but trying to create this wall to keep the water back with any level of effectiveness seems unlikely to me. I am pretty convinced that the guy next door hit a seam of some sort when excavating for his new home, and now, I simply have to live with the effects of his blunder.

So here is what I have done so far, with some level of success. Knowing that water will seek its own level, and the lowest point, I have given up trying to fight it. So I have installed an outdoor sump pit in my sewer trench about 6 feet off the house. This basically created a sump pit that is lower than the one in the basement, allowing this sump to share the load with the basement system as well.

So, unless we get a driving rain, the sewer trench sump pumps enough, being the lowest point, to completely dry out the pit in the basement. I know that I am still dependent on a sump pump that runs regularly to keep the basement dry, but I do feel more comfortable having this extra redundancy. I also feel better not hearing the sump in the basement all the time.

For now, I am pumping this water from the new sump pit into my front yard, which is making a little bit of a mess (winter here in Indiana). In a month or so I plan to trench to my backyard and install a drain pipe to the backyard where I can tap a large concrete drain pipe that leads to a small creek. This will pretty much button this whole mess up nicely.

I think this is the most reasonable solution. And yes, I do have a couple sumps with excellent back-up (home made) systems in the basement. My main pump actually runs off of inverter power for several hours when power fails. I don't trust those 12V back-up systems. They simply lack the capacity when you need it the most. I could always add a self starting generator to the home for extra measure but so far so good.