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-   -   sump pit/pump questions (http://www.diychatroom.com/f19/sump-pit-pump-questions-64383/)

aliasoink 02-14-2010 02:00 AM

sump pit/pump questions
 
I have a 13 year old house. We have lived here 10 years, and have never seen a drop of water in the sump pit. Recently, a couple of leaks have developed through wall cracks in the foundation. The water ran down the wall and underneath the carpet in our finished basement.

Where I live in eastern Missouri, there was over 50" of rain in each of the last two years, where normal rainfall is around 37"/year. The sump pit had no water in it at all. A waterproofing contractor told me the house does not have a typical corrugated french drain tile system, but it has a tray like system that sits on top of the footing, and drains into the sump pit via a 3/4" pvc pipe. Our sump pit has holes drilled into the sides and bottom of it, and it appears to be surrounded with rock. I assume this is to enable it to collect water that moves under the basement floor.

Here are my questions. Does a sump and drain tile system alleviate the level of the water table below the house? In other words, when the water table rises to the level of the sump pit and drain tray, the sump pit fills up and is subsequently pumped out by the sump pump? Or is the sump pit and drain tile system supposed to collect surface water that drains through to it? If this is the case, is it a concern that the drain tray system is defective and not doing it's job since water is leaking through two cracks in the basement wall and there is no water in the sump pit?
Or is the only problem the cracks in the wall, eventually leaking because of the high amount of rainfall the past two years?

The leaks through the basement wall cracks appear to leak mostly after heavy rains. If it doesn't rain for a few weeks, it takes a couple good soakers to get them leaking again. Thanks in advance for your comments on this.

AndrewF 02-14-2010 10:45 AM

Do you have gutters on your house? How far away do the downspouts discharge? It sounds like the issue is water is taking the route of least resistance as it drains thru the soil, coming into the basement wall cracks.

Typically a sump pump pit should keep the water level no higher than itself.

In my case, mine always has water in it and when it rains, it runs...up to 30x a day.

jomama45 02-14-2010 11:30 AM

Quote:

Originally Posted by aliasoink (Post 399514)
Here are my questions. Does a sump and drain tile system alleviate the level of the water table below the house? In other words, when the water table rises to the level of the sump pit and drain tray, the sump pit fills up and is subsequently pumped out by the sump pump? Or is the sump pit and drain tile system supposed to collect surface water that drains through to it? If this is the case, is it a concern that the drain tray system is defective and not doing it's job since water is leaking through two cracks in the basement wall and there is no water in the sump pit?
Or is the only problem the cracks in the wall, eventually leaking because of the high amount of rainfall the past two years?


Yes to both of those questions. It sounds like the system is a retro-fit. It sounds like it lacks the most important element (IMO) which is exterior draintile.

TANC 02-14-2010 11:33 AM

Quote:

Originally Posted by jomama45 (Post 399627)
Yes to both of those questions. It sounds like the system is a retro-fit. It sounds like it lacks the most important element (IMO) which is exterior draintile.

Ditto, draintile is super important. . .. A big job, consider getting it hired done.

The only bad part to it being right is your have to replace the pump often (my pump runs all the time). This will however save my basement from leaking. .

AndrewF 02-14-2010 01:24 PM

Quote:

Originally Posted by TANC (Post 399629)
Ditto, draintile is super important. . .. A big job, consider getting it hired done.

The only bad part to it being right is your have to replace the pump often (my pump runs all the time). This will however save my basement from leaking. .

Yup, I lost one a year ago. I always keep a spare on the shelf and have future plans to put two in the bit, with the floats at different levels.

jomama45 02-14-2010 01:36 PM

Quote:

Originally Posted by AndrewF (Post 399707)
Yup, I lost one a year ago. I always keep a spare on the shelf and have future plans to put two in the bit, with the floats at different levels.


Very good idea IMO. Never hurts to have one ready to go & waiting. I always reccomend this to customers that have a pump that runs alot. Also doesn't hurt to have the pipe cut & threaded into the spare pump, so if it goes out, you can simply loosen the fernco clamps on the check valve & install the new pump w/o looking/running for parts.

aliasoink 02-14-2010 01:45 PM

The house has gutters and downspouts on it, and they carry the water away from the house. The slope away from the house is a question mark for me, where the cracks are. There could be some improvement there. I have been told that maybe the surface water is not able to get to the drain tile system if the soil around the foundation has a high clay content. I do not know if this is the case.

arid 03-02-2010 11:19 PM

the system that you have suppose to alleviate the problem from below but that type of system is not too successful in doing that. when the water comes through the cracks, does it come through at eye level or more towards the bottom?

three things to make sure you have satisfactory....your gutters cleaned, your downspouts clear and extended about 5' away from the house and make sure the rain water doesn't come back towards the house and make sure the immediate 5' from your foundation on the outside is sloped away and no water pools up there. if all of that is taken care of, you most likely have a ground water issue.

Daniel Holzman 03-03-2010 12:41 AM

The OPS stated that he has a drain tile system, a corrugated one rather than a perf pipe. The OPS also stated that the sump pit is surrounded by gravel, and has the proper holes leading into it. The OPS also indicated that the pit is dry, even after prolonged rains. Based on this information, there is absolutely no indication that there is any problem at all with the sump pump system, it is never needed.

The subfloor drainage system can only collect groundwater. Surface water that drains downward eventually reaches the groundwater level, at which point it would be collected by the sump, except from your description the groundwater table is lower than the sump pit, so no groundwater or surface water is ever collected. The most reasonable conclusion is that some of the surface water is "hanging up" on its way down to the groundwater level, and leaking through some cracks in the walls.

This can be corrected as previously noted by insuring that surface water drains away from your house, either by use of gutters or by proper grading. You can also consider repairing the cracks in the wall, either by epoxy injection or similar techniques. Most probably your wall was not backfilled with select gravel, so the surface water cannot drain downward effectively. You could excavated and backfill the wall with free draining gravel, however this would be expensive and probably overkill for what sounds like a small leak.

Try the gutter solution first, fix the cracks second (if the gutters don't fix the problem), replace backfill last if all else fails. As for the pump, sounds like the system is never used, so it is impossible to say how well it would work. Worth testing the pump once a year anyway just to see if it runs.


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