GATE STRUCTURES FOR IRRIGATION CANALS. 
17 
it was necessary to build high curtain walls above the openings in 
order to bulkhead out the surplus waters. The canal below the struc- 
ture is 20 feet wide on the bottom, carries water 6 feet deep, and has 
side slopes 1 to 1. The structure as shown contains 197 ejibic yards of 
concrete, hand-mixed in a ratio of one part cen: -rrro seven parts 
river gravel taken bank run. The unit cost of the concrete was about 
$9.50 per cubic yard. The cement cost $1.50 per barrel f . o. b. Pueblo, 
while the cost of the gravel was practically nothing but the digging 
and the hauling. Earth and shale excavation cost 40 cents per cubic 
yard for 110 yards. 
Scale in feet: 
Drafted by Fred. C Sccbet 
Fig. 1. — Headgate, Doyle Arroyo feeder, Napesta Ditch & Reservoir Co., Colorado. 
The total cost of the structure, including the steel gates, which were 
made in Pueblo, was about $2,500. The lifting device is the double 
stem, bolted together with spool spreaders, a type which is much used 
in southeastern Colorado. 
HEADWORKS, NORTH LARAMIE LAND CO. CANAL, WYOMING. 
A good example of modern construction for a headgate serving a 
small canal is that of the North Laramie Land Co. (PL V, fig. 1.) 
A simple and efficient form of temporary diversion dam raises the 
water sufficiently to secure the desired discharge into the canal. This 
canal is 14 feet wide at the water line, 8 feet wide on the bottom, and 
45613°— Bull. 115—14 3 
