CONCKETE LINING FOE IRRIGATION CANALS. 
75 
the center line of the canal have been removed from the path of the 
slides. 
In the fall of 1909 the company undertook to enlarge and concrete 
line this canal and to provide for a maximum carrying capacity of 
725 second-feet and at the same time retain the old location. This 
entailed the removal of a heavy growth of willows skirting the banks 
and a large amount of excavation. On account of the unstable 
character of the materials and the steep cross slope of the hill on 
which the canal is located the lining of so large a channel presented 
unusual difficulties. These have been met, however, and the canal 
successfully operated for the past two seasons. 
The canal was provided with drainage at various stretches along 
its length through the use of 6-inch drain tiling laid in longitudinal 
trenches 10 to 20 inches deep. At intervals of about 800 feet these 
drains were connected to cross drains of the same construction to 
convey the drainage waters to the outside of the outer canal bank. 
),-*- -22 W/de - |- 
.6, u..-4, 4 '-^ -4-.4% 
5/4 ' twisted b.\ "'■^¥"'^ L ''\v< an d S"-^^^^" , 
i?4&-6'Me ^'6" tile \ 
K- — 7'- ^ 
Fig. 9.— (a) General type of concrete lining construction used for Davis and Weber Counties Canal, Ogden, 
Utah. (ft) Type of concrete lining used for weak foundations on the same canal. 
It was at first proposed to use a 6-inch thickness of lining, but on 
the recommendation of the writer this was reduced to a 4-inch thick- 
ness for all but the worst portions. Figure 9, a, represents a cross 
section of 4-inch lining used for the greater portion of the channel. 
Where the canal bank was weak and where slides were liable to occur, 
a form as shown in figure 9, b, was adopted. In reducing the thickness 
from 6 to 4 inches a somewhat richer mixture was used and more 
precautions were taken to secure good drainage. The specifications 
for concrete called for a 1:2:4 Portland cement, sand, and gravel 
mixture, on which the contract price per cubic yard for concrete in 
place was $6.80, while for a 1 : 2\ : 5 mixture, also used, $6.45 was paid. 
On all straight portions of canal the concrete was laid in sections 20 
feet wide. That placed on the bottom was first tamped into place 
and then carefully floated and smoothed. It was afterwards covered 
with sand kept moistened for a period of seven days by sprinkling. 
A 1 : 2 mortar of cement and sand was troweled over the surfaces of 
the slide slopes soon after the concrete had been tamped in and the 
