The All-American Canal, more than 3,000 miles of freshwater canals and drains, pulls 3.1 million acre-feet of Colorado River water per year to irrigate 500,000 acres of farmland in California’s Imperial Valley. The Water Department of the Imperial Irrigation District (IID) maintains the system.
Where the open canals cross roads or bridges, the water funnels through 48- to 72-inch concrete siphons, which trap materials. The biggest debris contributor is silt runoff from the fields. The Friday night ritual of kids throwing bales of alfalfa into the canals ranks second, followed by trash tossed from passing vehicles.
Blockages were a constant challenge, and the cleaning contractors IID hired weren’t always immediately available. Slow responses could jeopardize the valley’s agricultural industry, worth $1 billion per year.
Seeking a better solution, IID in 2006 purchased a combination cleaning/vacuum truck on a 2007 International chassis from Hi-Vac Corp. The Aquatech B-10 truck has a T-56 Hibon 3,600-cfm 18-inch Hg positive-displacement blower, 80-gpm/2,000-psi water pump, 10-cubic-yard debris tank, and four 250-gallon saddle tanks for water storage. The machine enabled IID to develop an annual preventive maintenance program, overseen by Ron Jones, superintendent of heavy equipment.
Field hand
Of the water IID transports, 97 percent is used for agriculture. The canal is the valley’s sole water source. “Our responsibility is to keep the siphons clear of blockages,” says Jones. “After jetting the silt into the canal, the suspended sediment flows downstream and back to the fields.”
Water in the canals can be 20 feet deep, and currents beneath the surface are swift, strong and hazardous. The biggest challenge maintenance crews faced with any combination truck was how to take on water once it left the yard. Consequently, the B-10 was modified to draw unfiltered water from the canals, as no other source was available.
Hi-Vac fabricated and mounted a bracket to the front bumper to hold a 250-gpm trash pump. The boom, which rotates 360 degrees, lowers the pump into the channel, while workers hook up the hydraulic and water hoses. The truck’s hydraulic system powers the pump.
Previously, when hay bales, organic matter and litter blocked siphons and backed up water, crews used rods with grappling hooks to break up the dams. “It was labor-intensive, time-consuming work,” says Jones. “With the jetter, we loosen and remove the debris in minutes. It’s a big help, especially when it’s 110 degrees in the shade.” IID hired two operators, and Hi-Vac trained them.
Silt is the enemy
Some canals are cement, but 75 percent are still earthen. In some areas, canals run underground to slow evaporation. “Before the truck arrived, maintaining those subsurface pipes was difficult,” says Jones. “The B-10 has doubled or tripled our production and efficiency.” Because the hose reel is mounted high on the back of the truck, workers can swing it over the above-ground manholes and jet in any scenario. Manholes are spaced one-quarter mile apart.
The IID also has 18- to 48-inch drain lines carrying leaching salts and agricultural runoff. Flows are much lighter in these pipes, enabling sediment to collect faster. “Our No. 1 enemy everywhere is silt, and it has the consistency of peanut butter,” says Jones. “That’s one reason why we selected the big Hibon. It vacuums heavy loads continuously and consistently.” Crews typically fill the debris tank two or three times to unclog an underground pipe.
The specialized B-10 and IDD’s canal maintenance program have assured Imperial Valley farmers that their water supplies arrive as scheduled and at the proper hydraulic flow.
