Intelligent Design Enables Conservation
Open ditch irrigation replaced by closed piped system with precise flow control
Gerald W. Knudsen, PE
General Manager, AgriTech Consulting
303-697-2123
knudsen@wispertel.net
As we progress into the 21st century, water
promises to be one of our most precious resources.
Wise management and proper conservation of this resource will become increasingly important, and innovative methods will have to be employed to save
water.
Automation coupled with intelligent design has
greatly increased manufacturing productivity worldwide while cutting waste and improving quality. A similar approach was taken in a recent project
implemented by the Montezuma Valley Irrigation
Company (MVIC, www.mvic.us) in Cortez, Colo. in
the western United States.
The MVIC is a private non-profit company that
is owned by and provides irrigation water to 1,400
shareholders who are farming and ranching 37,500
acres in Southwestern Colorado. The MVIC water distribution system provides water to the shareholders
from the Dolores River via two reservoirs, two main
canals and 17 distribution laterals. The canals and laterals cover a distance of 124 miles.
Figure 1: Open ditch irrigation canals were replaced with a closed poly pipe water distribution
system. The piping system saves water by reducing evaporation, cutting seepage and eliminating
end of channel water losses.
to also conserve one of the most precious resources
in the arid western U.S.
Our company worked with the MVIC on a study
to determine the best method to minimize water loss
in the May Lateral Canal. A decision was made to replace five miles of open ditch irrigation canals with a
poly pipe water distribution system. Projected savings
were on the order of 1,000 acre-feet of water per year.
The MVIC recognized that an opportunity existed to save substantial amounts of water by replacing the open ditch irrigation canals with a closed poly
pipe water distribution system (Figure 1). Towards that
end, they retained the services of our company,
AgriTech Consulting of Morrison, Colo.
Waste Not Want Not
As much as 60% of the water that enters an
open ditch irrigation canal is wasted via evaporation,
seepage and losses at the end of the canal. This
waste presented an opportunity for the MVIC to not
only save water and money for its shareholders, but
The pipe system has 45 branches off of the
main supply line. The main supply line High Density
Polyethylene (HDPE) pipe ranges from 12” to 36” in
diameter, and is pressurized from 30 to 50 psi as required for shareholder sprinkler irrigation systems.
The turnout pipes that serve each shareholder are
also HDPE with a transition to polyvinyl chloride.
Turnout pipe diameters range from four to eight
inches.
Each branch turnout from the main header to a
farm is supplied with an ultrasonic flow meter and two
butterfly valves. The meter measures the amount of
water passing through the turnout. The first butterfly
Figure 2: The transit
time flow meters use
two transducers
mounted on the
outside of the pipe,
both of which
function as an
ultrasonic transmitter
and receiver.
valve is controlled by the MVIC and is used to set
flows according to the number of shares of water allocated to that particular shareholder. The second butterfly valve can be used by an owner to shut off or
reduce water volume.
Each flow meter is either solar or battery powered, providing substantial savings by eliminating
power wiring. This green feature not only saved on installation, but will also provide ongoing savings in the
form of lower energy use. The key component of each
branch turnout is the flow meter, and the MVIC was
exacting in its requirements.
Reliable Flow Measurement
On older parts of the system, the MVIC is using
impeller flow meters that require annual maintenance
and are subject to plugging with sticks, moss and
other loose material in the irrigation water. To reduce
maintenance and eliminate plugging problems, a decision was made to use a non-intrusive flow meter.
“After extensive review of many types of meters
from various manufacturers, a decision was made to
purchase ultrasonic flow meters from Dynasonics,”
says Jim Siscoe general manager of the MVIC.
Dynasonics is a division of Racine Federated
(www.racinefed.com), and a number of factors
entered into the decision to purchase their Model
TFXL meters.
The transit time flow meters use two transducers mounted on the outside of the pipe, both of which
function as an ultrasonic transmitter and receiver (Figure 2). The flow meters operate by alternately transmitting and receiving a frequency modulated burst of
sound energy between the two transducers.
These particular meters were found to have the
lowest installed cost, especially for larger pipe sizes.
Because one meter could be used for many pipe
sizes, design was simplified and the MVIC was able
to minimize stocking requirements.
Prior flow measurement was made via Parshall
Flumes or weir boxes with 5% to 20% accuracy, while
the new meters provide an accuracy of 1%. Relatively
high accuracy is important because tight control of
flow guarantees sufficient yet not excessive water delivery to each shareholder.
Smaller turnouts aren’t solar powered or
provided with continuous power by any other means.
The MVIC ditch riders instead power the flow meter
with a portable 12-volt battery. “While the flow meter is
under battery power, the measured flow rate is used
to manually adjust flow via the butterfly valve immediately downstream from the meter, according to that
shareholder’s allowed rate. Most of these smaller
turnouts require only one setting per season, although
some turnouts are adjusted during the season based
on our company rules and weather conditions,” explains Siscoe.
Advantages of a
Closed Pipe System
• Reduces evaporation
• Cuts seepage
• Eliminates end of channel water losses
• Enables more precise flow measurement
• Allows installation of automated control valves
• Enables automation of entire system
Larger turnouts and main distribution lines are
being equipped with solar powered flow meters, allowing the MVIC staff and shareholders to read continuous or totalized flow at any time. Long-term goals
are to fully automate the system by installing wireless
flow meters and an automatic control valve downstream of the meter. See the Sidebar for more details
on this wireless system.
Flow Control Yields Savings
Water projects like this one are finding their way
to the top of state and federal project lists because
they fit two categories for stimulus funding, namely
Conservation and Public Works. Another reason for
prioritizing these projects is savings in annual operating costs.
Final project costs were $2.9 million. Annual
savings are projected to be $2 million, calculated from
using 1,000 acre feet less of water each year at an
average price of $2,000/acre foot. These numbers
would yield a payback period of about 18 months for
the project, but the company is also realizing immediate savings with creative financing.
The project was funded with a low-interest loan
from the Colorado Water Conservation Board, a grant
from the Colorado River Salinity Forum and company
resources. By using innovative financial management
and by self performing the work, the MVIC has been
able to provide the improvements with no costs to the
shareholders.
Operating experience over the past two years
has been excellent. “Our shareholders were skeptical
at first, but we’re now realizing the full potential of the
system. We especially like the non-intrusive aspect of
the flow meters which results in no maintenance, low
cost, flexibility and ease of installation. The Dynasonics flow meters are now our standard for both new
and retrofit applications, particularly replacement of
our impeller flow meters,” relates Siscoe. For calibration purposes, the MVIC purchased a Dynasonics
portable ultrasonic flow meter for both the new Dynasonics meters as well as older existing flow meters.
Based on positive operating experience, the
MVIC is converting troublesome sections of other
open canals to pipelines. Two miles of pipeline have
been installed this fall and others are in the planning
stage. “We plan to install flow meters on all the main
pipelines, and hope to eventually connect the flow
meters into a wireless supervisory control and data
acquisition (SCADA) system,” notes Siscoe.
Racine Federated, Power Controls and
AgriTech Consulting are developing a standard solar
power package that will lower cost and simplify future
installations. Using this standard solar power package, the MVIC is encouraging its shareholders to
retrofit all of the turnouts with solar power to provide
continuous flow as well as totalizer readings. The
USDA Natural Resources Conservation Service has
approved these meters for their on-farm irrigation improvement projects, easing the way for future stimulus
funds and grant approvals.
The closed pipe network project has been so
successful that the US Bureau of Reclamation is providing $2.1 million in stimulus grants to the MVIC for
construction of a second similar 7-mile pipeline project. “Positive operating experience, ongoing savings,
and government approvals and grants show us that
we made the right decision to proceed with this project – and also encourage us to continue expansion
and improvements,” concludes Siscoe.
Wireless at work
The Montezuma Valley Irrigation Company (MVIC)
nd AgriTech Consulting have received a $75,000 Con-
a
servation Innovation Grant (CIG) from the USDA Natural
Resources Conservation Service to automate portions of
the newly installed closed pipe irrigation network. Scope
items for the CIG grant include a solar-powered gate to
control water level in the feeder canal, and a wireless
flow control and measurement system.
The solar-powered gate has been installed and is
operating successfully for the second irrigation season.
Solar power eliminated the need to spend $25,000 for
an electrical service line to this remote location. The
gate automatically compensates for increased flow in the
canal and creates a constant head pressure for a lateral
pipeline inlet. Estimated savings are 1,000 acre-feet of
water per year. Based on the success of the first gate,
the MVIC has ordered an additional solar-powered flow
control gate that will be installed in another canal next
winter.
Figure 3: Flow control and measurement is
implemented via a wireless supervisory control
and data acquisition (SCADA) system. The SCADA
system consists of a telemetry receiver and master
control center in the main office connected to field
equipment via a wireless data link.
Flow control and measurement at two turnouts will
be implemented via a wireless supervisory control and
data acquisition (SCADA) system. This portion of the
project will demonstrate flow control and measurement
at a remote location where flow needs to be changed
frequently throughout the irrigation season.
The SCADA system consists of a telemetry receiver and master control center in the main MVIC office
connected to the two turnouts via a wireless data link.
Each turnout has a telemetry transmitter connected to a
flow meter, along with a modulating control valve that
can be adjusted from the office with the SCADA system
(Figure 3). All of the equipment at each turnout is solarpowered.
The meter reads the water flow rate and wirelessly
transmits this data to the master control center. Based
on the flow reading, a wireless signal is sent to the valve
to control water flow. Wireless automation at these two
turnouts will demonstrate to the MVIC and its shareholders the benefit of remote flow measurement and control.
The telemetry and computer equipment with associated
software has been ordered and installed at the master
control center.
All of the turnouts on the newly installed closed
pipe network have ultrasonic flow meters fitted with electronics capable of transmitting flow measurement data to
the master control center at the MVIC office. The equipment installed to date has been extremely well received
by the shareholders and has laid the groundwork for further automation of the MVIC system. This SCADA system itself is expandable and will provide a framework for
automation of other parts of the MVIC system.
Wireless supervisory control and data acquisition
(SCADA) systems are ideal for this and many other
measurement and control applications distributed over a
large geographical area. Possible future applications include mandated metering due to water compacts and
court decrees, data collection from remote locations, and
metering of irrigation equipment such as center pivots,
side rolls and gated pipes.
Dynasonics manufactures a complete line of ultrasonic flow measurement equipment, including portable, fixed position and multi-channel transit time
and Doppler flow meters. These meters are ideal for full pipe, liquid flow applications; they are non-invasive and provide a high degree of accuracy
(better than +/- 1% in many cases). Suited for a wide range of pipe materials, in pipe diameters from 1/4” (6.35 mm) to over 120” (3,048 mm), these
meters are designed for long service life and low maintenance cost. Additional Dynasonics products include insertion magnetic and heat flow meters.
Racine Federated Inc. 8635 Washington Ave. Racine, WI 53406-3738 USA
email to: info@racinefed.com Tel 262-639-6770 Fax 262-639-2267
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