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Swale to pull water away from house?  RSS feed

 
jeff charelbois
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Just curious if this will work or not any input appriciated. I currently get water in my basement from only very heavy rain falls the edge at the floor starts to weep. Id guess the water table is surpassing the footings and floor. I am wondering if while I work my plan to make a forest garden if a swale could solve this problem as well as get me to that goal? The land is sloped away and I have a few inches thick of mulch around it that seemed to help a bit. Im thinking a swale would draw the runoff away from the foundation more. would a swale the lenght of that wall a few feet away 6-8 accomplish this? I would likely then add more swales to pull the water further away to where id like it to be so kind of like a big "E" with the back of the "E" 6-8 ft from the wall. Not nessicarily straight but thats th genreal thought. Also the internet implies that plating in that area may make it worse but I dont see it that way I would think the roots of the shrubs and plants would assist me like a huglekulture soaking itin and keeping it from saturating to the point where my problem occurs? Opinions?
 
Cj Sloane
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Location: Vermont, off grid for 24 years!
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A swale can work and so can a berm. Even do both!

If I can remember the exact reference I'll let you know. May have been the geoff lawton PDC but I'm not sure.
 
Ben Stallings
Posts: 160
Location: Emporia, KS
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Hi, Jeff. The short answer is yes, this can work. I did it as one of the first improvements to my property, as the basement flooded twice in the first week we lived here! Our land doesn't slope much, so the swales are only a couple inches high, just enough to stop sheet flow from getting closer to the house. I dug them slightly off contour so that they overflow away from the house. Not only did the basement stop flooding, the lawn and garden were much healthier for the extra water!

Grading the ground around the foundation is also crucial. The magic ratio I've heard is 6" of rise over 6' of run. I built a wooden jig to help me determine if I had that much slope: a long board with a short board screwed to it at a right angle so that the inside measurements are 6' and 6" respectively; I strapped a level to the longer arm and walked around the house setting it down every few feet and marking the spots that didn't comply.

The final piece of the puzzle may be obvious, but I've seen many houses where people apparently didn't think of it -- your downspouts need to take the roof water more than 6' from the house and keep it there. If you don't have downspouts, the grading is all the more important. If you have rain barrels, make sure they have enough overflow to handle the heaviest rains and take it 6' or more away, or use a downspout diverter to reduce the flow to the barrels to a level their overflow can handle.
 
Walter McQuie
Posts: 49
Location: Northern New Mexico
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Hi Jeff, It's pretty hard to come up with an effective plan without an accurate diagnosis of the problem, and it's pretty hard to assess all the potential contributors to the problem without having seen the lay of the land, so to speak. So I'm just going with your observation that when you get heavy rain your local water table rises above the level of your basement flour and seeps in. You want to look at the lay of the nearby land to see if there is surface flow toward your house. If so can you intercept that flow with a berm placed to direct the flow to a area lower than the ground around your house. As Ben suggests the water that causes your water table to rise may be coming off your roof. Depending on the lay of your land, you may need to get that water more than 6' from the house. If, for example, it would just puddle up at the six foot point it may still be contributing to the water table rising into your basement.

As a matter of terminology, when you say swale, I think of a structure designed to prevent water from flowing down a slope, slowing it enough that it sinks into the ground. Seems you want just the opposite to happen. A simple ditch might do the trick. If more drainage is need you could dig a trench that gets deeper as it moves further from the building, add some large gravel/small stones and perforated drain pipe, call it a french drain and hope for the best. The drain could terminate in an area where you want to plant. But if that is only 6' or 8' feet away from your house, it could still be contributing to the level of the water table up against your basement at times when lots of water is added to the system. Again, this can't really be determined from afar. It can be very difficult to determine the contours of the water table near your house and the way it responds to big rain events without observing the contour of the land and even boring some test holes to see how permeable the soil is at various depths and distances from your foundation. Redirecting surface flow is a tool here; the objective is to alter the contours of the water table.

I assume that on-line advice not to plant near your foundation has to do with the tendency of plant roots to find cracks in your foundation and perhaps make them bigger. In reading about planting trees to help green the dessert, one learns that many people believe that this works because having trees puts more water into the water table than they remove. A hugelbed could suck up some of the water that is seeping into your basement, but not if it is already saturated when the big rain comes. Good luck, leaky basements are a challenge.
 
Rufus Laggren
Posts: 480
Location: Chicago/San Francisco
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Assuming a concrete basement (also CMU - cinderblock), some sealers seem to work, both inside and outside the wall; outside usually works better, of course. I have used a "Thoroseal" product inside a CMU full height basement with regular flooding problems; in the last 3 years it seems to have helped a lot. There are various similar products available; this company seems to have been selling this type of stuff for about as long/longer than anybody.

http://www.buildingsystems.basf.com/p02/USWeb-Internet/buildingsystems/en_GB/content/microsites/buildingsystems/products/items/Thoroseal

The surface needs to be cleaned for best results.

Whether you'd want to consider this option depends, of course, on how you want to spend your resources and what other "adjustments" you're making to your site. After providing good access to the walls/joints of concern I found (using power tools to clean and then brushing the sealer) it takes (very roughly) about 2-4 minutes/foot of joint to both clean the material and apply the sealer (but done as separate jobs). The more you do the less time per unit.

Rufus
 
jeff charelbois
Posts: 5
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Ben Stallings wrote:Hi, Jeff. The short answer is yes, this can work. I did it as one of the first improvements to my property, as the basement flooded twice in the first week we lived here! Our land doesn't slope much, so the swales are only a couple inches high, just enough to stop sheet flow from getting closer to the house. I dug them slightly off contour so that they overflow away from the house. Not only did the basement stop flooding, the lawn and garden were much healthier for the extra water!

Grading the ground around the foundation is also crucial. The magic ratio I've heard is 6" of rise over 6' of run. I built a wooden jig to help me determine if I had that much slope: a long board with a short board screwed to it at a right angle so that the inside measurements are 6' and 6" respectively; I strapped a level to the longer arm and walked around the house setting it down every few feet and marking the spots that didn't comply.

The final piece of the puzzle may be obvious, but I've seen many houses where people apparently didn't think of it -- your downspouts need to take the roof water more than 6' from the house and keep it there. If you don't have downspouts, the grading is all the more important. If you have rain barrels, make sure they have enough overflow to handle the heaviest rains and take it 6' or more away, or use a downspout diverter to reduce the flow to the barrels to a level their overflow can handle.


I do think i need more slope but to get 'll need to have the gas company raise my meter I've already added as much as i can without covering it. I do have extentions on my downspouts but the may not hit the 6ft mark I'll check that out stat. and probably move them out more even if they are 6ft. hand put them where i plan to put a swale and berm for the food forest. I guess i will see how much getting the meter moved will cost me too so I can add soil berm to the edge of the house. I also have a storm water collection basin in the back that may be the root of this problem but its pretty far from the house. It des fill at the same times as the basement gets wet. so id guess diverting everything from it into the grounds may also help. Thank you all for the responses It was a great help! any additional help is also appriciated!!!
 
Penelope Fortenberry
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Rufus Laggren wrote:Assuming a concrete basement (also CMU - cinderblock), some sealers seem to work, both inside and outside the wall; outside usually works better, of course. I have used a "Thoroseal" product inside a CMU full height basement with regular flooding problems; in the last 3 years it seems to have helped a lot.

Be careful with these. Since the standing water tends to then get stuck in the CMU behind the sealer, you can get evap and condensate up throughout that porous substance which can then leading toward in-wall mold problems in the living area. At least if the water gets into the basement and through the CMU, it floods, and dries, rapidly, but keeping the CMU constantly wet behind the seal and removing surface air exposure can be problematic. The only safe way to truly waterproof a basement is externally so that the inside becomes conditioned by the building envelope.
 
Roberto pokachinni
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Location: Fraser Headwaters, B.C., Zone3, Latitude 53N, Altitude 2750', Boreal/Temperate Rainforest-transition
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Some good advice already given here. I would reiterate that swales on the contour are NOT what you want here. Swales on the contour charge the water table down slope from them. You want them off contour, or dramatically off contour (a ditch), in order to divert flow and reduce seepage in the area of your home. It might look a bit ugly, at first before your forest takes form and the ditches show their purpose, but I wouldn't try to pretty them up with mulch, or soften the bottom with spike rooted plants. The ditching does not have to be dramatic, especially if the excavated material is mounded on the house side of the trench, just so that water hits it and drains along it and out of the area. Just from what you said, without having seen anything, I would do several of them.

Overkill on drainage, always, around your house.

All drainage and overflow near your house needs to be directed away, and if you are planning a food forest already and it has not been planted... sit down now and redesign it. Plan the flow pattern of the water off the slope above your house site, and from your house and it's catchments and overflows so that they are ALL directed to it, and are charging the water table, if at all possible, as down slope from your house as possible without being inconvenient for your handy foodie needs. It may have to move from your dream location in order to accommodate your more important need for a dry, mold free, home. Move it for the very reason that any forest, as it grows, is bound to increase your water table over time.

If you want to plant near your house do it on the mounds along your trenches with water lovers, like willow (but not the weeping ones or any willows that invade your basement and plumbing with roots-do some research on your local willows.). Coppicing the willows for crafts, rocket stove fuel, and other tasks, will remove moisture by forcing regrowth. Willows are super easy to grow, by jamming a cut piece in the ground in the early spring. It will root and take off (you can make rooting hormone from willows too). A line of comfrey would work too. You can chop it and haul it in a wheelbarrow to your food forest or compost, again forcing regrowth which draws water from that soil. A crop line of bamboo on the upper part of your property, again utilized to draw water by cutting it and making use of the stalks, will also stop overland flow and gather mulch for you.

Good luck.
 
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