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The rubble stone foundation walls wept every time it rained, creating a dank, humid basement. The destructive power of ice dams, and a huge, overhanging elm tree created maintenance issues, leaving our clients unwilling to replace the gutters original to the old two-story house. The lot sloping to the rear left the downhill neighbors’ yards saturated much of the year. How were we going to solve these problems? By installing a ground gutter system.
A ground gutter is similar to the French drains familiar to most builders, with a few additional components. On this project, we started by digging a trench along the foundation wall, 12 in. deep at the front and pitching 1/4 in. per foot toward the back of the house. The trench is 24 in. wide, enough to catch rain falling from the eaves. We lined the trench with 0.060-in.-thick EPDM, a rubber roofing product (thinner 0.040-in. EPDM can be purchased from landscaping suppliers). We didn’t attempt to attach the membrane to the stone foundation but took care in keeping it close to the wall as the trench was filled.
At the bottom of the trench we laid 4-in. perforated PVC pipe directly under the roof’s drip line. Where the pipes join and change direction we installed distribution boxes with removable covers, providing access in the event of a clog. At the distribution boxes we also tied in 6-in. solid PVC drains. We connected this to downspouts from the one section of gutter we did install on the addition roof, which is easily accessed and ice-dam resistant. We filled the trench with 3/4-in. washed crushed stone, placing a layer of permeable landscape fabric about 2 in. below the surface to keep silt and debris out of the trench.
The drains tie together into a single 6-in. perforated PVC line that leads to a dry well 8-ft. x 12-ft. x 5-ft. deep. The dry well is lined with landscape fabric and filled with 11/2 in. crushed stone. We covered the crushed stone with more fabric, a loam/compost mixture for a planting bed, and a layer of partially decomposed bark mulch. The dry well should be able to handle up to an inch of rain before filling up. The few times a year that the dry well reaches capacity, the excess rainwater will exit via a 6-in. outflow pipe just below grade.
The outflow pipe leads to a back corner of the property, where it exits onto riprap (6 in. crushed stone) to prevent erosion, behind a swale. Not only will this keep the neighbor’s yard dry, the rainwater will have several hundred feet of forest to be absorbed into before reaching a river. That’s a big improvement over the original gutters, which fed into the municipal storm drain—and directly into the river in big storms.
What our clients are happiest about, though, is their dry basement.
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5 Comments
Draining a very small spring 300' from its source
I used 4' corregated drain tubing but it collected mineral deposits and clogged. Will 4' pvc pipe do better? What minimum slope? Volume of spring water is 2 quarts per minute.
"Collected mineral deposits"?
John,
I'm not sure what you mean when you write that your perforated drain pipe "collected mineral deposits." Do you mean that it got clogged by silt? If so, the solution is to surround the pipe with adequate amounts of clean crushed stone. The crushed stone should be placed under, on either side of, and on top of the drain pipe. The stone should be protected on all sides with a "sausage" of folded landscape fabric. The purpose of the fabric is to prevent the pipe from getting clogged by silt particles.
PVC is better
It sounds to me like John is draining a point source of water that contains sediment. As the water runs through the pipe the sediment settles out. Interior plumbing drains have minimum slopes but also maximum slopes--the idea is that you don't want the water to "outrun" the solids. I've heard arguments for and against this rule of thumb, but 1/8" to 1/4" per foot is the usual recommended pitch.
Smooth-walled PVC pipe is better than corrugated plastic. It's a little more work to install but it's much easier to avoid low spots, it doesn't crush, and it's easy to include a necessary component of ANY drainage system---a cleanout. In the blog photo you can see one of a couple distribution boxes we installed to tie different lines together, but also to provide a spot from which the line can be snaked in the event of a clog.
When using rigid PVC, be sure to use "street 90's" at the corners--they provide a smoother transition between pipes.
Martin's suggestions are right on for perforated drains, for which PVC is also superior to corrugated pipe.
interesting to see
I've been using a similar gutter system for 35 yrs. I never did like the idea of normal gutters, having cleaned my dad's about 1,000 times. I dug a ditch at some slope, lined it with 8 or 10 mil visqueen, and laid PVC drain pipe in the bottom, holes down. I then filled the ditch with coarse aggregate and watched the first rains, and all since, splash about and run off. The dirt between the house and the "gutter" is bone dry, except for a little spray when it rains. Works for about 15-20 yrs, then I have to hog out boreal detritus that collects; pretty quick, really. Of note, there is a 3' roof overhang where I use this system.
EPDM Trench Liner Not Recommended
I have installed dozens of these systems here in Arkansas over the past 10 years where the average rainfall is 42" per year. We get a storm event of 1" per hour several times per year which is a heavy, severe storm. The EPDM trench liner is a seductive mistake lots of guys make: don't do it. I have seen several of these systems quickly fail even though carefully installed. Use filter fabric instead to prevent the drift of detritus into your clear gravel. The problem is the EPDM can lock out any "renegade rainfall" that misses the planned access from above. Any accidental (as in you didn't know it was there) underground water will also be locked out of the trench and can pressurize against the basement wall, leaking where there was no leak before the ground gutter. Trust the clear 1-1/2" gravel- the gaps between the stones are always the path of least resistance for the water- irresistible to the confounded stuff!
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