fluid dynamics basics of sewage
DTL
I would like to do a basic calculation of the pressure that our local
Village idiots would have had to apply to the sewer line on our street
in order for it to geyser a foot higher than our trap opening and
pumping 150+ gallons of raw sewage into our basement ( I realize the
total volume is not pertinent to the calculation, I just add it as
context to why I want to figure this out!)
It is a 3" line. The excess pressure they applied WHILE I was snaking
out a clog I assumed was between my trap and the street line, I
contend was over and above what would be a reasonably safe pressure
level. I would expect they would try to snake out the main sewer line
and get a flow going before applying high pressure to the line. I
would also expect a knock on the door warning residents of what they
were about to do.
I measured the splash mark on the wall and photographed it to get the
height. I have to cut out the lower sheet rock at that end of my
basement.
The professional cleaning service charged has billed well over the
$2000.00 deductible ... I have spent 2 sold days so far dealing with
this disaster and there is no end in sight. I had a major workshop/
electronics lab down there, I have to move and replace storage
units... My wife and I feel very strongly that we will sue the Village
where we live, I am researching possible grounds for this suit.
I am sure I can find the dimension of the main line, What I need is to
remember the calculus for and the formula for the quadratic that
models the geyser height where the pressure equals zero.
Someone post a link for basic sewage dynamics errrrr fluid dynamics!
lol
Bill
I need to get an estimate for the density of the sewage
none
> Hi group,
>
> I would like to do a basic calculation of the pressure that our local
> Village idiots would have had to apply to the sewer line on our street
> in order for it to geyser a foot higher than our trap opening and
> pumping 150+ gallons of raw sewage into our basement ( I realize the
> total volume is not pertinent to the calculation, I just add it as
> context to why I want to figure this out!)
>
> It is a 3" line. The excess pressure they applied WHILE I was snaking
> out a clog I assumed was between my trap and the street line, I
> contend was over and above what would be a reasonably safe pressure
> level. I would expect they would try to snake out the main sewer line
> and get a flow going before applying high pressure to the line. I
> would also expect a knock on the door warning residents of what they
> were about to do.
>
CFD would be overkill for this. Simpler would be to calculate what
pressure is needed to jet the water to whatever height it reached. With
Bernoulli's equation, all you need is
Pressure + rho velocity^2 / 2 + rho g height = constant.
-- you might want to check this!
At the maximu height, take the velocity = 0, and pressure 1 atm. From this
you can back-calculate the pressure at the discharge point - this WILL
require an estimate of the velocity at the discharge point, so your
knowledge of 150 gallons is useful; now you need to estimate how long you
think it took for that 150 gallons to enter your basement.
> I measured the splash mark on the wall and photographed it to get the
> height. I have to cut out the lower sheet rock at that end of my
> basement.
>
> The professional cleaning service charged has billed well over the
> $2000.00 deductible ... I have spent 2 sold days so far dealing with
> this disaster and there is no end in sight. I had a major workshop/
> electronics lab down there, I have to move and replace storage units...
> My wife and I feel very strongly that we will sue the Village where we
> live, I am researching possible grounds for this suit.
>
> I am sure I can find the dimension of the main line, What I need is to
> remember the calculus for and the formula for the quadratic that models
> the geyser height where the pressure equals zero.
>
> Someone post a link for basic sewage dynamics errrrr fluid dynamics! lol
>
> Bill
>
>
>
>
>
>
> I need to get an estimate for the density of the sewage
If you use water you won't be far off. Typical crude sewage, assuming that
the gross solids weren't involved, is around 200 - 400 mg/L of solids.