RE; Sewage backup article- really techie!
. Drain in basement floor.
G. Property sewer line to the street
After studying the Mechanical Engineering texts I have, and consulting with a
Mechanical engineer, the Bernoulli equation was used to determine the pressure.
This formula discusses such data points as Pressure, elevation, velocity,
specific weight of the fluid and gravitational acceleration constants, and
produces data in its least useable format. For instance velocity is expressed
in furlongs per fortnight. (just kidding) Since I don't use decimal points in
estimates, and the pressure rounded to 20 pound increments is adequate for the
application of a plug, I've tried to simplify the application. What you need to
know to compute the maximum pressure on a drain. a. the distance in inches from
the drain to the top of the stack or vent. b. The diameter of the stack. The
formula is A Multiply the diameter of the stack by the diameter of the stack
(square it) 4 x 4 = 16 B. Multiply the results of A above by .8. (actually
.7854) 16 x .8 = 12 C. Divide 231 (cubic inches per gallon) by the result of B
above. 231 / 12 = 20 (19.25) D. Divide the distance to the top of the stack in
inches by the results of C above. (round up) 120 \ 20 = 6 E. Multiply the
results of D above by 6.5 (weight of one gallon of water) 6 x 6.5 = 40 pounds
(actually 39) Forty pounds is roughly the maximum pressure on a drain 10 feet
down from the top of a 4 inch waste stack. In all likelihood you do not have a
4 inch stack. It's probably a 3 inch ID pipe. Measure it and do the arithmetic.
Then put in a plug that will withstand the computed pressure. THE BIGGEST
PROBLEM When to install the plugs. How will you know when to install them? If
you install plugs in the basement drains, you will probably have sewage in the
streets before you have sewage on the main level or upstairs. Not necessarily,
but a safe bet. When that occurs, install all the plugs. After the plugs are
installed, your way of life will change dramatically! Even if you have potable
water, you have no toilet facilities. You will have to find an alternate
solution. Every situation is different, but here are some suggestions. a. Find
public restrooms you can use that are still functioning. b. Use a thunder mug
for inside use, and pour it into a holding tank outside. The holding tank will
have to be emptied after the emergency is over. The holding tank must be
covered and sealed if possible. c. Relocate to an area where warm weather
procedures can be used. See FEMA's recommendations for warm weather disposal.
I'm no physician, but cholera, typhus, E-coli, and maybe even hepatitis are
dangers at this point. Much care and liberal use of disinfectant are called
for. Work with your neighbors and the local government to set up a early
warning system. Good Luck
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Roleigh Martin ourworld.compuserve.com
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