The Greeley Canal System serves 330 irrigation customers in summer months and 236 irrigation customers in winter months. The system has two points where it receives water and two points where unused water is spilled. This project will improve the existing Greeley Canal System facilities by replacing manually operated equipment with automated equipment.
Under the existing manually operated system, the operators set the flow rates into the canals usually based on peak demand to ensure all customers receive their allotted deliveries. Flow recorders located at the two spill locations are used to adjust flows. It takes approximately four hours for the water diverted at the upper Greely Canal to reach the lower Greely Canal. A valve between the upper and lower canals is partially closed to pressurize a portion of the canal upstream.
The amount of water diverted and sent through the Greely Canals corresponds to the pattern of spill volume. In other words, when more water is sent through the canal than is used by the customers that water is sent through the spill channel. The operators aim to achieve a spill volume that approaches zero but does not drop all the way to zero since at zero there is no way for them to determine if all customers received their delivery. As customer usage decreases during certain times of the day the spill flow increases, resulting in wasted water.
Flow variations in the Upper Greeley Canal also cause corresponding variations in the pressure in the piped downstream section of the canal. If these variations are too extreme, customers on portions of the pipe lose service. Also since deliveries to customers is based on pressure, variations in pressure result in inaccurate deliveries.
PCWA engineering and operations staff conducted a review of the flow data, which suggests a daily cycle of use and customer irrigation demands along the canal. Customer demands vary based on their needs, which include irrigation for farms and ponds etc. The proposed upgrades and equipment proposed as part of this project will install automated equipment to monitor these spill variations and make flow adjustments at the heads of the canals to minimize the peak spill flow rates. PCWA engineering staff anticipates the project will re-direct an estimated 360 acre-feet per year of water currently lost to the system and significantly reduce the amount of water that is unnecessarily spilled.
This project will install an electrically operated gate and meter combination to maintain a discharge flow-rate to the Upper Greeley Canal regardless of upstream conditions. It will be connected to the PCWA SCADA system where it will receive the target flow rate to discharge. It will automatically make adjustment to itself to achieve the desired flow. SCADA will monitor the spill flows and based on the usage patterns and travel time from beginning of canal to end, make adjustments to minimize the amount of water reaching the spills. Estimated peak spill reductions of around 2/3 are anticipated which equal approximately 360 acre-feet per year.
The automation of the valve between the Upper and Lower Greeley canals along with a pressure and flow meter at the site will enable the pressure in the pipe to be stabilized regardless of flow, preventing spilling at the spill associated with the pipe and stabilizing deliveries to the customers based on actual demand.
Current Status (December 2016)
Necessary land purchase and easement negotiations are nearly complete. Planning and design for this project is completed and ready for bidding, and construction will follow.
Lead Agency: Placer County Water Agency
Contact: Ken Powers, Engineer, 530-823-4950, KAPowers@pcwa.net
Measurable Physical Benefit: Water Supply