Installing a Basement-to-Daylight Drain Pipe
Like many on this forum, I’m considering different approaches to getting the water out of my basement, which is on a high water table. Here’s my question: assuming a site has the right topography, can directional boring (aka horizontal directional drilling or HDD) be used as a non-disruptive way to install an underground basement-to-daylight drain pipe? Specifically, I’m picturing a pipe that would give water a direct path from a sump basin to an outlet at a lower elevation, replacing the need for a mechanical sump pump.
I’m attaching a sketch (not to scale) that illustrates what I’m imagining for my particular site. I’m in Upstate NY (5A), with clay soil and plenty of slope to pitch the pipe steeper than the minimum ¼” per foot I’ve seen recommended on this website. The approximate distance from sump basin to swale is 70 feet.
Though I’m open to using a sump pump as a backup, The reason I don’t want to use one as the first line of defense is that my basement floor is currently right at the level of the water table. I worry about creating a continuously flowing river of water that will cause a pump to run all the time. I’d rather rely on gravity than a mechanical device.
I’d appreciate any guidance as to whether this approach is worth pursuing, and if so, what considerations or potential pitfalls I should keep in mind.
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You could also dig a trench with a mini excavator and run your line to daylight. This is much better than a sump as it is always working and would have a high capacity. Sump pumps can be overwhelmed, most are only 1.5".
Thanks for that idea, Doug. A trenched approach would definitely be more disruptive to my front yard, but it might be worth pricing out both options.
Yes, you can install this by directional drilling. I contract work like this out all the time (I just looked at a project yesterday in fact), but for telecom work -- to install fiber optic cable. You CAN use it to put in drain lines though, and I've done that too, but always for sump pumps. The big advantage is you just have to excavate a bore pit on one end, sometimes both, and you have no disruption to the terrain in between.
You have to be very careful when going under foundations or footings since the drill rig will disturb the soil there. Have the crew stop water flow while they go under the foundation to limit the erosion. The downside for the crew is no water = no cooling for the bit, so they won't want to run like that for very long. Ideally you'd only drill the last few feet without water, and pop into a small hole in the basement. A good crew can install a line with a slope (pitch), and it's done all the time when installing sewer lines this way.
You'll want to size your line based on gravity flow, so it will be quite a bit bigger than it would be for the same water volume if running with pressure like the outlet from a sump pump. You'll also want to put a screen (I recommend 1/2" mesh stainless steel welded wire hardware cloth) over the end of the pipe so that critters don't use it as an express tunnel to get into your basement.
So all that fun stuff aside, keep in mind you're going to be spending a good amount of money to install this. I typically pay around $12-15/foot for small(ish) projects of a few hundred feet, and I'm a commercial contractor, so I get better rates than a typical one-off homeowner would. With a very short project of ~70 feet or so, you're probably going to be around $25-30/foot, and that would assume you can be flexible with your scheduling so that the crew can use your job as filler between larger projects. Try telling them you're OK anytime as long as they can give you 24 hour notice, that might help get you better pricing. Many crews will offer discounts for Ben Franklin too, so that's another thing to try. The cost of your project will be in coming to the site, the installation itself will probably only take a few hours to complete.
You'll want to install at least a 3" line for gravity feed. I would use either schedule 40 duct, or try SDR11 or SDR13.5 (standards used in the utility industry). Be flexible here though, see if the crew has any left overs from other jobs that are close, and use those. Don't worry about the color you get EXCEPT DO NOT USE YELLOW (which is reserved for natural gas lines). 4" is a size commonly used in the telecom world, so that might be easier to get. We typically use 1.25", 1.5", 2", and then skip up to 4". Sizes in between those will be less common.
We usually just call this "directional drilling" or "directional boring" in the trades. Look up utility service companies to find contractors since many do not advertise. Try calling your local power company's service center and ask who they use, or try the service/engineering group for your local phone or cable TV company. Pretty much every telecom and power company uses directional drilling contractors, so once you find someone in the industry that will talk to you, they'll know what you're trying to do and will know who you need to talk to.
Bill
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Bill, thank you so much for such a thoughtful and thorough response. It's my first time posting to GBA (after a long time lurking) and I'm blown away by the quality of the info you've provided.
Another thing to consider is the on and off of a pump is what kills it, not run time. Having a longer horizontal pit to fill before the discharge would allow for fewer on/off cycles and more pumped water per cycle. You can look at French Drain Man https://youtube.com/c/FRENCHDRAINMAN on YouTube for more about that.
Unless the watertable freezes, it seems like you could have problems with needing to have the water flow, and having your drain freeze, without a bypass available.
Thanks Tom, that's a good point. I love FDM and have learned so much from his channel.
Doug_A,
It sounds like a good idea to me. If the cost per foot is prohibitive, maybe a hybrid approach would work, where you dig as far as you can before things get too deep, then go with directional boring from there.
The Achilles heel may be that the water near the outlet freezes before the water around the foundation. A sump pump may be a wise back up.
Malcolm, I have two sump pump lines I've put in that poke out of the ground over 100 feet from the house. I've never had either of them freeze in 15 years or so. I do think it's something to keep an eye on though, especially with a gravity feed system where the slower flow might gradually freeze and eventually seal off the end of the pipe.
Thanks very much for that advice, Malcolm.
There is another potential option to try: a vibratory plow. These are a sort of upside down shark fin looking thing that us is usually installed on the back of a small tractor. The plow vibrates and cuts a slit in the ground while pulling in the pipe. You can get down a foot or two this way, but you can't really put the line on a slope unless the grade itself is on a slope -- the plow pretty much keeps the pipe at a fixed depth below the surface as it's installed. This is a cheaper technology than directional drilling, but it's more disruptive (i.e. if you cut across asphalt, you'll be left with a crunched up "trench" you'll need to patch). You can't go as far, either -- I've had my directional drill crews go under entire interstate highways (3 lanes in each direction) with a bore before. They can easily go out several hundred feet in one shot. They start having a harder time controlling the bit as it gets farther from the drill rig though, especially in soft ground, but it's still fairly precise and not a big problem.
BTW, I should have mentioned that if you go with SDR pipe instead of "schedule" pipe, SDR is the opposite -- the bigger the number, the thinner the wall. SDR11 is thicker walled than SDR13.5, for example.
Note also that regular PVC fittings won't solvent weld to HDPE pipe, but you can glue them on with adhesives.
Bill
I just looked up some videos of vibratory plows in action. What a great machine! Besides this basement-drain project, I have another goal to run electricity to an outbuilding on my property. I had never considered anything but a trencher for that, but you've got me thinking I should explore these options too. Thank you!
Doug,
Electrical may be the one service you can't use a a vibratory plow for. I'd check your code first. Here the cable or conduit has to be surrounded by a layer of washed sand and topped with a warning tape.
Ah, makes total sense. Thank you!
You also have to put in electrical at a minimum depth (typically 18"). Vibratory plows can't usually reach very deep.
Malcolm, you probably have an exception for electrical installed by directional drilling. Almost all utility work is done that way now since it's so much less disruptive, so cities tend to be familiar with the technology (in my area, most municipalities REQUIRE directional drilling since it doesn't require road surfaces to be cut to install services). In my area, the only rule with electrical going in by directional drilling is that we still have to meet minimum code depth (which is easy with directional drilling, and I always spec deeper), and you have to use UL listed duct, which is often schedule 40 or schedule 80.
Bill