[HN Gopher] How French Drains Work
___________________________________________________________________
How French Drains Work
Author : chmaynard
Score : 468 points
Date : 2024-08-06 23:07 UTC (23 hours ago)
(HTM) web link (practical.engineering)
(TXT) w3m dump (practical.engineering)
| Rygian wrote:
| French drains should be part of the "Unexpectedly Eponymous" list
|
| https://notes.rolandcrosby.com/posts/unexpectedly-eponymous/
| ec109685 wrote:
| I don't think it qualifies. This drain is intentionally named
| after Mr. French.
| sbradford26 wrote:
| The would be the whole reason of it making the list. Most
| people would think it was named after the country or
| something not Mr. French.
| zeristor wrote:
| The coding language Julia; perhaps Ada should have been named
| Lovelace then?
| smt88 wrote:
| Julia doesn't count because it wasn't named after a person.
|
| Even then, neither of those would fit the theme of the list
| above because they aren't named after their _inventors_ (even
| though Ada is technically an eponym).
| lucideer wrote:
| I think narrowing the theme of the list to just inventors
| is more an accidental result of the author's selection
| rather than their intended theme - eponyms seems to be the
| theme.
| tialaramex wrote:
| The point is they're _unexpected_. Elo is a great
| example, people tend to assume this chess rating system
| is an abbreviation, but it 's somebody's name.
|
| It's not unexpected that Ada is named after Ada. It _is_
| unexpected that PageRank is named after a person named
| Page rather than web pages. It may seem less unexpected
| if you happen to know who Larry Page is, but the same
| could be said for Glen Bell, if you knew who he was then
| it 's "obvious" why the business is named Taco Bell
| right?
| belval wrote:
| Fun fact, in the French speaking part of Canada, "French drain"
| are fully translated to "Drain francais" because of this quirk
| even though we don't usually translate proper nouns.
| philistine wrote:
| Ben ken toe, un drain francais n'a rien a voir avec les
| francais.
| lucideer wrote:
| Great site! (though Unilever seems like a stretch, & gasoline
| is extremely contested).
|
| This reminds me, my partner recently bought me some "Coffey
| Whiskey" because I like coffee, which led to my own discovery
| of another one of these (albeit one requiring a spelling
| oversight).
| walthamstow wrote:
| Wow what a brilliant blog post. Full of OMG moments, not least
| Max Factor!
| gilleain wrote:
| Ah, like Arkhan Land and his Land Raider.
| billbrown wrote:
| Good point--added to the Wikipedia page.
| https://en.wikipedia.org/wiki/List_of_eponyms_(A%E2%80%93K)#...
| xg15 wrote:
| Spearheaded of course by the late E. P. Onymous, may he rest in
| peace.
| aristus wrote:
| I discovered French drains while trying to dig a hole for a fruit
| tree a while back. The land was on a hill and about 30cm down I
| hit this huge pile of dirty gravel. Ok, so maybe someone filled
| that spot with gravel. Sunk another hole a bit farther down. More
| gravel, etc. It took me longer than i'd like to admit to figure
| it out.
|
| Turns out it was the main drainage for the whole neighborhood.
| Heh. Moved my tree to the side and it thrived on all that lovely
| water.
| pfdietz wrote:
| And, if people are fertilizing their lawns, all that lovely
| fertilizer runoff.
| aristus wrote:
| Oh, yes. No lawns in that neighborhood but I thought hard
| about what might be going into the fruits. Years on, no ill
| effects.
| phsau wrote:
| Wouldn't it be better to keep the tree and its roots away
| from the drain? That growth might come at significant cost!
| pfdietz wrote:
| Fertilizer would be welcome, pesticides less so.
| Fortunately, one doesn't really need pesticides on lawns,
| particularly if one doesn't have a dislike of non-grass
| species (like clover, which helps with fertilizing anyway).
| cmiller1 wrote:
| Not uncommon for people to have their lawns treated for
| ticks here in the NE US
| pfdietz wrote:
| I live in a very high tick area in upstate NY, and I've
| never seen this. I certainly don't do it and have had no
| problems. Now, if I wander just off the lawn into the
| woods, I better be wearing my permethrin clothes.
| cityofdelusion wrote:
| Tree should be far away from the drain line. The roots will
| eventually grow into the pipe. Tree roots are incredible at
| finding water sources. Even a drop-at-a-time drip from a water
| pipe will be completely root wrapped in a few years.
| bell-cot wrote:
| > Turns out it was...
|
| Might I ask how well- (or ill-) documented the location of that
| kinda-important drain was?
| seanalltogether wrote:
| One thing I regret after moving into my new house was not getting
| a detailed list of drains installed in the property. I have lots
| of drainage issues and don't know if there is a drain there but
| inadequate for the amount of water we get, or just not installed
| at all.
| sbradford26 wrote:
| A major lesson of home ownership is that it is a continual
| fight against water. Keeping water away from places you don't
| want it, and keeping water in and available in the areas you do
| want it.
| anticorporate wrote:
| This is absolutely true. I think half of the home renovation
| projects I've done in my life have been to either move water,
| or repair the damage from where water ended up where it
| shouldn't be. These are never the fun projects, but in terms
| of protecting your property, probably the most important
| ones.
| pfdietz wrote:
| Does the house have a sump pump? In our current house, which we
| bought with full knowledge of the issue, there was seepage and
| no sump pump, and we ended up having one installed (after
| negotiating down the sale price a bit after the inspection.)
| This involved jackhammering through the unfinished basement
| floor around the perimeter and installing a drainage pipe, then
| repouring that part of the floor w. inspection/cleaning ports
| into the pipe, along with a sump and pump in one corner. Works
| like a charm now.
|
| There had been a drainage pipe but it was not working properly,
| probably being crushed or filled at some point by tree roots.
| philistine wrote:
| When I bought my house the previous homeowners legally had to
| declare whether or not there was a drain around the foundation.
| Very useful, it's the first thing we did and we never had any
| water breach the house.
| seanalltogether wrote:
| Sorry, I should have clarified, I meant for drainage in the
| yard. We live in a development that's on a hill so 2 of our
| neighbors are on properties above us.
| pfdietz wrote:
| I wonder if there's a way to get that mapped, say with
| earth-penetrating radar.
| bombela wrote:
| Redirecting the gutter downspouts away from the house can help
| if this isn't already done.
|
| EDIT: saw your other comment about drainage being an issue in
| the yard, not the house.
| engineer_22 wrote:
| Yea, often these improvements are not well documented, you are
| right that it would have been easiest to ask the prior owners
| while they still owned it.
| mdaniel wrote:
| Easily one of my favorite channels, and I'm glad Grady is on
| Nebula, too: https://nebula.tv/videos/practical-engineering-how-
| french-dr...
| diggan wrote:
| First time I hear about Nebula, and seemingly the website
| doesn't want to tell me what it is. Looks like a YouTube
| alternative?
|
| The FAQ mentions that it's owned by CuriosityStream, which I've
| heard about before, founded by John Hendricks who also founded
| the TV channel/network Discovery (now Warner Bros something
| something).
|
| As far as I've seen, CuriosityStream is mainly about "popular-
| science" stuff and over-dramatized American "documentaries", is
| Nebula something in the same vein? Would be weird to see Grady
| over there if so.
| WheatMillington wrote:
| Have I got the video for you. This will explain the
| connection between Nebula and CS.
|
| https://www.youtube.com/watch?v=3X18vKVSPao
| mdaniel wrote:
| That is rather unfortunate - if you were so inclined, you
| could contact their helpdesk <help@nebula.tv> as mentioned at
| the bottom of that FAQ page and tell them about your
| experience
|
| Regrettably, I have been following Nebula from its early
| years, so I don't have the elevator pitch to offer other than
| "videos on YouTube are dictated by YouTube, videos on Nebula
| are dictated by their creators" plus the obvious ad-free
| experience. This is some inside baseball from the channel
| that I recall introduced me to Nebula
| https://www.youtube.com/watch?v=Alqt6RCEWdM
|
| As for your popular science concern, in general my answer is
| "no," it's not marketing drivel designed to inject ads into
| your eyeballs. However, since it is just a video platform
| (err, and also classes, news, and podcasts) the content
| quality is ALL OVER the place. That was actually why I didn't
| subscribe for such a long time - it was like those "web 3"
| video platforms - only fringe stuff was on it, so it wasn't
| worth my time or dollars. Since then, they have gotten a lot
| more content that I value so I pay by the year now
|
| Merely as a frame of reference, here are some of the channels
| that I follow
|
| https://nebula.tv/thethoughtemporium
|
| https://nebula.tv/strangeparts
|
| https://nebula.tv/breakingtaps
|
| https://nebula.tv/minutephysics
|
| https://nebula.tv/coldfusion
|
| https://nebula.tv/extrahistory
|
| https://nebula.tv/extracredits
|
| https://nebula.tv/reallifelore
|
| https://nebula.tv/hai
|
| https://nebula.tv/realengineering
|
| https://nebula.tv/practical-engineering
|
| https://nebula.tv/wendover
| smallerize wrote:
| Curiosity Stream has a minority stake. The subscriptions used
| to have a significant discount if you bundled them, but
| starting last December, Nebula decided they wanted to be more
| premium. https://blog.nebula.tv/unbundle/
| gregmac wrote:
| I love the glimpse into topics like this, where one might
| initially think "what is so hard? Dig a trench and fill it with
| gravel" but it turns out to be way more complicated:
|
| > It is hard to overstate the importance of properly filtered
| drains for dams. If you don't believe me, take it from the
| Federal Emergency Management Agency in their 360-page report,
| Filters for Embankment Dams: Best Practices for Design and
| Construction. If that's not enough, try the Bureau of Reclamation
| in their 400-page report, Drainage for Dams and Associated
| Structures.
|
| To the point that:
|
| > A civil engineer could spend an entire career just thinking
| about subsurface drains
| pimlottc wrote:
| I wonder how many of these stories start with him discovering
| one of these massive government reports. They always seem to
| pop up in his videos! It really is impressive how much
| invaluable practical information is provided for free by the
| various federal agencies.
| engineer_22 wrote:
| A minor quibble - while the information is free to the world,
| those federal agencies cost the People money.
| rimunroe wrote:
| The fact that it costs the government money to do things is
| obvious to the point of pointlessness. I could understand
| pointing out the actual cost of producing the info if you
| had it, but just pointing out the fact that it cost them
| money to produce some report doesn't add anything to the
| discussion.
| extraduder_ire wrote:
| I have to assume most of these reports, standards, and other
| documents end up being tax-neutral or better from wider
| dissemination of this info and/or propping up the status quo
| in engineering and construction.
| LegitShady wrote:
| Learning the basics of designing the gradation of sand and
| gravel filters is Soil Mechanics 1 (think 2nd year
| university). The massive reports are because of massive
| problems caused by poorly functioning or failed filters, but
| the basic premise of much of these videos is "give the first
| lesson in some subject without any math and actually try to
| explain things instead of typical engineering prof
| standards".
|
| If you google "Gradation Design of Sand and Gravel Filters"
| you'll find Chapter 26 of the USDA's national engineering
| handbook, which will give the basics of how its done with
| some simple examples.
|
| This is baby engineer type stuff, for the most part. If
| you're designing for big structures or complicated situations
| it becomes a much more complicated exercise.
| avgDev wrote:
| Great video and I love this channel.
|
| My basement flooded recently, I'm going to rent some equipment
| and dig drains/grade. Previous owners spent money on fixing
| cracks and painting foundation with stuff that always fails.
|
| The best way to keep your basement dry is proper grade and if
| unable to achieve proper grade drains. It is literally that
| simple. This can help prevent formation of cracks and foundation
| problems as there is less pressure on them that way.
| finnh wrote:
| We cut a french drain into a below-grade room a few years ago.
| I was definitely happy to pay someone else to do it - cutting
| the concrete alone was a nasty piece of work and only the start
| of the job. Plus the unexpected footing running beneath an
| interior wall they had to cross below, such hard work.
| dboreham wrote:
| That's usually called a footer drain or foundation drain.
| French drain is typically a trench dug from the surface, some
| distance away from buildings.
| dboreham wrote:
| And this is why I own an excavator, loader and a dump trailer.
| avgDev wrote:
| I wish I had the space, I'm too close to the city and would
| need to buy some land.
|
| I feel like if software didn't pay this much I wouldn't mind
| having a business utilizing heavy equipment.
| refibrillator wrote:
| I've built quite a few french drains in residential settings,
| some lasting longer than others - I'll share a few hard earned
| lessons here:
|
| Soil migration is the number one failure mode. This is mentioned
| but perhaps a bit understated in the video.
|
| To prevent soil migration you absolutely need commercial grade
| geotextile fabric wrapping the gravel and pipe.
|
| You can buy pipe with much bigger and more numerous holes than
| the tiny slits depicted in the video. That also obviates the need
| to decide what orientation the holes should be.
|
| Void space is the most critical factor when choosing gravel. You
| need a lot of space between the rocks to support fast drainage.
| Do not use playground pebbles or anything similar. Pay close
| attention to the type of aggregate you're buying.
|
| Calculate how much water you actually need to drain. You can use
| the "100 year flood" values for your locale to get an upper bound
| on rainfall, then multiple by drainage area. This is especially
| important if your roof is part of the watershed.
|
| https://www.usgs.gov/special-topics/water-science-school/sci...
|
| Sometimes there is insufficient gradient to move the water
| anywhere, ie the land is too flat. In this case you may be better
| off building a drywell, which is constructed very similarly.
|
| https://en.m.wikipedia.org/wiki/Dry_well
| daedrdev wrote:
| The video also mentions that sometimes the geo textile fabric
| is not enough since it too can get clogged, though this seems
| important in dams and not so in simpler projects
| bshacklett wrote:
| If you live in a place with a lot of clay, geotextile fabric
| can certainly be problematic for simple residential settings.
| datavirtue wrote:
| The drain pipe is at the bottom of the drainage excavation.
| On top of the pipe is 3/4 aggragate, and on top of the
| aggregate is geotextile. Soil is filled in over the
| geotextile. There is no clogging risk in this design. Any
| soil particles that make their way to the pipe are carried
| away.
| cityofdelusion wrote:
| Fine clay and silt clogs the geotextile.
|
| A proper drain requires extensive soil testing for particle
| size. Video goes over this along with the issues of
| geotextiles.
| ejstronge wrote:
| >Calculate how much water you actually need to drain. You can
| use the "100 year flood" values for your locale to get an upper
| bound on rainfall, then multiple by drainage area
|
| How do you incorporate this into a drain design?
| toomuchtodo wrote:
| https://web.archive.org/web/20240807170330/https://www.ndspr.
| ..
|
| https://web.archive.org/web/20240807170407/https://urban-
| wat...
| ejstronge wrote:
| Both of these links include a dry well - if one is draining
| to daylight, how do you incorporate the 100-yr flow rate?
| toomuchtodo wrote:
| Can you share what daylight looks like for your use case?
| Where is your target for the water to be managed?
| ejstronge wrote:
| Daylight means a field whose elevation is below the area
| to be drained in this case
| hatsix wrote:
| Not sure you watched the whole video, he shows how soil
| migration causes failure (7:30), links to another video that
| covers that in-depth and discusses how geotextile isn't enough
| for things like damns (10:15). He also mentions that you can
| get pipe with holes all the way around (5:58).
| ryanisnan wrote:
| Definitely didn't watch the video. He also mentions hole
| direction and problems, as if the video didn't go at length
| into the topic.
| refibrillator wrote:
| I definitely watched it but missed a couple of those
| sentences so thanks for the timestamps above.
|
| Yes he does name soil migration as the biggest problem with
| subsurface drains, but to be fair the video is
| contextualized around dams.
|
| The spirit of my comment was intended to be helpful for
| folks attempting this stuff at home, not to suggest a lack
| of good info in the video.
| ryanisnan wrote:
| Ah, ok, no worries. Apologies, I should have given you
| the benefit of the doubt. Your comment was generally
| insightful.
| xg15 wrote:
| > _You can use the "100 year flood" values for your locale to
| get an upper bound on rainfall_
|
| I wonder, does climate change also affect those calculations,
| with the need to adjust those bounds upwards? I remember the
| (technical) term "100 year flood" getting lots of ridicule in
| the last years because we already got multiple "100 year
| floods" in the range of a decade.
| jnwatson wrote:
| Faster than climate change is development. The addition of
| impermeable surfaces like parking lots and buildings upstream
| causes more water to get to you.
|
| Development happens faster than the flood maps get redrawn.
| dv_dt wrote:
| Short answer yes, but as another comment suggested,
| development changes adding hard surfaces in new places in the
| neighborhood also rapidly change those calcs.
| magicalhippo wrote:
| If it was me I'd chop a zero off those N-year estimates.
|
| But that got me thinking, how often do they adjust these
| estimates? Was a "100 year flood" in 1950 less than in 2000,
| say?
|
| Obviously it'll be different for different areas, especially
| between countries, but still.
| mindslight wrote:
| FWIW "100 year flood" refers to the flooding that is expected
| to occur _in that specific area_ on average once every
| hundred years, _not_ an event that will happen only once over
| the whole country once per hundred years. So regardless of
| climate change it makes a lot of sense to be seeing many
| hundred year floods since mass media has us caring about many
| areas in parallel, not just the specific area we live.
| xg15 wrote:
| Ah, I wasn't aware of that definition. That makes a lot
| more sense, actually.
| tda wrote:
| Also, as people have a life expectancy in the order of 100
| years (75 perhaps?), there is a pretty good chance you will
| experience a 1:100 year event at some point in your life.
| Also a lot of infrastructure is built for 50-100 year life
| (or is still used after 100 years, even though it was
| designed for less).
|
| The 1:100 year safety level should thus be considered a
| bare minimum for high impact events. In the Netherlands
| water infrastructure is designed to withstand the 1:10.000
| year storm for catastrophic events, and e.g. 1:1.000 year
| storm for high impact events.
|
| But even with higher safety standards, it is key to design
| not only for the current climate, but for the future
| climate over the design life of whatever you are building.
| Extrapolating 1:10.000 year events from 30 years of
| observations might seem sketchy already, but with all the
| uncertainties in climate change predictions is a bit of a
| stretch.
| LegitShady wrote:
| the 100 year flood is basically a mathematical concept - its
| about the long term average recurrence interval - the
| probability that the given event will be equaled or exceeded
| in a given year. The "100 year flood" has a 1% probability to
| happen in a given year, based on historical data and a normal
| probability distribution (which is what we see in nature).
| datavirtue wrote:
| The roof should be shedding to solid drain pipe.
| orthecreedence wrote:
| Yes, "should." I've found that _should happen_ and _did
| happen_ are two very different things when it comes to a lot
| of homes.
|
| Incidentally, our roof had gutters/drainage originally. We
| put in our own french drain after about 8000 hours of
| research, and decided to re-route the roof drainage to right
| above the new french drain (separate pipes) because the roof
| drainage broke at some unknown point and was dumping water
| around our foundation piers (yay...). Well, our roofers came
| and installed gutter guards after all this, which caused the
| gutters to shed 60% of the water into the drainage area
| because of the way they're angled. If we hadn't put in a
| french drain, it'd be a real problem, but as it is now, it's
| a mild annoyance that I keep telling myself I'll fix.
| eitally wrote:
| Our first house was one a 1/2ac lot at the end (bottom -- this
| will become important later) of a cul-de-sac in a great semi-
| urban neighborhood in Cary, NC. We learned after repeated
| backyard flooding and near-incursion of storm water into our
| patio door that our street had been built on what had been the
| original stormwater collection pond for the larger
| neighborhood. The builder got permission from the city to move
| the pond to build our cul-de-sac, but that didn't stop our
| street from still being the lowest point in the neighborhood,
| where all surface water ran-off to, and our house was at the
| very lowest point.
|
| Long story short, we ended up installing a french drain on two
| sides of our house, putting a drain at the end of our driveway
| to redirect water [from just running down our driveway to our
| house], having the front wall foundation rebuilt and jacked up
| because the footer had nearly completely eroded (1970s house),
| and still needed to add two 24" square drain boxes in the back
| yard (with buried 4" PVC draining into the creek at the back of
| the property) to remediate all this. It was also a tree-filled
| lot and the drain boxes would almost immediately clog with
| leaves during heavy rains, so I spent a lot of time out there
| in ankle to knee deep water with a rake to keep the drains
| clear.
|
| This still wasn't enough! We got a so much surface run-off from
| our uphill neighbors that it looked like a sheet of rushing
| water across our backyard during heavy storms. We had a creek
| at the back of the property but were not allowed to mess with
| it because of Corps of Engineers easement regulations. At the
| end of the day, we _finally_ solved our problems by getting an
| agreement from our neighbor to let us dig a surface water drain
| from the low point in their yard into the creek, and then we 'd
| build a "temporary" (cf prior easement rules against permanent
| walls) berm along the property line to prevent surface water
| from coming into our yard at all. That "berm" was 76 bags of
| Qwikrete stacked three high and covered with grass clippings,
| yard waste & mulch. Technically we could have removed it if the
| city had inspected, but it was very much a cement wall.
|
| We have never since, and never will, build or purchase a house
| at the bottom of a hill.
| kbenson wrote:
| One of the prior houses I lived at had so much flooding and
| water leakage problems from poor construction (prior
| additions that weren't strictly legal) that lead to carpet
| and padding having to be removed from concrete floored rooms
| and eventually mold problems, that when I bought a house a
| few years after we'd ran away from that disaster of a house
| we made absolutely sure to my at the high point of the (new)
| neighborhood so we weren't in the drainage path for anyone.
|
| It's particularly demoralizing to see the scope of the
| problem when it's all that water flooding your property and
| know there's nothing you can do in the short term, and even
| the long term is just trying different things and hoping they
| work, knowing that it will probably take a few tries.
| smallbluedot wrote:
| This sounds like a nightmare
| opticfluorine wrote:
| I've ruled out several properties in my current homebuying
| search for this exact reason. Having lived next to the
| neighborhood collection pond once before (a rental
| thankfully), I'm extra paranoid about stormwater and drainage
| now.
|
| I've seen a number of homes in my area where the builder
| received special permission to build right where the drainage
| needs to go. Some were beautiful and I was tempted to give it
| a shot, but your story reminds me that I need to trust my gut
| on this issue and head for high ground.
| swayvil wrote:
| House in shallow valley. Basically bottom of 3 hills.
| Multiple floods yearly. Basement pretty trashed.
|
| Beat it with 2 ditches, a drain, a berm and 2 pumps.
| 01100011 wrote:
| I'm going to say that the vast majority of homeowners are not
| paranoid enough when it comes to buying their home. It is a
| huge investment and comes with very high transaction costs
| yet most people seem to make the decision based solely on
| superficial aesthetics.
| illiac786 wrote:
| What would you recommend noobs do, when buying a house? I
| guess hiring an expert would be the recommended approach,
| but all "experts" I have seen were all almost as
| superficial as I was - one literally assessed the wrong
| house. I'd pay good money for a good one, but it's hard to
| find.
| chiph wrote:
| 20+ years ago, I had moved into a newly built home. And the
| first serious rain we got, I had water come into the living
| room (flooded the porch and seeped under the door). There was
| no insurance coverage since it was "surface water" and thus
| excluded. So I had to use a shop-vac and rent a couple of
| blowers to dry it out.
|
| There was a ditch out back but it obviously wasn't deep
| enough. I did the math and ended up with an astounding amount
| of water flowing by (something like 20,000 gallons per
| minute[0]) and complained to the builder about it. They sent
| a couple of guys out there who installed two 4" corrugated
| drainage pipes and said it was good enough.
|
| When the next big rain happened, where those pipes emptied
| out there was a 3 foot tall fountain of water from the
| pressure. It was an amateur Bellagio, lol. The yard still
| flooded but luckily didn't come into the house again.
|
| Since then, the landscaping came in throughout the
| neighborhood which controlled the runoff. But it taught me a
| lot of respect for getting slopes & drains right - Always use
| a larger pipe than you think you'll need.
|
| [0] The formula seems to be: V = 0.408 x Q/(D^2) where V is
| velocity in feet-per-second, Q is the flow rate in gallons-
| per-minute, and D is the diameter of the pipe in inches. I
| estimated the diameter based on the land profile that was
| underwater, and timed the velocity by following twigs/leaves
| floating by.
| SonOfLilit wrote:
| You probably got a bit higher number than the true one,
| because water flows faster the farther it is from the
| floor/wall, and leaves float so they move like the fastest
| water, not the average water.
| GiorgioG wrote:
| Sorry to hear of your troubles. We live in Holly Springs, NC
| not far from Cary. When our builder was showing us land/lots
| that were available at the time they only had lots that had
| driveways that would pitch towards the homes (in other words
| the road was higher than the house, not by much maybe 2-3
| feet or so.) Of course developers and realtors always assure
| you it won't be a problem - I was not reassured and so we
| passed on these lots. A few months later a lot became
| available that was well above street level. We've been here
| 10 years and never had an issue through heavy rains and even
| a couple of hurricanes. But we've met the neighbors who
| bought those properties with the driveway pitching towards
| their homes and they complain about having water coming into
| their garages whenever we get heavy downpours. If you're
| going to live somewhere long enough that may experience heavy
| rainfall, it's best to be well above the low end of the
| neighborhood/street.
| ajb wrote:
| Depending on how deep it is a drywell can be an EPA regulated
| thing in the US. This is because it can be a bad idea to sink
| surface water directly into the aquifer - naturally it would be
| filtered by the overlying soils, if it goes in directly then
| any surface contamination is washed directly into a reserve of
| drinking water. But, I'm far from an expert so I can't give any
| advice as to when one would need registration etc.
| jiveturkey wrote:
| Are you in the construction or related business? I've had to
| learn some of these things the hard way myself. I learned I was
| outclassed and so I hired a geotechnical engineer to design my
| now-deployed drainage. (french drain plus site drainage)
|
| I wonder what building codes require, ie from engineering and
| inspection POV, like can the things you mention even be built
| today? If so isn't this a failure of the planning departments?
| Dumblydorr wrote:
| Anyone know how to maintain retaining wall pipes? Installed by
| previous owner of home, have no idea if they're done properly or
| if they're clogged or anything. Just want to keep that water
| moving! :D
| toomuchtodo wrote:
| What are the existing pipes made of?
| orthecreedence wrote:
| You might be able to ask a plumber to snake a camera into the
| outlets and do a visual inspection on the inside. That said, it
| might not tell you if they used real, actual drainage rock +
| fabric as opposed to just surrounding it in dirt just via
| visual inspection, although I suppose based on the amount of
| dirt buildup you might be able to tell.
| bane wrote:
| I had absolutely no idea this was named after an American!
|
| My parents home is on a mountainside. All the rainwater collects
| higher up the mountain and then moves down the mountain where
| their house is in the way. The soil is thin, mostly clay, and you
| hit bed rock very quickly. When it rained, water would have
| little place to go under the soil and would surge up under
| pressure in areas to the surface. One of those areas was that
| house.
|
| They purchased the house new and the builder neglected to
| consider this water reality, so for the first couple years the
| basement would flood _from the bottom_ , then later water would
| come rushing into the basement windows.
|
| They spent a small fortune with heavy equipment digging out
| underground trenches in this rocky environment and laying french
| drains around the perimeter of the house, and then also in a long
| diagonal in front of the house as a sort of catchment. The
| collected water was routed underground and around the house to an
| exit further down the mountain.
|
| This stopped all the flooding immediately, so much so that my
| parents finished the basement and turned it into a massive master
| suite where it stayed dry for decades.
|
| A handful of years ago, my father passed on, and early the next
| year when the rains started, the flooding starting up again. My
| mother, absolutely distraught had me come out, and the water had
| destroyed flooring, drywall, window treatments, furniture, books
| -- it looked like the aftermath of a hurricane. During one rain I
| watched waterfalls come in the windows...clearly something had
| gone wrong with the drainage system.
|
| We had engineers come out, concerned that the water had cracked
| and penetrated the foundation, but no, it turns out the French
| drains had failed in someway. Another small fortune, they were
| dug up, replaced, redone, and now....no flooding again.
|
| This is a great video that may have explained exactly what
| happened.
| hn_throwaway_99 wrote:
| > I had absolutely no idea this was named after an American!
|
| Yeah, I feel like French drains should be added to:
| https://news.ycombinator.com/item?id=23888725
| jnwatson wrote:
| It was in a comment by darkerside.
| HPsquared wrote:
| If it's important, I guess you could add some boreholes or
| sensors to check the groundwater level and see if it's creeping
| up over the years.
| falcolas wrote:
| A simple sump (basically a hole in your basement floor), and
| sump pump, can help identify it before it reaches your
| basement floor. IIRC, this is also covered (albeit briefly)
| in the video.
| kevin_thibedeau wrote:
| High water pressure at the basement walls can result in
| intrusion without ground water below the floor being a
| problem. I have no sump/drain in my basement as it never
| floods because it sits on well draining soil. A neighbor's
| driveway directs water toward my block foundation and, with
| heavy rains, the localized pressure in the saturated soil
| along the wall would produce a jet of water coming out of a
| hole in the mortar. I resolved it by digging a swale that
| diverted that excess water around the foundation. It is
| much easier to maintain than a French drain that would silt
| up rapidly given my soil.
| HPsquared wrote:
| I was thinking more, check for buildup of water upstream of
| the barrier as an early indication of blockage or
| restriction. If the gravel or whatever is clogged, you'll
| see high water behind it.
| throw0101a wrote:
| > _We had engineers come out, concerned that the water had
| cracked and penetrated the foundation, but no, it turns out the
| French drains had failed in someway. Another small fortune,
| they were dug up, replaced, redone, and now....no flooding
| again._
|
| Generally speaking you want some kind of inspection/clean-out
| port so you can snake a camera through the system to see what's
| going on:
|
| * https://www.drainbrainllc.com/what-you-should-know-about-
| the...
|
| (This is for both the sewer drain and French drain systems.)
| bane wrote:
| That's a good question, I'll have to check on this the next
| time I go out there.
| kwhitefoot wrote:
| > I had absolutely no idea this was named after an American!
|
| They're just called land drains or field drains elsewhere.
| seltzered_ wrote:
| As someone whos been thinking quite a bit about land restoration
| I cringed a bit when watching the video about the Henry French's
| philosophy.
|
| There's a more encompassing worldview perspective that should be
| taken where rather in terms of thinking about 'superfluous water'
| there should be an inquiry around what relation one wants with
| water - where are the areas you want to perhaps concentrate water
| (e.g. at a pond/rainwater harvesting) and dryness (e.g. where you
| have a human settlement structure), and how one can 'slow,
| spread, sink' water to have a healthier relationship to the
| greater watershed and relationship to atmospheric water vapor.
|
| Courses like https://waterstories.com and writings like
| https://climatewaterproject.substack.com/ may help with expanding
| with thinking this way, along with Brad Lancaster's books (
| http://harvestingrainwater.com/ ) on rainwater harvesting. From a
| farm perspective Chris Jones is also worth listening to for his
| critique of drainage tile (
| https://www.youtube.com/watch?v=Svwjd3FwNCY&t=5668s )
|
| (Bias: I've partly taken the water stories class, and an investor
| in the upcoming climate water project book)
| engineer_22 wrote:
| There are many places where there is no shortage of water, and
| for safe hygienic habitation it becomes necessary to remove it
| seltzered_ wrote:
| Yes but..
|
| We have to also think about _how_ waters being removed from
| land. Is it being removed so quickly that we end up with low
| rivers and risk of saltwater intrusion during drought
| conditions [0]? Is water drainage not getting buffered by
| say, growing vegetation?
|
| My argument isn't against French drains outright, but whether
| we're thinking more broadly about the impact of human
| relations with water.
|
| [0]: new orleans saltwater intrusion scare from 2023:
| https://www.axios.com/local/new-
| orleans/2023/09/28/louisiana...
| ComputerGuru wrote:
| I get where you are coming from but I feel when you look at the
| greater picture this concern would be completely mooted. The
| fact is that most unwanted water happens due to construction,
| with things like streets, parking lots, driveways, etc creating
| impermeable surfaces that force the water to build up and flow
| downhill and into foundations when, if things _had_ been truly
| left untouched, there would have been no problem at all to
| begin with.
|
| Surely that's a mitigating factor that makes it much more
| acceptable to geoengineer water removal?
| seltzered_ wrote:
| I think I'm trying to advocate for appropriate
| geoengineering, thinking about not just water removal but
| also how water should be removed (how quickly, where to
| concentrate water, atmospheric considerations)
|
| At the least I'm trying to advocate for say, pairing a French
| drain design with a rain garden or something to slow water
| down. In some areas they actually incentivize planting trees
| close to sewer drain areas since it helps manage water during
| flood events.
|
| Not trying to be pollyanna and advocate for a sponge city
| approach evrywhere either, I'm aware of the issues with
| permeable pavement potentially leading to sinkholes and such
| (ref: https://x.com/waterhodl/status/1660307940451000320 )
| zoklet-enjoyer wrote:
| All sewers lead to Paris
| aynyc wrote:
| As someone who battled water in basement in the last few years:
|
| 1. Make sure your house is not at the bottom of a hill or swamp
| or whatever. French drain will not stop surface run off from
| uphill. You need to divert that from the top. Which is almost
| impossible since it's most likely someone else's land.
|
| 2. Make sure your gutter is cleaned and properly installed. And
| Make sure your gutters drain into a solid PVC pipe and channel
| that solid pipe away from your house at a pitch as far as you
| possible can. Most likely to the street, but that kinda mess with
| downhill and town drainage.
|
| 3. Have sump pump(s) in your basement and make sure they work and
| have back up power.
|
| 4. If your yard has flooding issue, then try french drain and/or
| dry wells. I found dry well work better on flat ground.
|
| Just a side note, most french drains will fail at some point
| depending your soil and installer.
| morkalork wrote:
| What about humidity? I have no actual water seeping in anywhere
| but the endless humidity destroying my flooring.
| aynyc wrote:
| Do you have crawl space or basement? If you have crawl space,
| then you should encapsulate it.
|
| - Increase airflow in your basement or crawl space. Add a
| pest proof window that you can open and close. Or operate a
| fan based on humidity or temp, similar to a gable/attic fan.
|
| - Add a properly sized dehumidifier that pump water out of
| your house to keep the humidity low.
|
| - Keep plants away from your house if your house is swamped
| by plants. Plants hold ton of moisture and it's great for
| your air, but terrible at humidity.
| ChrisMarshallNY wrote:
| This drives home the power of water.
|
| Of all the natural disasters out there; volcanoes, wildfires,
| earthquakes, tornadoes, etc., the one that does the most damage,
| and kills the most people, is water.
|
| Floods, tsunamis, and storm surges are absolute blockbuster bombs
| of destruction.
|
| Up here, we had Sandy. It wasn't even that "powerful" a hurricane
| (I think Cat 2 or 3, by the time it got here), but the water that
| it brought with it, caused a _huge_ amount of damage and death.
| turtlebits wrote:
| This applies to houses as well, ideally you should have an air
| gap behind your siding to let moisture out (to prevent rot) -
| some common methods are strapping or ventilated rainscreens.
| uslic001 wrote:
| We just had French drains put in around a farmhouse we bought as
| it had major drainage issues. They seemed to be working well last
| weekend during a few thunderstorms. Given the current tropical
| storm pounding NC I am glad we did it before all this rain.
| wonder_er wrote:
| I think a french drain to a pit-type depression that can hold a
| few hundred gallons of water and drains across hours is the way
| to go.
|
| And the french drain can be simply a slight trench. It doesn't
| need to be underneath anything. This worked for me and water
| runoff management around an old house. The lot had a funky grade,
| and all I wanted to do was get the water away from the structure.
| A little light pickax/trenching work got me what I needed.
| hinkley wrote:
| Permaculture uses very shallow ditches to force water to
| serpentine across the property. What doesn't sink in shows up
| in the greater watershed much later in the precipitation. Not
| unlike urban rain gardens.
| jaquers wrote:
| Recent YT vid for how this is installed in practice (for a home
| in the mountains): https://youtu.be/nA_-
| SFRkY94?si=z6UYNNVS8Zdk0tIt
| JohnFen wrote:
| Everything I know about French drains I learned from this video.
| I was greatly amused, though, to learn that the "holes on top" vs
| "holes on bottom" thing is a bit of a holy war in that industry.
|
| We have so many similar highly charged but largely meaningless
| holy wars in our industry that it was fun to see the same thing
| in a different one.
| jiveturkey wrote:
| (1859)
| __turbobrew__ wrote:
| I remember there were PC Call of Duty 4 servers back in the day
| that would hack your game to add mods like paintball. Back in the
| day I thought this was cool but now all I can think of is how
| batshit insane it was to allow someone RCE on your PC. I know
| valve was looking into running games within a containerized
| runtime (Pressure Vessel) on Linux which is really what should be
| happening. The fact that games run as your user and have defacto
| access to all of your secrets and keys is crazy.
| arendtio wrote:
| When I read the title I wondered how speaking French would reduce
| the work to be done :-D
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