Ground Water Resources 1

[SpecB07]

Civil/Environmental Engineers

I am a Mechanical Engineer in search of some good resources for ground water and drainage fundamentals, i.e. books, websites etc. I have a somewhat leaky basement and a cracked foundation which I am trying to assess. I believe the resources that would be most helpful would have a variety of test methods for determining ground water issue so that I may try them. What is known so far is that the soil under my house is sand, over sandy loam where there used to be a large ravine and it was filled and compacted. The house is on a street that is a hill where my elevation is approximately 150MSL and the nottom of the street is very wet and at most 60 ft MSL so I have landscape for water to continue down the street. The other negative is that the house sits in a channel where the backyard slopes upwards into a large hill and the front of the house slops into the house from the street, BUT the backyard (also very wet at times) is lower then the house and semi flat until the property line where the neighbors yards is sloped down hill. Also, apparently there was a small stream which was piped where the house is now (but much deeper before it was filled. One corner of the property which clearly has the driveway and landscape graded into it, has water issues; however, I am trying to figure out if simply grading the property correctly will be my fix, or is there a high water table also causing me problems. The corner with water usually has some sign of a moisture line where the wall meets the floor and as stated before, it has water penetration during heavy rains. Any direction in identifying my true underlying problem would be of great help and I want to be as knowledgeable as possible if I need to call someone so I can assess whether they know what is really going on.

 

[cvg]

For starters, it sounds like your house was built in an unfortunate location and the builder didn't do you any favors...

this has been discussed quite a few times in the past. just searching for sump pump or french drain yields numerous posts that may provide some insight, see links below.

If you want to get to the bottom of it, you will need to do some more research or provide more details. Do you have a sump pump? Do you have a foundation drain, french drain? Is surface water drained around your house? Do you have posative drainage away from your foundation? Any idea how deep the groundwater table is? Is the foundation concrete, block, rubble, or some other type of construction? Is there any external or internal waterproofing? How old is it? How much rain have you had?

http://www.eng-tips.com/search.cfm?searchstring=sump pump&action=search

http://www.eng-tips.com/search.cfm?searchstring=french drain&action=search

 

[SpecB07]

The location has issues based on the current layout, but also has plenty of options to remedy them. (drainage basin in back yard at low spot although I don’t know where it goes or where the one pipe that constantly drips water in even in dry weather comes from), easement in front which can be tapped into. However you are correct to say the builder hasn't done me any favors! The questions are difficult to answer for me at this point and I am not sure how to find the information even but here is what I know of them.

1) sump pit present but no pump I believe, and its located on the right side of the front of the house as apposed to the left side of the front of the house where all the water issues reside.

2) I am unsure about the French drains around the home

3) The surface water is not directed around the property correctly and it certainly has the ability to puddle at the location that is wet most of the time, which I intend on attempting to fix this year HOWEVER, I am unsure if there is a deeper issue here for which I have reason to believe and I would rather not sink money into the repair and find out ground water is an issue (hence hoping to find resources that may allow me to perform tests to find out).

4) Not sure on the positive drainage, is it something I can measure?

5) I did look up the ground table from a basic map of the area once, where it showed the ground water lower then my property in elevation. I don’t know how accurate it was and my guess was since the area is "sandy loam" with sand filled it should have a heck of an absorption rate if the level was indeed much lower, hence I shouldn't have water issues right?

6) Foundation is poured concrete

7) Certainly no internal water proofing, ext. is unknown but I do not see any foam board sticking out from the ground near it.

8) Home was built in 1987

9) Rain has been bountiful, however, water was clearly present for an extended period of time since the floor was covered by a built up wood platform when home was purchased recently. Wood was removed to find it had rotted and mold was formed. Cleaned all the wood out and I observed the water that was supposedly never there and these observations were made:

The floor has a crack in it in this particular corner of the house. The crack and the seam of the wall against the floor in this particular corner always shows a line of moisture. The wall in this corner has signs of efflorescence all the way to the top so I do know that surface water is a concern. When it rains, this corner generally has a very shallow puddle which lasts sometimes weeks. When it rains a lot, water shows up in the other corner of this particular area and last time the water came up in the other corner, it left a thick layer of white power! I am guessing efflorescence again but it was a lot, like a ¼ inch think. This area is the foundation under the front porch where the inner wall is the structure of the house and the outer wall was poured to support the front porch. The two walls had corrugated steel placed across them and cement was poured on it. Another important note, this corner is also right next to the garage and the apron between the garage and the driveway has sunk as much as 3 to 4 inched in areas where tires drive constantly!! I literally have to jump the edge to get into the garage.

Any thoughts?

 

[cvg]

fix the surface drainage problems first, they usually have a very posative effect on water in your basement.

posative drainage means that water can flow off your property because the land is sloped. The ground should slope away from the foundation. Where the water comes down the hill it should be able to flow around your house without going uphill (it has a difficult time doing that).

If you have ponding areas, than you need to get rid of them. Fill with dirt and make sure you have a drainage swale running from one end to the other. Unless you have a very large lot, a pond near your house is a bad idea.

you need to do more investigating of the sump pit. is there a pipe coming into it from under the slab?

Do you have a drain in the basement? does water back up from the drain ever? Any sewage smell ever?

Is there a waterline or sewerline under the driveway apron that is broken or leaking?

 

[SpecB07]

I do plan to address the surface water issues this spring/summer although no easy choir. First that driveway apron needs to be raised so it doesn't make the interface between my garage and the driveway the lowest spot, Can i cut back a few feet and replace with cement? then water proof over it with the rest of the driveway? then I need to raise the walk way in front of the house and add underground drainage at some low spot where all the driveway water and walkway water can all collect into a basin and be piped. Now the difficult part, I have to pipe that to my backyard (or town drain I suppose) where my back yard has a catch basin I could tie into, but I dont know how much water the catch basin can support / where it dumps, etc etc and my back yard already is subjected to some ponding during heavy water time because for some reason the land does not absorb quickly (is that an indication the ground is saturated? or could there be other reasons the water won't percolate into the ground? because my catch basin never backs up and the water level in there is a good 5 or 6 feet down.

Is the catch basin water level a good indication of water table level since it is gravel at the bottom?

Anyway, then I need to pipe the water slightly ponding or atleast damp in the backyard and I just dont know how to do that without potentially pissing off some neighbors.

I will remove the cover to the pit soon, does it just pull out? It looks like it is set in with some adhesive holding it in around the edges similar to cement color but more powder like and not hard.

No drain in the basement, generally no sign of water backing up, except where it comes in the front. One other note, the basement is very moist in the summer, it smells of moisture (never sewage or anything) but in the summer with heavy rains, the grout lines in the tile down there turn dark in color and occasionally mold grow on the grout (I don’t know if its condensing or water table level under the foundation floor).

Sewage line in the house run straight out the front wall of home on the opposite side of driveway, same with water line (not saying they cant be under the drive way but it seems unlikely to run towards the right of my property when they could just go straight out to the street.

 

[Pearse29]

Have had very similar problems here in Ireland with leaking concncrete foundations and GW water ingress. Although there are a number of solutions and ideas on lowering GW water levels, it will depend on the specific underlying conditions, permeability, geology and soil dynamics. The question is do you want a solution to your leaking foundation, or do you want to resolve the whole underlying issue of rising GW. The later will be difficult to resolve (thanks to those who constructed the house) and expensive, invloving extensive excavation, sumps, pumps and drainage installation. However, if the leaking foundation is the main concern, then there is one low cost solution, see the link below;

http://www.mc-bauchemie.com/unternehmen.aspx

This has been a product we have used for years now on major water treament projects and deep foundations. The basic concept is injection of the resin into leaking cracks and foundations. Great product and works really well. You can also inject through walls and floors and it reacts with water the form a waterproof membrane (layer) surrounding the basement walls or foundations and has a gaurantee of 20-30 years. It is quite an expensive product, but may be an alternative to excavation and disturbance which can sometimes create more problems. Check it out, we have been using it for years on underground water and wastewater treatment plants. Although be warned, it is only suitable for concrete bases and walls due to the high pressures at which it is injected. I have worked in San Francisco for a year and have seen it used there so it should be sourced easily enough in the states.

 

[SpecB07]

Thank you all for the input. Suggestions are very helpful. However, I also want to understand what goes into looking at a peice of land and determining what is going on underground and the fundamentals of determining how the land can be used. I am assuming someone had to have come out and checked out this land after it was filled in with extra dirt and stamped it suitable for building a home. I have seen the soil compaction test in the town hall but that is about it. Can anyone point me to a good book which lays out fundamentals for ground water/soil dynamics for which the book may have field tests I can use as well?

 

[cvg]

before you jump to conclusions, there is insufficient evidence presented here to determine if this is a groundwater or a surface water problem. It could be both. Or it could just be shoddy construction and more of a structural problem. You can't solve it until you know what is causing the problem. If a surface water problem, you need a basic understanding of hydrology along with some knowledge of grading and geotechnical engineering. If this is a groundwater problem, then more geotechnical and geologic background is necessary. I'm not convinced you can quickly get to the bottom of this by reading some books. It might be better to find a civil or geotechnical engineer friend, have them take a look at it. Even a good contractor might be able to diagnose the problem and solution.

for good books,

Maidments book on hydrology
USBR Ground Water Manual
Cedergren on Seepage and Groundwater Control
USACE EM 1110-2-1421 Groundwater Hydrology

search the forums for many more, especially the geotechnical engineering, foundation, storm/flood and earthworks forums

 

[SpecB07]

Thank you very much for the resources, I agree with you in the fact that I will unlikely be able to accurately assess the current problem from reading a few books but knowledge is power and at this point, my back ground would not even allow me to assess if the contractor I choose to look at the problem has a good sense for what is going on. At this point, my goal is to have enough of a basic understanding to make that assessment. Thank you again for all your help.

 

[TDAA]

That is one advantage of having an engineer look at it vs just a contractor. Keep in mind, the engineer gets paid the same, regardless of the proposed fix. The contractor can get paid more depending on what fix he thinks should be done. This is not to say that an engineered solution will be cheaper though. I have put in some pretty elaborate systems behind some houses to control water issues.

By the way, how much grade change is there just on your property? If you do go with a drain keep in mind that you have to outlet it. Depending on the locality, they may not want you to outlet into their systems. If you outlet to your sump, be prepared to have it run a lot.

Speaking of the sump, pull the lid. If there is sufficient water in it and an inflow of water (or water above the inlet), get a pump, and draw it down. Keep track of roughly how much water is leaving and any change there may be.