WSPC03161

• File Number: 8040.950
• Description: Section D General Studies-General Water Studies
• Date: 1/1/1962
• Author: RD Dirmeyer Jr
• Title: Bentonite Program-Corres Reports-Dirmeyer-1960-1961-Progress Report of Clay Sealing Investigations During 1961
• Water Supply Pro - Doc Type: Report/Study

SEEPAGE CONTROL

Much of the recent lining and sealing of
canals and reservoirs in Colorado has been accom-
plished under two Federal Programs.

The first program is that of the Bureau of
Reclamation. Virtually all of the canals and reser-
voirs constructed by the USBR in Colorado (and
elsewhere as well) have included in recent years
adequate seepage control measures. In almost all
cases, the conventional and time-tested linings of
concrete, asphalt and compacted earth have been
used. The USBR IS Lower Cost Canal Lining Pro
gram is including tests of many types of linings and
sealers, but to our knowledge no actual construction
work has been accomplished recently by the USBR
in Colorado with locally-available low-cost clays and
methods as described herein.

The second program is the Agricultural
Conservation Program of the U. S. Department of
Agriculture. This is a cost-sharing program hand-
led by the local Agricultural Stabilization Commit-
tee office in each county--with the actual construc-
tion work supervised by the Soil Conservation Ser-
vice office in each area. This program is primarily
aimed at aiding individual farmers and ranchers.
Thus, the canal and pond lining phase of this pro-
gram is mainly concerned with on-farm practices.
such as concrete slip-form ditch linings. .Recently
however, and as an important part of the field trial
phase reported herein, an increasing number of
supply canals and ponds are being sealed with
Colorado clays under the Federal Agricultural
Conservation Program or cost-sharing program.

While the above-mentioned Federal prcgrams
are most important, our general impression after
travelling in almost every irrigated area of
Colorado is that only the surface of the general canal
and reservoir seepage problem has been touched by
the current work. Very few irrigation companies
or districts in Colorado are accomplishing (or even
planning) significant amounts of canal or reservoir
lining or sealing work.

Cost, and especially financing, seems to be
one retarding factor. When considering the major
costs of a comprehensive program of the depend-
able linings, such as those of concrete or asphalt,
many and perhaps most irrigation companies and
districts find themselves in a llno-manls-land" for
financing--too small for Federal loan programs,
such as the Small Projects Act, and too large for
the sponsoring irrigation group. Irrigation distric1s
or companies apparently are not directly eligible
for Federal cost-sharing support.

One possible answer to the financing
problem is for the State of Colorado to activate a
construction loan program for water projects, such
as offered by Wyoming and Utah.

Another potential answer to the canal and
pond lining or sealing problems is to provide truly
low-cost methods of sealing irrigation canals and
reservoirs that will be within immediate financial
reach of irrigation organizations--interim methods
such as the clay sealing methods described herein
that will save water until hard-surface linings or
even pipes can perhaps be afforded.

PREVIOUS CLAY SEALING

In virtually all irrigation areas, flows of
muddy flood water usually have been considered as
unfavorable. The obvious disadvantages, such as
deposition of sand and silt in canals and on irriga-
ted land, usually have been more noticeable than
the advantages. Frequently, the advantages, such
as canal sealing, have gone unnoticed until canal
cleaning or construction of an upstream dam
revealed the advantages of muddy water. In any
case, nature has provided many excellent examples
of previous clay-sealing work.

With flows of muddy water becoming increas ~
ingly uncommon in irrigation projects, many irriga-
tion companies and districts have tried "Silting!!
as a counter-measure to the clear water problems--
some with outstanding success but many with little
or no visible results of a favorable nature.
Apparently, the best results have been obtained
where the canal bed and bank material is a coarse
sand, gravel, or fractured rock. Commonly,
detailed information regarding the application
method is available, but pertinent data on the silt-
ing material itself is seldom available.

As a related type of work, mention should
be made of the significant work now underway in
regard to chemical sealants. The USBR is doing an
excellent job of encouraging and coordinating this
work, which is mostly being done by private com-
panies. Sealants under investigation and develop-
ment include: S5-13; chevron soil sealant; and
several cationic asphalt emulsion materials. Most
of these sealants mix readily with water and the
sealing action is concentrated in the high seepage
loss zones.

SCOPE OF PRESENT INVESTIGATIONS

The present Colorado State University
project work is preceded by extensive investigations,
started in July 1953, into the sedimenting or float-in
use of Wyoming high-swell bentonite for sealing
irrigation canals. In one major respect, the pre-
sent work is an extension of this previous project
work--with locally-occurring Colorado clays being
substituted for the Wyoming high-swell bentonite.
While the Wyoming bentonite is available commer-
cially as a uniform material of essentially known
characteristics. the Colorado clays are. for the

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