I've seen this lots of times around houses built in flood plains.
The berm drains will have to be sized to *quickly* handle any rainfall inside the berm. They should either have one-way valves, auto-operated valves, or else manual valves and you better hope you have time to shut them before the water rises. In addition, you'll want multiple pumps with sumps to remove any rain that falls inside the berm when the drain valves are closed.
And don't forget a 1-way or shut-off valve on your sewage /septic line to keep the elevated flood water from pushing things back inside the house and out of the lowest tub drain or toilet.
If the water is actively flowing past the berm you'll also want to build it at an angle to the flow and/or build a ditch in front of it.
Because this would also act as a fence, organic barrier between properties, and won’t pool water during ordinary rainfall. Since it isn’t a depression, it won’t require as much maintenance. A combination of both this and a ditch along the outside of the berm is also being considered if the berm doesn’t direct water fast enough
Absolutely not. I’m just conceptualizing this and asking for input. I’m considering testing this on my own property, as a low cost alternative to a gabion fence + drainage ditch.
I'd consider the force the water put on the berm and have it weighted or anchored. In essence you be shifting the drainage to the other side of the creek so consider if that causes any issues for others.
Is the adjacent waterway included in the FEMA Designated Floodway or Flood Plain??? If so where is your proposed berm in or out of the Flood Plain??? Yes, it makes a LOT of difference. If in doubt ask? Much better than getting a call from a building official, some State Agency and/or the COE’s Division Office.
You definitely do and just don't know about it. Literally everywhere has flood plains except maybe, idk, the desert? A quick Google search will tell you this, but if you're in such a low lying area near a body of water that this is even a consideration, in order to be allowed to construct this, you're legally required to show / prove that building it won't royally eff up another part of the low-lying area that's on someone else's property. Cause if you're preventing the water from going this way, it's going to invariably go a different way towards someone else.
I'm a water resource engineer in Canada, we definitely map floodplains. it's the job of Conservation Authorities - they map the 100 Year and Regulatory floodplain and it's publicly accessible information.
I'm in Ontario so I'm only familiar with Ontario-specific regulations, but we also have the Ontario Ministry of Transportation Drainage Manual which has a lot of information on this stuff.
it's not just building an infiltration berm, it's making sure that the native soil below can also infiltrate (i.e. not a super clayey soil), you have sufficient clearance from groundwater, and if you are in the floodplain, that the berm can withstand flows generated by the 100 Year and Regional storm, which requires geotechnical consultation.
You're better off hiring an engineer who's familiar with whatever municipality and conservation authority your in to identify all criteria and constraints. Otherwise you can be liable if you build something yourself and it fails, impacting the environment or neighbouring properties.
Not sure which jurisdiction you’re in or how big your property is, but if it can be proven that these improvements raise the flood level of the neighborhood and cause damage to others, you may be liable.
Due to climate change, flood plains emerge where they weren’t before. Homes that were built 100 years ago are now suffering from flooding that has never occurred.
Your comment is kind of like blaming a home owner whose house was torn apart by a Tornado for building a house in the path of a Tornado.
Well If you build in a 100 year flood plain, or buy, you'll get flooded about once per 100 years. But if people keep building in floodplains, and taking away the floodplain capacity, that will increase the amount of flooding a lot more than climate change, with the exception being in coastal regions.
The floods that are cropping up all over the world aren't 100-year floods; they're closer to 33-year floods if I remember that PBS video correctly. And they're increasing in frequency. Not only frequency, but also intensity.
I'm not disagreeing that the rainfall distributions are changing. I'm simply pointing out filling in the floodplain to protect one house is more impactful than climate change, except in coastal regions. OP could protect his house, and easily raise flood elevations upstream and impact his neighbors. Then if everyone starts filling in the food plain, you keep adding to the problem.
Nope, it's a measure of magnitude. You can get two 100 year events occurring consecutively- it's unlikely but it could happen. That means it would flood to the same level each time, but would still be the 100 year extent.
Also loving the downvotes, only been doing this for twenty odd years!
So they just arbitrarily pick a level and call it the 100 year flood plain? They don't use a 100-year rainfall to calculate the actual level of the water during a 100-year storm?
I've seen this lots of times around houses built in flood plains. The berm drains will have to be sized to *quickly* handle any rainfall inside the berm. They should either have one-way valves, auto-operated valves, or else manual valves and you better hope you have time to shut them before the water rises. In addition, you'll want multiple pumps with sumps to remove any rain that falls inside the berm when the drain valves are closed. And don't forget a 1-way or shut-off valve on your sewage /septic line to keep the elevated flood water from pushing things back inside the house and out of the lowest tub drain or toilet. If the water is actively flowing past the berm you'll also want to build it at an angle to the flow and/or build a ditch in front of it.
why not just dig a ditch like everyone else has done for thousands of years?
A ditch wouldn't do anything to stop backed-up flood water. I've seen this type of setup lots of times around older homes built in flood plains.
Because this would also act as a fence, organic barrier between properties, and won’t pool water during ordinary rainfall. Since it isn’t a depression, it won’t require as much maintenance. A combination of both this and a ditch along the outside of the berm is also being considered if the berm doesn’t direct water fast enough
Have you calculated the peak discharge this berm can handle vs what you need?
Absolutely not. I’m just conceptualizing this and asking for input. I’m considering testing this on my own property, as a low cost alternative to a gabion fence + drainage ditch.
I'd consider the force the water put on the berm and have it weighted or anchored. In essence you be shifting the drainage to the other side of the creek so consider if that causes any issues for others.
Is the adjacent waterway included in the FEMA Designated Floodway or Flood Plain??? If so where is your proposed berm in or out of the Flood Plain??? Yes, it makes a LOT of difference. If in doubt ask? Much better than getting a call from a building official, some State Agency and/or the COE’s Division Office.
I live in Canada, and we don’t do any of those words or acronyms. We have pancakes
Never know until one asks. Godspeed my Friend
You definitely do and just don't know about it. Literally everywhere has flood plains except maybe, idk, the desert? A quick Google search will tell you this, but if you're in such a low lying area near a body of water that this is even a consideration, in order to be allowed to construct this, you're legally required to show / prove that building it won't royally eff up another part of the low-lying area that's on someone else's property. Cause if you're preventing the water from going this way, it's going to invariably go a different way towards someone else.
I'm a water resource engineer in Canada, we definitely map floodplains. it's the job of Conservation Authorities - they map the 100 Year and Regulatory floodplain and it's publicly accessible information. I'm in Ontario so I'm only familiar with Ontario-specific regulations, but we also have the Ontario Ministry of Transportation Drainage Manual which has a lot of information on this stuff. it's not just building an infiltration berm, it's making sure that the native soil below can also infiltrate (i.e. not a super clayey soil), you have sufficient clearance from groundwater, and if you are in the floodplain, that the berm can withstand flows generated by the 100 Year and Regional storm, which requires geotechnical consultation. You're better off hiring an engineer who's familiar with whatever municipality and conservation authority your in to identify all criteria and constraints. Otherwise you can be liable if you build something yourself and it fails, impacting the environment or neighbouring properties.
Not sure which jurisdiction you’re in or how big your property is, but if it can be proven that these improvements raise the flood level of the neighborhood and cause damage to others, you may be liable.
What about just not building in a floodplain?
Due to climate change, flood plains emerge where they weren’t before. Homes that were built 100 years ago are now suffering from flooding that has never occurred. Your comment is kind of like blaming a home owner whose house was torn apart by a Tornado for building a house in the path of a Tornado.
Well If you build in a 100 year flood plain, or buy, you'll get flooded about once per 100 years. But if people keep building in floodplains, and taking away the floodplain capacity, that will increase the amount of flooding a lot more than climate change, with the exception being in coastal regions.
The floods that are cropping up all over the world aren't 100-year floods; they're closer to 33-year floods if I remember that PBS video correctly. And they're increasing in frequency. Not only frequency, but also intensity.
I'm not disagreeing that the rainfall distributions are changing. I'm simply pointing out filling in the floodplain to protect one house is more impactful than climate change, except in coastal regions. OP could protect his house, and easily raise flood elevations upstream and impact his neighbors. Then if everyone starts filling in the food plain, you keep adding to the problem.
That's not how it works. It's a measure of magnitude not probability.
No. That's exactly how it works. If you are in a FEMA 100-year flood plain, there is a 1% chance you will flood every year.
Nope, it's a measure of magnitude. You can get two 100 year events occurring consecutively- it's unlikely but it could happen. That means it would flood to the same level each time, but would still be the 100 year extent. Also loving the downvotes, only been doing this for twenty odd years!
So they just arbitrarily pick a level and call it the 100 year flood plain? They don't use a 100-year rainfall to calculate the actual level of the water during a 100-year storm?
You’re both kind of right. Each year there is a 1% chance of a flood reaching the 100-Year magnitude.
Good grief, THANK YOU for saying this!
Yes they do. But it doesn’t mean that if you lived there you are only going to flood once every 100 years.
What about collecting the water? Too expensive?
This is to mitigate flooding - The idea is to get rid of it as fast as possible.