enough so that the stop collar (3) will not pass through it; (6) desig-
nates two 1/2-inch set screws with locking nuts, holes for which are
drilled and tapped in the inner or "holding" pipe; and (7) is the ground
rod or post.

The driver is placed over rod with the rod extending an inch or two
beyond the upper end of the inner or "holding" pipe as shown in the dia-
gram and the set screws and locking nuts are tightened. The outer or
driving pipe is raised and lowered in a hammering motion on the head
of the ground rod and cannot be raised above or off the head of the ground
rod until set screws are loosened, this eliminates the possibility of
accidentally getting the hand between the driver and the ground rod.

All the hammering force of the driver is applied directly to the rod
whereas with some drivers the force strikes an anvil base whichrests on
the rod end, and continual hammering creates some play between the
anvil and the rod, causing some bounce, thereby losing some of the driv-
ing force. All movement of many drivers is above the rod whereas the
suggested driver extends 32 inches down from the top of the rod, thereby
doing away with some of the height hazard which is involved in operat-
ing some drivers.

NOVEL AND PORTABLE POWER UNIT

Personnel of the Buford-Trenton Irrigation District devised a unique
method for handling their large pumps as described below:

The Buford-Trenton Irrigation District is a 7, 800-acre project sup-
plied by three 80-cfs capacity pumps powered with 300-hp electric
motors.

The Project was constructed during World War II when materials
were critical and substitution for the more desirable materials and
items of equipment was necessary. Consequently, besides construct-
ing the pumping plant of timber, substitution had to be made as to the
type of overhead crane installed. This consisted of a chain hoist,
hand-operated movable crane. This type of equipment required two
2-man teams (heavyweight men) 24 man-days to remove, disassemble,
reassemble and reset the three units.

Upon investigating the possibility of motorizing the crane, an esti-
mate of $1540 was made by the supplier of the crane for converting it
to electrical operation. The District thought this too costly.

Further search by the Manager produced a 3-hp air-cooled gasoline

engine equipped with a gear reduction transmission with a hand-
operated clutch at a cost of $138. A suitable chain sheave cost an

17



PX-D- 40143

Figure 7

Figure 5 on the preceding page is a view of the Shirley Canal. The
surface runoff has damaged buried asphalt membrane lining on the
side slope.

Figure 6 also on the preceding page, shows the Glendive Canal on the
Buffalo Rapids Project. Membrane damage shown is attributed to
scour and erosion on the outside of the curve and in part to cleaning
with a dragline and sloper. Some membrane slippage also is apparent.

Figure 7 above is a view of the Main Canal, Angostura Unit, Missouri
River Basin Project. Grouted rock over buried asphalt membrane lin-
ing serves as a satisfactory surface water inlet.

Laboratory Evaluation of Asphalt Membrane Aging

One of the early research activities of the Bureau's Bituminous Labo-
ratory was the development of the buried asphalt membrane lining.

Through cooperation with industry, much laboratorv and field testing
was conducted to determine the best asphalt material available and
construction techniques for producing a durable watertight lining. As
aresult, the catalytically blown asphalt cement used today was devel-
oped. This asphalt cement is prepared by catalytically blowing asphaltic
materials obtained from crude oil to produce a special asphalt having
a very low temperature susceptibility, a high degree of toughness, re-
sistance to tearing or breaking, and an indicated high durability .

Since the first installation of the hot-applied buried asphalt membrane
type of lining in 1947 on the Klamath Project in California, very little
data have been reported relative to the effects of field aging upon the phys-
ical characteristics of the catalytically blown asphalt used in this type

ll


REMOVAL OF PACKING IN EXPANSION JOINTS
(Suggestion R1-64-30)

This suggestion was submitted by Raymond J. Michels, Plant Mechanic,
Region 1. He states that in replacing the 1-inch packing in the expan-
sion joints of penstock and outlet tubes, it was found that a corkscrew
type of packing puller would straighten out and would not pull out the
packing. By welding a self-tapping metal or wood screw to a quarter-
inch rod, as shown in the sketch below, the job was done very well,

and although some of the packing came out exceptionally hard, there
was no damage to material, and it could be used again.

The screw should be butt welded to the end of the quarter -inch rod,
using a slight excess of acetylene when there is a gas weld.

wry
ae
Fy

PACKING PULLER

FIGURE 6

21



sae
P423-D-50651NA

In 1960, the need became apparent for additional flow information to
be reported by radio. The existing radio equipment was replaced with
transistorized on-call equipment and two additional on-call radio
reporting systems were installed; one at the Taylor Ferry gage several
miles upstream from the Cibola gage, and another below Yuma, Arizona.
Several views of the physical facilities at the sites are shown in Fig-
ures 1 through 5.

Figure 1 below is a view of the river stage recording gage at Taylor's
Ferry. Figure 2 also is a view of the Taylor Ferry installation show-
ing the radio building, and the
small enclosure outside the build-
ing which protects the butane
tanks supplying fuel to the bu-
tane burning engine which drives
the generator to supply power
to the radio unit as discussed
later.

Figure 3 on the following page is
a view of the radio building and
antenna at the Adobe Ruin's
river stage recording gage of
the Cibola Field Division.

Figure 4, also on the following
page, shows the river stage
recording gage at the Adobe
Ruin's.

Figure 5, on page 4, is a view
of the Yuma gaging station of
the California side of the Colorado
River, downstream from Yuma,
Arizona. Commercial power as
discussed below made this instal-
lation a more conventional type.

Power Supply

Commercial power is not avail-
able at the Taylor Ferry and
Cibola gage sites. With the
advent of the transistorized FM
radio receiver and remote con-
trol tone equipment, it was fea-
sible todesignanon-call report-
ing system with storage-battery
power supply and propane-fueled
chargers. The receiver and

Figure 2


Photograph No. 1

additional $7.50. To make this motor movable, it was mounted ona
small wagon which cost $11.50. The work which formerly required

24 man-days is now accomplished in less than 8 man-days for an invest-
ment of only $157.00. The motor is also used to operate a concrete
mixer, weed sprayer and water pump as needed.

Photograph No. 1 above shows the unit mounted in a wagon.

HOW TO DRILL UNIFORM HOLES

(Reprinted by permission of GRIST, November/December 1963
issue, a publication by the National Conference on State Parks,
Washington, D.C.)

That friendly writer of many useful suggestions, Donald M. Black,
Naturalist with the Natchez Trace Parkway, says that in woodworking
he often finds it necessary to drill several holes just so deep."
Usually he has made a gauge or guide by cutting a piece of dowel rod
to a length which will prevent the drill bit from going deeper than de-
sired. He has made a hole down through the dowel, then slipped it
over his drill bit.

Although the dowel method is a good one, Don says that sometimes
"woodgrain and human weakness" cause the bit to drift a little while
making the hole through the middle, so that the thing comes out with
a slight slant or drift. Last summer he found a naturalist's answer
to the problem--he went across the road and picked up some dead
cane which had a tapering diameter with holes right down the middle.
All he does now is to cut a piece of cane of the length needed, hold it

18


PLEXIGLASS SHIELD FOR MOWER TRACTOR

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METAL FRAME BETWEEN FRAME. MODIFY SPACING AND
TWO PIECES OF WOOD LATH LENGTH AS NECESSARY TO
USE 3/16" x 1/4" STOVE BOLTS TO FIT MODEL OF TRACTOR.
8" 0c.

BACK VIEW

Figure 4

24 GPO 853-551



PX-D-50656NA

Photograph No, 2

See Text PX-D-50657 NA

Photograph No. 3

different sections of a 25- to 40-cfs canal. It was necessary to re-
move this material with water in the canal. The District found the
original 6-foot blade excellent for work.

sk OR ok ok

20


Figure 10

Section of the Chemical Engineering Branch, Division of Research,
Office of Chief Engineer. Copies of the report can be obtained by
writing the Chief Engineer, Bureau of Reclamation, Denver Federal
Center, Denver, Colorado 80225.

STEEL ROD OR POST DRIVER
(Suggestion R6-65S-37)

Earl J. Foster, Jr., a lineman with the Watertown Field Unit of the
Bureau of Reclamation, Watertown, South Dakota, suggests that the
driver shown in the sketch on the followi page, designed for driving
rod-type electrical grounds can also be made a little larger for driv-
ing fence posts for electrical grounds or fencir obs. By the numbers
(1) is made of 3-inch-diameter solid steel stock; (2) is extra strong
steel pipe; and (3) is a stop collar welded to the top end of the standard
weight "holding" pipe (4) with minimum inside diameter of 1 inch for
use with the rod-type ground and larger for fenceposts; (5) is the stop
plate welded to the lower end of the driver pipe with the hole in the
plate large enough to allow free movement of the driver and small



Monitoring and Alarm System

Since the gages are completely automatic and are called around the
clock, they have been designed with features to alert the calling
station if certain abnormal conditions develop. As mentioned above,
the engine- generator set at Taylor Ferry starts and stops automatically
as required and can be monitored while running by listening for the
ignition pulses on the radio. If, for any reason, the engine fails
to stop when it should, it may be stopped on command by dialing an
appropriate number. Conversely, it maybe started by dialing anappro-
priate number in case it fails to start automatically. If the thermo-
electric generator at Cibola fails for any reason, a steady tone is
received in lieu of the water level report when the gage is called.
By dialing a different number, the water level report can be obtained.
A technician is then notified. Failure of power or battery charger
at the Yuma gage results in this same response. If, for any reason,
the transmitter is not cut off automatically, a time-delay relay
locks it out after two minutes. This relay may be reset by dialing
an appropriate number.

Future Planning

These gages are a valuable aid in scheduling water on the Lower Colo-
rado River, however, more flow data is needed and this type of gage
has limited application due to its slow response and method of encod-
ing. It would not be practicable for a large number of frequently
called stations on a voice-shared radio network. A high-speed pro-
gramed telemetering and recording system is being considered. Such
a system could call in and record data from several locations in the
time required to interrogate one of the existing gages.

The fast-moving development of data collection, transmission, and
logging systems opens the way for improvement of water scheduling
and control techniques. The increasing shortage of water, with re-
sultant demands for better utilization and control emphasizes the need
for such improvement.

Assistance

For further information, please write the Regional Director, Attention:
Code 3-600, Bureau of Reclamation, P. O. Box 427, Boulder City,
Nevada 89005; or Chief Engineer, Code 400, Bureau of Reclamation,
Building 53, Denver Federal Center, Denver, Colorado 80225.



Figure 5



uBR te

P423-0-50652NA

S68:
P423-D-50653NA

Figure 4
3


SAFETY SUGGESTION FOR IMPROVED FENCE GROUND DRIVER

This driver is designed for the rod type ground (port No. 71.11) Can also be
made on a little larger scale for the fence post type ground (part No. 71.10)

1. 3" Solid stock.
2. Extra strong pipe.
3. Stop collar. (See Note 1.)
4. Standard weight pipe minimum
inside diameter 1. -

5. Stop plate. (See Note 2.) / =
6. Two !/2" set screws. |---> to
7. Ground rod.
O
2--—| "
|
ar |
37 H
|
|
|
Note I. 4-4
Stop collar welded near top end of hold |
pipe. Small enough to allow free movement |
of driver and large enough not to pass '
through stop plate hole. '
2)
9
I
|
I
t
{
|
i
|
|
|
|
i
y
Note 2. 5 eo
Stop plate welded on lower end of driver. = 5?
Hole made large enough to allow free 6-7
movement of driver and small enough
so stop collar will not pass through.

“9
OQ,



is simple, trouble- and maintenance-free, and holds almost constant
battery voltage.

Radio System

Each gage is equipped with a 12-volt, 30-watt, transistorized, FM,
mobile radio, as shown in Figure 6 and on the cover page. These
radios work into existing river control voice radio network repeaters.
Vacuum tubes are used in the final stages of the transmitter. To
keep the battery drain low, the transmitter tubes are heated only dur-
ing reporting. A twenty-second time delay between the call and the
report allows the tubes to warm up. This undesirable time lag can be
eliminated now through the use of new all-transistorized radio or
quick heat transmit tubes, without increasing battery drain.

Remote Control Signaling

Two commonly used systems are available for selective radio call.
The single or double tone system employs audio frequency tones sent
out by the calling station. A resonant decoder in the receiver re-
sponds to the appropriate tone or combination of two tones to close
a set of relay contacts. The two-tone system affords a good degree
of security against false operation from noise or voice frequencies.

The digital tone code system uses an audio tone which is pulsed or
interrupted by a telephone selector. The decoder is available with
five function contacts, each of which can be closed separately by dial-
ing appropriate numbers. This system has a high degree of inherent
security against false operation and affords a simple means of send-
ing more than one control signal to the gage, as described herein.
All electrical transistorized digital decoders are now available.

Water Level Encoder

All three of the gages described use drum-type float-operated encoders
with which most persons engaged in water measurement and controlare
familiar. A roller actuated micro-switch scans three stagger-ridged
drums oncommand. The resultant pulses are counted in groups to
decode the water surface elevation in feet, tenths, and hundredths.

These encoders scan the switch closures which normally would pulse
an audio oscillator to modulate the radio transmitter. However, since
transistorized radio power supplies contain an audio frequency oscil-
lator, it is only necessary to apply positive battery voltage to the un-
grounded microphone terminal, through a relay operated by the scan
switch, to produce a good quality audio tone from the transmitter.
This simple technique was discovered accidentally and precludes the
need for a separate audio oscillator.



ROTARY MOWER TRACTOR SAFETY SHIELD
(Suggestion R5R6-65S-4)

An operator of necessity must be able to frequently observe, for correct
operation, a mower being towed behind a tractor when cutting weeds on
canal banks and roadways. With rotary mowers, such as those used
advantageously on the Rio Grande Project in New Mexico and Texas,
Figure 1, the operator also of necessity must be protected from ob-
jects thrown by the mower blades. Drop chain and wire-screen-type
guards have not proved to be sufficiently effective in stopping all small
objects thrown by the mower. A more positive plexiglass shield was
suggested by Alfred L, Hulbert, an employee of the Ysleta Irrigation
Field Branch, and Chairman of the Ysleta Branch Safety Council on the
Bureau's Rio Grande Project.

Figure 1 below and Figures 2 and 3 on the following page are views of
the 3/16-inch by 4-foot by 4-foot plexiglass shield installed behind the
tractor operator to prevent him from being struck by objects thrown
from the mower blades.

Figure 4 on page 24 is a sketch of the shield.

With the plexiglass shield the operator may observe the mower in com-
plete safety at any and all times. The shield should be braced to the
tractor because of heavy vibration caused by the mower blades, how-
ever, metal braces can be easily adapted to any make or model tractor.
Also a special coating applied to the plexiglass will prevent excess dust
accumulation on the plexiglass caused by static electricity. The plexi-
glass shield should be edged with light angle iron for extra strength and
rigidity.

If additional information is desired, please write to the Project Manager,
Bureau of Reclamation, 211 U.S. Courthouse, El Paso, Texas 79901.

PX-D-50658NA

Figure 1

22


Department of the Interior, Bureau of Reclamation

IRRIGATION OPERATION AND MAINTENANCE

BULLETIN NO. 53

July, August, September 1965

LAST COPY - D0 NOT REMOVE

LAST COPY - DO NOT REMOVE

In This Issue:

Radio Reporting River Gages Aid Water Scheduling on
Lower Colorado

Evaluating Buried, Hot-Applied Asphalt Membrane Linings
Steel Rod or Post Driver

Novel and Portable Power Unit

How to Drill Uniform Holes

Large Bucket--Small Backhoe

Removal of Packing in Expansion Joints

Rotary Mower Tractor Safety Shield

LAST COPY - DO NOT REMOVE


Figure 2

Figure 3

Figure 1 shows the
Casper Main Canal,
on the Kendrick
Project. This is
a reach lined with
a buried asphalt
membrane in 1954
that is providing
excellent seepage
control and has
required no main-
tenance.

Figure 2 shows
Lateral R4-S on the
Shoshone Project.
This reach was
lined with a buried
asphalt membrane
in 1953.

Figure 3 is a view
of the Main lateral
of the Angostura
Unit of the Missouri
River Basin Project;
the lateral was lined
with a buried asphalt
membrane in 1952,
and is effectively
controlling seepage
and has required no
maintenance although
the membrane has
slipped and folded at
the top of the slope.

Figure 4 on the fol-
lowing page, shows
the Casper Main
Canal, Very stable
gravel protective
covers are used in
some buried asphalt
membrane lining
installations.


EVALUATING BURIED, HOT-APPLIED ASPHALT MEMBRANE LININGS

One present disadvantage of any buried membrane-type lining is the
uncertainty of the life of the membrane material as compared with
the hard-surface-type linings such as those composed of portland ce-
ment concrete and mortar. Some bentonite membranes have been in
service 25 years, the first linings of this type being installed in 1940.
Buried, hot-applied and prefabricated asphalt membranes have only
been in service from 14 to 16 years, plastics 10 years, and synthetic
rubber only 4 years. Most of the Bureau of Reclamation experience
has been with the hot-applied asphalt membranes and some 8 million
square yards of this type of lining have now been installed. However,
there is reason to believe that plastic and synthetic rubber sheeting
will prove equally as efficient and effective. All should provide some
of the tightest linings developed to date.

Field observations indicate that buried asphalt membrane linings, gen-
erally, have performed very satisfactorily over periods up to 16 years.
Most project operators are well satisfied with the performance of the
linings and would install or are installing more of this type of lining, ©
except in smaller canals and laterals where mechanical cleaning with-
out damage to the membrane is a problem. From the field observa-
tions it appears that the life of the membrane lining that is adequately
protected and maintained will be primarily dependent upon the life of
the membrane and recent laboratory tests of the hot-applied asphalt
membranes constructed of catalytically blown asphalt cements indi-
cate that little change in the membranes characteristics has occurred
since their application.

Field Observations

Very few reaches of buried asphalt membrane linings have failed.
Some have beendamaged. The damage hasbeen the result of: (1) place-
ment of the lining on unstable side slopes, (2) inadequate protection
of the membrane, (3) weed growth in cover material, (4) surface run-
off, (5) type of subgrade materials, (6) cleaning operations, (7) scour-
ing of cover material onthe outside of curves and subsequent exposure
of the membrane, (8) overtopping of the lining by operating, laterals
primarily, at greater than designed normal water depth, and(9) mem-
brane rupture or puncture. Rupture from hydrostatic pressure under
the lining has occurred, but once relieved the rupture apparently does
not become more serious.

The maintenance of buried asphalt membranes has consisted essentially
of providing a better quality cover material or adding to such cover;
removing silt and debris from channels; removing siltand grass berms
at the water line in channels; repairing membrane damage due to ero-
sion of the cover because of channel velocity or surface water flowing
down the side slopes; improving the subgrade material before replace-
ment of punctured or ruptured membrane; and providing surface water
inlets into the channels. Several views of some of the lined reaches
are shown in Figures 1 through 7 on the following pages.

8


decoder consume such a small amount of power that they can be ener-
gized on standby 24 hours a day andthe battery canbe maintained with
a trickle charge of a few hundred milliamps. Thus, the gage will re-
spond to selective call at any desired time.

The Taylor Ferry on-call radio reporting gage was developed first.
At that time, the gas-fueled thermoelectric generator, which has
been developed as a static low-power source of electrical energy, was
not commercially available. The cost of a suitable solar cell was
about equal to the total cost of all of the other equipment needed for
one installation. Thus, a small one-cylinder propane-fueled engine
generator set with automatic starting control was used. The equip-
ment for the Taylor Ferry installation is shown on the cover and in
Figure 6 on the preceding page.

In the Taylor Ferry installation, a contact-making ampere -hour meter
registers battery drain. Whena predetermined number of ampere -hours
have been used, the starting circuit is set up. The next time the gage
is called, the engine starts and runs until the battery is charged. A
small pulse voltage from the engine magneto points is used to modu-
late the transmitter. The background clicking noise heard on the
radio signifies that the engine is running but does not over-shadow the
tone coded water level report.

The second on-call gage at Cibola was designed with a thermoelectric
generator consisting of a thermopile (series of thermocouples, a gas
burner, cooling fins for the cold junction, anda transistorized con-
verter and rectifier. A view of a thermal electric generator as in-
stalled is shown in Figure 7. It produces up to one ampere of direct
current for charging a nickel-cadmium battery, has no moving parts,


Drill chuck-~~~_

Section of cane

“>~Center pith

with a pair of pliers while he
forces the turning drill down
through the hollow core, and
he's in business. If cane
doesn't grow in your park, he
suggests you get an old bamboo
fishing pole. One pole will sup-
ply depth gauges for a long time.

Incidentally, we sometimes use
an old spool from the wife's
sewing basket to make a drill
depth gauge.

The sketch at left describes

the assembly of the drill and
gives directions for making

one.

LARGE BUCKET--SMALL BACKHOE

Mr. Harold Sexton, Secretary-Manager of the Rogue River Valley
Irrigation District, Medford, Oregon, informs us, that over a year
ago a 6-foot-long bucket was designed for use on their hydraulically

cperated backhoe for cleaning canals and laterals.

The first bucket

was acomplete success and the photographs below and on the following

ft bu, Z
PX-D-50655 NA

Photograph No. 1

19

page are views of the District's
latest model--a 7-foot-long
bucket.

The photographs show the new
blade (bucket) rehabilitating a
small lateral. The lateral runs
through varied soil conditions,

as well as numerous fenced areas,
which makes use of conventional
ditchers only partially successful,
Note the oversize pad used on the
stabilizer to prevent tipping of
the tractor. This is necessary
with the use of the large blades.

Twice last year, due to local
conditions, a large amount of
silt and mud partially filled two


RADIO REPORTING RIVER GAGES AID
WATER SCHEDULING ON LOWER COLORADO

By R. E. Bellis and J. I. Sanders

On-cali radio reporting gages are helping the Bureau of Reclamation
operate the Lower Colorado River for maximum conservation and util-
ization of water. The Bureau, through its Region 3 Lower Colorado
River Control Office, is responsible for the operation of the Lower
Colorado River from Lees Ferry to the Mexican Boundary. Operation
of the river must be in accordance with the Colorado River Compact,
Boulder Canyon Project Act, Mexican Treaty, all water delivery con-
tracts, and the Supreme Court Decree of March9, 1964. Drought cycles
along with rapidly increased demand on the water supply of the Colo-
rado River have called for concentrated efforts by the Bureau for water
conservation. One of the methods used to conserve water was to im-
prove the accuracy of delivery by better river routing procedures.
Among other things, this called for improved reporting of river flows
at different locations (gaging stations) along the river. One of the
steps taken to accomplish this has been the development of improved
methods of radio reporting of river stages from the gages.

The drought cycle on the Colorado River during the period 1953 to
1956 emphasized the need for an improvement in our reporting proce-
dures on river flow as it progressed from storage rese:'voirs to points
of diversion. About five days are required to deliver stored water
from Lake Mead to Imperial Dam, the last major diversion point for
irrigation use in the United States. Another five to seven days are
required for flow diverted at Imperial Dam to reach the Coachella
Valley farmers at the end of the Coachella canal. The last storage
reservoir on the Colorado River at which some reregulation of storage
can be accomplished is in Lake Havasu, the reservoir formed by Parker
Dam near Parker, Arizona. Water released at this point is either
diverted to users along the river or lost to the Gulf of California.

In 1954, the first move was made to obtain telemetering equipment
for installation at Colorado River gages to report water stages to

the scheduling offices by radio. Soon thereafter a telemeter was
installed at the Colorado River gaging station below Cibola Valley,
Arizona, which is located about 24 hours' water travel time above
Imperial Dam. This gage reported onan FM river control radio system
to the Imperial Dam Office and the Boulder City River Control Office.
It reported by clock program every 6 hours and was used for several
years for advance information on flow that couldbe expected to arrive
at Imperial Dam 24 hours later. This allowed a 24-hour reduction in
the time required to make changes of releases of stored water at
Parker Dam to meet downstream requirements. During the drought
years, this was particularly important because only water for down-
stream requirements was being released from storage.



of construction. Under the Bureau's Lower Cost Canal Lining Pro-
gram, an extensive testing program was started in 1962 consisting
of visual observations and physical testing of asphaltic membrane
linings having service records of up to 12 years. The purpose of
this program was to obtain information relative to the effects of
field aging.

The laboratory report summarizes the test results on 65 samples
from 15 different canal or lateral installations on 9 Bureau projects.

On the average, 8-year field aging results in a reduction of 20 per-
cent in penetration, 30 percent in ductility, and an increase of 5 per-
cent in softening point. As evidenced by service performance and
visual examination, this change in physical properties of the asphalt
membranes did not materially affect their ability to provide a flex-
ible, watertight lining.

Based on change in physical properties as determined by softening
point, penetration, and ductility testing, it is indicated that approxi-
mately 90 percent of the aging of the asphalt membranes studied oc-
curred during the first 4 years of service. The change due to aging
decreased sharply after about 8 years' service, as shown in Figure 8
on the following page.

The results of visual observations and physical testing indicated that
one of the more important factors contributing to life of the asphalt
membrane is thickness. A minimum thickness of 0.20 inch, approxi-
mately 1.12 gallons per square yard, is required before longtime
service can be expected. (Bureau specifications now require a mini-
mum of 1.25 gallons per square yard.) A study of the reported field
observations and analysis of test results completed on membrane sam-
ples after up to 12 years' service did not reveal any information that
would signify serious deficiencies of the asphalt membrane lining.

Based on the comparison of the test results of 65 field membrane sam-
ples, most of which represent the oldest installations, with the test
results from the original asphalt cement at the time of application,

88 percent have demonstrated satisfactory resistance to field aging,
with only 12 percent in a fair to poor condition. The membranes in
poor condition resulted from accelerated aging due to construction
deficiencies such as holidays, incorporated subgrade material, and
nonuniformity in thickness.

The watertightness of asphalt membrane lining is evidenced by a field-
performed seepage test (ponding method) in an 11-year-old lateral in-
stallation where the seepage rate was determined to be only 0.08 cfd
(cubic foot per square foot per day). Ponding tests made in 1950 in
the same general area, prior to the installation of the asphalt mem-
brane lining indicated a seepage rate of 9.96 cfd.

12



Figure 9

Deficiencies noted in a number of membrane samples are as follows:
(a) Nonuniform thickness of membrane.

(b) Large rocks or clods contained in the membrane indicating im-
proper subgrade preparation, Figure 9, above.

(c) Sand, gravel, and silt mixed in the membrane as a result of
use of excessive spray-bar pressures or use of the spray bar too
close to the subgrade, or both.

(a) Accumulation of excessive silt, sand, and gravel on the mem-
brane before the second pass of spray application was completed.
This results in two thin membranes separated by a layer of soil,
as shown in Figure 10 on the following page.

Examination of the membrane samples gave evidence that better con-
struction control through more rigid inspection can be expected to pro-
duce a higher quality membrane significantly reducing deficiencies.

The laboratory studies summarized inthis article are contained in Report
No. B-34, prepared by F. H. Geier, of the Bituminous Laboratory

14


IRRIGATION OPERATION AND MAINTENANCE
Bulletin No. 53

JULY, AUGUST, AND SEPTEMBER 1965

INTRODUCTION

The use of on-call radio reporting gages by the Bureau of Reclamation
as an important aid in the operation of the Lower Colorado River and
the type of equipment used in some of the more remote areas are de-
scribed in an article beginning on page 1 prepared by R. E. Bellis
and J. I, Sanders of the Bureau's Region 3 staff in Boulder City,
Nevada.

An evaluation of buried asphalt membrane linings developed by and
installed on Bureau constructed projects over the past 14 to 16 years
is the subject of an article beginning on page 8 on the use of this
lower cost canal lining material. In addition to field performance
the results of laboratory tests on field specimens of the membranes
are discussed in the summarization of a laboratory report prepared
by the Bureau's Division of Research.

Several pieces of equipment designed and constructed by project
operation and maintenance personnel also are included in this issue
of the bulletin. These are: a device for driving rod-type electrical
ground and steel fenceposts, page 15; the use of a portable 3-hp gas-
oline engine to power a hoist on a movable crane to expedite the re-
moval, disassembly, reassembly and reinstallation of 80-cfs pumps
and their 300-hp electric motors, page 17; a large, but lightweight
bucket for cleaning smaller laterals and drains with a hydraulically
operated tractor-mounted backhoe, page 19; a simple device for re-
moval of packing from pipe and penstock expansion joints, page 21;
and on page 22, a plexiglass shield to protect the operator of rotary
weed mowing equipment.

%



PX-D-SO660NA

Figure 3

23


The Irrigation Operation and Maintenance bulletin is published quar-
terly, for the benefit of irrigation project people. Its principal pur-
pose is to serve as a medium of exchanging operation and maintenance
information. It is hoped that the reports herein concerning labor-
saving devices and less costly equipment and procedures, developed
by resourceful project people, will result in improved efficiency and
reduced costs on the systems of those operators adapting these ideas
to their needs.

To assure proper recognition of those individuals whose suggestions
are published in the bulletins, the suggestion number as well as the
person's name is given. All Bureau offices are reminded to notify
their Suggestions Award Committee when a suggestion is adopted.

Division of Irrigation Operations
Office of Chief Engineer
Denver, Colorado

Taylor-Ferry on-call radio reporting
gage equipment assembled for test.
Cover Photo No, P45-300-4340-2



Figure 6
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