Lecture 27
Hvorslev Slug Test Method
Fetter 7.5.3
Developed for a variety of well symmetries.
Can be applied in confined or unconfined.
Approximate solution.
Can use in water table aquifer, if screened/open interval below water table.
Incorporates construction of well.
Low permeability materials - well screen includes gravel/sand pack.
Technique of Analysis
1) Plot 
vs Time on semi log plot.
Plot of h/ho vs. time on semi-log plot
2) Draw straight line through data.
3) Determine To at 
4) Calculate K using To, r, L, R
If 
then use following formula:
 |
|
| K = hydraulic conductivity (L/T) (ft/d) | |
| r = radius of well casing (ft) | |
| R = radius of well screen (ft) | |
| Le = length of well screen (ft) | |
| To = time it takes for water level to rise or fall 37% of initial change (d) |
One of many formulas for different piezometer configurations.
Fetter example:
Slug of water withdrawn from a well.
Time (sec) |
Depth to Water (ft) |
Change in water level (ft) h |
|
Static Level |
13.99 |
||
0 |
14.87 |
0.88 (ho) |
1.00 |
1 |
14.59 |
0.60 |
0.682 |
2 |
14.37 |
0.38 |
0.432 |
3 |
14.20 |
0.21 |
0.239 |
4 |
14.11 |
0.12 |
0.136 |
5 |
14.05 |
0.06 |
0.068 |
6 |
14.03 |
0.04 |
0.045 |
7 |
14.01 |
0.02 |
0.023 |
8 |
14.00 |
0.01 |
0.011 |
9 |
13.99 |
0.00 |
0.000 |
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