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All Graduate Plan B and other Reports Graduate Studies

5-1965

Tests of a Suggested Piezometric Method for Determining Hydraulic Conductivity of Saturated Soils

K. R. Channarasappa

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Recommended Citation Channarasappa, K. R., "Tests of a Suggested Piezometric Method for Determining Hydraulic Conductivity of Saturated Soils" (1965). All Graduate Plan B and other Reports. 1136. https://digitalcommons.usu.edu/gradreports/1136

This Report is brought to you for free and open access by the Graduate Studies at DigitalCommons@USU. It has been accepted for inclusion in All Graduate Plan B and other Reports by an authorized administrator of DigitalCommons@USU. For more information, please contact [email protected]. TESTS OF A SUGGESTED PIE ZOMETRIC METHOD FOR

DETERMINING HYDRAULlC CONDUCTIVITY

OF SATURATED SOILS

by K. R. Channarasappa

Report submitted in partial fulfillment of the requirements for the degree

of

MASTER OF SCIENCE

in

Civil and Irrigation Engineering

Plan B

UTAH STATE UNIVERSITY Logan, Utah

1965 ACKNOWLEDGEMENTS

The writer greatly appreciates the counsel and critical review of his report by his thesis director, Professor J. E. Christiansen. He also expresses his gratitude to Dr. A. Alvin Bishop for providing the funds for equipment and other facilities. Sincere thanks are extended to Professor Joel Fletcher,

Professor Lyman S. Willardson and Professor Jack Keller for their advice and review of the thesis.

K. R. Channarasappa TABLE OF CONTENTS

Page

INTRODUCTION ...... 1

REVIEW OF LITERATURE 2

Methods of measuring hydraulic conductivity 3

Laboratory methods 3 Field methods ... 3

EQUIPMENT AND PROCEDURE 8

Equipment 8

Piezometers . 8 Auger rod ... 8 Semiflexible tubing . 8 Electrical sounder . 8 Other equipment 9

Procedure ...... 9

Piezometer installation 9 Formation of cavity . 9 Flushing technique .. . 9 Measurements ...... 10 Relative hydraulic conductivity 12

RESULTS ...... 13

Specimen calculations 13 Tables ...... 14 Discussion of results 25

Location A. 600 West 1400 North 25 Location B. Opposite to Logana Plunge 26 Location C. U.S.U. drainage farm. East of quonset shed ...... 26 Near the ditch. North of quonset shed .... 27 TABLE OF CONTENTS CONTINUED

Page

CONCLUSIONS AND RECOMMENDATIONS ...... 2 8

Conclusions ...... 28 Recommendations ...... 28

LITERATURE CITED ...... 30 LIST OF TABLES

Table Page

1. Results of tests at locatjon A, 600 West 1400 North . . . 14

2. Results of tests at location B, opposite Logana Plunge, 1400 North ...... 19

3. Results of tests at location C, U.S. U. drainage farm . . 23

4. Summary of results ...... 24 LIST OF FIGURES

Figure Page

1. Diagram showing the use of a single piezometer to determine relative hydraulic conductivity of soils 11 INTRODUCTION

A major factor in the design of drainage systems is the hydraulic

conductivity of the soil strata to be drained. Various methods for measuring

the hydraulic conductivity of soils in both the field and the laboratory have been devised. In many cases, however, laboratory methods fail to give reliable data since the natural field conditions under which flow actually takes place cannot be duplicated in the laboratory. Hence a need exists for a field method for measuring hydraulic conductivity of soils in situ. When a large number of tests are to be performed in a given location, a simple, quick, accurate, and inexpensive method would be very desirable.

After making studies of Lagunda de La Nava Project in Spain for the purpose of analyzing irrigation, drainage, and salinity problems, Professor

J. E. Christiansen (1964) Consultant for the Hydrotechnic Corporation, suggested a simple piezometer method for determining the relative hydraulic conductivity of the soils. Using this method and the formula suggested by

Professor Christiansen, several tests were performed in various locations.

The object of this report is to describe this piezometer method for determining the relative hydraulic conductivity of the soil strata and to present the results obtained in a limited field study, together with conclusions and recommendations. REVIBW OF LITERATURE

Henry Darcy (1856), the French hydraulic engineer, studied the move­ ment of water through sand. He developed and published an empirical law, now

w 1 knon as Darcy s law, which states that the groundwater flow is directly proportional to the hydraulic gradient. It can be expressed as

V ·- Ki in which

V is the flow velocity i is the h drauHc gradient K ls a proportionality constant

The constant of proportionality, K depends on the properties of both porous media and the fluid and is known as the "hydraulic onducti.vity." It has the dimensions of velocity, LT-l, and may be defined as the rate of a fluid

(water) through a unit c.;ross-sectional area under a unit hydraulic gradient during a unit period of time.

A modified form of Darcy1 s law is expressed as

V = Y- K'i /-""' in which

Y is the density of the fluid 14-- is the dynamic viscosity K' is a constant of proportionality, known as the intrinsic permeability 3

The intrinsic permeability depends on the·v, properties r). of soil only and dces not include the effects of fluid properties { It has the dimensions 2 of L .

Factors affecting hydraulic conductivity are: (1) shape and size of grain, (2) porosity, (3) structural arrangement, and (4) properties of fluid, such as denisty and viscosity.

Methods of measuring hydraulic conductivity

The methods and techniques for determining hydraulic conductivity fall into two classes, depending on whether representative soil samples are tested in the laboratory or whether the tests are made i!! sit-q_.

Laboratory methods. Hydraulic conductivity tests may be made on undisturbed soil cores or on samples of disturbed soil. The two common methods y used for measuring permeabilit are the constant head permeameter, devised by Meinzer, as cited by Kadir (1951), and the variable head permeameter, developed by Theis, as cited by Kadir (1951). Since the laboratory tests are not conducted under natural flow conditions the results obtained are only approximate.

Field methods. Various field methods have been developed for deter­ mining the hydraulic conductivity of soils. Two methods commonly used for measuring hydraulic conductivity of soils below the water table are: (1) the p'.ezometer method, and (2) the auger hole method.

Kirkham (1946) proposed a piezometer method for measuring the hydraulic conductivity of soils. In this method, the piezometer tube is installed by angering out a hole 6 inches at a time and then driving a tube to within 1 inch 4

of the bottom of the hole. The diameter of the auger should be 1/16 inch less

than the inside diameter of the tube. Upon reaching the desired depth, a

cylindrical cavity of known iength is augered out below the tube. Water rising

into the piezometer is removed several times by pumping or bailing in order to

flush the soil pores along the cavity wall. After flushing, the water is left to

rise to equilibrium with the water table. The water is then pumped out again

and the rate of rise is noted by means of an appropriate water level indicator

and a stop watch. The hydraulic conductivity, K, is then determined from the

relation

i.n which

R is the radius of the cavity h1 and h2 are the water levels below the equilibrium level at times t1 and t2, A is a factor depending on the geometry of the flow system.

In the auger hole method a hole is augered out to the desired depth below the water table and the water is allowed to rise in the hole until in equilibrium with the water table. The water level is then lowered by bailing or pumping, and the rate of rise of the water level in the hole is measured.

Several different formulas have been developed by various investigators

h for determining te hydraulic conductivity of the soil using the observed rate of rise of water in the auger hole. Hooghurdt and Ernst, as cited by Luthin (1957) 5

made improvements over t.he formula derived by Diserens, as cited by Luthin

i h (1957). Kirkham and van Bavel, as cited by Lu th n (1957), reexamined te problem of flow into an auger hole, from a more rigorous vie-wpoint, and van

Bavel and Kirkham, as cited by Luthin (1957), developed new field techniques for making the tests.

The auger hole method and the hydraulic conductivity of soil is described in a report by the ASAE Drainage Research Committee (1959), revised 1961.

One of the formulas presented is K - if R2 Ah dh dt in which

K is the hydraulic conductivity

R is the radius of the auger hole

h is the hydraulic head at time, t

A is a geometric factor

The equation may also be written 2 K= 2 11'R (h1 - h2) A (t2 - t1) (h1 + h2) in which

h1 and h2 are the head at times t1 and t2. 6

a Christiansen i1964. p. 10- ll suggested simpler method for measuring whfoh the relative hydraulic condu<'bvitv in t..iJ.!!. in the water enters the cavity below a piezome1er. He desr ribed the method as follows.

A transparent tube is mounted on top of the piezometer. This tube may be of glass or plastic, and it should be about the same outside diameter as the piezometer pipe. The tube should be graduated in milliliters reading from the top down­ so wards, or a :.;;cale should be attached to the tube and its inside diameter measured that the actual rate of flow into the soil can be determined by timing the rate of drop of the water surface. The technique suggested is as follows: After installation, the pie:z:ometer should be flushed and the water level in the pie10met0rof allowed to reach its static level. When the test is to be made, the piezometer should be filled quickly and the rate subsidence determined with a stop watch. Several readings on the scale might well be made as the wateris level subsjdesof in the transparent tube. Assuming that the effective hydraul:ic gradient producing the flow into u the soU a fnction the ratio of the head, y, to the radius of the piezometer, wh.ich is assumed to be the same as the transparent tube and applying the Darcy equation, one can show that K 0 kr ln (y /y1) (t1 - to) 0

2. 303 kr log (y /y1) (t1 - to)

in whichK

= the hydraulic: conductivity k = a proportionality factor dependent upon the d<�pth and sLroe of the cavity at the bottom of the piewmeter

r '"'·-= the mside radius of the transparent tu.be ln natural logarithm 0 log = l0garithm tc base) lO 0 y =- distance grom the top of the transparent tube to water table (t = distance from water level in tube to water table l . at time, t1 7

A modified form of this equation would be = t1 - to) K .k r�4_.y__ in which

drop in water surface in time, ·= O - l =- tl - to, y y.:::y meany value of y0 and Yl· To obtain actual hydraulic conductivity values, the pro­ portional Hy factor k would have to be evaluated by other means. The value of the parameter r A (t - t )y may, however, be 1 0 considered an index of the relative permeability of the materials at different depths. y /

The present report describes actual tests using this method and presents the results, together with conclusions and recommendations. EQlTIPMENT AND PROCEDURE

Equipment

The following equipment is suggested for performing the tests:

Piezometers. The piezometers consist of small diameter pipes, usually

3/8 inch diameter, which are driven into the soil. A rod the same length as the piezometer pipe having an external diameter slightly smaller than the internal diameter of the pjezometer was used to prevent the soil from getting into the pipe. This rod was removed when the piezometer was driven to the desired depth.

Auger rod. This consists of a 7 /16 inch (1. 1 cm) diameter rod of about of about 7 feet in length. On one end of the rod a 7 /16 inch auger is welded and the other end is provided with a threaded socket to connect either the handle or another piece of rod. The auger rod is very useful in forming a cavity of required depth and diameter.

Semiflexible tubing_. The tubing may be plastic or any other suitable material. It is used for flushing the cavity at the lower end of the piezometer.

The external diameter should not exceed 3/4 of the inside diameter of the piezometer.

Electrical sounder. The sounder is used for finding the water level in the piezometer when the equilibrium condition is reached. When the tip of the sounder touches the water surface, the sensitive voltmeter indicates a 9 deflection. The der:,th of the 'i',ate,r level is read directly on a scale mounted on the instrument. The electrical currerit is produced by two or three penlight batteries.

Other eguipmen.t Other pieces of equipment needed are: piezometer hammer, hand pump, pail or bucket, graduated transparent tubes, stop watch, tape, carpenter's level, tool box, and miscellaneous small hand tools.

Procedure

The location at 1hich the tests are to be made is cleaned and all grass is removed. The procedure for performing the tests is as follows:

Piezometer irn,tallatior.. Four steel pipes, 3/8 inch pipe size (1. 1 cm. inside diameter), 7 feet long (214 em. , were installed in a line 22 inches apart

(56 cm.). To keep the s n from entering the pipe a 7 /16 inch (l. 1 cm. ) steel rod was inserted int the piezometer before driving began. This rod was drilled and threaded at the top to facilitate connecting of a handle or another rod. A special piezometer hammer was then placed over the pie:wmeter and the piezometer was checked for its verticality, usi1g a carpenter's level. The piezometer was then driven mtr t e. soil to the reqmred depth.

E�t!Q.(l of cav·ty Wheo the piezometer was driven to the required depth, the inside rod was removed, using a handle at the top. An auger rod, with a 7/16 inch (L :.�cm,} auger was inserted rnto the pie2ometer and a cavity

10 cm. in length ag formed below the b ttom of the pipe.

Flushing te hnigue. After the cavity had been formed, the flexible tubing was inserted to the bottom of the pi.ezometer and the hand pump was 1.0 operated until the cavity at the bottom of the pipe was thoroughly cleaned. The

loosened material flowed upward aro1md the outside of the tubing and overflowed

from the top of the piezometer. The tubing was then ,v:ithdrawn slowly and the

flushing continued until the overflowing water was clear.

Measurements. After flushing a transparent tube of the same diameter

as that of the piezometer, graduated from the top downward, was connected to

the piez:ometer by means of a short length of rubber tubing.

The flexible tubing was inserted into the transparent tube and the water

was pumped into it until all air bubbles were removed and the transparent tube

was filled with water. Using a stop watch, the water level in the transparent

tube was noted at different intervals of time. The rate at which the water level

subsides is an indication of the permeability of the material encountered at the

lower end of the pipe.

After noting the rate of subsidence in the transparent tube and before

removing the transparent tube from the piezometer, the distance of the zero

graduati n from the top of the pie:wmeter was measured and denoted as "x."

The time required for the water level in the piezometer to reach its

equilibrium or static level depends on the permeability of the material and may

vary from only a few minutes to several days. When the water level in the

piezometer reaches its static level, its position from the top of the piezometer

is measured by means of the electric sounder and its value is denoted by y'.

Then the distance from the zero reading of the graduated transparent tube to the water table is denoted by y , and is equal to x plus y' (See Figure 1). 0 11

Zero reading of transparent tube

Water level in time 't'

Rubber tubing connection Top of piezometer

Ground surface

y y Y'. 0

Water table

Bottom of piezometer

1-afi�----- Cavity 10 cm long

Figure l. Diagram sho""ing the use of a single piezometer to determine relative hydrauli.c conductivity of soils 12

Relative hydraulic conductivity. The relative hydraulic conductivity is calculated using the formula K = kr A y as suggested by Christiansen. (t1 - to) Y m RESULTS

Specimen calculations

krA y K = t Ym

Assuming k = 1

= rA y RHC t Ym

Location: 600 West 1400 North

Piezometer: P 0

= Depth below ground surface: D 119. 5 cm. Test No. 1

Data obtained:

= r 0. 68 crn.

= 8 cm. y' 137.

x = 36. 2 cm.

= + x = 8 + = cm. y0 y' 137. 36. 2 174

y = 149 cm.

- A y = y O y = 174 - 149 - 25 cm.

Ym = O + = + 2 = (y y)/2 (l 74 149)/ 161. 5 t = t t = seconds - 0 12. 6 1

-4 = r Ay 0.68 X 25 = 84 x 10 cm/sec. RHC t Ym = 12. 6 X 161. 5 Table L Results of tests at location A, 600 West 1400 North

Depth below ground Mean and General mean surface standard and standard "Dn Yo AY Ym RHC deviation deviation ems Piezometer Test No. Cms Cms Cms Cms t sec Cms/sec pA±..c-=' µ±..c- y X 10 X 10-4 X 10-4

119.5 po 1 174 149 25 161. 5 12.6 84.0 2 174 149 25 161.5 14.2 77.0 3 174 149 25 161. 5 15.4 72. 6 4 174 149 25 161. 5 15.9 69.5 75.7 + 5.44 25 pl 1 178 153 165.5 71. 5 14.4 2 178 153 25 165.5 84.0 12. 2 3 178 153 25 165.5 106.2 9.7 12.1 + l.92 P2 1 178 153 25 165.5 742 1. 42 2 178 173 5 175.5 95 2.04 3 178 168 10 173.0 395 0.99 4 178 163 15 170.5 1089 0.55 1.25+ 0.55 P3 1 178 173 5 175.5 690 0.28 2 178 171 7 174.5 1050 0.26 0. 27 + 0.045 22.39 + 33.2

147 po 1 154 129 25 141.5 4.0 300 2 154 129 25 141. 5 4.2 286 3 154 129 25 141. 5 4.2 286 4 154 129 25 141.5 4.2 286 289 + 6.0 Table L Continued

Depth below ground Mean and General mean surface standard and standard " " D Yo AY Ym RHC deviation deviation += ems Piezometer Test No. Cms Cms Cms Cms t sec Cms/sec ? _..., }fi±.. a- y 4 X 10- X 10-4 X 10-4 pl 1 126 101 25 113.5 2.5 600 2 126 101 25 113.5 2.5 600 3 126 101 25 113.5 2.5 600 4 126 101 25 113.5 2.6 576 594 + 10.0 p2 1 154 129 25 141. 5 2.7 446 2 154 129 25 141. 5 2.7 446 3 154 129 25 141.5 2.8 430 4 154 129 25 141.5 3.0 401 430. 7 + 16. 0 P3 1 154 129 25 141. 5 4.5 268 2 154 129 25 141.5 4.5 268 3 154 129 25 141. 5 4.6 262 4 154 129 25 141.5 4.6 262 265 + 3 395 + 131

183 po 1 118 115 3 116.5 450 0.39 2 118 112 6 115.0 1020 0.347 3 118 109 9 113.5 1485 0.365 4 118 106 12 112.0 2035 0.368 5 118 103 15 110.5 2685 0.344 6 118 100 18 109.0 3270 0.344 7 118 94 24 106.0 4515 0.339 0.35 7 + 0. 0173 Table l. Continued

Depth below ground Mean and General mean surface standard and standard "D" Y o AY Ym RHC deviation deviation ems Piezometer Test No. Cms Cms Cms Cms t sec Cms/sec µ±_� y r-=-c- 4 4 4 X 10- X 10- X 10- 1 121 pl 118 3 119.5 270 0.63 2 121 115 6 118. 0 585 0.59 3 121 112 9 116. 5 900 0.585 4 121 109 12 115.0 1170 0.607 5 121 108 13 114.5 1215 0.635 6 121 105 16 113.0 1590 0.605 7 121 101 20 111.0 2010 0.61 8 121 97 24 109.0 2460 0.61 0.609 + 0. 016 1 p2 118 115 3 116.5 300 0.585 2 118 112 6 115.0 600 0.59 3 118 109 9 113. 5 960 0.562 4 118 106 12 112.0 1495 0.486 5 118 102 16 110.0 2155 0.46 6 118 100 18 109.0 2400 0.468 7 118 96 22 107.5 2880 0.525 0. 525 + 0.048 P3 1 119 116 3 117.5 1020 0. 171 2 119 115 4 117.0 1440 0. 162 3 119 114 5 116.5 1785 0.163 4 119 111 8 115.0 2910 0.163 5 119 110 9 114.5 3270 0. 163 Table 1. Continued

Depth below ground Mean and General mean surface standard and !Standard "D" Yo Ym RHC deviation deviation ems Piezometer Test No. Cms Cms Cms Cms t sec Cms/sec ±.. ;;:r y ,6, y µ µ-:._o- -4 4 4 X 10 X 10- � 10_ ___ , 6 119 97 22 108 8430 0.164 7 119 96 23 107.5 8910 0.163 8 119 94 25 106.5 9870 0.162 0.164 + 0. 002 0. 413 + 0. 18

214 po 1 194 192 2 193 1275 0.055 2 194 191 3 192.5 1830 0.058 3 194 190 4 192.0 2505 0.056 4 194 189 5 191.5 3330 0.054 5 194 187 7 190.5 4665 0.054 6 194 186 8 190.0 5700 0.050 0. 054 + 0. 003 pl 1 193 190 3 191. 5 750 0.142 2 193 184 9 188. 5 1580 0.23 3 193 181 12 187. 0 2080 0.21 4 193 178 15 185.5 2565 0.214 5 193 175 18 184.0 3045 0. 218 6 193 172 21 182. 5 3660 0.214 7 193 169 24 181.0 4260 0.212 0. 206 + 0. 027 P2 1 195 192 3 193.5 765 0.138 2 195 191 4 193.0 1110 0. 128 3 195 190 5 192.5 1335 0.134 4 195 189 6 192.0 1700 0. 121 Table L Continued

Depth below ground Mean and General meau surface standard and standard "D" Yo y 8Y Ym RHC deviation deviation ems Piezometer Test Noo Cms Cms Cms Cms t sec Cms/sec = µ ±:_c;=" µ+,_"'::d' 4 4 4 X 10- X 10- X 10-

5 195 187 8 191.0 2205 0o 129 6 195 186 9 190.5 2700 0,120 7 195 185 10 190.0 3135 0.114 8 195 178 17 186.5 6060 0.102 9 195 176 19 185.5 6900 0.101 0.121 + 0. 013 P 1 196 171 25 183.5 4 232 3 2 196 171 25 1830 5 4 232 3 196 171 25 1830 5 4 232 4 196 171 25 1830 5 4 232 232 + 890 8 58+ 28.07 Table 2. Results of tests at location B, opposHe Loga.na Plunge, 1400 North

Depth below ground Mean and General mean surface standard and standard "D" Yo y r..,.,y ym RHC deviation deviation ems Piezometer Test .No. Cms Cms Cms Cms t sec Cms/sec µ ±. 0= /J' ±_c- -4 -4 X 10 X 10 X 10-4 107 p 1 182 157 25 169.5 6 167 0 2 182 157 25 169.5 6 167 3 182 157 25 169.5 6 167 4 182 157 25 169. 5 6 167 167 + 0 P1 1 181 156 25 168.5 5.5 184 2 181 156 25 168.5 5.5 184 3 181 156 25 168.5 5.5 184 4 181 156 25 168.5 5.5 184 184 + 0 P2 1 181 156 25 168.5 8.0 126 2 181 156 25 168.5 8.0 126 3 181 156 25 168.5 9.0 112. 3 4 181 156 25 168.5 9.0 112.3 119. 5 + 6.8 P3 1 181. 5 156.5 25 169 5.5 183 2 181. 5 156.5 25 169 5.5 183 3 181. 5 156.5 25 169 6.0 168 4 181. 5 156.5 25 169 6.0 168 175. 5 + 7. 5 161.5+ 25.16

137.5 p 0 1 149 124 25 136.5 2.2 565 2 149 124 25 136.5 2.2 565 3 149 124 25 136.5 2.8 444 4 149 124 25 136.5 2.8 444 Table 2, Continued

Depth below ground Mean and General mean surface standard and standard I! "D Yo 6Y Ym RHC deviation deviation ems Piezometer Test No. Cms Cms Cms Cmia: t sec Cms/sec ±.if y µ JA-±.<::r 4 4 X 10- X 10- 10-4

pl 1 150 125 25 137,5 11. l 112 2 150 125 25 137.5 12.6 110 3 150 125 25 137.5 13.7 109 4 150 125 25 137.5 14.2 108.5 109. 5 + 1. 5 P2 1 149 124 25 136.5 6.0 209 2 149 124 25 136.5 6.8 185 3 149 124 25 136.5 7.9 159 4 149 124 25 136.5 8.3 151 176 + 4. 6

P3 1 156 131 25 143.5 2.8 424 2 156 131 25 143.5 3.0 390 3 156 131 25 143.5 3.5 340 4 156 131 25 143.5 3.5 340 373. 5 + 35. 5 290. 88+ 161. 1

168.0 p 1 116 91 25 103.5 1.8 906 2 116 91 25 103.5 1.8 906 3 116 91 25 103.5 1.8 906 4 116 91 25 103.5 2.0 820 884. 5 + 37. 2 Table 2. Continued

Depth below ground Mean and General mean surface standard and standard nn" Yo y AY ym RHC deviation devi.a ion ems Piezometer Test No. Cms Cms Cms C'ms t sec Cms/sec µ:±.:_y= 1-4-::_g- 4 -4 X 10- X 10 10 4 1 88 25 100.5 2.0 850 pl 113 2 113 88 25 100.5 2.0 850 3 113 88 25 100.5 2.0 850 4 113 88 25 100.5 2.2 775 831. 3 + 32.4 P2 1 115.5 190.5 25 103 2.9 570 2 115.5 190.5 25 103 3. 0 550 3 115.5 190.5 25 103 3.0 550 4 115.5 190.5 25 103 3.2 515 546. 3 + 17. 1 P3 1 114 89 25 101. 5 16.4 102 2 114 89 25 101. 5 17.0 98 3 114 89 25 101. 5 17.4 96 4 114 90 25 101. 5 17.6 95 97. 75 + 2.7 589. 96 + 312

214.0 Could not be drawn to this depth p0 pl 1 178 153 25 165. 5 2.2 468 2 178 153 25 165.5 2.2 468 3 178 153 25 165.5 2.4 428 4 178 153 25 165.5 2.4 428 448 + 20.28 p2 1 178 153 25 165.5 2.0 515 2 178 153 25 165.5 2.0 515 3 178 153 25 165.5 2.2 468 4 178 153 25 165.5 2.2 468 491. 5 + 23. 44 I-' Table 2, Continued

Depth below ground Mean and General mean surface standard and standard '1D'' Yo y A y Ym RHC deviation deviation ems Piezometer Test 0, Cms Cms Cms Cms t sec: Cms/sec µ ::_a- µ -::._y'"" 4 -4 X 10- 10 X 10-4

P3 1 178 153 25 165.5 2,0 515 2 178 153 25 165.5 2.0 515 3 178 153 25 165.5 2.0 515 4 178 153 25 165.5 2.0 515 515 + 0 484, 8 + 20. 28

2.0 275.0 pl 1 103 78 25 90.5 940 2 103 78 25 90.5 2.0 940 3 103 78 25 90.5 2.0 940 4 103 78 25 90.5 2.0 940 940 + 0 P2 1 104 79 25 91. 5 15.4 121 2 104 79 25 91. 5 15.4 121 3 104 79 25 91. 5 15.4 121 4 104 79 25 91.5 15.4 121 121 + 0 P3 1 104 79 25 91. 5 8.0 232 2 104 79 25 91. 5 8.0 232 3 104 79 25 91. 5 8. 0 232 4 104 79 25 91. 5 8.0 232 232 + 0 431 + 363 Table 3. Results of test8 at lc)Cation C, U. S. U. drainage fa.rm - --· -----�-- Depth below ground Mean and Ger1eral mean surface standard and standard nnn Yo AY ym RHC deviation deviation ems Pie:z:ometer Test No. Cms Cms Cms Cms t sec Cms/sec //4:.'::.� JV'-±. �r y 4 X 10-4 X 10-4 X 10-

East of shed

214 p 1 301 298.4 2.6 299.7 7320 . 0. 008 2 301 297.0 4.0 299. 0 11700 0.008 3 301 296.0 5.0 298.S 14100 0.008 0. 008 + 0 0. 008 + 0

Near the ditch

107 p 1 246 245.5 0.5 245.75 3600 0.008 2 246 245.0 1.0 245.5 5400 0.005 3 246 244.4 1. 6 245.2 9000 0.005 4 246 234.4 11.6 240.2 67800 0.005 0. 0057 + 0. 0013 0.0057+0.0013 Table 4. Summary of results

RANGE RHC (Min) RHC (Max) Mean RH Standard Location Depth ems ems/sec ems/sec ems/sec dFviatl .11 4 4 4 X 10- X 10- X 10-

600 West 1400 North 119.5 0.26 84.0 22.39 33.2 147. 0 262.0 600.0 395.0 131. 0 183. 0 0.162 0.607 0.413 0.18 214.0 0.05 232.00 58.00 28.07

Logana Plunge 107.0 112.3 184.00 161. 5 25.16 137.5 108.5 565.00 290.88 161. 10 168.0 95.0 906.00 589.96 312.00 214.0 428.0 515.00 484.80 20.28 275.0 121.0 940.00 431. 00 363.0

U. S. U. drainage farm East of shed 214.0 0.008 0.008 0.008 0.0

Near the ditch 107.0 0.005 0.008 0.0057 0.0013 25

Dis ussion of results

Location A. 600 West 1400 North. The four piezometers were first driven 119. 5 cm below average ground surface. They were numbered 0, 1,

2 and 3, east to west. The relative hydraulic-3 conductivity (RHC) of soil -5 O stratum at this depth ranged from 8. 4 x 10 cm. /sec. at P to 2. 8 x 10 cm. /sec. at P3. With repeated tests, the value of RHC decreased, probably due to sediment in the water plugging the pores in the soil cavity.

The piezometers were next driven 147 cm. below ground level. The O drop in water level was quite rapid. The RHC for piezometers P and P3 was nearly the same. For the middle two piezometers, P1 and P2, the RHC was about twice as high. When the tests were repeated, very little change was noted in the RHC.

The plezometers were then driven 183 cm. below the ground surface.

The RHC at this Itdepth was much lower, but did not vary greatly from piezometer to piezometer. remained nearly constant for repeated tests.

The piezometers were driven then 214 cm. below the ground surface.It

The RHC for this depth was still lower except for P , which was quite-2 high. -6 I 3 O varied from an average of 5. 4, x 10 cm. sec. for P to 2. 32 x 10 cm. /sec. 0 6 for P3. For piezometers P Pi and P2 variation was from 5. 4 x 10- to 5 1. 21 x l0- cm. /sec. The high value of RHC for P3 might have resulted from the cavity penetrating a crack or root channel in the clay, or a packet of more permeable material. 26

Location B. Opposite to Logana Plunge. The piezometers were first driven to a depth of 107 cm. below the ground surface. The permeability was

2 relatively high. The RHC varied from an average of 1. 12 x 10- for P2 to l. 84 x 10- 2 cm. /sec. for P . The RHC remained relaUvely constant for 1 repeated tests.

The p.iezometers were next driven 137. 5 cm. below the ground surface.• 0 2 2 The RHC varied from an average of L 1 x 10- for P1 to 5. 0 x 10- for P For repeated tests, the RHC remained almost constant.

The piezometers were then driven 168 cm. below the ground surface.

The RHC for this depth was generally higher except for P3, for which it was lower than at a depth of 13 7. 5 cm. For repeated tests, the RHC decreased only slightly.

The piezometers P1, P 2 and P3 were then driven to a depth of 214 cm. O below the ground surface. P could not be driven to this depth because the rod could not be inserted, possibly due to some bending of the piezometer. The RHC for different tests and also for the three piezometers remained almost constant. 2 The soil was highly permeable, the RHC averaging about 4. 8 x 10- cm. /sec.

The three piezometers were next driven to a depth of 275 cm. At this 2 depth also, the soil was quite permeable with the RHC varying from 1. 2 x 10- 2 to 9. 4 x 10 - cm. /sec. For repeated tests, the RHC remained constant .

. Location C:. U. S. lJ. Drainage Farm. East of quonset shed: One piezometer was driven 214 cm. below the ground surface. The soil at this

7 depthit was rather impermeable. The RHC at this depth was 8. 05 x 10- cm. /sec. and remained constant for repeated tests. 27

Near the ditch. ""ortb of quonset shed. One pie:zometer was driven

107 cm. below the ground surface. At this depth also the RHC was as low as

n 5. 7 x 10- 7 cm. /sec. ad remained nearly constant for the repeated tests. CONCLUSIONS AND RECOMMENDATIONS

Conclusions

The method suggested by Christiansen (1964) has many advantages.

In soils with fairly high permeability the water level in the graduated

transparent tube dropped quite rapidly and a number of tests could be conducted

in a short period of time.

Accurate measurements are possible since the water level in the tube

can be observed and read directly.

The method appeared to be very sensitive to variation in the RHC at

different depths.

The apparatus required for performing the tests is relatively simple

and inexpensive.

For soils of very low permeability, this method is quite time consuming,

although not more time consuming than for other field methods.

Recommendations

The procedure suggested by Christiansen (1964) for determining the

relative hydraulic conductivity of soils should be verified by comparison with other field methods. From such comparisons and possibly from theoretical reasoning, the value of the proportionality constant k might be determined so

l that actual vaue of the hydraulic conductivity could be obtained. 29

In the first tests performed at location A the RHC value decreased with repeated tests, but for subsequent tests only a slight or no decrease was noted for repeated testso Special care should be observed to see that the peizometer cavity is adequately flushed and that clear water is used for the testso

For performing the tests, four piezometers were used, spaced about

56 cmo aparL The piezometers in a given group were driven to the same depth.

At certain depths considerable variation in the RHC values were observed. Where such variation was observed soil samples might be collected near such cavity, to determine. hether the variation in RHC was due to differences in the soil strata penetrated or to some other cause such as crack or root channel in the material.

For low permeability soils, a larger size piezometer and a smaller size transparent tube might be used so that the drop in water level might be observed quickly The length of the soil cavity might also be increased to facilitate rapid drop in the water level in the transparent tube. LITERATURE CITED

America:r. Society of Agricultural Engineers Drainage Research Committee Report, 1959. Revised 1961. Measuring saturated hydraulic con­ dv.ctivity of soils. American Society of Agricultural Engineers. SL Joseph, Michigan.

Christiansen, J. E. 1943. Ground water studies in relation to drainage. Agricultural Engineering 24:339-342.

Christiansen, J. E. 1964. Drainage and salinity problems in the Laguna de La Nava, Spain. (multilithed)

Christiansen, J. E. 1962. The pumped-well method of determining trans- missibility·" of soils for drainage design. Paper presented at the meeting of the Irrigation and Drainage Division, American Society of Civil Engineers Convention, Houston, Texas. February 23, 1962.

Christiansen, J. E., and A. F. Pillsbury. 1947. Installing ground water piezometers by jetting for drainage investigations. American Society of Agricultural Engineers Journal 29(9):409-410. September.

Donnan, W. W. 1959. Field experiences in measuring hydraulic conductivity for drainage design-A symposium. American Society of Agricultural Engineers Journal 40{5):270-273, 280. May.

Kadir, Naji Abdul. 1951. Measurement of permeability of saturated soils below the water table. Ph. D Dissertation. Utah State University Library, Logan, Utah.

Luthin, J. N., and Don Kirkham. 1949. A piezometer method for measuring permeability of soil in situ below a water table. Soil Science 68(5): 349-358. November.

Luthin, J. No 1957. Drainage of agricultural lands. American Society of Agronomy. Madison, Wisconsin.

Winger, R. J. 1960. In-place permeability tests and their use in subsurface drainage prepared for the International Commission on Irrigation and Drainage. Fourth Congress. Madrid, Spain. Published by the Bureau of Reclamation, U. S. Department of Interior, Denver, Colorado.