Water loss in a storage pond 4

[EngineerofSteel]

A dairy pumps water into a large lagoon. Typically, the pressure head averages 10'.

Currently, they lose a lot of water due to permeable soil at the base.

They want to empty the lagoon and emplace a clay liner. Soil samples have been sent, and a K value is requested from the lab.

My task is to calculate the before and after water loss as part of an economic feasibility assessment.

However, in reviewing Darcy's law, it looks like I need to take two hydraulic head measurements in the field. Am I correct?

I have this equation: Q= -KAi
i= (h1 - h2)/L

h1 and h2 are the two hydraulic head measurements, and L the distance between them.

Is there a way to calc this with just the K value?

 

[fattdad]

rookierick: I just want to take a stab at your question. First of all, I can't confirm your modified derivation of Darcy's law, but will start from the beginning:

v=ki, where
v=Darcy's velocity
k=hydraulic conductivity
i=hydraulic gradient

Hydraulic gradient is expressed as:

DeltaH/DeltaL, were
DeltaH is the change in head along the flow path
DeltaL is the length of the flow path.

For a liner system, we have to now make some assumptions. Let's say at the top of the liner, the full head is the height of the pond water. Let's call this "H." Let's also say the full value of DeltaH throughout the flow path equals this value "H" (i.e., there is no tailwater head).

We can now say:

v=k*H/L, where "L" is the thickness of the liner.

Reconfiguring terms you'd then get:

L=(k*H)/v

I have no way of knowing what your required value of "v," but from here you should be able to work something up. . .

f-d

¡papá gordo ain’t no madre flaca!