Figure 7

could be installed to a relatively
impervious layer of material
which was 6 to 8 feet below
ground surface this recircula-
tion of pumped water would be
eliminated. Project Engineer
W. T. Lowe of the Drainage
Branch devised a shield to fit
the ladder-type excavators so
that a vertical roll of plastic up
to 12 feet long could be sus-
pended inside the shield andfed
out between the rollers at the
rear. After atrial run in firm
ground, about 1, 300 feet of
8-mil polyethylene plastic was
installed by the project forces
along the wasteway, and although
the plastic initially tended to bind
in the rollers at the rear of the

shield, this difficulty was generally corrected by remodeling the rollers
to use washing machine wringer rolls with sealed bearings. The depth
of the installed plastic varied from 6 to 10 feet.

The trial run is shown in Photographs 7 and 8. Photograph 7 is a closeup
of the plastic cutoff curtain being installed during early trials. Atrencher
was used to excavate to a depth of approximately 10 feet in preparation
for the commencement of the trial. One man is inside the project-

17

developed membrane laying
shield preparing to start feed-
ing plastic through the pairs
of hard rubber rollers visible
on the trailing edge. Further
experience indicated that a
more sophisticated roller sys-
tem might be required if the
cutoff curtain was to be laid in
wet trenches or in caving
ground,

Photograph 8 shows more
detail of the actual operation
along the wasteway. An aux-
iliary shield attached to the
trencher for protection against
sloughing ahead of the shield is
visible. The trencher isa
special model built for drain-
tile installation.


= S58

Improved Wooden Plugs

Loosening of wooden plugs used for securing screws can be prevented
by driving a wedge into the inner end of the plug. Slot one end of the
plug about twice the length of the wedge. This will prevent splitting.
Place the tip of the wedge in the slot and shove the plug gently into
place, then seat it firmly with ahammer. Make a pilot hole in the
plug to receive the screw.

SAFETY MEASURE FOR TRUCKS
(Suggestion R5RG-61-20)

While observing field crews working close to vehicles, especially dump
trucks and trucks with booms or other heavy equipment, Mr. Daniel
Farias, Hydraulic Engineer on the Rio Grande Project, Texas, became
aware of the imminent danger to those working or simply standing
behind these vehicles. It is often necessary for a driver in the midst
of operations to back up or maneuver his vehicle into position without
prior warning to others. The elimination of this danger could be of
incalculable value in preventing accidents.

The present method of signalling, if any, is such that under normal cir-
cumstances a worker who is absorbed in his labor may or may not see
or hear a warning. Mr. Farias suggested that a warning device be
installed that would immediately draw the attention of workmen located
around and behind a vehicle and alert them as to the intention of the
driver. This might be a horn located in the rear; making the sound
distinctly audible.

11



Figure 12

Figure 12 shows backfilling operations of the plastic cutoff curtain.
Note the caving area in front of the two workmen in center of the fig-
ure. Water is visible on the left side of the plastic curtain and directly
in front of the dozer in the foreground. Figure 13 is another view of
the backfill operations for the plastic curtain. Workman in the center
holds the plastic as dozers are filling on each side of it.

Fi
, Se be
P222-116-48993

Figure 13

21


The nutria is prolific; a female may have five litters in 2 years, at any
season, The young number from two to eight (average five) per litter.
Females first breed successfully at about a year of age. The gestation
period is about 130 days. The young are well developed at birth and get
about on their own in a few hours. By their second week they begin to
eat solid food, and they are weaned by the eighth week.

In its feeding habits the nutria is strictly herbivorous. Its natural foods
include a variety of aquatic plants--succulent green stems, rushes,
grasses, seeds, roots, and such coarse vegetation as cattails, reeds,
duckpotato, chufa roots, and sedges. The food is usually consumed on
the shore, particularly in the evening.

Establishment in the United States

In 1850, nutrias were abundant in the rivers, estuaries, and marshes

of their native Argentina. Changing fashions and requirements of the

fur trade, to the point where the demand for pelts was 100 times that of
the supply available from hunters and trappers, nearly led to their exter-

mination, Raising
nutrias in captivity
began in South Amer-
ica in 1922, farms
sprang up throughout
Argentina, and the
industry spread to
Europe and North
America, Nutria
farms were estab-
lished in Quebec,
Canada (1931), in
the Green River area
of the State of Wash-
ington (1932), on
Avery Island, Iberia
Parish, Louisiana

@ ESTABLISHED
te REPORTED

(1938), and else-
where. In most cases these proved to be costly investments, since more
money was spent on equipment, feed, and labor than was realized from
the sale of furs. Most nutria farms went out of business; many operators
turned the animals loose or allowed them to escape. From these releases
the nutria has spread and become widely established over the country.
Feral nutrias, as shown on the map above, have been reported from at
least 31 states and 3 Canadian provinces; established colonies apparently
exist in the wild in at least 16 states.

Economic Importance
As is often true of newly established foreign species, the nutria popula-

tion has built up rapidly in some areas. Breeding at the rate it does,
an animal of this size and with its voracious appetite can pose a serious


West Canal Installation

The success of both the experimental East Low and wasteway installa-
tions prompted two more extensive installations during the 1962-63
nonirrigation season. On the West Canal, leakage from one reach about
5, 050 feet long was a major contributor to a high water table threaten-
ing about 300 acres of land. Full lining of the canal was impracticable
because of the size of the canal and because irrigation from higher
ground could also contribute to the high water table, so that back pres-
sure could be expected against a full-lined perimeter.

The canal in this reach was excavated in sands, silts, and caliche with

a relatively impervious indurated material at varying depths below grade.
The saturated sands were quite unstable. In this situation, it appeared
that a vertical plastic cutoff wall along the inside toe of the lower bank
plus a side lining of the inside lower bank would form a barrier against
the migration of water from the canal and from the lands above the canal
into the lower areas. Accordingly, plans were prepared for the installa-
tion of 4,000 square yards of plastic membrane to be placed in the trench
to a maximum depth of 12 feet below grade, using the shield and equip-
ment developed for the wasteway installation. The plastic was to be topped
by a compacted blended earth side lining. The work was advertised and
awarded to a low bidder in the fall of 1962.

The contractor began by excavating for the side lining with a dragline. ~
The canal was dewatered to a point below the canal invert grade by digging

a drain trench along the right bottom of the canal and pumping water over

a dike at the downstream end. As permitted by the specifications, the

contractor decided to use the project-owned shield. The contractor also

leased the same ladder trencher used in the experimental installations,

and after completing the side lining excavation, beganthe installation of

the Government-furnished 10-mil polyvinyl chloride sheet.

Again difficulties were encountered because of the tendency of the plastic
to bind and tear as it emerged from the shield. After some 25 to 30 feet
of plastic had been installed and before the full depth of cutoff was reached
an equipment breakdown stopped work. During this enforced shutdown
period the contractor further modified the shield to improve its opera-
tions. These modifications consisted of lengthening the shield, so that

a second roll of membrane material could be placed within it; provid-

ing a sealed bearing for the plastic roll to be suspended from; and install-
ing a pipe for an air jet to keep silt and mud from settling in the bottom

of the shield.

Using the newly modified shield the contractor resumed work and placed
75 feet of plastic. Again some ripping and tearing occurred. In order

18



vt

P222-116-4512 7%.

Figure 16

Figure 16 is a view of the trench being excavated and the plastic cutoff
material in place. Figure 17 shows the completed work and the beach
belt protection provided to control erosion.

P222-116-45116

Figure 17

24


Figure 10

Figure 10 is another view of the trenching equipment and attached shield
containing a 400-footroll of the plastic. Figure 11 below is a view
from the left slope of the canal showing backfilling operations in badly
caving sand areas. Workman in the center is holding the plastic curtain
as dozers are filling around it. An air hose directly under the workman
on top of the plastic dispenser shield leads to an air pump located in the
bottom of the shield which in turn is used to pump out water and silt and
make sure the plastic rolls are turning freely.

FP 222-116-44990

Figure 11

20


Figure 4 shows work-
men placing the plastic
sheet in the reach shown
previously. Although
the filament tape anchored
to the upper edge of the
plastic was spaced 10 to
12 feet apart, it appeared
to be quite secure. Addi-
tional anchors were placed
to strengthen the hold on
the plastic after it was
determined the plastic
was being subjected to
considerable stress dur-
ing subsequent backfill-

“, Pe2g-6-43982 ing operations.

gre

Figure 4

Figure 5

Figure 5 is a view looking upstream showing backfilling operations.
The backfill corresponds closely to the top of the plastic sheet. Fig-
ure 6 at the top of the next page is a view of the canal looking down-
stream along the right bank showing conditions after completion of

15


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dung yUD
s0ydsy

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Jpq Apuds 0} padwnd \i9~~

1 /

'
YUD} OF PauUuNyeu |10%



sie terete ste este TP
SEE RET

(rele faT9 38
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. —- ——--— ”
: aa TE -
é SU TAN CUTOFES t

FT coqury

ore

Verioble distence trom £
of Gana] in right Donk

LOCATION MAP

NOTES

At Station 275620 there is 9 3'13' concrete box
cuuect under the coral Top oF culvert 15
EGIN PLASTIC CURTS Goprosimetaly 8 oelow berm
Por oe ee ryetocshannep There ore 4 wansverse investigation trenches,
“jor stofione) (ff mile Ged fill ond 2 jrensrerse investiga
Van trenches in the Mile 6.7 Fill ranging in
YOO om bt to te, mich must be hie
Goring berming operations.
See bug, 282-1. 38052 tor Logs of Exploration.

SECTION AA

Reconstructed Embonkment—

: Typical berm excovetion
Finuhed Section

Typical trench excavation
4 \

q vorigéle 22°44 or fe \
feluse! on sold Conche basalt
es steeper WO tercpan OO" ° ‘

ce! exshng,

| Eee eee oy
y

"Diashie sheet (gaigrny:cheride
ngitee peel Gaigeey here)
Government fermihed (7 (ar 743 | DELETED KEY AND VICINITY MAPS

250° fen gens a

3 cocumaa Basin PAOIECT ~WASHINETON
a EAST LOW CANAL ~ ADJACENT TO BOCK 43
PLASTIC CURTAIN CUTOFFS
LOCATION MAP @ TYPICAL SECTION

TYPICAL SECTION PLASTIC CURTAIN CUTOFFS wee ee

EAST LOW CANAL
ny aE

(RIGHT BAWK)
THAT waar EHP | 22 2- Ilo SLOSS

27 GPO 837-628



Over 80 percent of these raw furs have been exported to the European
markets. The few low-grade skins consumed in the United States have
been used principally for linings in cloth coats. Even the best nutria
garment is far less serviceable than fur seal, beaver, or sheared
raccoon. It is the high processing and manufacturing costs that make
the finished nutria fur coat a luxury item.

Ranch-raised nutria pelts produced in the United States have not been
significantly superior to the best grade of South American or Louisiana
wild nutria. Prices for these pelts have been disappointing, owing to

the inferior size and quality of the skins. By 1940, most American
ranchers had gone out of business. Those that continued, operated
mainly as centers of distribution, holding wild-caught animals for expor-
tation as breeding stock.

Wild Nutria Catch in U.S, in Recent Years

1960 1961
== 10
-- 1
31 5
Louisiana 694,110 716, 435

Maryland 34 --

Mississippi ........... . -- 384
North Carolina .. 536 36
Oregon 154 547
Texas 270 13, 402
Virginia . 74 92
Total 695, 208 730, 912

A Word of Warning

In recent years, promoters of nutria breeding stock have made fantastic
claims and have painted rosy pictures of quick and easy riches from the
stock they provide. Breeding pairs, claimed as being superior animals
of pedigreed stock, have been foisted upon a gullible public at $1,200 a
pair. As a result of one such operation, three promoters of a nutria
breeders association were indicted for mail fraud in the U.S. District
Court, Los Angeles, in 1961. They pleaded nolo-contendere and were
duly fined. Postal officials estimated that this breeding-stock scheme
had grossed over $3 million. The association represented has since
filed a petition in bankruptcy.

Persons interested in raising nutria as a business venture should con-
sult the National Better Business Bureau, Inc., 230 Park Avenue, New
York 17, N.Y., for current information.

Some states have adopted regulations with respect to importing, rearing
and releasing nutrias. Contact your State Conservation or Wildlife Agency
before embarking on a nutria project.



2m. Competition with native wildlife is one result - muskrats have
din areas where nutrias re on the increase. Habitats have
been altered and waterfowl marshes destroyed. In agricultural areas,
nutria burrows have seriously damaged dikes, bayou banks, drainage
and irrigation ditches. Cultivated crops have been ruined on
close to waterways. Alfalfa, sugarcane, rice, and young corn
particularly subject to attack, and the nutria also has a taste for
et potatoes, cabbage, clover, and most root crops

> i s. These damage problems are at present most intense
in parts of Louisiana and Texas. Both State and Federal Governments
are doing research and expending funds on control of the nutria where

i established in the wild and is proving detrimental to other interests.

iin the same manner as are the smaller muskrats,
t that the traps must be staked out more securely, The pelt is

"and fur side in, over a frame 30 to 35 inches long. The
condition, and color of the underfur determine the price received.
There is practically no commercial demand for pelts less than 22 inches
yehole to the bottom of the skin. Because of the extra work
required to prepare nutria, many Louisiana trappers prefer to concen-
trate on muskra In recent years the best wild-caught Louisiana
nutrias have broug! 2.50 a pelt; the average has been about $1.00.



Figure 6

the test installation. Gravel has been placed on the inside sideslope to
provide erosion protection. The drill at the right embankment toe is
installing an additional ground-water observation well to be used to
evaluate the effectiveness of the cutoff.

When water was put into the canal at the beginning of the irrigation sea-
son, there was some settlement of the loose backfill. However, this
consolidation had been expected and the bank was reshaped by operation
and maintenance forces when equilibrium was reached. Observation
well readings during the 1962 irrigation season indicated that the mem-
brane was not only affording protection to the canal banks but was also
reducing water loss through the bank. The rise in wells directly oppo-
site the lined reach was as much as 10 feet less than the rise in wells
at either end of the reach. Total direct construction cost including the
plastic and riprap for the successfully installed 200 feet of lining was
slightly more than $11.00 per foot. In spite of the difficulties encountered
in making this installation, it was obvious that a successful low-cost
side lining could be secured by installing a plastic membrane in a ver-
tical trench.

Second Trial Installation

The success of the first installation in the East Low Canal and the avail-
ability of a ladder-type excavator with a shield used for installing drain-
tile in wet and unstable ground suggested a possible solution of a differ-
ent problem. A portion of irrigable land adjacent to a wasteway could
only be drained by pumping into the wasteway but unfortunately the waste-
way was constructed in gravelly materials that would have rapidly
recharged the area being pumped. It was decided that if a cutoff wall

16


ASPHALT DISTRIBUTOR IMPROVED

(Reprinted by permission of GRIST, November/December, 1961
issue, a publication by the National Conference on State Parks,
Washington, D.C.)

One simple pipe added to an asphalt or road oil distributor, photo-
graph below, can improve operations considerably, saving from 15 to
30 minutes per ''shot,"' says Earl Mansor, a truck driver at Zion
National Park, who thought up the suggestion. This ''suck back'' line
is run from the hand spray line to the drain line. It prevents the hand
spray line from stopping up with asphalt and reduces puddling from
spray bars.

The system is shown diagrammatically on the following page, with the
darkened pipe, 3/4-inch or 1-inch, the one to be added. To operate,
close valves 2, 3, and 7, open valves 1, 4, 5 and 6, thus allowing oil
to return to the tank. If two-way valves are installed on your distrib-
utor, the operation becomes even simpler.



Total contract cost including the two -ply plastic was about $19.00 per
linear foot of lining. Early readings of observation wells below the
canal indicated much slower buildup of ground water than in previous
years. This apparently indicates that plastic curtain is performing
its job satisfactorily.

East Low Canal Installation

In the fall of 1962, three separate reaches of the East Low Canal were
selected for the installation of vertical plastic membrane side lining.
These were reaches where bank stability was questionable. In one of

the reaches a canal break had occurred at an apparent low spot in the
core bank. Free water was emerging in places along the toe of the

bank and there was sufficient moisture within the bank that efflorescence
from the evaporation of pore water was occurring on the operating road
on top of the bank. Probes with auger holes and cross trenches in the
banks indicated typically silty sand or sandy silt interspersed with streaks
of sand and caliche. The original ground below the bank was a low den-
sity loess and lime impregnated sandy silt (caliche) with occasional lenses
of open gravel. The material was considered free draining enough that

it could be expected to stand vertically for short periods of time.

Under these conditions a plastic cutoff wall similar to that previously
described on the East Low Canal appeared to offer an inexpensive and
satisfactory method of repair. Plans were prepared as shown on Draw-
ing No. 222-116-32835, page 27, and the work was advertised and
awarded to the low bidder. The contractor began work in the upstream
reach of the canal excavating the berm with a dozer and the trench with
a dragline.

The 10-mil polyvinyl chloride sheeting was furnished to the contractor,
accordian folded in 250-foot-long sheets. Renting hangar space at the
Ephrata, Washington Airport, thecontractor unfolded the plastic and
rolled it around a pipe spindle. The plastic was placed in the trench
by suspending the roll vertically from a second dragline and it was
then unrolled like a new carpet as excavation proceeded.

The method of installation proved fast and efficient and kept the plastic
close behind the excavation so the danger of trench sloughing before the
plastic was put in its place was kept to aminimum. Backfilling fol-
lowed as closely behind the plastic installation as possible. After com-
pleting the trench and berm backfill, a gravel beach belt was placed on
the inside slope of the lower canal bank.

Construction details are shown on Figures 14 through 18. Figure 14 on
the following page is a view of the plastic lining in the excavated trench
showing the spindle around which the plastic was rolled.

Figure 15 also on the next page is a view of the plastic curtain in place.

22



Department of the Interior
Bureau of Reclamation

OPERATION AND MAINTENANCE

EQUIPMENT AND PROCEDURES
RELEASE NO. 46

October, November and December 1963

(AST COPY - DO NOT REMOVE

P222-iI16-45117

LAST COPY - DO NOT REMOVE

CONTENTS

Nutria as a Possible Pest on Ditchbanks
Snow Plow Blade from Salvage

Asphalt Distributor Improved

Safety Brake for Scaffold

No-Slip Grips for Screws

Safety Measure for Trucks

Vertical Plastic Cutoff

inst CORY - DON PENNE




SAFETY BRAKE FOR SCAFFOLD
(Suggestion R2-63-48)

No provision had been made on scaffolds for use in the Folsom Field
Division of the Central Valley Project, to lock the wheels or casters
in place. The need for some means of accomplishing this and assur-
ing a safer working platform was recognized by Eugene H. Lee of the

Plant Maintenance Branch. Mr. Lee suggested the locking device shown
in the sketch below.

Several views of the brakes and the brake parts are shown on the fol-

lowing page. The brake locks the wheel and the turntable of the caster
at the same time.

Equally spaced holes in
circular plate for locking
wheels.

\Weld plate to wheel
support

Weld yolk to _- Weld
wheel support. _ en

Weld shoe
to arm



SNOW PLOW BLADE FROM SALVAGE

(Reprinted by permission of GRIST, November/December 1961 issue,
a publication by the National Conference on State Parks, Washington, D.C.)

Needing a pusher snow plow blade but not having the more than $100 required
to purchase one, personnel at Warren Dunes State Park, Michigan, cut
a piece out of a discarded 550-gallon water tank and mounted that on a
front-end loading tractor. The tank had just the right curve so that the
blade lets snow roll off easily.

The welder who handled the job cut a piece 20 inches high and 4-1/2 feet
long, in such a way as to have the riveted double edges from the tank rein-
force the blade edges. He then fitted brackets to the back of the blade.

Lyle McDonald, Park Manager, says the blade probably would last longer
if reinforced with an extra thickness of metal plate for a foot or so at

each end. Such reinforcing pieces could also be cut from the salvaged
tank.

“Suggested areas for reinforcing
on back of blade

sks ok



to use a material with greater resistance to binding and tearing, a
substitution of two-ply nylon reinforced polyethylene sheeting was
authorized for use.

A further complication was encountered where one reach of the canal
was on a curve and where caliche was at or near the canal invert grade.
The contractor found that the caliche in this reach could be ripped suf-
ficiently to be excavated, but that the trencher could not be turned on a
short enough radius to negotiate the curve. Therefore the trench in this
caliche reach was ripped with a tractor, excavated to a width of 3 feet
with a backhoe and refilled with the same blended earth mixture designed
for the side lining above the cutoff. The blended earth lining was placed
in four short reaches where depth to caliche was a maximum of only

2 feet.

The machine was used, however, to install 2, 740 lineal feet of plastic
in soft and unstable ground. The depth of the machine-excavated trench
varied from about 2 feet to a maximum of 9 feet, which was the greatest
depth before caliche was reached. Even ina firm trench the maximum
installed depth of plastic is about 10-1/2 feet because of the tendency of
the material to slump when backfill was placed against it. In unstable
ground about 7.5 to 8 feet was the maximum depth that can be installed
using the ladder excavator and shield.

During the winter the sandy upstream reach of the canal that had pre-
viously tended to slough dried out sufficiently so that a trench could be
excavated to a depth of about 8-1/2 feet with a backhoe. A roll of
plastic material was suspended on end in the trench, then unrolled to
form a vertical cutoff. After the cutoff was completed, the contractor
placed a 1-foot-thick layer of preblended lining material over the
membrane -lined trenches before constructing the remainder of the com-
pacted blended earth side lining by
conventional methods.

Details of the work are shown in Photo-
graphs 9, 10, 11, 12, and 13.

Photograph 9 is a view of the trench-
ing equipment and attached Government-
owned shield containing a 400-foot roll
of 10-mil polyvinyl chloride plastic to
be installed to a depth to 12 feet below
the toe of the left bank of the West
Canal.

Photo 9

19



Figure 18

Except for some minor sloughing when too much trench was opened up on
too steep a slope, work was completed on this reach of cutoff without inci-
dent, The contractor reported some holes or voids were encounteredinor
below the bank during excavation. When the canal was primed at the
beginning of the 1963 irrigation season there was some settlement over
the work area but this had been expected.

Typical of this settlement is that shown in Figure 18 above. The bank
will be dressed up by project forces when settlement is complete.

Total construction cost including Government-furnished plastic mem-
brane for this plastic curtain job was about $9.65 per linear foot.


NUTRIA AS A POSSIBLE PEST ON DITCHBANKS

Our attention has been called by the Commissioner's Office, Washington,
to the nutria (or coypu) as a possible pest on ditchbanks, by a copy of the
Fish and Wildlife Service Leaflet 445, discussing ''The Nutria in the United
States.'' Our specific attention was called to the fact that nutria burrows
have seriously damaged dikes, bayou banks, drainage canals and irriga-
tion ditches. With reference to a map in the Leaflet nutrias have been
reported in 14 of the 17 continental Western States.

The Commissioner has suggested that irrigation districts be advised of the
potential danger of these animals and that the Bureau of Reclamation in
turn be advised if nutria have been found. The Regional Director, Sacra-
mento, California, has subsequently reported that information obtained
from the California Department of Fish and Game indicates that nutriahave
been imported into the State by fur farmers and some have escaped. Musk-
rat trappers have taken them at widely scattered points throughout Califor-
nia in the past 10 years. However, at no location do they seem to thrive,

at least thus far. The ''clean"' type of ditch maintenance practiced, plus the
lack of vegetation which they prefer, seems to militate against their becom-
ing established. The Department of Fish and Game is alert to their potential
as pests and state law requires that they be kept in pens.

The text of the Leaflet is reproduced for general information on the following
pages.

THE NUTRIA IN THE UNITED STATES

By Richard H. Manville
Branch of Wildlife Research
Bureau of Sport Fisheries and Wildlife
United States Department of the Interior

In the last few decades a native South American mammal, the nutriaor coypu
(Myocastor coypus), has became widely established in the United States.

For a time ft was regarded as a desirable furbearer, but it soon became
evident that it might become as distinct a liability as the introduced starling
and house rat. Interest in the nutria has increased in recent years. Encour-
aged by the claims of commercial promoters, many people have investigated
possibilities of raising nutria as a profitable venture; most of them have
been disillusioned.

Natural History

The nutria is a large aquatic rodent that rarely attains a weight of 25 pounds.
Superficially it resembles a muskrat, with reddish-brown fur, a long rounded
tail, and hind feet that are partially webbed. The family is raised, and may

persist as a colony, in bank burrows or in platform nests anchored to marsh

vegetation or built up from the bottom.



VERTICAL PLASTIC CUTOFF
By
K. S. EHRMAN
Chief, Waterways Design Branch
Columbia Basin Project

Earth canals and laterals in sidehill locations often need linings for
bank safety and seepage control. If irrigation is planned above the
canal, a rising water table may create back pressures that could rup-
ture conventional canal linings. However, where a relatively imper-
vious layer of silt, clay, or rock exists within a reasonable distance
below bottom grade, a vertical cutoff wall in the lower bank may pro-
vide the required safety and seepage control, Such a condition existed
on the Columbia Basin Project constructed and presently operated by
the U.S. Bureau of Reclamation.

Approximately 5, 934 linear feet of vertical plastic membrane cutoffs
were constructed along two canals on the Columbia Basin Project in
March and April of 1963. Work on one canal consisted of installing

2, 334 linear feet of 10-mil black polyvinyl chloride sheeting 24 feet
wide in a nearly vertical trench to strengthen the canal's lower bank.
On the second canal 3, 600 linear feet of two-ply reinforced polyethylene
sheeting 12 feet wide was installed in a vertical trench along the lower
inside toe of the canal and this was topped by compacted blended earth
lining along the inside lower canal bank to reduce seepage. The work
on both canals was performed by contract under specifications pre-
pared by the Bureau. The installations were the culmination of exper-
imental work with plastic membrane cutoffs performed on the Boise
Project in Idaho in 1959 and on the Columbia Project in 1962.

Vertical plastic curtain walls of the type installed on the Boise Project
in the spring of 1959 appeared to offer a low-cost answer to the project
needs. Accordingly, in the spring of 1962, a 300-foot experimental
test reach was selectedon the Columbia Basin Project's East Low Canal
for installation of a 20-foot-wide plastic membrane. In this reach,
leaching and piping over a period of years through intermingled layers
and pockets of sand and caliche in and below the canal bank had caused
occasional breaks. A plastic membrane cutoff could sever these layers
and prevent future canal breaks.

Experimental Installation

The experimental work in 1962 was advertised, but the only bid received
was rejected as being excessive. Accordingly, the work was accom-
plished by Government forces to the specifications illustrated on Draw-
ing No. 222-116-32355, page 26. When completed the actual installation
covered only approximately 200 feet because of construction problems
encountered.

A 300-foot-long by 28-foot-wide strip of 8-mil-thick black polyethylene
membrane accordian folded was ordered for the work. Upon its arrival,
it was discovered that the supplier had substituted 6-mil-thick plastic.
Because of time limitations, however, this thinner plastic was used and

12


Figure 2

Figure 1 on the preced-
ing page is a view of the
cutoff trench. In gen-
eral, the trench was
standing in a nearly ver-
tical position, although
excavation was complete.

Figure 2 shows the method
of tying the anchor ropes to
a loop formed by a piece

of filament tape to anchor
the top edge of the plastic.
This tape works very well
on clean plastic.

Figure 3 below is a view looking downstream showing the plastic sheet
lying on the operating road preparatory to placingit in the trench. This
sheet extends approximately 118 feet and the decision was made to install
this piece of plastic before additional caving could occur.

P222-116-43981 ©

Figure 3

14


OPERATION AND MAINTENANCE
EQUIPMENT AND PROCEDURES
Release No. 46

OCTOBER, NOVEMBER AND DECEMBER 1963

INTRODUCTION

The Operation and Maintenance Equipment and Procedures release,
published quarterly, is circulated for the benefit of irrigation proj-
ect operation and maintenance people. Its principal purpose is to
serve as a medium for exchanging operation and maintenance infor-
mation. It is hoped that the labor-saving devices orless costly
equipment developed by the resourceful water users will be a step
toward commercial development of equipment for use on irrigation
projects in a continued effort to reduce costs and increase operat-
ing efficiency.

Included in this issue of the bulletin are several suggestions for
improving equipment and procedures by project operating personnel
and several ideas borrowed from GRIST reporting improvements
made by the National Park Service's operating personnel.

The possible damage that can be caused by nutria on western irri-
gation projects is called to your attention in an article beginning on
page 1. It has been suggested that the Government be informed of
the presence of these animals and of the damage that has been
reported from their activities.

Beginning on page 12 there is an article on vertical plastic mem-

brane cutoffs constructed on the Columbia Basin Project to reduce
seepage from the canals, The cutoffs were used in lieu of linings

in areas where high ground-water tables exist.

To assure proper recognition of those individuals whose sugges-
tions 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 Awards Committee when a suggestion is
adopted.

Division of Irrigation Operations

Office of Chief Engineer
Denver, Colorado



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Cover page. Backfilling against a plastic curtain cutoff provided
for the East Low Canal, Columbia Basin Project, Washington.
P222-116-45117


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NO-SLIP GRIPS FOR SCREWS

(Reprinted by permission of GRIST, November/December, 1961
issue, a publication by the National Conference on State Parks,
Washington, D.C.)

If you think the various
metal and plastic commer-
cial screw anchors are

the only answer except
cementing for holding
screws in masonry, take

a look at these sketches
and words from Straits
State Park, Michigan:

Copper Grip Sleeve

(1) Using copper tubing
of a diameter which will
assure its fitting snugly
when forced into the hole,
cut a length to correspond to the depth of the hole. (2) Make a saw
slot in the outer end to allow for expansion of the sleeve. (3) Witha
nail or similar object placed horizontally on the sleeve, hammer dents
into it which would correspond roughly to threads of the screw.

(4) Insert sleeve into hold and drive the screw, which will then anchor
firmly.

|

Foil Sleeve

Around a nail or other object of a diameter smaller than the screw,
wrap ordinary household-use foil to a thickness to fit the hole prepared
for the screw. Remove the nail and place the foil in the masonry hole.
The screw, with its tip placed in the hole in the foil, will than fit and
thread into the metal much as it would in a common lead expansion
anchor.

10


a price adjustment secured from the supplier. Essentially the proce-
dure was to blade a berm at an elevation 18 inches above water sur-
face with a dozer; then to excavate a vertical-sided trench about

25.5 feet deep and 4.5 feet wide with a 1-cubic-yard dragline. The
plastic was unfolded, suspended with ropes in the trench and the trench
backfilled with the dozer. The excavation was into damp sand which
had some tendency to slough, particularly after it dried out.

Due to a breakdown of the dragline, it was impossible to finish all 300 feet
of trench fast enough to avoid some sloughing. To minimize this danger
a 100-foot strip of the plastic was suspended from the bank of the first
excavated portion of the trench and backfilling began by pushing the mate-
rial from the canal side into the trench by dozer, Unfortunately a large
slough occurred while backfilling was in progress. The sloughing mate-
rial fell against the plastic and tore it loose from most of its anchors,
with most of the plastic sheeting falling into the bottom of the trench.
Since safety requirements prohibited entering the trench, the entire reach
was backfilled and a new trench re-excavated through it. In spite ofsome
additional sloughing, the remaining 200 feet of plastic was successfully
installed. Loose backfill was placed through the intermediate reach,
water was added to the backfill at the ends of the trench to make aslurry
to seal the ends in place. Gravel protection was then placed along the
inside slope of the canal.

Figures 1, 2, 3, 4, 5, and 6 illustrate various stages of this installation.

“116-43979

Figure 1

13