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Water leak from crawlspace trench

Water leak from crawlspace trench

Water leak from crawlspace trench

In order to fix the crawlspace water problem, I installed a drainage system with perimeter trench + perf pipe + sump pump. Everything has been installed correctly and it's working. But currently there is still some standing water and I believe the root cause is the leakage of the trench. Here are some clues:
1. The soil type is clay (in some areas the clay contains gravel and sand)
2. The surface soil (4 inch) is mud and standing water, but the soil under that is totally dry and solid (I tested in many areas, which can prove that the water is not from underground)
3. The boundary of trench is mud, 80% of standing water is near the trench. which means the standing water comes from the trench
4. Water level in the trench is not high

Does any one has solution to solve this problem? Thanks a lot!
BTW, the sump pump pit is in the middle of crawlspace and just next to a pier post. Do I need to worry about the post?

RE: Water leak from crawlspace trench

In order to understand, please attach some sketches. One should be a general plan drawing (looking down on the basement layout). Also some cross sectional views. the more detail you can provide, the better the results. Amy idea as to where the water does come from would help also.r perforated pie. What type material, hole sizes and where located in the perimeter, (bottom only, etc.? )? Any backfill to the pipe and what type material? I am wondering about proper filter there. On the cross section drawing draw flow lines, those lines that show the flow paths of water from its source, through soil and to the trench or pipe. The cross section should be to scale at least vertically. These lines are roughly parallel to each other and do not cross. On the cross section show soil types that you are sure of.

Interesting, I once lived in a house with a pond in the crawl space. It came from artesian water from a nearby hill.

Looking at the title boxes above in your computer screen there is one showing how to upload and insert images, preferably taken with a camera, JPG files.. The square has a little circle on the lower right corner. Reduce the photos to fit the screen, usually about 1,000 units wide. Edit any photos to increase density of drawn lines, if necessary.

RE: Water leak from crawlspace trench

Thank you so much for your reply and I will send pictures when I get home.
The water comes from the bottom of foundation wall footer, the footer stands on the surface of crawlspace soil and can clearly see the water flows in.
The trench is just next to the footer, 5 inch deep, the PVC pipe sit on top of a layer of fabric and gravel is on top of the pipe.
The system is working well because i can see the water flows into the sump pump and the water level in the trench keeps very low.
Thank you again for your help.

RE: Water leak from crawlspace trench

Added question. Can a schematic also show the higher ground outside, the possible source of the water? What is the drainage outside the building for roof water, etc.? What is the geology of the area? The schematic cross section should include the other direction, (downhill) land elevation? ARE YOU SURE YOU DON'T HAVE ANY EROSION OF SOIL FROM UNDER THE FOOTING. It may take a filled trench, filled with clean sand, NOT GRAVEL. Any trench alongside or lower than the footing is questionable. If you blocked the flow that is seen, what pressure head might develop? Water doesn't always flow in the direction you might think.

RE: Water leak from crawlspace trench

Let me try my best to answer your questions because I'm not professional.
We are at the low point in the neighborhood, according to the line of white powder on the foundation wall, the water table outside is 5 feet above the crawlspace soil.
I attached some pictures.

The pipe is just installed, and as far as i can see, the water is flowing to the pump and the surface of gravel is dry, which indicates the water is not over flowing.
I dont know how to tell if the soil has any erosion.
The pipe holes face down.
I'm sure all the soil type i see is clay.

RE: Water leak from crawlspace trench

Do i need to worried about the pier posts settlement?

RE: Water leak from crawlspace trench

Here is my view of your situation. The soil likely is fine grained and slow seepage occurs. Your perimeter trench only catches some water. To effectively dewater the area, any trenches must cut off the flow. That means any one of these arrows must be cut off somewhere, as with a deep perimeter trench inside or outside. Your footing trenches won't do it alone.

A series of inside drenches as deep as possible also may do it. I'd not do any deeper alongside the outside walls, for fear of causing loss of support.
If you do this added work, I'd forget about using fabric, since that is work intensive and can be done wrong. Instead use a perforated pipe holes down, in the bottom of trench, with some sand under it and fill all trench with ASTM C-33 concrete sand. That is a great filter yet lets plenty of water flow.

RE: Water leak from crawlspace trench

Some questions:
1. If i make my current trench very deep, will it impact the support of foundation wall?
2. The deepest standing water in the middle is just about 2 inches, will it work if I back fill 4 inches dirt and cover it?
3. Will the standing water cause settlement for the pier posts in the middle of crawlspace? This is my biggest worry.
4. I dug the soil under the standing water, only the 2 inches soil on the surface is wet and muddy, but the soil below is very dry and solid. If your theory is correct, the underneath soil should also be wet, right?

RE: Water leak from crawlspace trench

So help on this, what is the age of the building? If it has been there for years, one thing, maybe no problem. If new, maybe a problem.

1. I'd not deepen the trench along side the footing. You will be weakening resistance to footing settlement.

2. Not sure about filling doing any good. The basic question I have is what is the local soils geology? If there has been filling in the area, likely more porous paths for water can be any place, and in some natural conditions there are differences in permeability from place to place, especially where the soil is water deposited. They can affect how site is treated.

3. Usually standing water has no significant effect on support, if was there when built, etc. Saturation of some soils (makes them more buoyant and less able to support loads.

4. Let's talk about degree of saturation. Loose soil, soft soil can carry quite a lot of water in the voids and may appear muddy. Dense soil, with a water table (surface) higher than its position, likely is saturated in the fewer voids and may not show any free water when cut open.

A wet crawl space may or may not have to be "drained". If it "sends" moisture up in the living area (due to high humidity) or causes rotting of posts to individual footings, etc. maybe try to drain it. However, if the space can be vented some, water there maybe nothing to worry about. The old house I once lived in had a pond under the ho9se in the crawl space, yet it was causing no problem with house occupants. It was a mess however when one had to go there for fixing pipes, etc.

To really resolve the water situation, you need detailed site soil information, along with water situations. This would take some test borings and perhaps water observation wells in those borings to use for figuring out how to fix things, if necessary. A local geotech may be able to do this. Providing a cross sectional drawing, with elevations drawn to scale, showing water level, as with test holes, etc. some guidance may help.

Off hand, I sometimes refer to a situation something like this as suppose this was a castle surrounded by a moat, then you maybe can fix things. However, suppose there is upward or horizontally flowing water in more porous places, the seepage water may not all be cut off by even deep trenches.

RE: Water leak from crawlspace trench

The house is built in 1987, and i do observe the soil is much harder near the posts.
Do you think it's possible that the water actually spreads horizontally through the muddy layer as illustrated below?

I don't know why the soil 2 inches below is so much dense than the surface, but is it possible that the dense soil will turn to mud as it's under the standing water?
I can live with the 2 inches standing water if it will not cause obvious settlement to the posts and piers.

RE: Water leak from crawlspace trench

OG here again.

Assuming your drawing is to scale, any excavation below and next to the footing grade is questionable. If you have a dense WELL GRADED gravel as the trench fill, maybe no problem, but I suspect single sized stone even if compacted won't provide much resistance to a slip or settlement. Liken that gravel as bunch of marbles, or nearly so.

With your question, if your "clay" has any montmorillonite mineral or other expansive mineral, swelling can occur.

Many areas of the world have expansive clays, but I suspect yours is not the "real worst stuff" or you would notice heaving and settling as moisture changes through the years and seasons. In technical terms that soil may not be what we define as clay, but coarser material likely in the silt range. For that house age, I suspect nothing unusual would result in the future with water there, or you would have noticed that long ago.

If you care to give the approximate location,that may help me.

RE: Water leak from crawlspace trench

It's in Bothell, WA.
The footer is fully exposed in the crawlspace, which means the trench is below the footing grade. I'm really worried now. The trench is 5 inches deep and 6 inches wide, and 5 inches away from the footing. What should i do now to prevent the slip and settlement? Thanks!!

RE: Water leak from crawlspace trench

It may or may not be a problem. However, If you want to mitigate and hopefully prevent movement, look at the mechanics of it. A slip or bulge of the material under the footings would go towards the trench. Assuming you have enough of that fabric on the sides of the tench, I'd fold it over the gravel and pipe. Then load up what you can on that trench area, possibly with left over gravel (SEE NOTE BELOW), or clean sand to counter the slippage bulging up of the trench filling material. Those footings need material to the side as well as underneath and taking some of it away tends to reduce the stability. At least covering the trench with porous soil won't have much effect on drainage performance. However, do NOT have any "mud" between the fabric covered gravel and where water emerges from the footing area. Perhaps extend up the fabric against the footing to accomplish this there. That means gravel, not being a filter, must have a filter before water enters. Thus concrete sand would work fine, since it is a universal filter.

As to expansive clays in your area, there may be some. Many of the volcanic derived clays are highly expansive. An example is the higher suburbs just west of Denver.

RE: Water leak from crawlspace trench

Thanks a lot for your help!
I don't know why they exposed the footer when the house was built, but I will do whatever you suggested and hope it will not cause big problem within 5 years.
Meanwhile, I will hire someone to raise the soil level in the crawlspace by back-filling some dirt and compact it, hopefully the standing water would be controlled below the surface.

RE: Water leak from crawlspace trench

One more thought. That soil on the outside of the wall exerts some pressure on the wall. Fortunately loads on the wall from above tend to keep it from sliding in, but add to the risk of a slippage as my sketch shows. A reduction of horizontal loads on he outside might be considered. Be sure surface drainage goes well away from the wall. There are ways to waterproof the ground surface to minimize infiltration of water. It is that water from above that adds to the pressure on the outside. One might even think about an external drain instead of what you did inside. If more on this, such as drain details, waterproof, etc. ask the question here and I suspet help can come forth.

On adding "dirt" to raise the grade, I'd not be too sure you can depend that the water table elevation won't rise also. Much depends on exactly where the water comes from, s I sketched as a strong possibility.

RE: Water leak from crawlspace trench

I just checked again and realized that two trenches were dug just next to the foundation wall, and the soil under these footers is already very soft. What should i do now? Will it work if I change the trench to a concrete trench (a trench built with 2 inches thick concrete)

RE: Water leak from crawlspace trench

While I may be able to advise on these matters usefully, there may be something I don't know that is important and may affect things. One of those factors is exactly what is the soil and ground water situation at your place? Unfortunately you may have caused some serious problem with the trenches next to footings. Then again, maybe not. At this stage, I'd check the yellow pages on a large community, perhaps even a few hundred miles away, if necessary, and see about AN EXPERIENCED geotech engineer, under ENGINEERS, CONSULTING section. Someone with at least 10 to 20 years experience in geotechnical engineering would be the start. I'd ask for a site visit st start and then there may be the need for some test borings or other examination there. This person should have experience working with specialty contractors, such as underpinning experienced contractors. A VERY experienced structural engineer may be OK, but someone with experience in underpinning foundation ENGINEERING would be best, not just a contractor. It may cost something not expected, but at least a visit to start is needed. My thought at what I see is that the adding of load on your filled trench and against the footing would lessen the chance of problems. A dense material that will not only filter some weeping water but also have better resistance to movement is the mixed sand and gravel that is the aggregate for concrete. A clean mix of sand and gravel would be OK, but there should be no silt that would clog the voids. Place that on the trench backfill and against the footing in 6 inch layers, each thoroughly tamped as with a 4 x 4, 4 ft. long is a start and maybe all that is needed. I'd tamp it into that soil under the footing where exposed also. I'd stack it up at least as high as the footing top there and taper it out, removing that plastic sheet first. I'd examine the walls carefully and look for cracks. At any cracks, old or new, clean off the dirt and draw a pencil or deep scratch across the crack. Then put two cross lines on that line, 2 inches apart. Keep a record of the distance between those marks, as well as any change dimension of the main line where it might displace in-out, up-down.

I'd start any filling like described above at the mid point of affected walls, since there is the most need for improvement. Adding concrete may sound good, but you need a way for water to travel also.

RE: Water leak from crawlspace trench

the purpose of all these actions are trying to avoid the soil to be reduced under the footer, correct? But why the soil is so soft underneath the footer? I thought they should be as hard as rock, is it because of the trench too?

RE: Water leak from crawlspace trench

I just took a look at Seattle, Belleview area consulting engineers doing a Google search. One in particular stood out, among many. An individual Professional
Engineer, a P.E. That is good. He is "on his own" also good. initials JKG. Another firm had plenty of adds and a neat web site, but no indication that the engineers ever graduated from college, or them being licensed professional engineers, which takes licensing, a definite requirement.. The person you use must be licensed as a PE and hopefully MANY YEARS expedience.

RE: Water leak from crawlspace trench

I'll consult someone about this as you suggested. I highlighted the impacted foundation walls below, luckily the majority of them is the garage walls, which do not take roof loads. And my foundation walls are concrete pouring walls which are not easy to crack. BTW, i failed to find the JKG, can you share his information here?

RE: Water leak from crawlspace trench

Is there any building code that mentions "no digging under footing grade"? My contractor says it's safe to do so.

RE: Water leak from crawlspace trench

Building codes don't usually dictate construction limits, but give approximate rules in regard to foundations such as how to size theB. Limited digging under and along size of foundations in common, in limited ares, such a when a pipe has to be placed under them, as for a water line coming in, etc.. but filing that excavation up with compacted material is good practice. What was done, in my view, a trench along side a footing and BELOW IT was very careless. The original plan for dewatering should have been reviewed by an experienced engineer. Other thoughts now, such as filling to not expose water again needs experienced guidance. At least a phone call to an experienced PE should be made, even if one is concerned about his fee. Your potential damages may well exceed any fee by very much. "Bite the bullet". It will be well worth it.

An edit here. I'm being kind using the word "careless".

One more edit. Link to a PE was deleted, because it is apparent the poster believes all contrators are better at these problems than engineers, apparently. Try a contactor site instead of here.

Good Bye

RE: Water leak from crawlspace trench

I made a call to Keith yesterday and am waiting for his reply. The contractor i mentioned here is the guy who dug the trench, sorry about my second language.
Thank you oldestguy, i really appreciate your help!
Good Bye, and best wishes to you.

RE: Water leak from crawlspace trench

OK Yi: That WEB site may be old. He may be dead. Look for someone with the same qualifications and experience and try not to second guess them. Offer a retainer. On your English, it's perfect.

OG back here with a point. I'd document everything in writing everything, dates, timing of work, items such as "changed to mud". You may be faced with significant cost to fix up the mistake you are facing. If the contractor doing the work had ANY input as to what to do where,when, document that, because you may have a significant claim against him. The document must be in writing or equal. Document payments, and later all payments and expenses for the consultant. It all may be the cost for the contractor now.

RE: Water leak from crawlspace trench

OG with a story: Let's hope your story of using a contractor instead of an engineer does not have the same outcome. My older brother at age 37 didn't believe in doctors. He used chiropractors. I visited him once and we met on the beach at Erie, PA. on Sunday. He didn't feel like swimming, but planned to see a chiropractor the next day due to a "Strain"" in his back. The next day his wife said he went to the chiropractor, but then was so pained that he could hardly walk to his car. He then went to a small clinic and signed in. A few days later, his wife said he was getting worse, so I drove to see him in the clinic-hospital. There I watched him die on Thursday. As he died, he turned yellow because there was significant infection in his liver, due to a case of hepatitis and it broke loose due to the manipulations of the chiropractor and went through his whole body. If he had only seen a medical doctor then he might even be alive now at age 95.

The story is: So now and then someone working in a given field may be pretty good on some things, but they may miss important factors that are very important. Even though I have many excellent contractor friends, I have some as VERY good friends due to me saving them lots of bucks now and then when otherwise they would have been in trouble.

By the way, my nearby neighbor is a chiropractor and we are great friends, but he is not getting any "jobs" from me. He does get help from me however.

RE: Water leak from crawlspace trench

The P.E you recommended replied and came to my house and did an inspection. He said he is not worried about the footing. And he also gave me some suggestions about the water problem. He is very nice and knowledgeable.

RE: Water leak from crawlspace trench

Nice suggestion OG...

RE: Water leak from crawlspace trench

Good to hear you made the contact. Follow the advice.

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