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Heavy rain floods basement, mainline to street system

Heavy rain floods basement, mainline to street system


  #1  
Old 11-16-18, 10:20 AM
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Heavy rain floods basement, mainline to street system

Hi, All --
Not sure if I'm posting this in the right spot, but here goes:

My wife and I bought a house a month and a half ago and have since weathered a few rain storms without issue. This past week, however, has brought more rain and some snow, and there's now water seeping rather quickly into the basement. The water is coming in from multiple parts of the stone foundation along the walls, and quickly from a pinpoint hole in middle of the basement where a cement post meets the ground. The cement covers the chimney, but the water doesn't appear to be coming down the chimney, as it has a cap and the old ash and inner brick walls inside the clean out are dry. The water continues to flow for more than a day after the rain stops. I'm not sure yet how melted snow will exacerbate the issue.

At the same time the water is coming in, it appears the issue is somehow connected to our mainline getting backed up from the street. We've had two plumbers and the city over to snake the mainline (102 feet to the street), so I know for sure at this point there's no blockage. The plumbers doubted the two issues could be connected, but the back up only happens during rain, so I'm having a difficult time discerning to two issues. I have a sump pump, which is keeping the water down, which is my only saving grace at the moment.

The house is old (1910-ish) with an irregular unfinished basement. We're on a hill set back from a somewhat densely populated city street.

The odd this is that when we visited the house multiple times before moving in (and once while it was raining) there was no evidence of water issues in the basement, which makes me fear this is all somehow self-inflicted. (I have reached out to the former owners to see if this is something they dealt with, but haven't heard back yet).

Any and all advice would be greatly appreciated.
Thanks,
Eli - At wit's end
 
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  #2  
Old 11-16-18, 10:52 AM
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How is the house equipped to handle the rain water on the outside?
Does the house have guttering? If so, is the water from the gutters piped away from the house?
Is the back fill around the perimeter of the house sloped away from the house?
 
  #3  
Old 11-16-18, 11:01 AM
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Old house, fieldstone foundation, hill, storm water--I know them well.

It is not a surprise that water will infiltrate a fieldstone foundation. They are nearly impossible to waterproof even from the outside.

You need to figure out where the water is coming from. What are the conditions outside? Do you have gutters and downspouts to direct water from the roof away from the house? Does the land slope away from the house on all sides?

Water coming in at the center of the floor slab indicates a high water table (like the house is a boat sitting in the middle of a puddle and water is forced up through the pinhole). This is due to the topography of the land and water flow through it. If you are halfway up a hill then any water that flows off the hill will back up against your wall and seep in and under the floor.

Your sump pump may be trying to lower the water table but obviously cannot be large enough to handle all the water that flows toward you. Is there french drain piping around the perimeter of the floor either inside or outside? That would intercept the water and should be routed to the sump pit to be pumped away. Where does your sump pump discharge? Outside? Into your "mainline" sewer? (Not legal in most places.)

A neighborhood as old as yours could possibly have a combined system that discharges storm water into the sanitary sewer. An overload from heavy rain would overwhelm the capacity of the sewer and cause backups as you experienced. A back flow (or check valve) on your mainline connection would prevent that.
 
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Old 11-16-18, 11:05 AM
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Originally Posted by Wirepuller38
How is the house equipped to handle the rain water on the outside?
Does the house have guttering? If so, is the water from the gutters piped away from the house?
Is the back fill around the perimeter of the house sloped away from the house?
Thanks for the reply.
The house is guttered, which I've cleared of all debris, leaves. The gutter system is designed to empty on the downhill side of the house at both the front and back, about 3-5 feet from the foundation and, it appears to be working OK. I originally connected the backside gutter system into what looks like an underground downspout, but after the flooding started I thought it might be related, so I disconnected it. The problem, nonetheless, persists.
As for slope, there is a strip of pavement on the uphill side abutting the house that is rather flat. The other sides of the house appear to be properly slopped away from the house.
Thanks again,
E
 
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Old 11-16-18, 11:17 AM
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Originally Posted by 2john02458
Old house, fieldstone foundation, hill, storm water--I know them well.

It is not a surprise that water will infiltrate a fieldstone foundation. They are nearly impossible to waterproof even from the outside.

You need to figure out where the water is coming from. What are the conditions outside? Do you have gutters and downspouts to direct water from the roof away from the house? Does the land slope away from the house on all sides?

Water coming in at the center of the floor slab indicates a high water table (like the house is a boat sitting in the middle of a puddle and water is forced up through the pinhole). This is due to the topography of the land and water flow through it. If you are halfway up a hill then any water that flows off the hill will back up against your wall and seep in and under the floor.

Your sump pump may be trying to lower the water table but obviously cannot be large enough to handle all the water that flows toward you. Is there french drain piping around the perimeter of the floor either inside or outside? That would intercept the water and should be routed to the sump pit to be pumped away. Where does your sump pump discharge? Outside? Into your "mainline" sewer? (Not legal in most places.)

A neighborhood as old as yours could possibly have a combined system that discharges storm water into the sanitary sewer. An overload from heavy rain would overwhelm the capacity of the sewer and cause backups as you experienced. A back flow (or check valve) on your mainline connection would prevent that.
Thank you! This is all really helpful information.
1) The gutters are designed to empty on the downhill side of the house at both the front and back, about 3-5 feet from the foundation and appear to be working OK. I originally connected the backside gutter system into what looks like an underground downspout, but after the flooding started I thought it might be related, so I disconnected it. The problem continues. As for slope, there is a strip of pavement on the uphill side abutting the house that is rather flat. The other sides of the house look to be properly slopped away from the house.
2) I don't think there is a french drain inside. What should I look for outside?
3) The sump pump empties outside on the downhill side of the house about five feet from the foundation.
4) I'm going to look into a back flow valve now!
Thanks again,
E
 
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Old 11-16-18, 02:08 PM
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I don't think there is a french drain inside. What should I look for outside?
It is not likely that one was installed when your house was built. If someone added one later you should find gravel above it. If you dug down 6-12 inches about a foot or so near the foundation and found a layer of gravel that continues down, there might be a perforated pipe at the bottom. You probably can't investigate where the concrete apron is against the house on the uphill side. Below that is where a french drain would be if there was one.

Typically a fieldstone foundation was constructed from the outside-in by digging a trench with a vertical face on the inside. Then stones were packed into the trench to form the foundation (2-3 feet thick.) the trench was then filled in at the outside (against mostly irregular stone work) and the cellar excavated from inside leaving (almost) vertical walls. The irregularity of the outside of the wall makes adding a french drain later very difficult.

A french drain could flow to a drywell underground or be open-to-air on the downhill side. If a drywell it is probably silted up after all these years. (Your "underground downspout connection" probably goes to an old drywell and is probably not working.)

You could look in your sump to see if there are any pipes (4 inch or so) emptying into it.

In 45 years I have devised several ways of dealing with the river that runs through my basement. Let me know if you are interested.
 
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Old 11-16-18, 02:32 PM
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Originally Posted by 2john02458
In 45 years I have devised several ways of dealing with the river that runs through my basement. Let me know if you are interested.
Thank you!
I'm going to prod around to see if I can find any of these things tomorrow.
I'm very interested to hear more about how you've dealt with your basement.
Best,
E
 
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Old 11-16-18, 02:44 PM
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Look for areas that seem wetter than surrounding. A drywell in 1910 would have been a hole in the ground filled with rocks. There might be a depression where there is one. Pipes open-to-air will have been covered over by now but also might show up as wetter spots.

Not likely that any original items would be usable now or can be restored.

More about my fixes later.
 
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Old 11-16-18, 03:27 PM
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When we bought our 1912 house with fieldstone foundation in 1975 there was a 3/8 inch plywood on flat 2X4s wooden floor built up over a section of the basement concrete floor near the rear wall. It covered about 1/3 of the area of the basement. That wall is at the uphill side of the lot at the base of a large hill. When it rained or snow melted water would FLOW through the back wall across the concrete floor (under the wood floor and across the exposed concrete floor) to a pit near the front of the house where the sewer cleanout is about 18 inches below the floor. The cleanout cap was left open and storm water would flow into the sewer (illegal).

Also at that time the brick driveway at the front and side of the house followed the steep profile of the lot (about 30 degree rise). About halfway up storm water would seep out between the bricks and run down the driveway to the street. This would continue for several days after it rained and iced up in winter.

In 1978 (after the blizzard--Boston area) we excavated the driveway to level it and realized the extent of the water flowing out of the side of the hill. We dealt with that by adding french drains above the driveway and along that side of the house to direct the water to the downhill side of the excavation. At that time our city did not require containment of storm water so it still flows into the street. Now they would require an on-site drywell and possibly a connection to the separate storm sewer.

We also found clay tile pipe underground that was originally installed to take water from the downspouts. They just ended underground about 30 feet from the downspout--no drywells

Meanwhile inside the basement wood floor rotted out to the point that several years later we removed it. That made all of the basement unusable whenever it rained and during snow melt.

First, we added a sump pump in the pit that discharges through the wall into the french drain piping at the side of the house and closed the cleanout cap.

Next we created a dike along the walls where the water comes in using steel angle iron screwed into the concrete floor, garage door weather stripping and roofing cement. The dike runs to the sump pit and the water is directed there to be pumped out. Also we can see that water under the concrete floor follows the path of the underfloor sewer line from back-to-front into the cleanout pit.

This arrangement was about 80% effective. About 15 years ago we finally got around to adding a french drain across the back of the house about 12 feet away from the back wall. There is a deck and greenhouse there against the house so we could not get closer. The french drain is about 2 feet deep and is connected to the french drain piping at the side of the house. Under the deck a short french drain was added near a window opening where a lot of the water enters through the wall. It slopes away from the house to the french drain further out. Also the area under the deck was sloped away from the house and covered with a tarp so that any water that drips through the deck is directed to the french drain at the perimeter.

Now I would say that the arrangement is 98% effective with only slight seepage in the worst conditions (usually when ground outside is frozen.)

Boiler, laundry equipment and workshop equipment is raised on 2 inch pedestals "just-in-case" but the entire basement is now usable for storage, workshop, laundry, and wine cellar.
 
 

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