60 BULLETIN 115, U. S. DEPARTMENT OF AGRICULTURE. 



TYPES OF WASTE GATES. 



There are two general types of wastes. The first comprises those 

 acting purely as spillways, having a crest height deemed the control- 

 ling elevation of the safe high-water line of the canal. Excess water 

 reaching the waste tops the crest wall and is carried off in a natural 

 watercourse or an auxiliary ditch constructed for the purpose. If 

 the canal is located along a hillside, with no levee on the upper bank, 

 thus allowing surface storm water to come directly into the canal, 

 it is advisable to make the crest wall of such a waste gate of sufficient 

 length that a heavy increase in the water may top the waste and not 

 flow past it. The crest of the above type is sometimes made sta- 

 tionary and sometimes adjustable, being altered by flashboarcls in- 

 serted in slots. Obviously, this type of gate is not adapted to wasting 

 all of the water in the canal. The siphon principle has been success- 

 fully used to increase the discharge and decrease the crest length. 



The second type of gate has an adjustable opening extending down 

 to or below the grade line of the canal, permitting all of the water 

 to be turned out if necessary. It is quite common practice now to 

 construct such a waste gate with the tops of the shutters below the 

 crest of the side and wing walls so that when the gate is closed com- 

 pletely it still acts as a waste gate of the first type, discharging water 

 from the canal when the water level tops the crest of the shutters. 

 The radial gate is readily adaptable to this form of combination 

 gate, and sand gates operated with radial shutters usually are made 

 so that waste water can top their crests. This is easily done by 

 simply omitting the curtain wall between the piers for a sufficient 

 height to allow of a waste way over the tops of the shutters. 



WASTE GATES, YAKIMA PROJECT, "UNITED STATES RECLAMATION SERVICE, 



WASHINGTON. 



Plate XI, figure 2, shows an easily adaptable waste way for small 

 laterals or ditches subject to sudden increases of water. Where the 

 ditch crosses a natural drainage way a concrete waterway is set in 

 the levee on the lower side and the levee up and down stream for a 

 short distance is paved with rubble laid in cement. This should 

 have a level crest so that water will top it in an even sheet. Slots 

 are set near the front of the waterway so that flashboards may be 

 set and the general level of the water in the ditch adjusted by them, 

 or they may be " pulled " and all the water wasted. An increase of 

 water which would endanger the ditch or a structure below the 

 waste gate passes completely over the whole structure into the 

 drainage channel- 



