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Advanced Delivery System Saving Water and Money |
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Sunday, 25 April 2010 |
The days of daily ditch riding are over in one section of Montezuma Valley Irrigation Company's (MVIC) water delivery network. Below the rugged pinon and juniper-clad hills surrounding Cortez, Colorado, a new pipeline and automated water control and delivery system has eliminated the need for daily ditch checking along a five mile stretch of line called the May Lateral.
Headquartered in southwestern Colorado in the city of Cortez, MVIC serves 1,400 customers spread over an area of 37,500 square miles. In the past, irrigation water has been moved exclusively via miles of open canals and ditches. For decades, daily checking of lateral ditches and turnouts has been the norm. But all that is changing with the advent of MVIC's new underground pipeline and improved water delivery system.
Conserving precious water was the original impetus for the project. In the arid region around Cortez, annual precipitation amounts to only 13 inches - a fraction of the water needed for the alfalfa, grass pasture and other crops produced in the Montezuma Valley. The remaining water required by the crops is supplied by mountain runoff stored in three area reservoirs; the Groundhog, Narraguinnep and McPhee, and delivered to farms via MVIC's network of canals and smaller lateral ditches.
Unlined earthen channels can lose more than half of the water passing through them via seepage, evaporation and losses at the end of the channel. MVIC saw an opportunity to save money by eliminating water losses from unlined ditches. The May Lateral line was chosen due to its existing need for maintenance.  The new water delivery system project began with the installation of a solar-powered water level control gate on one of MVIC's main feeder canals in 2008. The new gate, which replaced a crude rock structure, controls water delivery to the May lateral. The gate automatically compensates for increased flow in the canal and creates a constant head pressure for the May Lateral pipeline inlet. By using solar power to control the gate, MVIC saved $25,000 that would have been spent running electrical service line to the gate's remote location.
Next, work began on the May Lateral; with the conversion of five miles of open, unlined ditch into impermeable, underground pipeline. The pipeline is made of High Density Polyethylene (HDPE) ranging from 36" to 12" in diameter, and buried at least two and half feet deep. The elevational decline of the pipeline creates sufficient hydraulic head pressure to supply shareholder sprinkler irrigation systems, saving each producer thousands of dollars in equipment and electricity.
Each of the 45 turnouts branching from the former ditch were converted
from existing weir or flume water measurement devices to an HDPE "Tee"
transitioning to polyvinyl chloride (PVC) pipe equipped with butterfly
control valves. The diameter of pipe used at the turnouts varied
depending on the amount of water required to be delivered. All of the
turnouts were fitted with ultrasonic flow meters. The new ultrasonic
flow meters are 99% accurate, which significantly improved flow
measurement accuracy.
The ultrasonic flow meter transducers
mount as paired units on the outside of the pipe, which eliminates
impellor plugging and minimizes maintenance. A flow meter unit is
comprised of two identical transducers and the meter. Flow is measured
by alternately transmitting and receiving bursts of sound energy
between the two transducers. The meter analyzes the signals and
calculates flow velocity and volume based on the pipe size. The
external mounting feature enables MVIC to use one model of flow meter
to measure flow in pipes of different sizes.
 Several
types of flow meters were considered by MVIC, but Dynasonics Series
TFXL and TFX Ultra transit time meter units were ultimately selected as
having the best combination of desired features, including:
□ Accurate measurement (99%) even in water with moderate amounts of suspended solids.
□ Lowest installed cost.
□ External mounting, which eliminates impellor plugging and minimizes maintenance.
□
Power source alternatives; the control units can be powered by 12 to 30
volt batteries which can be recharged with solar panels or AC power.
□ Flexibility; one meter can be used for different pipe sizes, simplifying maintenance requirements and reducing costs.
Solar panels were installed to power a portion of the flow meters and
butterfly valves. Using solar power eliminated costs associated with
running ground-based electrical wire to the isolated turnout locations,
and it was better for the environment.
The flow meters and
valves are programmable and can wirelessly communicate their status
using radio telemetry to a receiver and master control center at the
MVIC office. In addition to the convenience and cost-savings, the
two-way wireless communication system is expandable and provides a
framework for automation of other parts of the MVIC system.
The
software that manages the new system has an integrated geographic
information system (GIS) component which displays the new automated
system as a map on the control computer monitor. "Combining our new
radio telemetry-control system with GIS has created a powerful
management tool that allows us to keep tabs on this section of our
water delivery system in real time" says Jim Siscoe, Executive Director
at MVIC. At any moment of the day, Siscoe and his staff can view the
control system monitor and determine the flow rate in the main pipeline
and at the larger turnouts. They can also open and close valves to
adjust flow at two demonstration turnouts - all without leaving the
office. "It is truly a quantum leap forward" says Siscoe. "Our hearty
forbearers who built the original ditch system would be amazed at how
far technology has taken water delivery."
 The
smaller diameter turnouts are not equipped with continuous power
sources currently, as their flow rates are not changed frequently
during the irrigation season and the additional cost of full-time
electronic flow measurement and control could not be justified.
Instead, MVIC staff periodically check flow rates in the smaller
turnouts by attaching a portable 12-volt battery to the permanently
installed flow meters.
Installing the solar powered, automated
control system has saved MVIC staff time and equipment - which
translates into lower operating costs. But the largest potential cost
savings has come through water conservation. Since the pipeline
essentially eliminated water losses, Mr. Siscoe estimates that MVIC
saved 1,200 acre-feet last year. At $2,000 per acre foot downstream
value, the savings was equivalent to $2.4 million dollars.
The total cost of the project was $2.9 million. Thus, the new system
would normally pay for itself in less than a year and a half. But for
MVIC, the system has already returned its investment, thanks to partial
project funding from the Colorado Water Conservation Board (CWCB) a
Conservation Innovation Grant (CIG) from the USDA-Natural Resources
Conservation Service and a grant from the Colorado River salinity
program.
 The system was designed by AgriTech
Consulting, an engineering company based in Morrison, Colorado. "This
project brings together a variety of technologies - radio telemetry,
ultrasonic flow measurement, solar power generation, and hardware and
software control systems, even installation-friendly HDPE pipe - to
create one integrated system that has reduced MVICs' costs and
increased its efficiency," says AgriTech Consulting General Manager
Gerald Knudsen, P.E.
Based on the success of the first flow
control gate installed on the feeder canal, MVIC is installing another
solar-powered flow control gate this winter to measure and regulate
flow. And, due to the success of the overall project, the U.S. Bureau
of Reclamation is providing a $2.1 million ARRA grant to MVIC to
construct a similar pipeline project in another area of the water
delivery network.
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