We have an unprotected dishcarge point from our power plant's cooling pond. It is possible that swimmers can come near it and we need to decide how to protect against someone becoming trapped in the flow of water. We are considering either a cage around the discharge or just floating barriers with warning signs. At it's smallest point the pipe (which starts at the bottom of the pond, about 5 ft below the surface) is 70" diameter and the flow rate is about 1 m3/s. Therefore, the average flow speed is 1.3 ft/s. How fast of water flow would be enough to trap a person?
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Entrapment in cooling pond disharge
- Thread starter Andy22
- Start date
btrueblood
Mechanical
Trap them how? Is there a wall or other obstruction that you think the flow could pin somebody against? Seems that a discharge pipe, when flowing, is no hazard - somebody nearing it while swimming will feel a current tending to carry them away from it. If they swim directly into the current, perhaps there is a hazard that they'll bump their head on the pipe edge? Or swim up into the pipe and become trapped?
- Thread starter
- #3
btrueblood
Mechanical
Okay, the discharge is flowing into the pipe, and swimmer could become entrapped in the flow, submerged, etc. Got ya.
1. Put up a fence around the pond with "no swimming" signs.
2. String a safety rope upstream of the inlet (such that if someone falls in by accident, they have a last chance to grab onto something and pull themselves to safety.
A local irrigation channel is about 12 ft. deep, with water flowing up to 10 mi/hr (guesstimating here). The channel enters several siphon tubes along its ~30 mile run, enabling the flow to traverse deep valleys. The only thing preventing somebody from drowning in a siphon are the items listed above. I think some of the siphon inlets located near a state park also have an alarm switch rigged to the safety rope, to let somebody know when something big has snagged the rope.
Floating, moored buoys with a rope attached could work too, perhaps even with danger/warning signs painted/affixed on the part of the buoy above water.
A safety cage can work, but how do you keep a submerged swimmer from getting "pinned" on it (I'd argue that it's not my problem if 1 and 2 are there too, it's the swimmers own damn fault). Also, it will act as a strainer, and need to be periodically cleaned of leaves/branches/beer cans etc. etc.
1. Put up a fence around the pond with "no swimming" signs.
2. String a safety rope upstream of the inlet (such that if someone falls in by accident, they have a last chance to grab onto something and pull themselves to safety.
A local irrigation channel is about 12 ft. deep, with water flowing up to 10 mi/hr (guesstimating here). The channel enters several siphon tubes along its ~30 mile run, enabling the flow to traverse deep valleys. The only thing preventing somebody from drowning in a siphon are the items listed above. I think some of the siphon inlets located near a state park also have an alarm switch rigged to the safety rope, to let somebody know when something big has snagged the rope.
Floating, moored buoys with a rope attached could work too, perhaps even with danger/warning signs painted/affixed on the part of the buoy above water.
A safety cage can work, but how do you keep a submerged swimmer from getting "pinned" on it (I'd argue that it's not my problem if 1 and 2 are there too, it's the swimmers own damn fault). Also, it will act as a strainer, and need to be periodically cleaned of leaves/branches/beer cans etc. etc.
I guess I would adress this from a legal side as well. Contact the state or your private insurance carrier or whoever is in charge of your employee safety and ask them.
tom
Thomas J. Walz
Carbide Processors, Inc.
tom
Thomas J. Walz
Carbide Processors, Inc.
btrueblood
Mechanical
Man, what a can of worms that will be!
I can see the warning labels on fences now:
"WARNING - Don't fall in!"
"Caution: Water can cause drowning"
Seriously, Tom is right. Start with your corporate attorney.
I can see the warning labels on fences now:
"WARNING - Don't fall in!"
"Caution: Water can cause drowning"
Seriously, Tom is right. Start with your corporate attorney.
Andy22,
> Sorry for the confusion - is a person were to get caught in the flow it could carry them into a 70" diameter pipe that is at least 50 ft long. They could then bump their head and/or become trapped part-way through the pipe.
Are you insane!!!!!????
Let me re-phrase that: "If the person were to get caught in the tube THEY WOULD DIE."
Also, have you decided yet whether it is sucking water in or blowing it out yet? Kind of important to know this.
> Sorry for the confusion - is a person were to get caught in the flow it could carry them into a 70" diameter pipe that is at least 50 ft long. They could then bump their head and/or become trapped part-way through the pipe.
Are you insane!!!!!????
Let me re-phrase that: "If the person were to get caught in the tube THEY WOULD DIE."
Also, have you decided yet whether it is sucking water in or blowing it out yet? Kind of important to know this.
- Thread starter
- #8
gwolf,
Yes, I realize that a person would die - I just did not think I had to actually say it.
The water would suck someone into the pipe. What I am looking for is whether or not the flow is enough to suck someone in. A lawyer or insurance agent will not be able to tell me that. I would like to have some idea how much of a danger it really is before we go and do something drastic. Once we install some kind of a guard we are stuck with it - if the danger is high enough to install a guard then we will have to maintain and inspect it, etc.
Yes, I realize that a person would die - I just did not think I had to actually say it.
The water would suck someone into the pipe. What I am looking for is whether or not the flow is enough to suck someone in. A lawyer or insurance agent will not be able to tell me that. I would like to have some idea how much of a danger it really is before we go and do something drastic. Once we install some kind of a guard we are stuck with it - if the danger is high enough to install a guard then we will have to maintain and inspect it, etc.
btrueblood
Mechanical
Worse yet, what if the person is unconscious, or is disabled, or partially disabled by the fall, etc. etc. I don't think you can use inlet velocity as a "filter" for the potential liability here. You could look up on the internet or other sources to find "typical" swimmer speeds, assuming whatever age/sex/physical fitness/ etc. etc. criteria you want; but if your system guards against the 98th percentile swimmer, how will you defend against a lawyer who argues you should have rigged it so that a 99th percentile swimmer could make it?
Make it difficult to impossible for a person to get into the pond in the first place, with plenty of warning signs, add a simple two-layer guard system (floating rope with a signal, outer fixed barrier/cage. Then run it past the attorneys.
I'd also look into your local/state codes regarding irrigation ditches, siphons, etc. and see what the minimum for these hazards is.
Make it difficult to impossible for a person to get into the pond in the first place, with plenty of warning signs, add a simple two-layer guard system (floating rope with a signal, outer fixed barrier/cage. Then run it past the attorneys.
I'd also look into your local/state codes regarding irrigation ditches, siphons, etc. and see what the minimum for these hazards is.
Andy22
An "Attrative Nuisance"; A legal term.
Do whatever you can to exclude anyone who is not authorized to be at that pond, from entering that pond.
This includes razor wire fence to a hard top cover, whatever.
Do not let it be on your watch that a small child, a teen or drunk adult get's sucked down the tube because someone did not think it possible. If you can think it's possible then it can happen. Do you want that?
I wish you well
pennpoint
An "Attrative Nuisance"; A legal term.
Geez! Andy! here in California you had better be talking the worst case scenario, cause there are people out here who would be willing to sacrifice their children or anyone else to make big bucks from deep pockets. You have to say those hard words or else no one will listen and then only then a few will. You'll have to say it more than once. If you cannot convence these corporate types then maybe you should leave. It's up to you of course. My advise is...
Do whatever you can to exclude anyone who is not authorized to be at that pond, from entering that pond.
This includes razor wire fence to a hard top cover, whatever.
Do not let it be on your watch that a small child, a teen or drunk adult get's sucked down the tube because someone did not think it possible. If you can think it's possible then it can happen. Do you want that?
I wish you well
pennpoint
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