56 BULLETIN 115, U. S. DEPARTMENT OF AGEICULTUEE. 



stalls between them guide the sand around into a direction at right 

 angles to the flow in the canal and discharge it out through the waste 

 gate forming an L with the check gate. One of these gates is included 

 in the joint head works spoken of on page 14. 



SAND GATE, MAXWELL LAND & IRRIGATION CO., MAXWELL, N. MEX. 



After trying out a wooden structure, the Maxwell Land & Irriga- 

 tion Co. has designed a concrete gate to eliminate the sand and coal 

 dirt from its water, TOO feet below the river headgate. At this point 

 an arroyo leads back into the river. 



The canal, which is 32 feet wide on the bottom, carrying water 

 T feet deep, with the top of the levees 3 feet above high-water mark, 

 is lined with 6 inches of concrete for a distance of 400 feet above the 

 gates. This lining (fig. IT) commences at the normal grade of the 

 canal and slopes on a grade of 1 foot per 100 feet on the side next 

 to the river and 3 inches per 100 feet on the other. This slope forms 

 a long pit having a maximum depth of 4 feet directly in front of 

 the gates, and it is expected that even a small head of water in the 

 canal will effectually sluice out all silt deposited on the concrete 

 lining. The end of the pit terminates in a vertical wall, crested with 

 a rectangular weir, which serves the double purpose of deepening 

 the pit by the height of the weir and giving an approximate measure- 

 ment of the water in the canal, after the proper bottom-contraction 

 conditions are effected by sluicing out the deposit above the weir. 



The shutters are simple wooden slides with double stems separated 

 by iron bolts and spreaders, on the principle of the one on Plate I, /. 

 An iron-mounted lever 12 feet long gives a fast and effective lift 

 when inserted under the bolts. The silt above such gates causes 

 them to stick, and some lift is necessary which will jerk the gate, 

 rather than to exert a steady pull. For this reason the lever is better 

 than a screw lift. 



Bids for the concrete construction varied from $3 to $3.60 per 

 cubic yard, the company to furnish the material at the site. Bids 

 on the excavation for the structure were 14 and 18 cents per yard. 

 This will make the total cost of the concrete in place $10.50 to $11.25 

 per yard. 



SAND AND WASTE GATE, AMITY CANAL, COLORADO. 



One of the best examples of the modern construction and use of 

 the " Land " sand gate is the concrete sand and waste gate installed 

 on the Amity Canal by the Arkansas Valley Sugar-Beet & Irrigated 

 Land Co. This structure (as shown on Plate XI, fig. 1) forms an 

 L, one leg of which extends across the canal and acts as a check 

 gate, while the other leg contains the openings of the sand ducts at 



