$2\mathrm{.}4K_s-$Calculation

We use Darcy's law to calculate the saturated hydraulic conductivity. Darcy's law is defined as:

$q=K_s\frac{{}_H}{L}$

After rearrangement, the saturated hydraulic conductivity can be calculated as:

$K_s=\frac{q*L}{{}_H}$

Report the saturated hydraulic conductivity in $c\frac{m}{m}in.$ Hint: The water is ponding $4\mathrm{.}6$ cm

high over the sample. Use this ponding depth and the length of the sample to calculate ${}_H.$I Purpose

In this lab you will use the undisturbed samples in the small cylinders to measure the satu$-$

rated hydraulic conductivity $K_s$ using the constant head method.

$2$ Steps

$2.$I Cylinder Geometry

Take a ruler and a caliper to measure the inner diameter and the length of the cylinder:

Diameter $d$:$5cm$

Length $L$:$6cm$

Use the diameter $d$ to compute the cross sectional area $A$ of the cylinder.

Cross sectional area $A$ :

$2\mathrm{.}2$ Sample Preparation

Take the samples out of the cold room and bring them to the lab.

Use cheese cloth and a rubber band on the bottom of the soil sample to create an inter

face. Use an empty cylinder and a piece of bicycle tubing to connect the empty cylinder

to one of the samples.

Place the sample in a plastic container.

Slowly fill the plastic container with tap water with a $5mMCaS{O}_4$ solution. Stop once

the water level is about I cm $.$

Allow the soil to equilibrate and gas to escape the sample.

Keep adding water after $I^{-2}h$ until the water level is at the end of the bottom cylinder.

$2\mathrm{.}3$ Constant Head Measurements

Add enough water to the constant head apparatus and turn the pump on$.$

Quickly move one soil sample onto the apparatus. Make sure the u$-$tube is full of water

Important: Do not allow the soil sample to desaturate during the transfer. If you have a

very sandy soil you may have to have somebody help you with the transfer adding water

to the sample to keep it saturated.

After all samples are on the apparatus swap the Erlenmeyer flasks and start the stop

watch.