36 BULLETIN 115, 17. S. DEPARTMENT OF AGRICULTURE. 
LATERAL HEADGATE, CALIFORNIA DEVELOPMENT CO., CALIFORNIA. 
The engineers of the California Development Co. have designed 
standard plans for a reinforced concrete branch canal or lateral 
headgate. These plans are based on their experience of 10 years 
with wooden structures which these are designed to replace. The 
plans (fig. 8) show a gate with a minimiun amount of concrete, 
heavily reinforced with steel to give the required strength. Un- 
usual local conditions render great economy in concrete necessary in 
this region, as it costs as high as $18 per cubic yard. For this reason 
much time was spent in making a theoretically economic design. 
The form work would be relatively expensive for this structure, and 
in adapting the plans for a region where unit cost of concrete would 
not be so great the cost of forms may be reduced by altering the 
plans slightly. For instance, the division walls, now made of re- 
inforced posts braced by similar members, could be made solid pier 
walls: the arched supports for the operating platform might be 
made slightly heavier of a reinforced rectangular-section slab; the 
counterfort walls under the front wings might slope directly from 
the upper edge to the floor, omitting the reentrant angle at the back. 
The cut-off walls of this gate are of wooden sheet piling extending 
12 feet into the bed of the canals. In adapting the plans, light con- 
crete cut-off walls may be used. The depth would be determined by 
local conditions. For a canal well lined with cobblestones, there- 
fore not in danger from erosion below the gate, a very shallow cut- 
off will suffice. A good anchorage already is secured by the weight 
of earth filling on the floor outside the walls and wings. 
The girdered floor and the counterfort supports to the side and 
wing walls are features which may be adopted to advantage in the 
design of other gates. The girders and counterforts are reinforced 
to take the tension, thus enabling the intervening slabs to be made 
much lighter than if the girders and counterforts were omitted. 
The shutters are of wood, constructed so that the main regulation 
is effected with flashboards. but a similar board is attached to the 
lower end of a stem so that the whole panel may be lifted as a single 
unit by a raek-and-pinion or other lifting device. This allows the 
water to be delivered either under or over the shutter or both. The 
plans shown are for a 3-bay gate, while the bill of material includes 
quantities for 3. 1, 5. and 7 bay structures. 
The development company delivers 30 to 150 second-feet of water 
through these gates to the branch canals or laterals of the mutual 
water companies of the Imperial Valley, who purchase water by 
wholesale from the development company. All structures below the 
headgate in the lateral are owned and operated by the mutual com- 
panies. 
